Toxic component of a type II toxin-antitoxin (TA) system. Upon expression in E.coli and M.smegmatis inhibits cell growth and colony formation. Its toxic effect is neutralized by coexpression with cognate antitoxin MazE7 (PubMed:19016878, PubMed:20011113). Probably an endoribonuclease (By similarity). Forms a complex with cognate antitoxin MazE7. Belongs to the PemK/MazF family.