Issue 11, 2008

Replisome dynamics and use of DNA trombone loops to bypass replication blocks

Abstract

Replisomes are dynamic multiprotein machines capable of simultaneously replicating both strands of the DNA duplex. This review focuses on the structure and function of the E. colireplisome, many features of which generalize to other bacteria and eukaryotic cells. For example, the bacterial replisome utilizes clamps and clamp loaders to coordinate the actions required of the trombone model of lagging strand synthesis made famous by Bruce Alberts. All cells contain clamps and clamp loaders and this review summarizes their structure and function. Clamp loaders are pentameric spirals that bind DNA in a structure specific fashion and thread it through the ring shaped clamp. The recent structure of the E. coli β clamp in complex with primed DNA has implications for how multiple polymerases function on sliding clamps and how the primed DNA template is exchanged between them. Recent studies reveal a remarkable fluidity in replisome function that enables it to bypass template lesions on either DNA strand. During these processes the polymerases within the replisome functionally uncouple from one another. Mechanistic processes that underlie these actions may involve DNA looping, similar to the trombone loops that mediate the lagging strand Okazaki fragment synthesis cycle.

Graphical abstract: Replisome dynamics and use of DNA trombone loops to bypass replication blocks

Article information

Article type
Review Article
Submitted
09 Jul 2008
Accepted
15 Aug 2008
First published
18 Sep 2008

Mol. BioSyst., 2008,4, 1075-1084

Replisome dynamics and use of DNA trombone loops to bypass replication blocks

N. Y. Yao and M. O’Donnell, Mol. BioSyst., 2008, 4, 1075 DOI: 10.1039/B811097B

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