Antitoxin component of an atypical, type II toxin-antitoxin chaperone (TAC) system. Probably neutralizes the toxic effects of cognate toxin HigB1, which also requires SecB-like chaperone MT2006 (AC Q7D7P7). Autorepresses its operon (higB1-higA1-MT2006). Interacts with SecB-like chaperone MT2006. Autorepresses its operon (higB1-higA1-MT2006).