6pbn
Pseudopaline Dehydrogenase with (R)-Pseudopaline Soaked 1 hour
Structural highlights
FunctionODH_PSEAE Catalyzes the NAD(P)H-dependent reductive condensation of alpha-ketoglutarate to the intermediate formed by the adjacently encoded enzyme PA4836, namely (2S)-2-amino-4-{[(1S)-1-carboxy-2-(1H-imidazol-4-yl)ethyl]amino}butanoate, leading to the production of pseudopaline. This is the last step in the biosynthesis of the metallophore pseudopaline, which is involved in the acquisition of nickel and zinc, and thus enables bacterial growth inside the host, where metal access is limited. Therefore, this enzyme probably contributes to Pseudomonas virulence. Can use neither pyruvate nor oxaloacetate in place of alpha-ketoglutarate (PubMed:29091735, PubMed:29618515). Is two-fold more efficient using NADPH than NADH as the electron donor (PubMed:29618515).[1] [2] Publication Abstract from PubMedPseudopaline and staphylopine are opine metallophores biosynthesized by Pseudomonas aeruginosa and Staphylococcus aureus, respectively. The final step in opine metallophore biosynthesis is the condensation of the product of a nicotianamine (NA) synthase reaction (i.e. L-HisNA for pseudopaline and D-HisNA for staphylopine) with an alpha-keto acid (alpha-ketoglutarate for pseudopaline and pyruvate for staphylopine), which is performed by an opine dehydrogenase. We hypothesized that the opine dehydrogenase reaction would be reversible only for the opine metallophore product with (R) stereochemistry at carbon C2 of the alpha-keto acid (prochiral prior to catalysis). A kinetic analysis using stopped-flow spectometetry with (R)- or (S)-staphylopine and kinetic and structural analysis with (R)- and (S)-pseudopaline confirmed catalysis in the reverse direction for only (R)-staphylopine and (R)-pseudopaline, verifying the stereochemistry of these two opine metallophores. Structural analysis at 1.65 - 1.85 A resolution captured the hydrolysis of (R)-pseudopaline and allowed identification of a binding pocket for the L-histidine moiety of pseudopaline formed through a repositioning of Phe-340 and Tyr-289 during the catalytic cycle. Transient-state kinetic analysis revealed an ordered release of NADP+ followed by staphylopine, with staphylopine release being the rate-limiting step in catalysis. Knowledge of the stereochemistry for opine metallophores has implications for future studies involving kinetic analysis, as well as opine metallophore transport, metal coordination, and the generation of chiral amines for pharmaceutical development. Staphylopine and pseudopaline dehydrogenase from bacterial pathogens catalyze reversible reactions and produce stereospecific metallophores.,McFarlane JS, Zhang J, Wang S, Lei X, Moran GR, Lamb AL J Biol Chem. 2019 Oct 15. pii: RA119.011059. doi: 10.1074/jbc.RA119.011059. PMID:31615895[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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