3o07

Publication Abstract from PubMed

In most eubacteria, fungi, apicomplexa, plants, and some metazoans, the active form of vitamin B6, pyridoxal 5-phosphate (PLP) is de novo synthesized from three substrates, ribose 5-phosphate (R5P), dihydroxyacetone phosphate (DHAP), and ammonia hydrolyzed from glutamine by a complexed glutaminase. Of the three active sites of deoxyxylulose 5-phosphate (DXP)-independent PLP synthase (Pdx1), the R5P isomerization site has been assigned, but the sites for DHAP isomerization and PLP formation remain unknown. Here, we present the crystal structures of yeast Pdx1/Snz1, in apo-, glyceraldehyde 3-phosphate (G3P)- and PLP-bound forms, at 2.30, 1.80, and 2.20 A, respectively. Structural and biochemical analysis enabled us to assign the PLP-formation site, a G3P-binding site and a G3P-transfer site. We propose a putative catalytic mechanism for Pdx1/Snz1 in which R5P and DHAP are isomerized at two distinct sites and transferred along well-defined routes to a final destination for PLP synthesis.

Structural insights into the catalytic mechanism of the yeast pyridoxal 5-phosphate synthase Snz1.,Zhang X, Teng YB, Liu JP, He YX, Zhou K, Chen Y, Zhou CZ Biochem J. 2010 Oct 5. PMID:20919991^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.