Single-molecule analysis of the Escherichia coli replisome and use of clamps to bypass replication barriers

The process of chromosome duplication faces many obstacles. One way to circumvent blocks is to hop over them by placing a new clamp on a downstream primer. This resembles lagging strand synthesis, where the tight grip of polymerase to the clamp and DNA must be overcome upon completing each Okazaki fragment so it can transfer to new primed sites. This review focuses on recent single-molecule studies showing that Escherichia coli Pol III can hop from one clamp to another without leaving the replication fork. This capability provides a means to circumvent obstacles like transcription or DNA lesions without fork collapse. (C) 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.