Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
EMBO J. 2011 May 4;30(9):1830-40. doi: 10.1038/emboj.2011.84. Epub 2011 Mar 25.

E. coli DNA replication in the absence of free β clamps.

Author information

  • 1Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA.

Abstract

During DNA replication, repetitive synthesis of discrete Okazaki fragments requires mechanisms that guarantee DNA polymerase, clamp, and primase proteins are present for every cycle. In Escherichia coli, this process proceeds through transfer of the lagging-strand polymerase from the β sliding clamp left at a completed Okazaki fragment to a clamp assembled on a new RNA primer. These lagging-strand clamps are thought to be bound by the replisome from solution and loaded a new for every fragment. Here, we discuss a surprising, alternative lagging-strand synthesis mechanism: efficient replication in the absence of any clamps other than those assembled with the replisome. Using single-molecule experiments, we show that replication complexes pre-assembled on DNA support synthesis of multiple Okazaki fragments in the absence of excess β clamps. The processivity of these replisomes, but not the number of synthesized Okazaki fragments, is dependent on the frequency of RNA-primer synthesis. These results broaden our understanding of lagging-strand synthesis and emphasize the stability of the replisome to continue synthesis without new clamps.

PMID:
21441898
[PubMed - indexed for MEDLINE]
PMCID:
PMC3101994
Free PMC Article

Images from this publication.See all images (4)Free text

Figure 1
Figure 2
Figure 3
Figure 4
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk