4els

Structure of E. Coli. 1,4-dihydroxy-2- naphthoyl coenzyme A synthases (MENB) in complex with bicarbonate

spinqualitylabelsall models 4els, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4els is a 6 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: BCT, CL, EDO, GOL, PEG Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [MENB_ECOLI] Converts o-succinylbenzoyl-CoA (OSB-CoA) to 1,4-dihydroxy-2-naphthoyl-CoA (DHNA-CoA). Publication Abstract from PubMed 1,4-Dihydroxy-2-naphthoyl coenzyme A (DHNA-CoA) synthase, or MenB, catalyzes a carbon-carbon bond formation reaction in the biosynthesis of both vitamin K1 and K2. Bicarbonate is crucial to the activity of a large subset of its orthologues but lacks a clearly defined structural and mechanistic role. Here we determine the crystal structure of the holoenzymes from Escherichia coli at 2.30 A and Synechocystis sp. PCC6803 at 2.04 A, in which the bicarbonate cofactor is bound to the enzyme active site at a position equivalent to that of the side chain carboxylate of an aspartate residue conserved among bicarbonate-insensitive DHNA-CoA synthases. Binding of the planar anion involves both nonspecific electrostatic attraction and specific hydrogen bonding and hydrophobic interactions. In the absence of bicarbonate, the anion binding site is occupied by a chloride ion or nitrate, an inhibitor directly competing with bicarbonate. These results provide a solid structural basis for the bicarbonate dependence of the enzymatic activity of type I DHNA-CoA synthases. The unique location of the bicarbonate ion in relation to the expected position of the substrate alpha-proton in the enzyme's active site suggests a critical catalytic role for the anionic cofactor as a catalytic base in enolate formation. Active Site Binding and Catalytic Role of Bicarbonate in 1,4-Dihydroxy-2-naphthoyl Coenzyme A Synthases from Vitamin K Biosynthetic Pathways.,Sun Y, Song H, Li J, Jiang M, Li Y, Zhou J, Guo Z Biochemistry. 2012 May 24. PMID:22606952 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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