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Updated: Oct 4, 2026

Applying an Inducible Expression System to Study Interference of Bacterial Virulence Factors with Intracellular Signaling
Published on: June 25, 2015
The pAM beta 1 CopF repressor regulates plasmid copy number by controlling transcription of the repE gene
E Le Chatelier1, S D Ehrlich, L Jannière
1Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique, Jouy en Josas, France.
Abstract:
pAM beta 1 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 pAM beta 1-encoded CopF protein is involved in negative regulation of the plasmid copy number. CopF represses approximately 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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