Pheromone cCF10 and plasmid pCf10-encoded regulatory molecules act post-transcriptionally to activate expression of downstream conjugation functions

Expression of aggregation protein Asc10 from the prgB gene of conjugative plasmid pCF10 in Enterococcus faecalis is induced by the peptide pheromone cCF10. Genes required for Asc10 production, prgQ and prgS, lie 3-5 kb upstream, but can function at much greater distances. The prgQ transcripts encode a pheromone inhibitor peptide (iCF10) at the extreme 5' end. Neither production of this peptide nor translation of the 5' end of prgQ transcripts was found to be necessary for prgB expression. Pheromone cCF10 is required to activate prgB expression, even in the absence of iCF10 production, and does not affect initiation of transcription. The prgS gene encodes a 10.5 kDa protein that appears to be required for translation of prgS, and a non-coding RNA at the 3' end of prgS may be required for readthrough of transcription to prgS from the prgQ promoter. Although the entire positive control region is transcribed constitutively from the prgQ promoter, translation of PrgS and transcriptional readthrough to prgB occur only after induction with pheromone. The combined data are consistent with a model in which the positive regulatory molecules and pheromone cCF10 activate prgB expression post-transcriptionally.