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Structure, Flexibility, and Repair of Two Different Orientations of the Same AlkylInterstrand DNA Cross-Link†

Biomedical Sciences Research Institute Computer Science Research Institute Environmental Sciences Research Institute Nanotechnology & Advanced Materials Research Institute

Noll, DM, Webba da Silva, Mateus, Noronha, AM, Wilds, CJ, Colvin, OM, Gamcsik, MP and Miller, PS (2005) Structure, Flexibility, and Repair of Two Different Orientations of the Same AlkylInterstrand DNA Cross-Link†. Biochemistry, 44 . [Journal article]

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DOI: 10.1021/bi050014n

Abstract

Interstrand DNA cross-links are the principal cytotoxic lesions produced by chemotherapeuticbifunctional alkylating agents. Using an N4C-ethyl-N4C interstrand DNA cross-link to mimic this classof clinically important cancer chemotherapeutic agents, we have characterized the repair, structure, andflexibility of DNA that contains this cross-link in two different orientations. Plasmid DNAs in which thecytosines of single CpG or GpC steps are covalently linked were efficiently processed by repair proficientand homologous recombination deficient strains of Escherichia coli. Repair in a nucleotide excision repair(NER) deficient strain was less efficient overall and displayed a 4-fold difference between the two crosslinkorientations. Both the structure and flexibility of DNA containing these cross-links were examinedusing a combination of 1H NMR, restrained molecular dynamics simulations, and atomic force microscopy(AFM). The NMR structure of a decamer containing a CpG interstrand cross-link shows the cross-linkeasily accommodated within the duplex with no disruption of hydrogen bonding and only minorperturbations of helical parameters. In contrast, disruptions caused by the GpC cross-link producedconsiderable conformational flexibility that precluded structure determination by NMR. AFM imaging ofcross-link-containing plasmid DNA showed that the increased flexibility observed in the GpC cross-linkpersists when it is embedded into much larger DNA fragments. These differences may account for thedifferent repair efficiencies seen in NER deficient cells.

Item Type:Journal article
Faculties and Schools:Faculty of Life and Health Sciences
Faculty of Life and Health Sciences > School of Pharmacy and Pharmaceutical Science
Research Institutes and Groups:Biomedical Sciences Research Institute
Biomedical Sciences Research Institute > Molecular Medicine
Biomedical Sciences Research Institute > Molecular Medicine > Transcriptional Regulation & Epigenetics
ID Code:18295
Deposited By:Dr Mateus Webba da Silva
Deposited On:03 May 2011 11:12
Last Modified:04 Dec 2012 14:25

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