Antitoxin component of a type II toxin-antitoxin (TA) system. Neutralizes the toxic effect of cognate toxin HipA; overexpression in wild-type or a hipAB deletion temporarily inhibits cell growth. Binds operator DNA; in the ternary phosphoserine-HipA-HipB-DNA complex the DNA is bent about 125 degrees. Homodimer, binds DNA. Forms a HipA(2)HipB(2)-DNA complex with cognate toxin HipA; has higher affinity for the latter when HipB is prebound to DNA and HipA is phosphorylated. Expressed in late-exponential phase; part of the hipBA operon. Essential; a single hipB deletion cannot be made, probably due to toxicity of HipA. Belongs to the HipB antitoxin family.