4HUT

Structure of ATP:co(I)rrinoid adenosyltransferase (CobA) from Salmonella enterica in complex with four and five-coordinate cob(II)alamin and ATP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.232 
  • R-Value Work: 0.175 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Structural Insights into the Mechanism of Four-Coordinate Cob(II)alamin Formation in the Active Site of the Salmonella enterica ATP:Co(I)rrinoid Adenosyltransferase Enzyme: Critical Role of Residues Phe91 and Trp93.

Moore, T.C.Newmister, S.A.Rayment, I.Escalante-Semerena, J.C.

(2012) Biochemistry 51: 9647-9657

  • DOI: 10.1021/bi301378d

  • PubMed Abstract: 
  • ATP:co(I)rrinoid adenosyltransferases (ACATs) are enzymes that catalyze the formation of adenosylcobalamin (AdoCbl, coenzyme B(12)) from cobalamin and ATP. There are three families of ACATs, namely, CobA, EutT, and PduO. In Salmonella enterica, CobA ...

    ATP:co(I)rrinoid adenosyltransferases (ACATs) are enzymes that catalyze the formation of adenosylcobalamin (AdoCbl, coenzyme B(12)) from cobalamin and ATP. There are three families of ACATs, namely, CobA, EutT, and PduO. In Salmonella enterica, CobA is the housekeeping enzyme that is required for de novo AdoCbl synthesis and for salvaging incomplete precursors and cobalamin from the environment. Here, we report the crystal structure of CobA in complex with ATP, four-coordinate cobalamin, and five-coordinate cobalamin. This provides the first crystallographic evidence of the existence of cob(II)alamin in the active site of CobA. The structure suggests a mechanism in which the enzyme adopts a closed conformation and two residues, Phe91 and Trp93, displace 5,6-dimethylbenzimidazole, the lower nucleotide ligand base of cobalamin, to generate a transient four-coordinate cobalamin, which is critical in the formation of the AdoCbl Co-C bond. In vivo and in vitro mutational analyses of Phe91 and Trp93 emphasize the important role of bulky hydrophobic side chains in the active site. The proposed manner in which CobA increases the redox potential of the cob(II)alamin/cob(I)alamin couple to facilitate formation of the Co-C bond appears to be analogous to that utilized by the PduO-type ACATs, where in both cases the polar coordination of the lower ligand to the cobalt ion is eliminated by placing that face of the corrin ring adjacent to a cluster of bulky hydrophobic side chains.


    Organizational Affiliation

    Department of Bacteriology, University of Wisconsin, Madison, WI 53706, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Cob(I)yrinic acid a,c-diamide adenosyltransferase
A, B
191Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)Gene Names: btuR (cobA)
EC: 2.5.1.17
Find proteins for P31570 (Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720))
Go to UniProtKB:  P31570
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ATP
Query on ATP

Download SDF File 
Download CCD File 
A, B
ADENOSINE-5'-TRIPHOSPHATE
C10 H16 N5 O13 P3
ZKHQWZAMYRWXGA-KQYNXXCUSA-N
 Ligand Interaction
EDO
Query on EDO

Download SDF File 
Download CCD File 
A
1,2-ETHANEDIOL
ETHYLENE GLYCOL
C2 H6 O2
LYCAIKOWRPUZTN-UHFFFAOYSA-N
 Ligand Interaction
MG
Query on MG

Download SDF File 
Download CCD File 
A, B
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
B12
Query on B12

Download SDF File 
Download CCD File 
A, B
COBALAMIN
C62 H89 Co N13 O14 P
LKVIQTCSMMVGFU-DWSMJLPVSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.232 
  • R-Value Work: 0.175 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 59.862α = 90.00
b = 74.223β = 90.00
c = 92.396γ = 90.00
Software Package:
Software NamePurpose
MOLREPphasing
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
REFMACrefinement
HKL-3000data reduction
HKL-3000data collection

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-01-23
    Type: Initial release
  • Version 1.1: 2013-02-20
    Type: Database references