Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report | Ligand Interaction

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 29.65 kDa 
• Atom Count: 2360 
• Modelled Residue Count: 266 
• Deposited Residue Count: 271 
• Unique protein chains: 1

1G68

PSE-4 CARBENICILLINASE, WILD TYPE

• PDB DOI: 10.2210/pdb1G68/pdb

• Classification: HYDROLASE
• Organism(s): Pseudomonas aeruginosa
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 2000-11-03 Released: 2001-02-21 
• Deposition Author(s): Lim, D., Sanschagrin, F., Passmore, L., De Castro, L., Levesque, R.C., Strynadka, N.C.J.

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Experimental Data Snapshot

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

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

• PubMed: 11148033 
• DOI: 10.1021/bi001653v
• Primary Citation of Related Structures:  
  1G68, 1G6A


• 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 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.

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Organizational Affiliation: 

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

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
BETA-LACTAMASE PSE-4	A	271	Pseudomonas aeruginosa	Mutation(s): 0  Gene Names: pse4, carB1 EC: 3.5.2.6
UniProt
Find proteins for P16897 (Pseudomonas aeruginosa) Explore P16897  Go to UniProtKB:  P16897

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
SO4	B [auth A]	SULFATE ION O4 S QAOWNCQODCNURD-UHFFFAOYSA-L

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.95 Å
• R-Value Free: 0.212 
• R-Value Work: 0.167 
• R-Value Observed: 0.167 
• Space Group: P 4₁ 2₁ 2

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 95.197	α = 90
b = 95.197	β = 90
c = 62.793	γ = 90

Software Package:

Software Name	Purpose
DENZO	data reduction
SCALEPACK	data scaling
AMoRE	phasing
CNS	refinement

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2000-11-03 
• Released Date: 2001-02-21 
Deposition Author(s): Lim, D., Sanschagrin, F., Passmore, L., De Castro, L., Levesque, R.C., Strynadka, N.C.J.

Revision History  

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