1C9K

THE THREE DIMENSIONAL STRUCTURE OF ADENOSYLCOBINAMIDE KINASE/ ADENOSYLCOBINAMIDE PHOSPHATE GUALYLYLTRANSFERASE (COBU) COMPLEXED WITH GMP: EVIDENCE FOR A SUBSTRATE INDUCED TRANSFERASE ACTIVE SITE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Three-dimensional structure of adenosylcobinamide kinase/adenosylcobinamide phosphate guanylyltransferase (CobU) complexed with GMP: evidence for a substrate-induced transferase active site.

Thompson, T.B.Thomas, M.G.Escalante-Semerena, J.C.Rayment, I.

(1999) Biochemistry 38: 12995-13005


  • PubMed Abstract: 
  • The X-ray crystal structure of adenosylcobinamide kinase/adenosylcobinamide phosphate guanylyltransferase (CobU) from Salmonella typhimurium bound to GMP has been determined by molecular replacement to 2.2 A resolution. CobU is a bifunctional enzyme, ...

    The X-ray crystal structure of adenosylcobinamide kinase/adenosylcobinamide phosphate guanylyltransferase (CobU) from Salmonella typhimurium bound to GMP has been determined by molecular replacement to 2.2 A resolution. CobU is a bifunctional enzyme, which catalyzes the phosphorylation of the 1-amino-O-2-propanol side chain of the adenosylcobinamide ring and subsequently functions as a guanylyltransferase to form adenosylcobinamide.GDP. The transferase activity involves a covalent enzyme-guanylyl intermediate that is most likely a phosphoramidate linkage to His(46). Previous studies have shown that the enzyme is a homotrimer and adopts a pinwheel shape. Each subunit consists of a single domain of six parallel beta-strands and one antiparallel strand flanked on either side by a total of five alpha-helices and one helical turn. Interestingly, His(46) in the apoenzyme is located a considerable distance from the kinase active site or P-loop motif and is solvent-exposed [Thompson, T. B., et al. (1998) Biochemistry 37, 7686-7695]. To examine the structural relationship of the two active sites, CobU was cocrystallized with GTP and pyrophosphate. Crystals belong to space group P2(1)2(1)2(1) with the following unit cell dimensions: a = 58. 4 A, b = 87.8 A, and c = 101.6 A. The structure shows electron density for the hydrolysis product GMP rather than the expected covalent guanylyl intermediate which appears to have been hydrolyzed in the crystal lattice. Even so, CobU exhibits a substantial conformational rearrangement. The helix axis containing His(46), the site of guanylylation, rotates 30 degrees and translates 11 A relative to the apo structure and is accompanied by compensatory unwinding and rewinding at the helix ends to allow the induction of a guanosine binding pocket between beta-strand 2 and alpha-helix 2. This conformational change brings the C(alpha) of His(46) approximately 10 A closer to the P-loop motif such that a phosphate ion located in the P-loop is only 6 A from the alpha-phosphate of GMP. This suggests that the P-loop motif may be used to coordinate the terminal phosphates in both the transferase and kinase reactions and implies that the active sites for both reactions overlap.


    Organizational Affiliation

    Institute for Enzyme Research, Department of Biochemistry, University of Wisconsin, Madison 53705, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
ADENOSYLCOBINAMIDE KINASE
A, B, C
180Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)Mutation(s): 0 
Gene Names: cobU
Find proteins for Q05599 (Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720))
Go to UniProtKB:  Q05599
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PO4
Query on PO4

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Download CCD File 
A, B
PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
 Ligand Interaction
POP
Query on POP

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Download CCD File 
C
PYROPHOSPHATE 2-
H2 O7 P2
XPPKVPWEQAFLFU-UHFFFAOYSA-L
 Ligand Interaction
MG
Query on MG

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Download CCD File 
C
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
5GP
Query on 5GP

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Download CCD File 
A, B, C
GUANOSINE-5'-MONOPHOSPHATE
C10 H14 N5 O8 P
RQFCJASXJCIDSX-UUOKFMHZSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 58.380α = 90.00
b = 87.770β = 90.00
c = 101.640γ = 90.00
Software Package:
Software NamePurpose
TNTrefinement
SCALEPACKdata scaling
DENZOdata reduction
AMoREphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1999-08-18
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2018-01-31
    Type: Experimental preparation