DNA binding of PriA protein requires cooperation of the N-terminal D-loop/arrested-fork binding and C-terminal helicase domains.
PriA protein is essential for RecA-dependent DNA replication induced by stalled replication forks in Escherichia coli. PriA is a DEXH-type DNA helicase, ATPase activity of which depends on its binding to structured DNA including a D-loop-like structure. Here, we show that the N-terminal 181-amino acid polypeptide can form a complex with D-loop in gel shift assays and have identified a unique motif present in the N-terminal segment of PriA that plays a role in its DNA binding. We have also identified residues in the C terminus proximal helicase domain essential for D-loop binding. PriA proteins mutated in this domain do not bind to D-loop, despite the presence of the N-terminal DNA-binding motif. Those mutants that cannot bind to D-loop in vitro do not support a recombination-dependent mode of DNA replication in vivo, indicating that binding to a D-loop-like structure is essential for the ability of PriA to initiate DNA replication and repair from stalled replication forks. We propose that binding of the PriA protein to stalled replication forks requires proper configuration of the N-terminal fork-recognition and C-terminal helicase domains and that the latter may stabilize binding and increase binding specificity.
Tanaka
Taku
T
Department of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan.
Mizukoshi
Toshimi
T
Taniyama
Chika
C
Kohda
Daisuke
D
Arai
Ken-ichi
K
Masai
Hisao
H
D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D004265:DNA Helicases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000502:physiology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D016415:Sequence Alignment
D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D000251:Adenosine Triphosphatases; C506743:priA protein, E coli; D004265:DNA Helicases