[ { "id": "authors:rq9yy-0yq96", "collection": "authors", "collection_id": "rq9yy-0yq96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200219-092723280", "type": "conference_item", "title": "DNA-mediated charge transport: From metal complexes to metalloproteins", "author": [ { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Double helical DNA can serve as a conduit for efficient charge transport (CT) over long mol. distances. Expts. to probe this chem. began more than twenty years ago by examg. electron transfer between simple metal complexes bound to DNA. Over the past several years, [4Fe4S] clusters have been found in DNA-binding proteins involved in genome maintenance and we have turned to asking whether the metal cofactors might utilize this long range CT chem. within the cell. The [4Fe4S] clusters, common redox cofactors, are assocd. not only with DNA repair proteins but also with DNA polymerases, indeed a host of proteins involved in DNA processing. Studies are described to characterize DNA-mediated charge transport by these DNA-binding metalloproteins. Expts. indicate that DNA CT chem. may provide a first step in how DNA repair proteins may localize in the vicinity of lesions. Moreover, DNA-mediated signaling among [4Fe4S] clusters may serve to coordinate the proteins involved in replication. This redox chem. mediated by the DNA helix provides a route for long range signaling among DNA-processing proteins contg. metallo-cofactors across the genome.", "publisher": "Caltech Library", "publication_date": "2020-03" }, { "id": "authors:twem4-x1m60", "collection": "authors", "collection_id": "twem4-x1m60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190812-140452621", "type": "conference_item", "title": "Assessing and improving specificity of rhodium metalloinstertors in targeting MMR deficient cancer", "author": [ { "family_name": "Threatt", "given_name": "Stephanie", "clpid": "Threatt-S-D" }, { "family_name": "Synold", "given_name": "Timothy W.", "clpid": "Synold-T-W" }, { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Mismatch repair (MMR) deficiencies are a hallmark for 16% of all solid tumors and 80% of hereditary nonpolyposis colon cancers, and many patients with these types of malignancies are resistant to current oncol. treatments. Our lab. has conducted much work to develop mols. able to target the mismatches that result from MMR deficient cancers selectively. By incorporating particularly wide, arom., ancillary ligands, our Rh complexes are able to detect thermodynamically destabilized mismatch sites via a binding mode known as metalloinsertion, in which the inserting ligand binds DNA via the minor groove and results in ejection of the destabilized mismatched base pairs. We hypothesize that the complex binding site is later recognized as a lesion by the DNA repair machinery, which ultimately induces cytotoxicity. Our lab. evaluates different metalloinsertor complexes by comparing their biol. effects on mismatch repair proficient and deficient human colorectal cancer cell lines (HCT116). Currently, our most promising Rh complex [Rh(phen)(chrysi)( 2-(Pyridine-2-yl)propan-2-ol)]^(2+) (Rh-PPO) involves a unique rhodium-oxygen bond coordination with a puckered 5,6-chrysenequinone diimine inserting ligand. The complex displays submicromolar potency and can significantly differentiate the biol. activity between MMR -proficient and -deficient cell lines. Research in the lab has focused on further assessing Rh-PPO's promise as a chemotherapeutic by conducting in vivo pharmacokinetic and efficacy studies within mice. These animal studies have given insight into the best tolerated dose levels and administration routes, the impact of Rh-PPO treatment on mouse survival, and the chem. stability of Rh-PPO in vivo. These efforts have further validated the potential use of Rh-PPO as a targeted therapeutic for MMR deficient cancers.", "publisher": "Caltech Library", "publication_date": "2019-08" }, { "id": "authors:1xp14-a5g98", "collection": "authors", "collection_id": "1xp14-a5g98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170912-130142244", "type": "conference_item", "title": "Synthesis, characterization, and biological activity of DNA mismatch-targeting rhodium complexes", "author": [ { "family_name": "Boyle", "given_name": "Kelsey M.", "orcid": "0000-0002-6728-8403", "clpid": "Boyle-Kelsey-M" }, { "family_name": "Barton", "given_name": "Jacqueline", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "DNA base pair mismatches are a promising target for chemotherapeutic design due to their relative abundance\nin cancers with mismatch repair (MMR) deficiencies. Rhodium metalloinsertors are a family of metal complexes that can target these mismatches with high selectivity in vitro and in cell culture. Mismatch targeting is directed by an expansive inserting ligand, 5,6-chrysiquinone diimine (chrysi), which is able to displace a thermodynamically destabilized mispair and replace it within the DNA \u03c0-stack. Recent studies have led to the development of unique metalloinsertors contg. rhodium-oxygen coordination of an ancillary ligand. This new ligand framework has been assocd. with nanomolar potency and improved selective cytotoxicity towards MMR deficient cells over MMR proficient cells. To gain addnl. insight into the surprising behavior of these complexes, this family has been further expanded through alteration of the remaining ancillary ligand, which has been varied in steric bulk and lipophilicity. This newest family of rhodium metalloinsertors has been synthesized and characterized, and the biol. activity of these complexes, including