1JHP

Three-dimensional Structure of CobT in Complex with 5-methoxybenzimidazole


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.295 
  • R-Value Work: 0.179 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structural investigation of the biosynthesis of alternative lower ligands for cobamides by nicotinate mononucleotide: 5,6-dimethylbenzimidazole phosphoribosyltransferase from Salmonella enterica.

Cheong, C.G.Escalante-Semerena, J.C.Rayment, I.

(2001) J.Biol.Chem. 276: 37612-37620

  • DOI: 10.1074/jbc.M105390200
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Nicotinate mononucleotide (NaMN):5,6-dimethylbenzimidazole phosphoribosyltransferase (CobT) from Salmonella enterica plays a central role in the synthesis of alpha-ribazole, a key component of the lower ligand of cobalamin. Surprisingly, CobT can pho ...

    Nicotinate mononucleotide (NaMN):5,6-dimethylbenzimidazole phosphoribosyltransferase (CobT) from Salmonella enterica plays a central role in the synthesis of alpha-ribazole, a key component of the lower ligand of cobalamin. Surprisingly, CobT can phosphoribosylate a wide range of aromatic substrates, giving rise to a wide variety of lower ligands in cobamides. To understand the molecular basis for this lack of substrate specificity, the x-ray structures of CobT complexed with adenine, 5-methylbenzimidazole, 5-methoxybenzimidazole, p-cresol, and phenol were determined. Furthermore, adenine, 5-methylbenzimidazole, 5-methoxybenzimidazole, and 2-hydroxypurine were observed to react with NaMN within the crystal lattice and undergo the phosphoribosyl transfer reaction to form product. Significantly, the stereochemistries of all products are identical to those found in vivo. Interestingly, p-cresol and phenol, which are the lower ligand in Sporomusa ovata, bound to CobT but did not react with NaMN. This study provides a structural explanation for how CobT can phosphoribosylate most of the commonly observed lower ligands found in cobamides with the exception of the phenolic lower ligands observed in S. ovata. This is accomplished with minor conformational changes in the side chains that constitute the 5,6-dimethylbenzimidazole binding site. These investigations are consistent with the implication that the nature of the lower ligand is controlled by metabolic factors rather by the specificity of the phosphoribosyltransferase.


    Organizational Affiliation

    Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Nicotinate Mononucleotide:5,6-Dimethylbenzimidazole Phosphoribosyltransferase
A
356Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)Mutation(s): 0 
Gene Names: cobT
EC: 2.4.2.21
Find proteins for Q05603 (Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720))
Go to UniProtKB:  Q05603
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PO4
Query on PO4

Download SDF File 
Download CCD File 
A
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
 Ligand Interaction
5OB
Query on 5OB

Download SDF File 
Download CCD File 
A
5-METHOXYBENZIMIDAZOLE
C8 H8 N2 O
ILMHAGCURJPNRZ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.295 
  • R-Value Work: 0.179 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 71.700α = 90.00
b = 89.980β = 90.00
c = 47.630γ = 90.00
Software Package:
Software NamePurpose
TNTphasing
TNTrefinement
XDSdata reduction
XDSdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-10-18
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Derived calculations, Version format compliance