The pAM beta 1 CopF repressor regulates plasmid copy number by controlling transcription of the repE gene
1994
Le Chatelier, Emmanuelle | Ehrlich, Dusko S | Janniere, Laurent
pAMβ1 is a low‐copy‐number, promiscuous plasmid from Gram‐positive bacteria that replicates by a unidirectional theta‐type mode. Its replication is initiated by an original mechanism, involving the positive rate‐limiting RepE protein. Here we show that the pAMβ1‐encoded CopF protein is involved in negative regulation of the plasmid copy number. CopF represses ‐10‐fold the transcription initiated at the promoter of the repE gene and binds to a 31 bp segment which is located immediately upstream of the ‐35 box of the repE promoter. We propose that CopF inhibits initiation of transcription at the repE promoter by binding to its operator.
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