| Type: | Family | Name: | Pyridoxal 5'-phosphate synthase subunit PdxS/SNZ |
| Description: | This entry represents a family of pyridoxal 5'-phosphate synthase subunit, known as pdxS/SNZ family. Proteins in this family occur in organisms in four kingdoms and form one of the most highly conserved family []. PdxS/SNZ proteins have aclassic (beta/alpha)8-barrel fold, consisting of eight parallel beta-strands alternating with eight alpha helices []. They are involved in vitamin B6 biosynthesis.The term vitamin B6 is used to refer collectively to the compound pyridoxine and its vitameric forms, pyridoxal, pyridoxamine, and their phosphorylatedderivatives. Vitamin B6 is required by all organisms and plays an essential role as a co-factor for enzymatic reactions. Plants, fungi, bacteria,archaebacteria, and protists synthetize vitamin B6. Animals and some highly specialised obligate pathogens obtain it nutritionally. Vitamin B6 has twodistinct biosynthetic pathways, which do not coexist in any organism. The pdxA/pdxJ pathway, that has been extensively characterised in Escherichiacoli, is found in the gamma subdivision of the proteobacteria. A second pathway of vitamin B6 synthesis involving the pdxS/SNZ and pdxT/SNO protein families, which are completely unrelated in sequence tothe pdxA/pdxJ proteins, is found in plants, fungi, protists, archaebacteria, and most bacteria.PdxS/SNZ and pdxT/SNO proteins form a complex which serves as a glutamine amidotransferase to supply ammonia as a source of the ring nitrogen of vitaminB6 []. PdxT/SNO and pdxS/SNZ appear to encode respectively the glutaminasesubunit, which produces ammonia from glutamine, and the synthase subunit, which combines ammonia with five- and three-carbon phosphosugars to formvitamin B6 []. | Short Name: | PdxS/SNZ |
