2E0K

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


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.218 
  • R-Value Observed: 0.221 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

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.

(2007) FEBS J 274: 563-573

  • DOI: 10.1111/j.1742-4658.2006.05611.x
  • Primary Citation of Related Structures:  
    2E0K, 2E0N

  • PubMed Abstract: 
  • 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 ...

    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.


    Organizational Affiliation

    Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Japan. keiwada@bio.sci.osaka-u.ac.jp



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Precorrin-2 C20-methyltransferaseA, B259Chlorobaculum tepidumMutation(s): 0 
Gene Names: cbiL
EC: 2.1.1.130
UniProt
Find proteins for Q8KFD9 (Chlorobaculum tepidum (strain ATCC 49652 / DSM 12025 / NBRC 103806 / TLS))
Explore Q8KFD9 
Go to UniProtKB:  Q8KFD9
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8KFD9
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.10 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.218 
  • R-Value Observed: 0.221 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 88.214α = 90
b = 88.214β = 90
c = 123.697γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
BSSdata collection
HKL-2000data reduction
HKL-2000data scaling
MOLREPphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-01-16
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Advisory, Version format compliance