cytotoxicity and subcellular localization, has been measured. Unlike earlier generations of metalloinsertors, even the most lipophilic complexes in this family do not exhibit excessive off-target mitochondrial localization, allowing them to maintain high selective cytotoxicity towards MMR deficient cells and reduced off-target cytotoxicity in MMR proficient cells. Overall, the biol. activity of metalloinsertors contg. this Rh-O ligand coordination appears to be highly robust regardless of substitution of the ancillary ligands. This ligand framework could serve as an excellent scaffold for future conjugation to cytotoxic or fluorescent payloads for therapeutic or diagnostic use.", "publisher": "Caltech Library", "publication_date": "2017-08" }, { "id": "authors:2ep9g-m4r87", "collection": "authors", "collection_id": "2ep9g-m4r87", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170912-101414660", "type": "conference_item", "title": "DNA damage recognition mediated by repair proteins carrying [4Fe4S] clusters and understanding proton-coupled\n electron transfer processes using a lipid-modified electrochemical platform", "author": [ { "family_name": "Tse", "given_name": "Edmund C. M.", "orcid": "0000-0002-9313-1290", "clpid": "Tse-Edmund-C-M" }, { "family_name": "Gewirth", "given_name": "Andrew", "orcid": "0000-0003-4400-9907", "clpid": "Gewirth-A-A" }, { "family_name": "Rauchfuss", "given_name": "Thomas", "clpid": "Rauchfuss-T-B" }, { "family_name": "Barton", "given_name": "Jacqueline", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "In my postdoctoral work (Caltech), I unraveled the mechanism by which a collection of DNA-processing\nproteins contg. redox-active [4Fe4S] metallocofactors detects DNA lesions and upholds genome integrity in a\ntimely and synchronized fashion. DNA damage, as arise with defective repair, lead to cancer. I utilized\nelectrochem., AFM, EPR, UV-Vis, CD, EMSA gel assay, and in vivo growth and rescue assay to understand the\nsignaling and damage detection processes facilitated by [4Fe4S] enzymes with low cellular copy nos. Exptl.\nand biophys. modeling results validate a DNA damage search mechanism enabled by redox-active [4Fe4S] cluster proteins via long-range DNA-mediated charge transfer that explains the fast lesion detection kinetics obsd. in living organisms. My PhD work (UIUC) includes facilitating and controlling the oxygen redn. reaction by using bio-inspired catalysts and so-called hybrid bilayer membranes (HBMs), which are self-assembled monolayers covered by a lipid layer. The latter work explores how HBMs supported on electrodes can be used to independently control the thermodn. and kinetics of both proton and electron transfer processes in proton-coupled electron transfer reactions and thereby modulate the turover frequency and selectivity of catalysts. Over the course of my academic training and research career, I have published 13 papers (with 6 addnl.\nmanuscripts in prepn.). My interests are broad, but center around self-assembly, electrocatalysis, synthesis, and\nprotein and reaction dynamics. I have always enjoyed opportunities to conduct research that crosses\ntraditional fields of study. My postdoctoral fellowship will end in July 2018 and I am eager and ready to start my\nindependent academic career. Building upon a strong foundation in inorg., anal., and biol. chem., I will devise\nnew methodologies to understand reaction landscape in a complex environment and develop org.-inorg. hybrid\nplatforms to promote efficient catalysis relevant to alternative energy conversion scheme.", "publisher": "Caltech Library", "publication_date": "2017-08" }, { "id": "authors:5spae-9nn03", "collection": "authors", "collection_id": "5spae-9nn03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170912-100733809", "type": "conference_item", "title": "Rhodium-cyanine fluorescent probes for detection and signaling of mismatches in DNA", "author": [ { "family_name": "Nano", "given_name": "Adela", "orcid": "0000-0002-1984-5770", "clpid": "Nano-Adela" }, { "family_name": "Barton", "given_name": "Jacqueline", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Mismatched (non-Watson-Crick) base pair damage in DNA occurs naturally from errors during the replication process.\nDeficiencies in the mismatch repair (MMR) machinery, a DNA repair pathway, strongly predispose cells to cancer development. Therefore, efficiently detecting DNA mismatches will greatly enable early detection of MMR-deficient precancerous cells. Herein, we report the synthesis and characterization of a bifunctional fluorescent probe that combines a rhodium\nmetalloinsertor with indol trimethine cyanine, Cy(3), the luminescent reporter, via a PEG-type linker. The conjugate displays low luminescence when free in soln. or in the presence of well-matched DNA but exhibits a luminescence increase up to 9-fold in the presence of a 27-mer oligonucleotide contg. a central CC mismatch. DNA photocleavage expts. demonstrate that upon\nphotoactivation, the conjugate can cleave the DNA backbone near the mismatch site on a 27-mer oligonucleotide, thus providing further evidence for mismatch targeting. Fluorescence titrns. of the Rh conjugate with genomic DNA (gDNA) extd. from MMR-deficient and MMR-proficient HCT116 cell lines show a luminescence differential between gDNA from MMR-deficient and - proficient cell lines, reflecting the sensitive detection of differences in mismatch frequency.", "publisher": "Caltech Library", "publication_date": "2017-08" }, { "id": "authors:krmkd-1ep70", "collection": "authors", "collection_id": "krmkd-1ep70", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170913-103008005", "type": "conference_item", "title": "Sensors