Transcription regulator that binds to an inverted DNA repeat with the consensus sequence 5'-TAC[GT]AC-NNNNN-GT[AC]GTA-3' and regulates genes involved in antibiotic transport, detoxification and cell wall function. Also regulates its own transcription. Binds DNA as a dimer. Homodimer. Autoregulated. Up-regulated by amoxicillin. Upon exposure to beta-lactams, proteolytic cleavage at a single site may impair dimerization and abolish repressor activity. Was identified as a high-confidence drug target. Belongs to the BlaI transcriptional regulatory family.