The ordered assembly of the phiX174-type primosome. III. PriB facilitates complex formation between PriA and DnaT.
The properties of two mutant PriA proteins, PriA C439Y and PriA C445Y have been used to reveal the role of PriB during assembly of the phiX174-type primosome. The replication defects of both mutant PriA proteins could be rescued by high concentrations of DnaT. Analysis of the formation of intermediate complexes in primosome assembly and the effect of PriB on PriA binding to DNA demonstrated that the mutant PriA proteins could not form a PriA-PriB complex on DNA carrying a primosome assembly site. Consequently, the mutant proteins also could not form PriA-PriB-DnaT complexes at concentrations of DnaT sufficient to form such a complex with wild-type PriA. In addition, PriB was found to stabilize wild-type but not mutant PriA proteins on DNA. At high concentrations of DnaT, both mutant and wild-type PriA proteins could form a PriA-DnaT complex and support PriB-independent phiX174 complementary strand DNA replication. Thus, during primosome assembly, PriB facilitates complex formation between PriA and DnaT.
Liu
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J
Graduate Program in Molecular Biology, Cornell University Graduate School of Medical Sciences, New York, New York 10021, USA.
Nurse
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Marians
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D001426:Bacterial Proteins / Q000378:metabolism*; D010584:Bacteriophage phi X 174 / Q000235:genetics* / Q000378:metabolism; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000378:metabolism; D004279:DNA, Viral / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D016297:Mutagenesis, Site-Directed; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; C086004:PriB protein, E coli