using DNA charge transport", "author": [ { "family_name": "Barton", "given_name": "Jacqueline", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Many expts. have now shown that double helical DNA can serve as a conduit for efficient charge transport over long mol. distances. This chem. is exquisitely sensitive to perturbations in the DNA base stack, such as arise with base mismatches, lesions, and protein binding. We describe how this chem. may be applied in constructing DNA-based electrochem. sensors for DNA-binding proteins and lesions. For example, using a two electrode multiplexed platform, human DNMT1 methyltransferase activity is easily detected from crude cell lysates. The effect of magnetic fields on DNA charge transport chem. has also been explored. These results point to sensitive mechanisms to consider in sensing magnetic fields.", "publisher": "Caltech Library", "publication_date": "2017-08" }, { "id": "authors:5a5q7-2y234", "collection": "authors", "collection_id": "5a5q7-2y234", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170913-104137841", "type": "conference_item", "title": "DNA-mediated signaling among proteins with [4Fe4S] clusters", "author": [ { "family_name": "Barton", "given_name": "Jacqueline", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Double helical DNA can serve as a conduit for efficient redox chem. over long mol. distances. We have now been exploring how this chem. may be used within the cell for long range signaling. Increasingly, [4Fe4S] clusters are being found in DNA-binding proteins involved in genome maintenance. These [4Fe4S] clusters, common redox cofactors, are assocd. not only with repair proteins but also DNA polymerases and primase. Studies are described to characterize DNA-mediated charge transport by these metalloproteins. Expts. indicate that this chem. is important in the context of oxidative damage and may provide a first step in how DNA repair proteins may localize in the vicinity of lesions. Moreover, DNA-mediated signaling among clusters may serve to coordinate the proteins involved in replication. This redox chem. at a distance, mediated by the DNA helix, thus offers a route for long range signaling among DNA-processing proteins across the genome.", "publisher": "Caltech Library", "publication_date": "2017-08" }, { "id": "authors:ry7xk-2mm42", "collection": "authors", "collection_id": "ry7xk-2mm42", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170912-101702393", "type": "conference_item", "title": "DNA-processing repair proteins containing redox-active [4Fe4S] metallocofactors facilitate DNA lesion detection", "author": [ { "family_name": "Tse", "given_name": "Edmund C. M.", "orcid": "0000-0002-9313-1290", "clpid": "Tse-Edmund-C-M" }, { "family_name": "Barton", "given_name": "Jacqueline", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "DNA stores vital genetic information from which the foundation of life is built upon. Oxidative stress poses a\nrecurrent threat to genome integrity and a continual risk of cancer development. The ability for charge to be\ntransferred through DNA has implications in its structural maintenance assisted by repair proteins carrying\nredox-active [4Fe4S] clusters. In this presentation, I will present our work on establishing the importance of\nthe redox state of the [4Fe4S] inorg. cofactor in the DNA damage detection process. Specifically, [4Fe4S]\nclusters primarily in the oxidized state abolish the ability of repair proteins to differentiate between well-matched and damaged DNA strands. Conversely, [4Fe4S] metallocofactors primarily in the reduced state\nenable repair proteins to redistribute onto DNA duplexes contg. a C:A mismatch. We further devised a biophys. model that focuses on the electrostatic interactions between [4Fe4S] cluster proteins and DNA to explain the exptl. obsd. change in DNA binding affinity upon switching the oxidn. state of the [4Fe4S] cluster proteins. I will also present our new findings on how far and how fast electrons travel across DNA duplexes. Techniques: (i) DNA-modified electrode, (ii) at.-force-microscopy-based redistribution assay, (iii) gel-based electrophoretic mobility shift assay, (iv) biophys. electrostatic differential binding model, (v) ESR, (vi) UV-visible spectroscopy, (vii) electrochem., (viii) CD. Significance: Repair proteins carrying [4Fe4S] clusters modulate their binding strength to DNA by switching the redox state of the [4Fe4S] inorg. cofactors to regulate the ability of the repair proteins to search for DNA damage via DNA-mediated charge transfer in response to cellular oxidative stress. Figure Captions: (A) Biophys. electrostatic model, (B) DNA-modified electrode to\ngenerate primarily reduced or oxidized proteins carrying [4Fe4S] clusters, and (C) DNA damage search mechanism enabled by DNA-mediated electron transport.", "publisher": "Caltech Library", "publication_date": "2017-08" }, { "id": "authors:p9tdm-9dn09", "collection": "authors", "collection_id": "p9tdm-9dn09", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170911-143259871", "type": "conference_item", "title": "Functional role for the [4Fe4S] cluster in human DNA primase as a redox switch using DNA charge transport", "author": [ { "family_name": "O'Brien", "given_name": "Elizabeth", "clpid": "O'Brien-Elizabeth" }, { "family_name": "Holt", "given_name": "Marilyn", "orcid": "0000-0002-3164-869X", "clpid": "Holt-M-E" }, { "family_name": "Thompson", "given_name": "Matthew K.", "clpid": "Thompson-M-K" }, { "family_name": "Salay", "given_name": "Lauren