Livingston Alison L, O'Shea Valerie L, Kim Taewoo, Kool Eric T, David Sheila S
Department of Chemistry, University of Utah, 315 South 1400 East, Salt Lake City, Utah 84112, USA.
Nat Chem Biol. 2008 Jan;4(1):51-8. doi: 10.1038/nchembio.2007.40. Epub 2007 Nov 18.
Escherichia coli MutY has an important role in preventing mutations associated with the oxidative lesion 7,8-dihydro-8-oxo-2'-deoxyguanosine (OG) in DNA by excising adenines from OG.A mismatches as the first step of base excision repair. To determine the importance of specific steps in the base pair recognition and base removal process of MutY, we have evaluated the effects of modifications of the OG.A substrate on the kinetics of base removal, mismatch affinity and repair to G-C in an E. coli-based assay. Notably, adenine modification was tolerated in the cellular assay, whereas modification of OG resulted in minimal cellular repair. High affinity for the mismatch and efficient base removal required the presence of OG. Taken together, these results suggest that the presence of OG is a critical feature that is necessary for MutY to locate OG.A mismatches and select the appropriate adenines for excision to initiate repair in vivo before replication.
大肠杆菌MutY通过从DNA中的氧化损伤产物7,8-二氢-8-氧代-2'-脱氧鸟苷（OG）上切除腺嘌呤，在预防与该损伤相关的突变中发挥重要作用。作为碱基切除修复的第一步，将OG与腺嘌呤错配。为了确定MutY在碱基对识别和碱基切除过程中特定步骤的重要性，我们在基于大肠杆菌的检测中评估了OG.A底物修饰对碱基切除动力学、错配亲和力以及修复为G-C的影响。值得注意的是，在细胞检测中腺嘌呤修饰是可以耐受的，而OG的修饰导致细胞修复极少。对错配的高亲和力和高效的碱基切除需要OG的存在。综上所述，这些结果表明OG的存在是一个关键特征，对于MutY在体内复制前定位OG.A错配并选择合适的腺嘌呤进行切除以启动修复是必要的。
