1L0G

X-ray Crystal Structure of AmpC S64G Mutant beta-Lactamase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.50 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.189 

Starting Model: experimental
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This is version 2.2 of the entry. See complete history


Literature

Structural bases of stability-function tradeoffs in enzymes.

Beadle, B.M.Shoichet, B.K.

(2002) J Mol Biol 321: 285-296

  • DOI: https://doi.org/10.1016/s0022-2836(02)00599-5
  • Primary Citation of Related Structures:  
    1L0D, 1L0E, 1L0F, 1L0G

  • PubMed Abstract: 

    The structures of enzymes reflect two tendencies that appear opposed. On one hand, they fold into compact, stable structures; on the other hand, they bind a ligand and catalyze a reaction. To be stable, enzymes fold to maximize favorable interactions, forming a tightly packed hydrophobic core, exposing hydrophilic groups, and optimizing intramolecular hydrogen-bonding. To be functional, enzymes carve out an active site for ligand binding, exposing hydrophobic surface area, clustering like charges, and providing unfulfilled hydrogen bond donors and acceptors. Using AmpC beta-lactamase, an enzyme that is well-characterized structurally and mechanistically, the relationship between enzyme stability and function was investigated by substituting key active-site residues and measuring the changes in stability and activity. Substitutions of catalytic residues Ser64, Lys67, Tyr150, Asn152, and Lys315 decrease the activity of the enzyme by 10(3)-10(5)-fold compared to wild-type. Concomitantly, many of these substitutions increase the stability of the enzyme significantly, by up to 4.7kcal/mol. To determine the structural origins of stabilization, the crystal structures of four mutant enzymes were determined to between 1.90A and 1.50A resolution. These structures revealed several mechanisms by which stability was increased, including mimicry of the substrate by the substituted residue (S64D), relief of steric strain (S64G), relief of electrostatic strain (K67Q), and improved polar complementarity (N152H). These results suggest that the preorganization of functionality characteristic of active sites has come at a considerable cost to enzyme stability. In proteins of unknown function, the presence of such destabilized regions may indicate the presence of a binding site.


  • Organizational Affiliation

    Department of Molecular Pharmacology and Biological Chemistry, Northwestern University School of Medicine, 303 East Chicago Avenue S215, Chicago, IL 60611-3008, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
beta-lactamase
A, B
358Escherichia coliMutation(s): 1 
Gene Names: K12
EC: 3.5.2.6
UniProt
Find proteins for P00811 (Escherichia coli (strain K12))
Explore P00811 
Go to UniProtKB:  P00811
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00811
Sequence Annotations
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  • Reference Sequence
Oligosaccharides

Help

Entity ID: 2
MoleculeChains Length2D Diagram Glycosylation3D Interactions
beta-D-fructofuranose-(2-1)-alpha-D-glucopyranose
C
2N/A
Glycosylation Resources
GlyTouCan:  G05551OP
GlyCosmos:  G05551OP
Biologically Interesting Molecules (External Reference) 1 Unique
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.50 Å
  • R-Value Free: 0.212 
  • R-Value Work: 0.189 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 118.387α = 90
b = 76.329β = 115.76
c = 97.665γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
CNSrefinement
CNSphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2002-08-14
    Type: Initial release
  • Version 1.1: 2008-04-28
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 2.0: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Atomic model, Data collection, Derived calculations, Non-polymer description, Structure summary
  • Version 2.1: 2021-10-27
    Changes: Database references, Structure summary
  • Version 2.2: 2023-08-16
    Changes: Data collection, Refinement description