2e0k

Crystal structure of CbiL, a methyltransferase involved in anaerobic vitamin B12 biosynthesis

spinqualitylabelsall models 2e0k, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2e0k is a 2 chain structure with sequence from Chlorobaculum tepidum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.1Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q8KFD9_CHLTE 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 During anaerobic cobalamin (vitamin B12) biosynthesis, CbiL catalyzes methylation at the C-20 position of a cyclic tetrapyrrole ring using S-adenosylmethionine as a methyl group source. This methylation is a key modification for the ring contraction process, by which a porphyrin-type tetrapyrrole ring is converted to a corrin ring through elimination of the modified C-20 and direct bonding of C-1 to C-19. We have determined the crystal structures of Chlorobium tepidum CbiL and CbiL in complex with S-adenosylhomocysteine (the S-demethyl form of S-adenosylmethionine). CbiL forms a dimer in the crystal, and each subunit consists of N-terminal and C-terminal domains. S-Adenosylhomocysteine binds to a cleft between the two domains, where it is specifically recognized by extensive hydrogen bonding and van der Waals interactions. The orientation of the cobalt-factor II substrate was modeled by simulation, and the predicted model suggests that the hydroxy group of Tyr226 is located in close proximity to the C-20 atom as well as the C-1 and C-19 atoms of the tetrapyrrole ring. These configurations allow us to propose a catalytic mechanism: the conserved Tyr226 residue in CbiL catalyzes the direct transfer of a methyl group from S-adenosylmethionine to the substrate through an S(N)2-like mechanism. Furthermore, the structural model of CbiL binding to its substrate suggests the axial residue coordinated to the central cobalt of cobalt-factor II. Crystal structures of CbiL, a methyltransferase involved in anaerobic vitamin B biosynthesis, and CbiL in complex with S-adenosylhomocysteine--implications for the reaction mechanism.,Wada K, Harada J, Yaeda Y, Tamiaki H, Oh-Oka H, Fukuyama K FEBS J. 2007 Jan;274(2):563-73. PMID:17229157 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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