Probable toxic component of a putative type VII toxin-antitoxin (TA) system, probably an RNase. Probably neutralized by cognate antitoxin MJ0435. Neutralization may be due to AMPylation by MJ0435. Homodimer, probably forms a complex with cognate antitoxin MJ0435. Modified by cognate antitoxin MJ0435; probably at least 2 successive AMPylation events occur on Tyr-82. In the N-terminal section; belongs to the HepT RNase toxin family. In the C-terminal section; belongs to the gamma-glutamylcyclotransferase family.