A two-protein strategy for the functional loading of a cellular replicative DNA helicase.
The delivery of a ring-shaped hexameric helicase onto DNA is a fundamental step of DNA replication, conserved in all cellular organisms. We report the biochemical characterization of the bacterial hexameric replicative helicase DnaC of Bacillus subtilis with that of the two replication initiation proteins DnaI and DnaB. We show that DnaI and DnaB interact physically and functionally with the DnaC helicase and mediate its functional delivery onto DNA. Thus, DnaB and DnaI form a pair of helicase loaders, revealing a two-protein strategy for the loading of a replicative helicase. We also present evidence that the DnaC helicase loading mechanism appears to be of the ring-assembly type, proceeding through the recruitment of DnaC monomers and their hexamerization around single-stranded DNA by the coordinated action of DnaI and DnaB.
Velten
Marion
M
Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, Domaine de Vilvert, 78352 Jouy en Josas, France.
McGovern
Stephen
S
Marsin
Stéphanie
S
Ehrlich
S Dusko
SD
Noirot
Philippe
P
Polard
Patrice
P
D000255:Adenosine Triphosphate / Q000378:metabolism; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication / Q000235:genetics*; D053488:DnaB Helicases; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D008938:Mitosis / Q000235:genetics*; D015394:Molecular Structure; D009154:Mutation / Q000235:genetics; D011108:Polymers / Q000378:metabolism; D014178:Translocation, Genetic / Q000235:genetics
D001426:Bacterial Proteins; C071702:DnaC protein, E coli; C448302:DnaI protein, Bacillus subtilis; D029968:Escherichia coli Proteins; D011108:Polymers; D000255:Adenosine Triphosphate; D004247:DNA; D004265:DNA Helicases; D053488:DnaB Helicases