Antitoxin component of a type II toxin-antitoxin (TA) system. Functions as an mRNA interferase antitoxin preventing effects of the HicA toxin (By similarity). Probably forms a complex with the probable mRNA interferase HicA; when complexed with HicA inhibits the toxin activity. Belongs to the HicB antitoxin family. Extended N-terminus. Extended N-terminus.