PriB stimulates PriA helicase via an interaction with single-stranded DNA.
The frequency with which replication forks break down in all organisms requires that specific mechanisms ensure completion of genome duplication. In Escherichia coli a major pathway for reloading of the replicative apparatus at sites of fork breakdown is dependent on PriA helicase. PriA acts in conjunction with PriB and DnaT to effect loading of the replicative helicase DnaB back onto the lagging strand template, either at stalled fork structures or at recombination intermediates. Here we showed that PriB stimulates PriA helicase, acting to increase the apparent processivity of PriA. This stimulation correlates with the ability of PriB to form a ternary complex with PriA and DNA structures containing single-stranded DNA, suggesting that the known single-stranded DNA binding function of PriB facilitates unwinding by PriA helicase. This enhanced apparent processivity of PriA might play an important role in generating single-stranded DNA at stalled replication forks upon which to load DnaB. However, stimulation of PriA by PriB is not DNA structure-specific, demonstrating that targeting of stalled forks and recombination intermediates during replication restart likely resides with PriA alone.
Cadman
Chris J
CJ
School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, United Kingdom.
Lopper
Matthew
M
Moon
Peter B
PB
Keck
James L
JL
McGlynn
Peter
P
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000502:physiology*; D001483:Base Sequence; D002384:Catalysis; D004247:DNA / Q000737:chemistry; D004265:DNA Helicases / Q000502:physiology*; D004277:DNA, Single-Stranded / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000502:physiology*; D053488:DnaB Helicases; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000502:physiology*; D008969:Molecular Sequence Data; D009691:Nucleic Acid Denaturation; D009841:Oligonucleotides / Q000737:chemistry; D011485:Protein Binding; D011995:Recombination, Genetic; D013696:Temperature
D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D009841:Oligonucleotides; C086004:PriB protein, E coli; D004247:DNA; D000251:Adenosine Triphosphatases; C506730:dnaB protein, E coli; C506743:priA protein, E coli; D004265:DNA Helicases; D053488:DnaB Helicases