1CLA

EVIDENCE FOR TRANSITION-STATE STABILIZATION BY SERINE-148 IN THE CATALYTIC MECHANISM OF CHLORAMPHENICOL ACETYLTRANSFERASE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.34 Å

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Evidence for transition-state stabilization by serine-148 in the catalytic mechanism of chloramphenicol acetyltransferase.

Lewendon, A.Murray, I.A.Shaw, W.V.Gibbs, M.R.Leslie, A.G.

(1990) Biochemistry 29: 2075-2080


  • PubMed Abstract: 
  • The function of conserved Ser-148 of chloramphenicol acetyltransferase (CAT) has been investigated by site-directed mutagenesis. Modeling studies (P. C. E. Moody and A. G. W. Leslie, unpublished results) suggested that the hydroxyl group of Ser-148 c ...

    The function of conserved Ser-148 of chloramphenicol acetyltransferase (CAT) has been investigated by site-directed mutagenesis. Modeling studies (P. C. E. Moody and A. G. W. Leslie, unpublished results) suggested that the hydroxyl group of Ser-148 could be involved in transition-state stabilization via a hydrogen bond to the oxyanion of the putative tetrahedral intermediate. Replacement of serine by alanine results in a mutant enzyme (Ala-148 CAT) with kcat reduced 53-fold and only minor changes in Km values for chloramphenicol and acetyl-CoA. The Ser-148----Gly substitution gives rise to a mutant enzyme (Gly-148 CAT) with kcat reduced only 10-fold. A water molecule may partially replace the hydrogen-bonding potential of Ser-148 in Gly-148 CAT. The three-dimensional structure of Ala-148 CAT at 2.34-A resolution is isosteric with that of wild-type CAT with two exceptions: the absence of the Ser-148 hydroxyl group and the loss of one poorly ordered water molecule from the active site region. The results are consistent with a catalytic role for Ser-148 rather than a structural one and support the hypothesis that Ser-148 is involved in transition-state stabilization. Ser-148 has also been replaced with cysteine and asparagine; the Ser-148----Cys mutation results in a 705-fold decrease in kcat and the Ser-148----Asn substitution in a 214-fold reduction in kcat. Removing the hydrogen bond donor (Ser-148----Ala or Gly) is less deleterious than replacing Ser-148 with alternative possible hydrogen bond donors (Ser-148----Cys or Asn).


    Related Citations: 
    • Refined Crystal Structure of Type III Chloramphenicol Acetyltransferase at 1.75 Angstroms Resolution
      Leslie, A.G.W.
      (1990) J.Mol.Biol. 213: 167
    • Crystal Structure of the Aspartic Acid-199 (Right Arrow) Asparagine Mutant of Chloramphenicol Acetyltransferase to 2.35-Angstroms Resolution: Structural Consequences of Disruption of a Buried Salt Bridge
      Gibbs, M.R.,Moody, P.C.E.,Leslie, A.G.W.
      (1990) Biochemistry 29: 11261
    • Substitutions in the Active Site of Chloramphenicol Acetyltransferase. Role of a Conserved Aspartate
      Lewendon, A.,Murray, I.A.,Kleanthous, C.,Cullis, P.M.,Shaw, W.V.
      (1988) Biochemistry 27: 7385
    • Crystallization of a Type III Chloramphenicol Acetyl Transferase
      Leslie, A.G.W.,Liddell, J.M.,Shaw, W.V.
      (1986) J.Mol.Biol. 188: 283
    • Structure of Chloramphenicol Acetyltransferase at 1.75-Angstroms Resolution
      Leslie, A.G.W.,Moody, P.C.E.,Shaw, W.V.
      (1988) Proc.Natl.Acad.Sci.USA 85: 4133


    Organizational Affiliation

    Department of Biochemistry, University of Leicester, U.K.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
TYPE III CHLORAMPHENICOL ACETYLTRANSFERASE
A
213Escherichia coliGene Names: cat3
EC: 2.3.1.28
Find proteins for P00484 (Escherichia coli)
Go to UniProtKB:  P00484
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CLM
Query on CLM

Download SDF File 
Download CCD File 
A
CHLORAMPHENICOL
C11 H12 Cl2 N2 O5
WIIZWVCIJKGZOK-RKDXNWHRSA-N
 Ligand Interaction
CO
Query on CO

Download SDF File 
Download CCD File 
A
COBALT (II) ION
Co
XLJKHNWPARRRJB-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.34 Å
  • Space Group: H 3 2
Unit Cell:
Length (Å)Angle (°)
a = 107.340α = 90.00
b = 107.340β = 90.00
c = 123.280γ = 120.00
Software Package:
Software NamePurpose
PROLSQrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1990-07-15
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Derived calculations, Version format compliance