A phage-encoded inhibitor of Escherichia coli DNA replication targets the DNA polymerase clamp loader
Article first published online: 18 JAN 2011
© 2011 Blackwell Publishing Ltd
Volume 79, Issue 5, pages 1325–1338, March 2011
How to Cite
Yano, S. T. and Rothman-Denes, L. B. (2011), A phage-encoded inhibitor of Escherichia coli DNA replication targets the DNA polymerase clamp loader. Molecular Microbiology, 79: 1325–1338. doi: 10.1111/j.1365-2958.2010.07526.x
- Issue published online: 21 FEB 2011
- Article first published online: 18 JAN 2011
- Accepted manuscript online: 28 DEC 2010 01:29AM EST
- Accepted 20 December, 2010.
Coliphage N4 infection leads to shut-off of host DNA replication without inhibition of host transcription or translation. We report the identification and characterization of gp8, the N4 gene product responsible for this phenotype. N4 gp8 is an Escherichia coli bacteriostatic inhibitor that colocalizes with the E. coli replisome in a replication-dependent manner. Gp8 was purified and observed to cross-link to complexes containing the replicative DNA polymerase, DNAP III, in vivo. Purified gp8 inhibits DNA polymerization by DNA polymerase III holoenzyme in vitro by interfering with polymerase processivity. Gp8 specifically inhibits the clamp-loading activity of DNAP III by targeting the delta subunit of the DNAP III clamp loader; E. coli mutations conferring gp8 resistance were identified in the holA gene, encoding delta. Delta and gp8 interact in vitro; no interaction was detected between gp8 inactive mutants and wild-type delta or between delta gp8-resistant mutants and wild-type gp8. Therefore, this work identifies the DNAP III clamp loader as a new target for inhibition of bacterial growth. Finally, we show that gp8 is not essential in N4 development under laboratory conditions, but its activity contributes to phage yield.