Yao Nina Y, Georgescu Roxana E, Finkelstein Jeff, O'Donnell Michael E
Howard Hughes Medical Institute, Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Proc Natl Acad Sci U S A. 2009 Aug 11;106(32):13236-41. doi: 10.1073/pnas.0906157106. Epub 2009 Aug 3.
Single-molecule techniques are developed to examine mechanistic features of individual E. coli replisomes during synthesis of long DNA molecules. We find that single replisomes exhibit constant rates of fork movement, but the rates of different replisomes vary over a surprisingly wide range. Interestingly, lagging strand synthesis decreases the rate of the leading strand, suggesting that lagging strand operations exert a drag on replication fork progression. The opposite is true for processivity. The lagging strand significantly increases the processivity of the replisome, possibly reflecting the increased grip to DNA provided by 2 DNA polymerases anchored to sliding clamps on both the leading and lagging strands.
单分子技术被开发用于在长DNA分子合成过程中检测单个大肠杆菌复制体的机制特征。我们发现单个复制体表现出恒定的叉形移动速率，但不同复制体的速率在一个惊人的宽范围内变化。有趣的是，后随链合成降低了前导链的速率，这表明后随链操作对复制叉的推进产生了阻力。持续性则相反。后随链显著增加了复制体的持续性，这可能反映了由锚定在前导链和后随链上滑动夹钳上的两种DNA聚合酶提供的对DNA增强的抓地力。
