3SH9

Crystal structure of fluorophore-labeled beta-lactamase PenP in complex with cefotaxime


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.200 

Starting Model: experimental
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This is version 2.1 of the entry. See complete history


Literature

Increased structural flexibility at the active site of a fluorophore-conjugated beta-lactamase distinctively impacts its binding toward diverse cephalosporin antibiotics

Wong, W.-T.Chan, K.-C.So, P.-K.Yap, H.-K.Chung, W.-H.Leung, Y.-C.Wong, K.-Y.Zhao, Y.-X.

(2011) J Biol Chem 286: 31771-31780

  • DOI: https://doi.org/10.1074/jbc.M110.198895
  • Primary Citation of Related Structures:  
    3SH7, 3SH8, 3SH9

  • PubMed Abstract: 

    The Ω-loop at the active site of β-lactamases exerts significant impact on the kinetics and substrate profile of these enzymes by forming part of the substrate binding site and posing as steric hindrance toward bulky substrates. Mutating certain residues on the Ω-loop has been a general strategy for molecular evolution of β-lactamases to expand their hydrolytic activity toward extended-spectrum antibiotics through a mechanism believed to involve enhanced structural flexibility of the Ω-loop. Yet no structural information is available that demonstrates such flexibility or its relation to substrate profile and enzyme kinetics. Here we report an engineered β-lactamase that contains an environment-sensitive fluorophore conjugated near its active site to probe the structural dynamics of the Ω-loop and to detect the binding of diverse substrates. Our results show that this engineered β-lactamase has improved binding kinetics and positive fluorescence signal toward oxyimino-cephalosporins, but shows little such effect to non-oxyimino-cephalosporins. Structural studies reveal that the Ω-loop adopts a less stabilized structure, and readily undergoes conformational change to accommodate the binding of bulky oxyimino-cephalosporins while no such change is observed for non-oxyimino-cephalosporins. Mutational studies further confirm that this substrate-induced structural change is directly responsible for the positive fluorescence signal specific to oxyimino-cephalosporins. Our data provide mechanistic evidence to support the long-standing model that the evolutionary strategy of mutating the Ω-loop leads to increased structural flexibility of this region, which in turn facilitates the binding of extended spectrum β-lactam antibiotics. The oxyimino-cephalosporin-specific fluorescence profile of our engineered β-lactamase also demonstrates the possibility of designing substrate-selective biosensing systems.


  • Organizational Affiliation

    Department of Applied Biology and Chemical Technology, State Key Laboratory of Chirosciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Beta-lactamase
A, B
266Bacillus licheniformisMutation(s): 1 
Gene Names: penP
EC: 3.5.2.6
UniProt
Find proteins for P00808 (Bacillus licheniformis)
Explore P00808 
Go to UniProtKB:  P00808
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00808
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.200 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 43.386α = 90
b = 91.626β = 104.5
c = 66.008γ = 90
Software Package:
Software NamePurpose
REFMACrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2011-07-27
    Type: Initial release
  • Version 1.1: 2011-08-10
    Changes: Non-polymer description
  • Version 1.2: 2013-06-19
    Changes: Database references
  • Version 2.0: 2018-09-19
    Changes: Atomic model, Data collection, Derived calculations, Non-polymer description, Structure summary
  • Version 2.1: 2023-11-01
    Changes: Data collection, Database references, Derived calculations, Refinement description