Replication fork assembly at recombination intermediates is required for bacterial growth.
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.
Liu
J
J
Molecular Biology Graduate Program, Cornell University Graduate School of Medical Sciences, New York, NY 10021, USA.
Xu
L
L
Sandler
S J
SJ
Marians
K J
KJ
D001419:Bacteria / Q000235:genetics* / Q000254:growth & development*; D010584:Bacteriophage phi X 174 / Q000235:genetics*; D001483:Base Sequence; D004258:DNA Polymerase III / Q000378:metabolism; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D016366:Open Reading Frames; D011995:Recombination, Genetic; D051716:Replication Protein A; D013698:Templates, Genetic
D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D051716:Replication Protein A; D004258:DNA Polymerase III