This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.Pyridoxol-5'-phosphate (PLP)is the biologically active form of vitamin B6 and a critical cofactor for various enzymes that catalyze metabolic reactions. Its mechanistic function is the stabilization of carbanions adjacent to amino groups. This cofactor therefore plays a key role in amino acid metabolism; PLP containing enzymes catalyze racemization, decarboxylation, transamination, and side-chain substitution reactions of amino acids. PLP is biosynthesized in bacteria, fungi, and plants but it is an essential nutrient in animals. The subunits of PLP synthase complex are a PLP synthase (YaaD) which has a classic (alpha/beta)8 fold , and a glutamine amidotransferase (YaaE) which has a (alpha/beta) three layer sandwich fold. Ammonia is formed in YaaE, obtained by the hydrolysis of glutamine to glutamate. This ammonia is shuttled through an ammonia channel to the active site of YaaD where the PLP ring forms. The complex functions in a new de novo pathway for the synthesis of PLP. This pathway is distinct from the Escherichia coli-like pathway, which has been extensively characterized.
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