Structural highlights
FunctionG2M827_HELPX Catalyzes the NADPH-dependent reduction of beta-ketoacyl-ACP substrates to beta-hydroxyacyl-ACP products, the first reductive step in the elongation cycle of fatty acid biosynthesis.[RuleBase:RU366074] Publication Abstract from PubMedThe short-chain dehydrogenase/reductase (SDR) superfamily members acyl-ACP reductases FabG and FabI are indispensable core enzymatic modules and catalytic orientation controllers in type-II fatty acid biosynthesis. Herein, we report their distinct substrate allosteric recognition and enantioselective reduction mechanisms. FabG achieves allosteric regulation of ACP and NADPH through ACP binding across two adjacent FabG monomers, while FabI follows an irreversible compulsory order of substrate binding in that NADH binding must precede that of ACP on a discrete FabI monomer. Moreover, FabG and FabI utilize a backdoor residue Phe187 or a "rheostat" alpha8 helix for acyl chain length selection, and their corresponding triad residues Ser142 or Tyr145 recognize the keto- or enoyl-acyl substrates, respectively, facilitating initiation of nucleophilic attack by NAD(P)H. The other two triad residues (Tyr and Lys) mediate subsequent proton transfer and (R)-3-hydroxyacyl- or saturated acyl-ACP production. The Molecular Basis of Catalysis by SDR Family Members Ketoacyl-ACP Reductase FabG and Enoyl-ACP Reductase FabI in Type-II Fatty Acid Biosynthesis.,Zhou J, Zhang L, Wang Y, Song W, Huang Y, Mu Y, Schmitz W, Zhang SY, Lin H, Chen HZ, Ye F, Zhang L Angew Chem Int Ed Engl. 2023 Nov 13;62(46):e202313109. doi: , 10.1002/anie.202313109. Epub 2023 Oct 12. PMID:37779101[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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This page was last modified 11:11, 22 November 2023.