Probable toxic component of a putative type VII toxin-antitoxin (TA) system, probably an RNase. Probably neutralized by cognate antitoxin AF_0948. Neutralization may be due to AMPylation by AF_0948. Homodimer, probably forms a complex with cognate antitoxin AF_0948. Modified by cognate antitoxin AF_0948; probably at least 2 successive AMPylation events occur on Tyr-98. Belongs to the HepT RNase toxin family.