Antitoxin component of a type II toxin-antitoxin (TA) system (PubMed:24923448). A labile antitoxin that counteracts the effect of cognate toxin YafQ (PubMed:24923448). The YafQ-DinJ heterotetramer binds the consensus sequence 5'-TTTGAGCTACA-3' in the dinJ promoter; DinJ also binds DNA but not as well as the YafQ-DinJ complex (PubMed:24923448). Binding to the dinJ represses expression of the promoter (By similarity). Probably a dimer in solution, forms a heterotetramer with antitoxin DinJ, with 2 YafQ-DinJ dimers associated via the N-terminus of the DinJ antitoxins (YafQ-(DinJ)2-YafQ) (PubMed:24923448). Belongs to the RelB/DinJ antitoxin family.