FIG 2.
The pCF10 regulatory region. Induction and expression of the conjugation machinery from pCF10 are responsive to signaling by the peptide pheromone cCF10 (C; sequence, LVTLVFV) in association with PrgX tetramers which decrease repression the prgQ promoter. PrgX, in complex with iCF10 (I; sequence, AITLIFI) enhances PrgX repression of prgQ and reduces downstream conjugation machinery transcription. Antisense interactions between small RNAs (sRNAs; QS and anti-Q) from the 5′ ends of the prgQ and prgX operons mediate reciprocal negative-regulatory functions, amplifying the effects of peptides and PrgX in controlling prgQ transcription extension through the entire operon. See the text for more details.