Antitoxin component of a type II toxin-antitoxin (TA) system that counteracts the effect of the HigB toxin (PubMed:19423702, PubMed:8645296, PubMed:24257752). Binds to its own promoter and regulates transcription of the higB/higA operon (PubMed:24257752). Forms a complex with the mRNA interferase HigB which inhibits the mRNA interferase activity (PubMed:19423702). The heterodimer dimerizes to form a HigB-(HigA)2-HigB tetramer that is able to bind to the DNA (PubMed:24257752).