文章基本信息

标题：Binary complex crystal structure of DNA polymerase β reveals multiple conformations of the templating 8-oxoguanine lesion
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作者：Vinod K. Batra ; David D. Shock ; William A. Beard 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2012
卷号：109
期号：1
页码：113-118
DOI：10.1073/pnas.1112235108
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Oxidation of genomic DNA forms the guanine lesion 7,8-dihydro-8-oxoguanine (8-oxoG). When in the template base position during DNA synthesis the 8-oxoG lesion has dual coding potential by virtue of its anti- and syn-conformations, base pairing with cytosine and adenine, respectively. This impacts mutagenesis, because insertion of adenine opposite template 8-oxoG can result in a G to T transversion. DNA polymerases vary by orders of magnitude in their preferences for mutagenic vs. error-free 8-oxoG lesion bypass. Yet, the structural basis for lesion bypass specificity is not well understood. The DNA base excision repair enzyme DNA polymerase (pol) {beta} is presented with gap-filling synthesis opposite 8-oxoG during repair and has similar insertion efficiencies for dCTP and dATP. We report the structure of pol {beta} in binary complex with template 8-oxoG in a base excision repair substrate. The structure reveals both the syn- and anti-conformations of template 8-oxoG in the confines of the polymerase active site, consistent with the dual coding observed kinetically for this enzyme. A ternary complex structure of pol {beta} with the syn-8-oxoG:anti-A Hoogsteen base pair in the closed fully assembled preinsertion active site is also reported. The syn-conformation of 8-oxoG is stabilized by minor groove hydrogen bonding between the side chain of Arg283 and O8 of 8-oxoG. An adjustment in the position of the phosphodiester backbone 5'-phosphate enables 8-oxoG to adopt the syn-conformation.
关键词：oxidative DNA lesion ; X-ray crystallography