1DJB

STRUCTURE OF BETA-LACTAMASE PRECURSOR, S70A MUTANT, AT 298K


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Work: 0.170 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Structure and kinetics of the beta-lactamase mutants S70A and K73H from Staphylococcus aureus PC1.

Chen, C.C.Smith, T.J.Kapadia, G.Wasch, S.Zawadzke, L.E.Coulson, A.Herzberg, O.

(1996) Biochemistry 35: 12251-12258

  • DOI: 10.1021/bi961153v
  • Primary Citation of Related Structures:  1DJA, 1DJC

  • PubMed Abstract: 
  • Two mutant beta-lactamases from Staphylococcus aureus PC1 which probe key catalytic residues have been produced by site-directed mutagenesis. In the S70A enzyme, the nucleophilic group that attacks the beta-lactam carbonyl carbon atom was eliminated. ...

    Two mutant beta-lactamases from Staphylococcus aureus PC1 which probe key catalytic residues have been produced by site-directed mutagenesis. In the S70A enzyme, the nucleophilic group that attacks the beta-lactam carbonyl carbon atom was eliminated. Consequently, the kcat values for hydrolysis of benzylpenicillin and nitrocefin have been reduced by 10(4)-10(5) compared with the wild-type enzyme. The crystal structure of S70A beta-lactamase has been determined at 2.1 A resolution. With the exception of the mutation site, the structure is identical to that of the native enzyme. The residual activity is attributed either to mistranslation that leads to production of wild-type enzyme and/or to remaining features of the active site that stabilize the tetrahedral transition state. Soaking of the crystals with ampicillin or clavulanate, followed by flash-freezing, has been carried out and the structures examined at 2.0 A resolution. For both experiments, the difference electron density maps revealed buildup of density in the active site that presumably corresponds to beta-lactam binding. However, neither electron density is sufficiently clear for defining the atomic details of the bound compounds. The K73H beta-lactamase has been prepared to test the possible role of Lys73 in proton transfer. It exhibits no detectable activity toward benzylpenicillin, and 10(5)-fold reduction of kcat for nitrocefin hydrolysis compared with the wild-type enzyme. No significant recovery of activity has been measured when the pH was varied between 5.0 and 8.0. The crystal structure of K73H beta-lactamase has been determined at 1.9 A resolution. While the overall structure is similar to that of the native enzyme, the electrostatic interactions between His73 and neighboring residues indicate that the imidazole ring is positively charged. In addition, the hydroxyl group of Ser70 adopts a position that is incompatible with nucleophilic attack on substrates. A crystal soaked with ampicillin was flash-frozen, and diffraction data were collected at 2.1 A resolution. The electron density map showed no indication of substrate binding.


    Related Citations: 
    • Refined Crystal Structure of Beta-Lactamase from Staphylococcus Aureus Pc1 at 2.0
      Herzberg, O.
      (1991) J.Mol.Biol. 217: 701
    • An Engineered Staphylococcus Aureus Pc1 Beta-Lactamase that Hydrolyses Third-Generation Cephalosporins
      Zawadzke, L.E.,Smith, T.J.,Herzberg, O.
      (1995) Protein Eng. 8: 1275
    • Bacterial Resistance to Beta-Lactam Antibiotics. Crystal Structure of Beta-Lactamase from Staphylococcus Aureus Pc1 at 2.5 A Resolution
      Herzberg, O.,Moult, J.
      (1987) Science 236: 694


    Organizational Affiliation

    Center for Advanced Research in Biotechnology, University of Maryland Biotechnology Institute, Rockville 20850, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
BETA-LACTAMASE
A
257Staphylococcus aureusGene Names: blaZ
EC: 3.5.2.6
Find proteins for P00807 (Staphylococcus aureus)
Go to UniProtKB:  P00807
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.1 Å
  • R-Value Work: 0.170 
  • Space Group: I 2 2 2
Unit Cell:
Length (Å)Angle (°)
a = 53.700α = 90.00
b = 93.300β = 90.00
c = 138.300γ = 90.00
Software Package:
Software NamePurpose
XENGENdata scaling
X-PLORrefinement
X-PLORmodel building
X-PLORphasing
XENGENdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1997-03-12
    Type: Initial release
  • Version 1.1: 2008-03-21
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2011-11-16
    Type: Atomic model