Homologous-pairing activity of the Bacillus subtilis bacteriophage SPP1 replication protein G35P.
Genetic evidence suggests that the SPP1-encoded gene 35 product (G35P) is essential for phage DNA replication. Purified G35P binds single-strand DNA (ssDNA) and double-strand (dsDNA) and specifically interacts with SPP1-encoded replicative DNA helicase G40P and SSB protein G36P. G35P promotes joint molecule formation between a circular ssDNA and a homologous linear dsDNA with an ssDNA tail. Joint molecule formation requires a metal ion but is independent of a nucleotide cofactor. Joint molecules formed during these reactions contain a displaced linear ssDNA strand. Electron microscopic analysis shows that G35P forms a multimeric ring structure in ssDNA tails of dsDNA molecules and left-handed filaments on ssDNA. G35P promotes strand annealing at the AT-rich region of SPP1 oriL on a supercoiled template. These results altogether are consistent with the hypothesis that the homologous pairing catalyzed by G35P is an integral part of SPP1 DNA replication. The loading of G40P at a d-loop (ori DNA or at any stalled replication fork) by G35P could lead to replication fork reactivation.
Departmento de Biotecnologia Microbiana, Centro Nacional de Biotecnologia, Consejo Superior de Investigaciones Cientificas, Campus Universidad Autónoma de Madrid, Madrid 28049, Spain.
Silvia
S
Ayora
Riccardo
R
Missich
Pablo
P
Mesa
Rudi
R
Lurz
Shixin
S
Yang
Edward H
EH
Egelman
Juan C
JC
Alonso
D000255:Adenosine Triphosphate / Q000378:metabolism; D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D015153:Blotting, Western; D002384:Catalysis; D002845:Chromatography; D004247:DNA / Q000378:metabolism; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D008274:Magnesium / Q000494:pharmacology; D008854:Microscopy, Electron; D008954:Models, Biological; D008957:Models, Genetic; D009690:Nucleic Acid Conformation; D020161:Physical Chromosome Mapping; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity; D017361:Viral Nonstructural Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*
D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C467734:G35P protein, bacteriophage SPP1; D017361:Viral Nonstructural Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D008274:Magnesium