COUNTERTRANSCRIPT-DRIVEN ATTENUATION SYSTEM OF THE PAM-BETA-1 REPE GENE

The plasmid-encoded RepE protein is absolutely essential and rate-limi ting for replication of the promiscuous plasmid pAM beta 1 originating from Enterococcus faecalis. We previously showed that the rep gene is transcribed from a promoter that is negatively regulated (similar to 10-fold reduction) by the CopF repressor. In this report, we show that this transcription is decreased a further similar to 10-times by a co untertranscript-driven transcriptional attenuation system. Extensive m utagenesis revealed that this system operates by a mechanism similar t o that previously described for the unrelated repC gene of plasmid pT1 81.