PMID:15016358

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Citation

Price, AC, Zhang, YM, Rock, CO and White, SW (2004) Cofactor-induced conformational rearrangements establish a catalytically competent active site and a proton relay conduit in FabG. Structure 12:417-28

Abstract

beta-Ketoacyl-acyl carrier protein reductase (FabG) is a key component in the type II fatty acid synthase system. The structures of Escherichia coli FabG and the FabG[Y151F] mutant in binary complexes with NADP(H) reveal that mechanistically important conformational changes accompany cofactor binding. The active site Ser-Tyr-Lys triad is repositioned into a catalytically competent constellation, and a hydrogen bonded network consisting of ribose hydroxyls, the Ser-Tyr-Lys triad, and four water molecules creates a proton wire to replenish the tyrosine proton donated during catalysis. Also, a disordered loop in FabG forms a substructure in the complex that shapes the entrance to the active site. A key observation is that the nicotinamide portion of the cofactor is disordered in the FabG[Y151F].NADP(H) complex, and Tyr151 appears to be necessary for high-affinity cofactor binding. Biochemical data confirm that FabG[Y151F] is defective in NADPH binding. Finally, structural changes consistent with the observed negative cooperativity of FabG are described.

Links

PubMed Online version:10.1016/j.str.2004.02.008

Keywords

Alcohol Oxidoreductases/chemistry; Alcohol Oxidoreductases/metabolism; Binding Sites; Calcium/metabolism; Catalytic Domain; Crystallography, X-Ray; Escherichia coli/enzymology; NADP/metabolism; Protein Binding; Protein Conformation; Protons

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