ABSTRACT
The majority of early transcripts of the phi 29 bacteriophage are produced throughout the lytic cycle but the levels of a class of transcripts from the right end of the phi 29 genome are significantly reduced late in the infection. We have isolated a phage early protein which selectively interferes with the initiation in vitro of transcription from promoters at the right end of the phi 29 genome. The amino acid sequence of the purified inhibitory protein correlates to the sequence predicted from the phi 29 gene 6 reading frame. In addition the inhibitory protein was not detectable in cells infected with phage mutated in gene 6 and the decrease in transcription did not occur in vivo when nonpermissive cells were infected with phi 29(sus6). The results indicate that the gene 6 protein modulates transcription from the right side of the phi 29 genome.
Subject(s)
Bacteriophages/genetics , Transcription Factors/genetics , Viral Proteins/genetics , Bacillus subtilis/genetics , DNA, Viral/metabolism , DNA-Directed RNA Polymerases/metabolism , Gene Expression Regulation , Promoter Regions, Genetic , RNA, Viral/biosynthesis , Repressor Proteins/genetics , Transcription, GeneticABSTRACT
A crude P-100 fraction prepared from Bacillus subtilis 21 min after infection with wild-type phage phi 29 supported the in vitro synthesis of late phi 29 RNA by added RNA polymerase. Synthesis of late RNA was also detected when purified phi 29 DNA was transcribed by RNA polymerase in the presence of an S-150 fraction obtained by lysis of phi 29-infected cells in the presence of 1 M NaCl. Late phi 29 RNA was not synthesized when either the P-100 or the S-150 fraction was prepared from cultures infected with phi 29 having a mutation in gene 4.
