1f6y

MAD CRYSTAL STRUCTURE ANALYSIS OF METHYLTETRAHYDROFOLATE: CORRINOID/IRON-SULFUR PROTEIN METHYLTRANSFERASE (METR)

spinqualitylabelsall models 1f6y, resolution 2.20Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1f6y is a 2 chain structure with sequence from Moorella thermoacetica. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Related: 1ad4, 1ad1, 1aj0, 1aj2, 1ajz Resources: FirstGlance, OCA, RCSB, PDBsum Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed BACKGROUND: Methyltetrahydrofolate, corrinoid iron-sulfur protein methyltransferase (MeTr), catalyzes a key step in the Wood-Ljungdahl pathway of carbon dioxide fixation. It transfers the N5-methyl group from methyltetrahydrofolate (CH3-H4folate) to a cob(I)amide center in another protein, the corrinoid iron-sulfur protein. MeTr is a member of a family of proteins that includes methionine synthase and methanogenic enzymes that activate the methyl group of methyltetra-hydromethano(or -sarcino)pterin. We report the first structure of a protein in this family. RESULTS: We determined the crystal structure of MeTr from Clostridium thermoaceticum at 2.2 A resolution using multiwavelength anomalous diffraction methods. The overall architecture presents a new functional class of the versatile triose phosphate isomerase (TIM) barrel fold. The MeTr tertiary structure is surprisingly similar to the crystal structures of dihydropteroate synthetases despite sharing less than 20% sequence identity. This homology permitted the methyl-H4folate binding site to be modeled. The model suggests extensive conservation of the pterin ring binding residues in the polar active sites of the methyltransferases and dihydropteroate synthetases. The most significant structural difference between these enzymes is in a loop structure above the active site. It is quite open in MeTr, where it can be modeled as the cobalamin binding site. CONCLUSIONS: The MeTr structure consists of a TIM barrel that embeds methyl-H4folate and cobamide. All related methyltransferases are predicted to fold into a similar TIM barrel pattern and have a similar pterin and cobamide binding site. The observed structure is consistent with either a 'front' (N5) or 'back' (C8a) side protonation of CH3-H4folate, a key step that enhances the electrophilic character of the methyl group, activating it for nucleophilic attack by Co(I). Crystal structure of a methyltetrahydrofolate- and corrinoid-dependent methyltransferase.,Doukov T, Seravalli J, Stezowski JJ, Ragsdale SW Structure. 2000 Aug 15;8(8):817-30. PMID:10997901 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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