InterPro: IPR001917 Aminotransferase, class-II, pyridoxal-phosphate binding site

Aminotransferases share certain mechanistic features with other pyridoxal-phosphate dependent enzymes, such as the covalent binding of the pyridoxal-phosphate group to a lysine residue. On the basis of sequence similarity, these various enzymes can be grouped into subfamilies. One of these, is called class-II. It consists of Serine palmitoyltransferase (EC:2.3.1.50), Histidinol-phosphate aminotransferase (EC:2.6.1.9), Glycine acetyltransferase EC:2.3.1.29), 5-aminolevulinic acid synthase (EC:2.3.1.37) and 8-amino-7-oxononanoate synthase (EC:2.3.1.47).

The crystal structures of a number of the aminotransferases have been determined including the structure of l-histidinol phosphate aminotransferase from Escherichia coli (HisC) [1]. HisC is a dimeric enzyme with a mass of approximately 80 kDa. Like most pyridoxal-5'-phosphate (PLP)-dependent enzymes, each HisC monomer consists of two domains, a larger PLP-binding domain having an alpha/beta/alpha topology, and a smaller domain. The N-terminal arm contributes to the dimerization of the two monomers. The PLP-binding domain of HisC shows weak sequence similarity, but significant structural similarity with the PLP-binding domains of a number of PLP-dependent enzymes.