MazF enzyme is a toxin protein in the toxin-antitoxin module of E. coli. It possesses endoribonuclease activity and specifically cleaves single-stranded RNA (ssRNA) at 5' ACA sequences. MazF does not cleave double-stranded RNA (dsRNA), double-stranded DNA, or single-stranded DNA. The mRNA interferase-MazF enzyme is supplied as a fusion protein of E. coli MazF and Trigger Factor, which is an E. coli chaperone protein.