1q8a

Cobalamin-dependent methionine synthase (1-566) from Thermotoga maritima (Cd2+:L-Hcy complex, Se-Met)

spinqualitylabelsall models 1q8a, resolution 1.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1q8a is a 2 chain structure with sequence from Atcc 43589. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: CD, HCS NonStd Res: MSE Related: 1q7m, 1q7q, 1q7z, 1q85 Activity: Methionine synthase, with EC number 2.1.1.13 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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 B(12)-dependent methionine synthase (MetH) is a large modular enzyme that utilizes the cobalamin cofactor as a methyl donor or acceptor in three separate reactions. Each methyl transfer occurs at a different substrate-binding domain and requires a different arrangement of modules. In the catalytic cycle, the cobalamin-binding domain carries methylcobalamin to the homocysteine (Hcy) domain to form methionine and returns cob(I)alamin to the folate (Fol) domain for remethylation by methyltetrahydrofolate (CH(3)-H(4)folate). Here, we describe crystal structures of a fragment of MetH from Thermotoga maritima comprising the domains that bind Hcy and CH(3)-H(4)folate. These substrate-binding domains are (beta alpha)(8) barrels packed tightly against one another with their barrel axes perpendicular. The properties of the domain interface suggest that the two barrels remain associated during catalysis. The Hcy and CH(3)-H(4)folate substrates are bound at the C termini of their respective barrels in orientations that position them for reaction with cobalamin, but the two active sites are separated by approximately 50 A. To complete the catalytic cycle, the cobalamin-binding domain must travel back and forth between these distant active sites. Structures of the N-terminal modules imply large domain motions during catalysis by methionine synthase.,Evans JC, Huddler DP, Hilgers MT, Romanchuk G, Matthews RG, Ludwig ML Proc Natl Acad Sci U S A. 2004 Mar 16;101(11):3729-36. Epub 2004 Jan 29. PMID:14752199 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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