E.", "clpid": "Salay-L-E" }, { "family_name": "Ehlinger", "given_name": "Aaron C.", "clpid": "Ehlinger-A-C" }, { "family_name": "Chazin", "given_name": "Walter J.", "orcid": "0000-0002-2180-0790", "clpid": "Chazin-W-J" }, { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "DNA-mediated charge transport (DNA CT) provides an avenue for long-range, rapid signaling between redox-active moieties coupled into duplex DNA. Several DNA-processing enzymes have moreover been shown to contain [4Fe4S] clusters, common redox cofactors. Eukaryotic DNA primase, the heterodimeric enzyme responsible for initiating DNA replication, contains a [4Fe4S] cluster in the C-terminal domain of the large subunit (p58C). Primase synthesizes a short RNA primer on a single-stranded DNA template and subsequently hands this template off to DNA polymerase \u03b1, another [4Fe4S] protein, through a mechanism which is unclear. Here we show electrochem. evidence that the [4Fe4S] cluster in the p58C domain of human DNA primase\nperforms redox chem. on DNA, cycling reversibly between a tightly DNA-bound, oxidized [4Fe4S]^(3+) state, and\na loosely assocd., reduced [4Fe4S]^(2+) state. We demonstrate through structural, biochem., and electrochem.\ncomparisons of wild type and mutant p58C that the redox switch is mediated by a pathway of tyrosine residues between the cluster and bound DNA. Charge transfer pathway mutations in full-length primase, addnl., abrogate initiation of primer synthesis on single-stranded DNA but do not affect nucleotide polymn. We further compare primer elongation on a well-matched and mismatched DNA template, showing that a single-base mismatch in the nascent primer inhibits primase termination. Thus primer termination appears to be gated by mismatch-sensitive DNA charge transport. Based on our exptl. evidence, we propose a model in which electron transfer between [4Fe4S] clusters, gated by DNA-mediated charge transport, regulates DNA\nbinding and substrate handoff between primase and polymerase \u03b1 to begin replication.", "publisher": "Caltech Library", "publication_date": "2017-08" }, { "id": "authors:ztrsc-zah34", "collection": "authors", "collection_id": "ztrsc-zah34", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170503-144923412", "type": "conference_item", "title": "Identifying cancer-relevant DNA damage via a charge transfer mechanism involving [4Fe4S] cluster proteins", "author": [ { "family_name": "Tse", "given_name": "Edmund C. M.", "orcid": "0000-0002-9313-1290", "clpid": "Tse-Edmund-C-M" }, { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "The goal of this project is to develop new in vitro and in vivo techniques to understand the mechanism by which teams of FeS cluster repair proteins detects DNA defects and upholds genome integrity. DNA defects, as arise with defective repair, lead to tumorous cell proliferation and cancerous disease development. My research objective aims at understanding the signaling and repair processes of damaged DNAs by a collection of [4Fe4S] proteins with the use of long range DNA mediated electron transfer. (A) Electrochem. using DNA modified multiplex electrode chip with 16 independently addressable gold working electrodes, ESR, and UV Vis spectroscopy to characterize proteins in various redox state. (B) Binding redistribution assay utilizing at. force microscopy specifically tailored to visualize the position of [4Fe4S] proteins on DNA and provide robust biophys. data at physiol. conditions. The redox properties and long range CT ability of DNA bound [4Fe4S] proteins is established. In particular, the oxidn. state of [4Fe4S] clusters modulates DNA binding and in turn controls protein activity. These initial studies support the mechanism that at least two proteins work in concert to\nscreen one DNA. For DNA with no mismatch or lesion, a cluster in the reduced state binds to one end of a DNA and reduces an oxidized cluster at the other end of the DNA. In the event of a base pair mismatch or lesion, electronic communication between two DNA bound clusters is disrupted. A signaling disruption increases the retention time of [4Fe4S] proteins on a defective DNA. Using a processive mechanism, these damage localized DNA binding proteins of similar redox potential work together to trace and repair the damage. This work not only delineates a distinct role for these redox active proteins in sensing and repairing DNA damage for cancer treatment, but also establishes DNA signaling as a new mechanistic framework for protein communication across the genome.", "publisher": "Caltech Library", "publication_date": "2017-04" }, { "id": "authors:rrq6b-a9n83", "collection": "authors", "collection_id": "rrq6b-a9n83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160913-160418397", "type": "conference_item", "title": "Rhodium-conjugate fluorescent probes for diagnostic of mismatched DNA", "author": [ { "family_name": "Nano", "given_name": "Adela", "orcid": "0000-0002-1984-5770", "clpid": "Nano-Adela" }, { "family_name": "Barton", "given_name": "Jacqueline", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "In healthy cells, DNA base pair mismatches, as well as some other base pair anomalies derived from DNA base damage,\nare cor. through the mismatch repair (MMR) machinery. If left unrepaired, mismatches cause mutations, some of which\npromote cancerous transformations. Currently, there is a lack of effective mol. sensors for early cancer diagnosis.