Toxic component of a type VII toxin-antitoxin (TA) system. Overexpression in E.coli inhibits cell growth. Neutralized by cognate antitoxin MntA (PubMed:33045733). Neutralization is probably due to AMPylation by MntA (Probable). Probably an RNAase (By similarity). Modified by cognate antitoxin MntA; probably at least 2 successive AMPylation events occur on Tyr-82. Belongs to the HepT RNase toxin family.