Transcription-termination-mediated immunity and its prevention in bacteriophage SfV of Shigella flexneri.
The temperate phage SfV encodes the genes responsible for the serotype conversion of Shigella flexneri strains from serotype Y to 5a. Bacteriophages often encode proteins that prevent subsequent infection by homologous phages; the mechanism by which this is accomplished is referred to as superinfection immunity. The serotype conversion mediated following lysogenization of SfV is one such mechanism. Another mechanism is the putative lambda-like CI protein within SfV. This study reports the characterization of a third superinfection mechanism, transcription termination, in SfV. The presence of a small immunity-mediating RNA molecule, called CI RNA, and its essential role in the establishment of immunity, is shown. The novel role of the gene orf77, located immediately downstream from the transcription termination region, in inhibiting the establishment of CI RNA-mediated immunity is also presented.
Roberts
Fleur
F
School of Biochemistry and Molecular Biology, College of Science, The Australian National University, Canberra, ACT 0200, Australia.
Allison
Gwen E
GE
Australian National University Medical School, The Australian National University, Canberra, ACT 0200, Australia.|School of Biochemistry and Molecular Biology, College of Science, The Australian National University, Canberra, ACT 0200, Australia.
Verma
Naresh K
NK
School of Biochemistry and Molecular Biology, College of Science, The Australian National University, Canberra, ACT 0200, Australia.
D001435:Bacteriophages / Q000235:genetics / Q000254:growth & development* / Q000276:immunology*; D008242:Lysogeny; D016366:Open Reading Frames; D022661:RNA, Untranslated / Q000502:physiology*; D012367:RNA, Viral / Q000502:physiology*; D012763:Shigella flexneri / Q000821:virology*; D014158:Transcription, Genetic
D022661:RNA, Untranslated; D012367:RNA, Viral