\nTherefore, developing mol. probes capable of detecting and signaling DNA base mismatches directly would be a\npowerful tool to this end. Previous studies have shown that rhodium metalloinsertors bind mismatches in double-strained\nDNA with high specificity. Nevertheless, these rhodium complexes show poor luminescence properties. Here we\ndescribe the design and study of rhodium conjugates tethered to environmentally sensitive fluorophore scaffolds. The\nfluorophore of choice is a cyanine dye where fluorescence emission strongly depends on its cis-/transphotoisomerization\nthrough excitation under appropriate wavelengths; photoisomerization, however, appears to be\ninhibited for DNA-binding by cyanine, leading to a signal-on emission. In our luminescent switches, the cyanine was\ncovalently attached to a rhodium(III) metalloinsertor complex through a linear spacer i.e. polyamine or polyethylene glycol\nchain. The spectroscopic measurements in the presence of well matched and mismatched DNA support the notion that\nour systems are interesting probes for mismatch detection and signaling.", "publisher": "Caltech Library", "publication_date": "2016-08" }, { "id": "authors:61avw-nmh81", "collection": "authors", "collection_id": "61avw-nmh81", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160406-095957303", "type": "conference_item", "title": "DNA-mediated signaling", "author": [ { "family_name": "Barton", "given_name": "Jacqueline", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Many expts. have now shown that double helical DNA can serve as a conduit for efficient charge transport over long mol.\ndistances. This chem. is exquisitely sensitive to perturbations in the DNA base stack, such as arise with base mismatches,\nlesions, and protein binding. We have now been exploring how this chem. may be used within the cell for long range signaling.\nIncreasingly, 4Fe-4S clusters are being found in DNA-binding proteins involved in genome maintenance. These 4Fe-4S clusters,\ncommon redox cofactors, are assocd. not only with repair proteins but also DNA polymerases and primase. Studies are\ndescribed to characterize DNA-mediated charge transport by these metalloproteins. Expts. indicate that long range DNA\ncharge transport can provide a first step in how DNA repair proteins may localize in the vicinity of lesions. DNA charge\ntransport, in carrying out redox chem. at a distance, offers a route for long range signaling and coordination of DNA repair and\nDNA-processing proteins across the genome.", "publisher": "Caltech Library", "publication_date": "2016-03" }, { "id": "authors:wz4pw-fte42", "collection": "authors", "collection_id": "wz4pw-fte42", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140814-094753667", "type": "conference_item", "title": "Two electrode platforms for DNA sensing based on DNA charge transport", "author": [ { "family_name": "Furst", "given_name": "Ariel L.", "clpid": "Furst-A-L" }, { "family_name": "Hill", "given_name": "Michael G.", "clpid": "Hill-M-G" }, { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Recently, we have developed a new DNA array platform that is formed electrochem. and addressed using a secondary electrode. Electrochem. activation of a copper catalyst, patterned with one electrode, enables precise placement of different DNA sequences onto a second electrode surface. The two-electrode patterning and detection platform allows for both high spatial resoln. of the patterned DNA array and optimization of detection through DNA-mediated charge transport with electrocatalysis. These platforms have been used for the successful detection of single base mismatches, specific hybridization events, and sequence-specific binding of transcription factors. We describe the application of this two-electrode platform in the development of new cancer diagnostics.", "publisher": "Caltech Library", "publication_date": "2014-08" }, { "id": "authors:37jvr-65s59", "collection": "authors", "collection_id": "37jvr-65s59", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140506-142144076", "type": "conference_item", "title": "Synthesis and characterization of a heterobimetallic Rh(III)/Pt(II) metalloinsertor conjugate", "author": [ { "family_name": "Weidmann", "given_name": "Alyson G.", "clpid": "Weidmann-A-G" }, { "family_name": "Komor", "given_name": "Alexis C.", "clpid": "Komor-A-C" }, { "family_name": "Schneider", "given_name": "Curtis J.", "clpid": "Schneider-C-J" }, { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Deficiencies in the mismatch repair (MMR) machinery lead to DNA defects that cause cancer. Cancers that exhibit MMR\ndeficiency are typically resistant to cisplatin and carboplatin, but can be treated in part with oxaliplatin. Recently, we have\nshown that rhodium metalloinsertors, which bind DNA at mismatched sites with over 1000 fold selectivity, exhibit antiproliferative\nand cytotoxic activity selectively in cells that are MMR-deficient. A bimetallic complex, consisting of a rhodium metalloinsertor\ntethered to an oxaliplatin deriv., was synthesized to improve platinum efficacy in an MMR-deficient human colorectal carcinoma\nline (HCT116O). The addn. of the rhodium metalloinsertor significantly increases cytotoxic activity and whole-cell platinum\nuptake compared to that of unconjugated platinum, as well as cisplatin and oxaliplatin. DNA binding studies show that the\ncomplex interacts with DNA through both metalloinsertion at a mismatch as well as the formation of Pt-DNA crosslinks.", "publisher": "Caltech Library", "publication_date": "2014-03" }, { "id": "authors:tt741-mqe94", "collection": "authors", "collection_id": "tt741-mqe94", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140424-105311067", "type": "conference_item", "title": "DNA protection by the bacterial ferritin Dps via DNA charge transport", "author": [ { "family_name": "Arnold", "given_name": "Anna R.", "clpid": "Arnold-A-R" }, { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Dps proteins, bacterial mini-ferritins that protect DNA from oxidative stress, are implicated in the survival and virulence of\npathogenic bacteria. These proteins are thought to protect DNA by depleting ferrous iron and hydrogen peroxide, which can\notherwise produce damaging hydroxyl radicals via Fenton chem. We seek to elucidate more specifically the mechanism of E.