A P subtype restriction enzyme that recognizes the double-stranded sequence 5'-GGWCC-3' and cleaves after G-1 (PubMed:7607523, PubMed:12654995). This system is more active than isoschizomeric RM.HgiBI (PubMed:7607523). Endonucleolytic cleavage of DNA to give specific double-stranded fragments with terminal 5'-phosphates. Belongs to the TdeIII type II restriction endonuclease family.