2xt6

Crystal structure of Mycobacterium smegmatis alpha-ketoglutarate decarboxylase homodimer (orthorhombic form)

spinqualitylabelsall models 2xt6, resolution 2.74Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2xt6 is a 2 chain structure with sequence from Mycs2. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CA, MG, TPP Related: 2xt8, 2xt5, 2xta, 2xt7, 2xt9 Activity: 2-oxoglutarate decarboxylase, with EC number 4.1.1.71 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [KGD_MYCS2] Shows three enzymatic activities that share a first common step, the attack of thiamine-PP on 2-oxoglutarate (alpha-ketoglutarate, KG), leading to the formation of an enamine-thiamine-PP intermediate upon decarboxylation. Thus, displays KGD activity, catalyzing the decarboxylation from five-carbon 2-oxoglutarate to four-carbon succinate semialdehyde (SSA). Also catalyzes C-C bond formation between the activated aldehyde formed after decarboxylation of alpha-ketoglutarate and the carbonyl of glyoxylate (GLX), to yield 2-hydroxy-3-oxoadipate (HOA), which spontaneously decarboxylates to form 5-hydroxylevulinate (HLA). And is also a component of the 2-oxoglutarate dehydrogenase (ODH) complex, that catalyzes the overall conversion of 2-oxoglutarate to succinyl-CoA and CO(2). The KG decarboxylase and KG dehydrogenase reactions provide two alternative, tightly regulated, pathways connecting the oxidative and reductive branches of the TCA cycle. Publication Abstract from PubMed The alpha-ketoglutarate dehydrogenase (KDH) complex is a major regulatory point of aerobic energy metabolism. Mycobacterium tuberculosis was reported to lack KDH activity, and the putative KDH E1o component, alpha-ketoglutarate decarboxylase (KGD), was instead assigned as a decarboxylase or carboligase. Here, we show that this protein does in fact sustain KDH activity, as well as the additional two reactions, and these multifunctional properties are shared by the Escherichia coli homolog, SucA. We also show that the mycobacterial enzyme is finely regulated by an additional acyltransferase-like domain and by the action of acetyl-CoA, a powerful allosteric activator able to enhance the concerted protein motions observed during catalysis. Our results uncover the functional plasticity of a crucial node in bacterial metabolism, which may be important for M. tuberculosis during host infection. Functional plasticity and allosteric regulation of alpha-ketoglutarate decarboxylase in central mycobacterial metabolism.,Wagner T, Bellinzoni M, Wehenkel A, O'Hare HM, Alzari PM Chem Biol. 2011 Aug 26;18(8):1011-20. PMID:21867916 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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