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Crystal structures of a dual coenzyme specific glyceraldehyde-3-phosphate dehydrogenase from the enteric pathogen Campylobacter jejuni
journal contributionposted on 03.08.2021, 16:26 by Adnan Ayna, Peter CE Moody
Campylobacter jejuni is a pathogenic bacteria that causes gastrointestinal disorders and is thus of great importance. Phosphorylating Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is a ubiquitous cellular enzyme that has a well-defined role in glycolysis and other pathways where it catalyses the oxidative phosphorylation of glyceraldehyde 3-phosphate (2-hydroxy-3-oxopropyl dihydrogen phosphate) to 1,3-Bisphosphoglycerate ((2-Hydroxy-3-phosphonooxy-propanoyloxy)phosphonic acid). The C. jejuni genome encodes a single GAPDH enzyme (CjGAPDH) which displays dual (NAD/NADP) coenzyme specificity. NAD-specific GAPDHs are given the EC classification of 184.108.40.206, whereas NADP-specific GAPDHs are classed as 220.127.116.11. GAPDH's with dual specificity are in the class 18.104.22.168. Here we present the X-ray crystal structure of this enzyme (at 2.25 Å), this comprises superimposed structures of NAD- and NADP- complexes showing the structural adaptation that allows this dual specificity, and we consider this in the context of the pathogen's metabolism. There are no previous reports of EC 22.214.171.124 structures that compare the binding of the two co-enzymes. Furthermore, we also report the structure (at 2.05 Å) of the enzyme complexed with the nucleoside ADP and consider this with respect to the reported “moonlighting” activities of GAPDH.