1G6A

PSE-4 CARBENICILLINASE, R234K MUTANT


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.209 
  • R-Value Work: 0.178 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Insights into the molecular basis for the carbenicillinase activity of PSE-4 beta-lactamase from crystallographic and kinetic studies.

Lim, D.Sanschagrin, F.Passmore, L.De Castro, L.Levesque, R.C.Strynadka, N.C.

(2001) Biochemistry 40: 395-402

  • Primary Citation of Related Structures:  1G68

  • PubMed Abstract: 
  • PSE-4 is a class A beta-lactamase produced by strains of Pseudomonas aeruginosa and is highly active for the penicillin derivative carbenicillin. The crystal structure of the wild-type PSE-4 carbenicillinase has been determined to 1.95 A resolution b ...

    PSE-4 is a class A beta-lactamase produced by strains of Pseudomonas aeruginosa and is highly active for the penicillin derivative carbenicillin. The crystal structure of the wild-type PSE-4 carbenicillinase has been determined to 1.95 A resolution by molecular replacement and represents the first structure of a carbenicillinase published to date. A superposition of the PSE-4 structure with that of TEM-1 shows a rms deviation of 1.3 A for 263 Calpha atoms. Most carbenicillinases are unique among class A beta-lactamases in that residue 234 is an arginine (ABL standard numbering scheme), while in all other class A enzymes this residue is a lysine. Kinetic characterization of a R234K PSE-4 mutant reveals a 50-fold reduction in k(cat)/K(m) and confirms the importance of Arg 234 for carbenicillinase activity. A comparison of the structure of the R234K mutant refined to 1.75 A resolution with the wild-type structure shows that Arg 234 stabilizes an alternate conformation of the Ser 130 side chain, not seen in other class A beta-lactamase structures. Our molecular modeling studies suggest that the position of a bound carbenicillin would be shifted relative to that of a bound benzylpenicillin in order to avoid a steric clash between the carbenicillin alpha-carboxylate group and the conserved side chain of Asn 170. The alternate conformation of the catalytic Ser 130 in wild-type PSE-4 may be involved in accommodating this shift in the bound substrate position.


    Organizational Affiliation

    Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
BETA-LACTAMASE PSE-4
A
271Pseudomonas aeruginosaGene Names: pse4 (carB1)
EC: 3.5.2.6
Find proteins for P16897 (Pseudomonas aeruginosa)
Go to UniProtKB:  P16897
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.75 Å
  • R-Value Free: 0.209 
  • R-Value Work: 0.178 
  • Space Group: P 41 21 2
Unit Cell:
Length (Å)Angle (°)
a = 95.033α = 90.00
b = 95.033β = 90.00
c = 62.678γ = 90.00
Software Package:
Software NamePurpose
CNSphasing
DENZOdata reduction
SCALEPACKdata scaling
CNSrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2001-02-21
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance