Nucleotidyltransferases (EC 2.7.7) comprise a large enzymefamily with diverse roles in polynucleotide synthesis andmodification. This domain is structurally related to kanamycinnucleotidyltransferase (KNTase) and forms a complex with HI0073,a sequence homolog of the nucleotide-binding domain of thisnucleotidyltransferase superfamily [1]. Nucleotidyltransferase substrate binding protein like NTase_sub_bind