Production of beta-Lactamase and penicillin-binding protein 2a (which mediate staphylococcal resistance to beta-lactam antibiotics) is regulated by a signal-transducing integral membrane protein and a transcriptional repressor. The signal transducer is a fusion protein with penicillin-binding and zinc metalloprotease domains. The signal for protein expression is transmitted by site-specific proteolytic cleavage of both the transducer, which auto-activates, and the repressor, which is inactivated, unblocking gene transcription. Homologues to this peptidase domain, which corresponds to Merops family M56, are also found in a number of other bacterial genome sequences.

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