title: Bacillus subtilis bacteriophage SPP1-encoded gene 34.1 product is a recombination-dependent DNA replication protein.
abstract: SPP1-encoded replication and recombination proteins, involved in the early steps of the initiation of concatemeric DNA synthesis, have been analyzed. Dimeric G34.1P exonuclease degrades, with a 5' to 3' polarity and in a Mg2+-dependent reaction, preferentially linear double-stranded (ds) DNA rather than single-stranded (ss) DNA. Binding of the replisome organizer, G38P, to its cognate sites (oriDNA) halts the 5' to 3' exonucleolytic activity of G34.1P on dsDNA. The G35P recombinase increases the affinity of G34.1P for dsDNA, and stimulates G34.1P activity on dsDNA, but not on ssDNA. Then, filamented G35P promotes limited strand exchange with a homologous sequence. The ssDNA binding protein, G36P, protects ssDNA from the G34.1P exonuclease activity and stimulates G35P-catalyzed strand exchange. The data presented suggest a model for the role of G34.1P during initiation of sigma replication: G38P bound to oriDNA might halt replication fork progression, and G35P, G34.1P and G36P in concert might lead to the re-establishment of a unidirectional recombination-dependent replication that accounts for the direction of DNA packaging.
authors.affiliation: Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, CSIC, Darwin 3, Campus de la Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
authors.forename: María I
authors.initials: MI
authors.lastname: Martínez-Jiménez
authors.forename: Juan C
authors.initials: JC
authors.lastname: Alonso
authors.forename: Silvia
authors.initials: S
authors.lastname: Ayora
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001412:Bacillus subtilis / Q000821:virology*; D001435:Bacteriophages / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000378:metabolism; D004261:DNA Replication; D004277:DNA, Single-Stranded / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D005092:Exonucleases / Q000378:metabolism; D016678:Genome; D046911:Macromolecular Substances; D008274:Magnesium / Q000737:chemistry; D008957:Models, Genetic; D008970:Molecular Weight; D009841:Oligonucleotides / Q000737:chemistry; D010710:Phosphates / Q000378:metabolism; D020161:Physical Chromosome Mapping; D010957:Plasmids / Q000378:metabolism; D011995:Recombination, Genetic; D018741:Replication Origin / Q000235:genetics; D013997:Time Factors; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; C467734:G35P protein, bacteriophage SPP1; D046911:Macromolecular Substances; D009841:Oligonucleotides; D010710:Phosphates; D017361:Viral Nonstructural Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D005092:Exonucleases; D004265:DNA Helicases; D008274:Magnesium