Two modes of PriA binding to DNA.
The role of PriA, required for the assembly of the phiX174-type primosome on DNA, in cellular DNA replication has been unclear since its discovery. Recent evidence, based on the phenotypes of strains carrying priA null mutations, has led to proposals that the primosome assembly activity of PriA was required to load replication forks at intermediates such as D loops during homologous recombination. McGlynn et al. (McGlynn, P., Al-Deib, A. A., Liu, J., Marians, K. J., and Lloyd, R. G. (1997) J. Mol. Biol. 270, 212-221) demonstrated that PriA could, in fact, bind D loops. We show here that there are two modes of stable binding of PriA to DNA. One mode, in which the enzyme binds 3'-single-stranded extensions from duplex DNAs, presumably reflects the 3' --> 5' DNA helicase activity of PriA. The D loop DNA binding activity of PriA can be accounted for by the second mode, where the enzyme binds bent DNA at three strand junctions.
Nurse
P
P
Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, Cornell University Graduate School of Medical Sciences, New York, New York 10021, USA.
Liu
J
J
Marians
K J
KJ
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D004247:DNA / Q000737:chemistry*; D004265:DNA Helicases / Q000378:metabolism; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides
D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D004247:DNA; D000251:Adenosine Triphosphatases; D004265:DNA Helicases