1L10

STRUCTURAL STUDIES OF MUTANTS OF THE LYSOZYME OF BACTERIOPHAGE T4. THE TEMPERATURE-SENSITIVE MUTANT PROTEIN THR157 (RIGHT ARROW) ILE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Observed: 0.173 

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This is version 2.0 of the entry. See complete history


Literature

Structural studies of mutants of the lysozyme of bacteriophage T4. The temperature-sensitive mutant protein Thr157----Ile.

Grutter, M.G.Gray, T.M.Weaver, L.H.Wilson, T.A.Matthews, B.W.

(1987) J Mol Biol 197: 315-329

  • DOI: https://doi.org/10.1016/0022-2836(87)90126-4
  • Primary Citation of Related Structures:  
    1L01, 1L10

  • PubMed Abstract: 

    To understand the roles of individual amino acids in the folding and stability of globular proteins, a systematic structural analysis of mutants of the lysozyme of bacteriophage T4 has been undertaken. The isolation, characterization, crystallographic refinement and structural analysis of a temperature-sensitive lysozyme in which threonine 157 is replaced by isoleucine is reported here. This mutation reduces the temperature of the midpoint of the reversible thermal denaturation transition by 11 deg.C at pH 2.0. Electron density maps showing differences between the wild-type and mutant X-ray crystal structures have obvious features corresponding to the substitution of threonine 157 by isoleucine. There is little difference electron density in the remainder of the molecule, indicating that the structural changes are localized to the site of the mutation. High-resolution crystallographic refinement of the mutant lysozyme structure confirms that it is very similar to wild-type lysozyme. The largest conformational differences are in the gamma-carbon of residue 157 and in the side-chain of Asp159, which shift 1.0 A and 1.1 A, respectively. In the wild-type enzyme, the gamma-hydroxyl group of Thr157 participates in a network of hydrogen bonds. Substitution of Thr157 with an isoleucine disrupts this set of hydrogen bonds. A water molecule bound in the vicinity of Thr155 partially restores the hydrogen bond network in the mutant structure, but the buried main-chain amide of Asp159 is not near a hydrogen bond acceptor. This unsatisfied hydrogen-bonding potential is the most obvious reason for the reduction in stability of the temperature-sensitive mutant protein.


  • Organizational Affiliation

    Institute of Molecular Biology, University of Oregon, Eugene 97403.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
T4 LYSOZYME164Tequatrovirus T4Mutation(s): 0 
EC: 3.2.1.17
UniProt
Find proteins for P00720 (Enterobacteria phage T4)
Explore P00720 
Go to UniProtKB:  P00720
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00720
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Observed: 0.173 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 61.2α = 90
b = 61.2β = 90
c = 96.8γ = 120
Software Package:
Software NamePurpose
TNTrefinement
AGROVATA / ROTAVATAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1988-04-16
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Advisory, Version format compliance
  • Version 1.3: 2017-11-29
    Changes: Derived calculations, Other
  • Version 1.4: 2020-07-22
    Changes: Data collection, Database references, Other, Refinement description
  • Version 1.5: 2021-06-30
    Changes: Data collection
  • Version 2.0: 2022-11-23
    Type: Remediation
    Changes: Advisory, Atomic model, Data collection, Database references, Other, Source and taxonomy