Functions as both a membrane-bound sensor and transducer of bacitracin availability to activates transcription of the bcrABD operon in the presence of bacitracin (PubMed:15388429, PubMed:18227063, PubMed:30777814). Binds specifically to two inverted repeat sequences on the bcrABD promoter, irrespective of bacitracin concentration (PubMed:18227063). Constitutively bound to the bcrABD promoter (PubMed:18227063, PubMed:30777814). Requires bacitracin for activation, probably through a conformational change, such as the oligomerization of inactive dimers to form active tetramers (PubMed:30777814). Contains an N-terminal helix-turn-helix DNA-binding domain, an intermediate oligomerization domain and a C-terminal transmembrane domain.