This is a HEPN-like nuclease. Part of mobile integron element. The integron cassettes are known to be activated by stress conditions, thereby allowing swapping of genetic material that might be of adaptive value. Hence it is hypothesized that the HEPN domains present in some integron cassettes contribute to the stress response by functioning as RNases that induce dormancy by probably inhibiting translation and thus enabling survival of harsh conditions [1].

1: Comprehensive analysis of the HEPN superfamily: identification of novel roles in intra-genomic conflicts, defense, pathogenesis and RNA processing. Anantharaman V, Makarova KS, Burroughs AM, Koonin EV, Aravind L; Biol Direct. 2013;8:15. PMID:23768067