\nColi Dps protection of DNA. DNA charge transport (CT), whereby charge is effectively conducted through the base pair\n\u03c0-stack, is proposed to be utilized within the cell in, for example, the long-range activation of redox-active transcription factors.\nCan the DNA-binding protein Dps similarly utilize DNA CT to protect the genome from a distance That is, must oxidizing equiv.\ndiffuse specifically to the di-iron ferroxidase sites of Dps, or can Dps also become oxidized from a distance through DNA CT We\nemploy an intercalating ruthenium photooxidant to generate oxidative DNA damage via the flash-quench technique. The\ninjected electron hole localizes to guanine repeats, the sites of lowest potential in DNA. Because the lifetime of the guanine\nradical is long relative to the timescale of DNA CT, the guanine radical can interact with DNA-bound redox-active proteins. We\nfind that Dps loaded with ferrous iron significantly attenuates the yield of oxidative DNA damage, in contrast to Apo-Dps and\nferric iron-loaded Dps which lack reducing equiv. In this manner, ferrous iron-loaded Dps is selectively oxidized to fill guanine\nradical holes, thereby restoring the integrity of the DNA. Luminescence studies indicate no direct interaction between the\nruthenium photooxidant and Dps, supporting the DNA-mediated oxidn. of ferrous iron-loaded Dps. Thus DNA CT may be a\nmechanism by which Dps efficiently protects the genome of pathogenic bacteria from a distance.", "publisher": "Caltech Library", "publication_date": "2014-03" }, { "id": "authors:dex09-c9388", "collection": "authors", "collection_id": "dex09-c9388", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131016-081918900", "type": "conference_item", "title": "Targeting DNA mismatches with metalloinsertors", "author": [ { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Deficiencies in the mismatch repair pathway are assocd. with several types of cancers, as well as resistance to commonly used\nchemotherapeutics Our lab. has developed bulky rhodium complexes that target DNA mismatches through metalloinsertion.\nThese octahedral complexes include an expansive tetracyclic arom. ligand that can only be accommodated by DNA at a\nthermodynamically destabilized mismatch site. The first generation compd., Rh(bpy)_2chrysi^(3+) (chrysi = 5,6-chrysenequinone\ndiimine), binds 80% of all possible DNA mismatches and with remarkable specificity for the mismatched site. High resoln.\ncrystals structures of metal complexes bound to single base mismatches within a DNA oligonucleotide duplex reveal the\ndistinctive binding mode of metalloinsertion at the mismatched site, where the mismatched bases are ejected, replaced by the\nmetallonsertor. The family of metalloinsertors shows both selective inhibition of cellular proliferation and selective cytotoxicity\nof cells deficient in mismatch repair. Targeting of genomic DNA mismatches provides a unique cell-selective strategy in the\ndesign of novel chemotherapeutics.", "publisher": "Caltech Library", "publication_date": "2013-09" }, { "id": "authors:4e822-p4642", "collection": "authors", "collection_id": "4e822-p4642", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20131016-132512862", "type": "conference_item", "title": "DNA-mediated oxidation of transcription factor p53: Dependence upon DNA sequence and cysteine residues", "author": [ { "family_name": "Schaefer", "given_name": "Kathryn N.", "clpid": "Schaefer-K-N" }, { "family_name": "Geil", "given_name": "Wendy M.", "clpid": "Geil-W-M" }, { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Transcription factor p53 controls many cellular processes in response to cellular stress. As a redox-active\nprotein, p53 binds DNA in its reduced state and dissocs. upon oxidn. Transcription factor p53 can be\ndirectly oxidized via DNA-mediated charge transport (DNA-CT). The ability of certain consensus sites to be\nresponsive to DNA-CT induced oxidn. of p53 correlates to the oxidn. potential of the consensus sequence\nnucleobases. Greater p53 oxidative dissocn. is obsd. from consensus sequences contg. purine sequences with\nlow oxidn. potential; a guanine triplet is far more favorable to conduct DNA-CT to p53 than an adenine triplet.\nThis characteristic property was studied in vitro by EMSA and guanine oxidn. PAGE assays among multiple\nunnatural and human p53 consensus sequence oligonucleotides tethered with an anthraquinone photooxidant.\nEMSAs of mutant p53 have indicated that cysteine 275 is a key residue for successful p53 oxidative dissocn.