5zxl
Structure of GldA from E.coli
Structural highlights
FunctionGLDA_ECOLI Catalyzes the NAD-dependent oxidation of glycerol to dihydroxyacetone (glycerone). Allows microorganisms to utilize glycerol as a source of carbon under anaerobic conditions. In E.coli, an important role of GldA is also likely to regulate the intracellular level of dihydroxyacetone by catalyzing the reverse reaction, i.e. the conversion of dihydroxyacetone into glycerol. Possesses a broad substrate specificity, since it is also able to oxidize 1,2-propanediol and to reduce glycolaldehyde, methylglyoxal and hydroxyacetone into ethylene glycol, lactaldehyde and 1,2-propanediol, respectively.[1] [2] [3] [4] Publication Abstract from PubMedEscherichia coli (strain K-12, substrain MG1655) glycerol dehydrogenase (GldA) is required to catalyze the first step in fermentative glycerol metabolism. The protein was expressed and purified to homogeneity using a simple combination of heat-shock and chromatographic methods. The high yield of the protein ( approximately 250 mg per litre of culture) allows large-scale production for potential industrial applications. Purified GldA exhibited a homogeneous tetrameric state ( approximately 161 kDa) in solution and relatively high thermostability (Tm = 65.6 degrees C). Sitting-drop sparse-matrix screens were used for protein crystallization. An optimized condition with ammonium sulfate (2 M) provided crystals suitable for diffraction, and a binary structure containing glycerol in the active site was solved at 2.8 A resolution. Each GldA monomer consists of nine beta-strands, thirteen alpha-helices, two 310-helices and several loops organized into two domains, the N- and C-terminal domains; the active site is located in a deep cleft between the two domains. The N-terminal domain contains a classic Rossmann fold for NAD(+) binding. The O1 and O2 atoms of glycerol serve as ligands for the tetrahedrally coordinated Zn(2+) ion. The orientation of the glycerol within the active site is mainly stabilized by van der Waals and electrostatic interactions with the benzyl ring of Phe245. Computer modeling suggests that the glycerol molecule is sandwiched by the Zn(2+) and NAD(+) ions. Based on this, the mechanism for the relaxed substrate specificity of this enzyme is also discussed. Structure of glycerol dehydrogenase (GldA) from Escherichia coli.,Zhang J, Nanjaraj Urs AN, Lin L, Zhou Y, Hu Y, Hua G, Gao Q, Yuchi Z, Zhang Y Acta Crystallogr F Struct Biol Commun. 2019 Mar 1;75(Pt 3):176-183. doi:, 10.1107/S2053230X19000037. Epub 2019 Feb 21. PMID:30839292[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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