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The minor capsid protein gp7 of bacteriophage SPP1 is required for efficient infection of Bacillus subtilis
Author(s) -
Vinga Inês,
Dröge Anja,
Stiege Asita C.,
Lurz Rudi,
Santos Mário A.,
Daugelavičius Rimantas,
Tavares Paulo
Publication year - 2006
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2006.05327.x
Subject(s) - biology , capsid , bacillus subtilis , bacteriophage , genome , dna , microbiology and biotechnology , gene , phagemid , virology , genetics , escherichia coli , bacteria
Summary 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 (SPP1 del7 ) with reduced burst‐size. SPP1 del7 infections led to normal assembly of virus particles whose morphology, DNA and protein composition was undistinguishable from wild‐type virions. However, only ∼25% of the viral particles that lack gp7 were infectious. SPP1 del7 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 SPP1 del7 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 SPP1 del7 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.