\nby DNA-CT. To det. which of the 10 cysteine residues in pseudo-wild type and mutant p53 form a terminal\ndisulfide pair within the oxidized protein, differential thiol labeling characterized by mass spectrometry is being\nutilized.", "publisher": "Caltech Library", "publication_date": "2013-09" }, { "id": "authors:6xhkz-p9w70", "collection": "authors", "collection_id": "6xhkz-p9w70", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130722-132209522", "type": "conference_item", "title": "Redox signaling through DNA by metalloproteins", "author": [ { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Many expts. have now shown that DNA-mediated charge transport can arise over long mol. distances but in a reaction that is\nexquisitely sensitive to perturbations in the DNA base stack. Indeed, DNA charge transport chem. reports on the integrity of the\nDNA helix. Increasingly, proteins involved in DNA replication and repair have been found to contain 4Fe-4S clusters, common\nredox cofactors in biol. DNA-modified electrodes have been utilized to det. redox potentials for these metalloproteins bound to\nDNA; this electrochem. establishes the ability of the metalloproteins to carry out redox chem. at physiol. potentials in the DNAbound\nform. Studies are also described to characterize how these DNA-binding proteins contg. 4Fe-4S clusters may utilize DNA\ncharge transport chem. for long range signaling.", "publisher": "Caltech Library", "publication_date": "2013-04" }, { "id": "authors:m54nd-36v50", "collection": "authors", "collection_id": "m54nd-36v50", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130717-152842022", "type": "conference_item", "title": "Cell-selective activity of rhodium metalloinsertors correlates with subcellular localization", "author": [ { "family_name": "Komor", "given_name": "Alexis C.", "clpid": "Komor-A-C" }, { "family_name": "Schneider", "given_name": "Curtis J.", "clpid": "Schneider-C-J" }, { "family_name": "Ernst", "given_name": "Russell J.", "clpid": "Ernst-R-J" }, { "family_name": "Weidmann", "given_name": "Alyson G.", "clpid": "Weidmann-A-G" }, { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Deficiencies in the mismatch repair (MMR) pathway have been assocd. with various cancers, and many commonly used\nchemotherapeutics have decreased effectiveness against MMR-deficient cancers. There is consequently a need for\nchemotherapies that selectively target MMR-deficient cancer cells. Research in our lab. has uncovered a class of compds.,\nrhodium metalloinsertors, that selectively binds to DNA mismatches with high affinity and specificity. These rhodium\nmetalloinsertors bear an expansive arom. chrysi ligand (chrysi= chrysene-5,6-quinonediimine) which, upon mismatch binding,\ninserts into the DNA duplex from the minor groove and ejects the mismatched bases. These metalloinsertors exhibit selective\ncytotoxicity, preferentially inducing necrosis in MMR-deficient cells over MMR-proficient cells. They have been found to localize\nin the nuclei of MMR-deficient cells at concns. sufficient for mismatch detection, and their ability to selectively target MMRdeficient\ncells has been shown to be contingent upon low mitochondrial rhodium accumulation.", "publisher": "Caltech Library", "publication_date": "2013-04" }, { "id": "authors:hr2xb-pxq98", "collection": "authors", "collection_id": "hr2xb-pxq98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130716-131303443", "type": "conference_item", "title": "ATP-stimulated DNA-mediated charge transport by the repair helicase XPD", "author": [ { "family_name": "Mui", "given_name": "Timothy P.", "clpid": "Mui-T-P" }, { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "The XPD helicase contains a redox active [4Fe-4S] cluster and the protein is required for both nucleotide excision repair and\ntranscription. Using ATPase and helicase mutants of XPD, we have demonstrated that the DNA-bound redox signal is a sensitive\nreporter of ATP hydrolysis and reports on DNA conformational changes assocd. with enzymic function. Other XPD mutants,\nwhich are assocd. with disease, show low abs. signals without ATP, reflecting poor protein/DNA electronic coupling. In an AFM\nassay, monitoring the first step in searching for lesions, those mutants that show low electronic signaling are unable to\nredistribute onto DNA strands contg. a single base mismatch. This reduced efficiency in DNA-mediated signaling may therefore\nbe implicated in diseases assocd. with DNA repair. Therefore, we have begun exploring the in vivo effects of varying CT\nproficiency in both yeast Rad3 and SaXPD proteins to explore the biol. consequences of deficiencies in DNA-mediated signaling.", "publisher": "Caltech Library", "publication_date": "2013-04" }, { "id": "authors:zmbx4-cr473", "collection": "authors", "collection_id": "zmbx4-cr473", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130802-084957563", "type": "conference_item", "title": "DNA electrochemistry of the E. coli helicase, DinG", "author": [ { "family_name": "Grodick", "given_name": "Michael A.", "clpid": "Grodick-M-A" }, { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Coli helicase DinG, which can be induced by DNA damage, previously has been shown to have a [4Fe-4S] cluster. While the\nprimary in vivo role of DinG has not been revealed, the protein has been implicated in clearing stalled replication forks that arise\nfrom the collision of oppositely oriented transcription and replication machinery. We have explored the DNA-bound redox\npotential of DinG using electrochem. on gold modified with a helicase substrate, a 20-mer oligonucleotide with a 15-mer\noverhang. The [4Fe-4S] cluster can be reduced and oxidized reversibly at a DNA-bound redn. potential of \u223c 80 mV vs. This\nDNA-mediated electrochem. signal, moreover, is stimulated by ATP-hydrolysis. Results from cellular activity assays suggest that\nDinG may cooperate with other DNA-processing enzymes that have [4Fe-4S] clusters to locate and process DNA damage\nproducts.", "publisher": "Caltech Library", "publication_date": "2013-04" }, { "id": "authors:ztpm0-qbr61", "collection": "authors", "collection_id": "ztpm0-qbr61", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130716-132849585", "type": "conference_item", "title": "Luminescent