Replication fork assembly at recombination intermediates is required for bacterial growth
- †Molecular Biology Graduate Program and ‡Biochemistry and Structural Biology Graduate Program, Cornell University Graduate School of Medical Sciences, New York, NY 10021; §Department of Microbiology, University of Massachusetts at Amherst, Amherst, MA 01003; and ¶Molecular Biology Program, Memorial Sloan–Kettering Cancer Center, New York, NY 10021
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Edited by Charles M. Radding, Yale University School of Medicine, New Haven, CT, and approved January 27, 1999 (received for review November 16, 1998)
Abstract
PriA, a 3′ → 5′ DNA helicase, directs assembly of a primosome on some bacteriophage and plasmid DNAs. Primosomes are multienzyme replication machines that contribute both the DNA-unwinding and Okazaki fragment-priming functions at the replication fork. The role of PriA in chromosomal replication is unclear. The phenotypes of priA null mutations suggest that the protein participates in replication restart at recombination intermediates. We show here that PriA promotes replication fork assembly at a D loop, an intermediate formed during initiation of homologous recombination. We also show that DnaC810, encoded by a naturally arising intergenic suppressor allele of the priA2∷kan mutation, bypasses the need for PriA during replication fork assembly at D loops in vitro. These findings underscore the essentiality of replication fork restart at recombination intermediates under normal growth conditions in bacteria.
Footnotes
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↵ ‖ To whom reprint requests should be addressed. e-mail: k-marians{at}ski.mskcc.org.
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This paper was submitted directly (Track II) to the Proceedings Office.
- ABBREVIATION:
- SSB,
- single-stranded DNA-binding protein
- Copyright © 1999, The National Academy of Sciences
