Autorepression of RctB, an initiator of Vibrio cholerae chromosome II replication

The RctB protein binds to the origin of replication of Vibrio cholerae chromosome II (chrII) and is required for oriCII_Vc-based replication. Here, we found that RctB acts as an autorepressor, inhibiting rctB transcription. Integration host factor promotes rctB transcription, while Dam and DnaA, factors required for replication of both V. cholerae chromosomes, influence RctB autorepression. Thus, RctB appears to regulate chrII replication as both an initiator and a transcription repressor, and its synthesis is modulated by factors that govern replication of both chromosomes.