Toxic component of a type II toxin-antitoxin (TA) system. Upon expression in E.coli partially inhibits cell growth after one cell generation (PubMed:16611633). Its cognate antitoxin is MazE2. Probably an endoribonuclease (By similarity). Forms a complex with cognate antitoxin MazE2. Belongs to the PemK/MazF family.