1G68

PSE-4 CARBENICILLINASE, WILD TYPE

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.167 

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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:  

  • 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 aeruginosaMutation(s): 0 
Gene 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: 1.95 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.167 
  • Space Group: P 41 21 2
Unit Cell:
Length (Å)Angle (°)
a = 95.197α = 90.00
b = 95.197β = 90.00
c = 62.793γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
DENZOdata reduction
AMoREphasing
SCALEPACKdata scaling

Structure Validation

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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