title: The minor capsid protein gp7 of bacteriophage SPP1 is required for efficient infection of Bacillus subtilis.
abstract: Gp7 is a minor capsid protein of the Bacillus subtilis bacteriophage SPP1. Homologous proteins are found in numerous phages but their function remained unknown. Deletion of gene 7 from the SPP1 genome yielded a mutant phage (SPP1del7) with reduced burst-size. SPP1del7 infections led to normal assembly of virus particles whose morphology, DNA and protein composition was undistinguishable from wild-type virions. However, only approximately 25% of the viral particles that lack gp7 were infectious. SPP1del7 particles caused a reduced depolarization of the B. subtilis membrane in infection assays suggesting a defect in virus genome traffic to the host cell. A higher number of SPP1del7 DNA ejection events led to abortive release of DNA to the culture medium when compared with wild-type infections. DNA ejection in vitro showed that no detectable gp7 is co-ejected with the SPP1 genome and that its presence in the virion correlated with anchoring of released DNA to the phage particle. The release of DNA from wild-type phages was slower than that from SPP1del7 suggesting that gp7 controls DNA exit from the virion. This feature is proposed to play a central role in supporting correct routing of the phage genome from the virion to the cell cytoplasm.
authors.affiliation: Unité de Virologie Moléculaire et Structurale, CNRS UMR 2472, INRA UMR1157 and IFR 115, Bâtiment 14B, CNRS, 91198 Gif-sur-Yvette, France.
authors.forename: Inês
authors.initials: I
authors.lastname: Vinga
authors.forename: Anja
authors.initials: A
authors.lastname: Dröge
authors.forename: Asita C
authors.initials: AC
authors.lastname: Stiege
authors.forename: Rudi
authors.initials: R
authors.lastname: Lurz
authors.forename: Mário A
authors.initials: MA
authors.lastname: Santos
authors.forename: Rimantas
authors.initials: R
authors.lastname: Daugelavicius
authors.forename: Paulo
authors.initials: P
authors.lastname: Tavares
mesh_terms: D017103:Bacillus Phages / Q000235:genetics / Q000502:physiology*; D001412:Bacillus subtilis / Q000821:virology*; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology / Q000821:virology; D004279:DNA, Viral / Q000378:metabolism / Q000648:ultrastructure; D017353:Gene Deletion; D016679:Genome, Viral; D014771:Virion / Q000235:genetics / Q000378:metabolism
chemical_list: D036022:Capsid Proteins; D004279:DNA, Viral