Antitoxin component of a type II toxin-antitoxin (TA) system. Upon expression in E.coli or S.cerevisiae neutralizes the effect of cognate toxin VapC2, partially inhibits the RNase activity of VapC2. Forms complexes with VapC2; probably VapC2(4):VapB2(2) in the absence of DNA, and VapC2(4):VapB2(4) in the presence of DNA. Crystallizes as heterodimers with stoichiometry VapC2(4):VapB2(4) in the presence of its probable promoter DNA. The heterodimers are in contact via alternative VapC-VapC and VapB-VapB interactions. This subunit contacts DNA. Belongs to the VapB family.