probes for DNA base mismatches", "author": [ { "family_name": "McConnell", "given_name": "Anna J.", "orcid": "0000-0001-7329-4319", "clpid": "McConnell-Anna-J" }, { "family_name": "Barton", "given_name": "Jacqueline", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Mismatch repair deficiency has been implicated in a no. of diseases, such as cancer, and DNA base mismatches accumulate when\nmismatch repair pathways are defective. The metal complex [Rh(bpy)2(chrysi)]3+ has been shown to be selective for DNA base\nmismatches due to the sterically expansive chrysi ligand, and there is interest in developing a luminescent analog for diagnosing\nmismatch repair deficiencies. The complex [Ru(bpy)2(dppz)]2+ is a light switch for DNA and shows enhanced luminescence in\nthe presence of DNA defects. In an effort to improve the luminescence response for mismatched over matched DNA, a new\nfamily of ruthenium(II) complexes has been prepd. with sterically expansive ligands and their luminescence responses to DNA\ndefects have been investigated.", "publisher": "Caltech Library", "publication_date": "2013-04" }, { "id": "authors:5ymdb-akr77", "collection": "authors", "collection_id": "5ymdb-akr77", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120822-080618079", "type": "conference_item", "title": "Signaling through DNA", "author": [ { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "DNA charge transport chem. offers an opportunity to carry out redox chem. at a distance and thus provides a powerful platform for signaling, whether in the design of new sensors or in activating responses across the genome. Many expts. have now shown that DNA-mediated charge transport can arise over long mol. distances but in a reaction that is exquisitely sensitive to perturbations in the DNA base stack. Studies are described to illustrate this chem., to design new DNA-based sensors, and to characterize how DNA-binding proteins utilize DNA charge transport for long range signaling.", "publisher": "Caltech Library", "publication_date": "2012-08" }, { "id": "authors:67vqb-kmj34", "collection": "authors", "collection_id": "67vqb-kmj34", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120822-083550375", "type": "conference_item", "title": "Cellular accumulation and localization of rhodium metalloinsertors", "author": [ { "family_name": "Schneider", "given_name": "Curtis J.", "clpid": "Schneider-C-J" }, { "family_name": "Komor", "given_name": "Alexis C.", "clpid": "Komor-A-C" }, { "family_name": "Weidmann", "given_name": "Alyson", "clpid": "Weidmann-A-G" }, { "family_name": "Barton", "given_name": "Jacqueline K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Polypyridyl rhodium complexes bearing the sterically expansive chrysene diimine ligand are known to bind selectivity to mismatched base pairs in duplex DNA through insertion via the minor groove. These complexes are selectively cytotoxic in cell cultures bearing the microsatellite instability (MSI) phenotype, a marker for deficiencies in mismatch repair. The MSI phenotype has been found in a variety of carcinomas including hereditary nonpolyposis colorectal cancer, ovarian cancer, and treatment-related secondary leukemia. The effects of ancillary ligand substitution on the cellular accumulation and cytotoxicity were explored using a variety of H-bonding, anionic, or aliph. substituted ancillary ligands. Variations in the biol. activity are discussed in the context of uptake and localization of the complexes.", "publisher": "Caltech Library", "publication_date": "2012-08" }, { "id": "authors:cgynw-kb358", "collection": "authors", "collection_id": "cgynw-kb358", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120815-155147072", "type": "conference_item", "title": "DNA-mediated signaling", "author": [ { "family_name": "Barton", "given_name": "J. K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Many expts. have now shown that double helical DNA can serve as a conduit for efficient charge transport reactions over\nlong distances. In particular, oxidative damage to DNA can be promoted from a distance through DNA-mediated charge\ntransport. Importantly, this chem. is exquisitely sensitive to perturbations in the DNA base stack, such as arise with base\nmismatches, lesions, and protein binding. As a result, DNA charge transport chem. can be harnessed for the design of\nsensitive diagnostics. Studies will be described to characterize biol. roles for DNA charge transport. This chem. may be\nused advantageously within the cell in long range signaling to DNA-bound proteins, both to regulate transcription and to\nactivate repair of base lesions under conditions of oxidative stress. DNA charge transport chem. provides an opportunity\nto carry out redox chem. at a distance.", "publisher": "Caltech Library", "publication_date": "2010-12" }, { "id": "authors:c3erp-70g49", "collection": "authors", "collection_id": "c3erp-70g49", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120815-152507575", "type": "conference_item", "title": "DNA charge transport chemistry", "author": [ { "family_name": "Barton", "given_name": "J. K.", "orcid": "0000-0001-9883-1600", "clpid": "Barton-J-K" } ], "abstract": "Charge migration through the DNA base stack results in oxidative damage 200 \u00c5 from the site of the remotely bound\noxidant, but this reaction from a distance is exquisitely sensitive to perturbations in the intervening base stack.\nPhotophys., electrochem. and biochem. expts. have been conducted to characterize this chem.", "publisher": "Caltech Library", "publication_date": "2010-12" } ]