Members of this family are bacterial and archaeal RNA ligases that are able to ligate tRNA half molecules containing 2',3'-cyclic phosphate and 5' hydroxyl termini to products containing the 2',5' phosphodiester linkage. Each member of this family contains an internal duplication, each of which contains an HXTX motif that defines the family. The structure of a related protein is known. They belong to the 2H phosphoesterase superfamily. They share a common active site, characterized by two conserved histidines, with vertebrate myelin-associated 2',3' phosphodiesterases, plant Arabidopsis thaliana CPDases and several several bacteria and virus proteins.