A genetic approach to the identification of functional amino acids in protein p6 of Bacillus subtilis phage phi 29.
Protein p6 of the Bacillus subtilis phage phi 29 is essential for in vivo viral DNA replication. This protein activates the initiation of phi 29 DNA replication in vitro by forming a multimeric nucleoprotein complex at the replication origins. The N-terminal region of protein p6 is involved in DNA binding, as shown by in vitro studies with p6 proteins altered by deletions or missense mutations. We report on the development of an in vivo functional assay for protein p6. This assay is based on the ability of protein p6-producing B. subtilis non-suppressor (su) cells to support growth of a phi 29 sus6 mutant phage. We have used this trans-complementation assay to investigate the effect on in vivo viral DNA synthesis of missense mutations introduced into the protein p6 N-terminal region. The alteration of lysine to alanine at position 2 resulted in a partially functional protein, whereas the replacement of arginine by alanine at position 6 gave rise to an inactive protein. These results indicate that arginine at position 6 is critical for the in vivo activity of protein p6. Our complementation system provides a useful genetic approach for the identification of functionally important amino acids in protein p6.
Bravo
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Centro de Biología Molecular Severo Ochoa (CSIC-UAM), Universidad Autónoma, Madrid, Spain.
Hermoso
J M
JM
Salas
M
M
D017103:Bacillus Phages / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D001412:Bacillus subtilis / Q000821:virology; D001483:Base Sequence; D004261:DNA Replication / Q000502:physiology; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011994:Recombinant Proteins; D013329:Structure-Activity Relationship; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D014779:Virus Replication / Q000502:physiology
D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D014764:Viral Proteins; C080198:viral protein p6