1SML

METALLO BETA LACTAMASE L1 FROM STENOTROPHOMONAS MALTOPHILIA


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Free: 0.233 
  • R-Value Work: 0.180 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

The crystal structure of the L1 metallo-beta-lactamase from Stenotrophomonas maltophilia at 1.7 A resolution.

Ullah, J.H.Walsh, T.R.Taylor, I.A.Emery, D.C.Verma, C.S.Gamblin, S.J.Spencer, J.

(1998) J Mol Biol 284: 125-136

  • DOI: 10.1006/jmbi.1998.2148
  • Primary Citation of Related Structures:  
    1SML

  • PubMed Abstract: 
  • The structure of the L1 metallo-beta-lactamase from the opportunistic pathogen Stenotrophomonas maltophilia has been determined at 1.7 A resolution by the multiwavelength anomalous dispersion (MAD) approach exploiting both the intrinsic binuclear zin ...

    The structure of the L1 metallo-beta-lactamase from the opportunistic pathogen Stenotrophomonas maltophilia has been determined at 1.7 A resolution by the multiwavelength anomalous dispersion (MAD) approach exploiting both the intrinsic binuclear zinc centre and incorporated selenomethionine residues. L1 is unique amongst all known beta-lactamases in that it exists as a tetramer. The protein exhibits the alphabeta/betaalpha fold found only in the metallo-beta-lactamases and displays several unique features not previously observed in these enzymes. These include a disulphide bridge and two substantially elongated loops connected to the active site of the enzyme. Two closely spaced zinc ions are bound at the active site with tetrahedral (Zn1) and trigonal bipyramidal (Zn2) co-ordination, respectively; these are bridged by a water molecule which we propose acts as the nucleophile in the hydrolytic reaction. Ligation of the second zinc ion involves both residues and geometry which have not been previously observed in the metallo-beta-lactamases. Simulated binding of the substrates ampicillin, ceftazidime and imipenem suggests that the substrate is able to bind to the enzyme in a variety of different conformations whose common features are direct interactions of the beta-lactam carbonyl oxygen and nitrogen with the zinc ions and of the beta-lactam carboxylate with Ser187. We describe a catalytic mechanism whose principal features are a nucleophilic attack of the bridging water on the beta-lactam carbonyl carbon, electrostatic stabilisation of a negatively charged tetrahedral transition state and protonation of the beta-lactam nitrogen by a second water molecule co-ordinated by Zn2. Further, we propose that direct metal:substrate interactions provide a substantial contribution to substrate binding and that this may explain the lack of specificity which is a feature of this class of enzyme.


    Organizational Affiliation

    Division of Protein Structure, National Institute of Medical Research, The Ridgeway, Mill Hill, London, NW7 1AA, UK.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
PROTEIN (PENICILLINASE)A269Stenotrophomonas maltophiliaMutation(s): 0 
Gene Names: L1
EC: 3.5.2.6
Find proteins for P52700 (Stenotrophomonas maltophilia)
Explore P52700 
Go to UniProtKB:  P52700
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ZN
Query on ZN

Download CCD File 
A
ZINC ION
Zn
PTFCDOFLOPIGGS-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Free: 0.233 
  • R-Value Work: 0.180 
  • Space Group: P 64 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 105.23α = 90
b = 105.23β = 90
c = 97.72γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
REFMACrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1999-09-20
    Type: Initial release
  • Version 1.1: 2007-10-16
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance