Dual regulation of HEPN RNase in fused MNT-HEPN toxin-antitoxin systems via protein OligoAMPylation and oligomerization

Enzymatic toxins targeting nucleic acids are a widespread strategy for resolving biological conflicts. Ubiquitous HEPN domain-containing proteins harbor a conserved RNase motif and are found in both prokaryotes and eukaryotes. In prokaryotes, HEPN domain toxins frequently pair with adjacent MNT domain antitoxins to form the prevalent type VII HepT/MntA toxin-antitoxin (TA) system. Here, we identified a group of fused MNT-HEPN proteins (renamed FhepTA) carried by mobile genetic elements in the Sh