1A59

COLD-ACTIVE CITRATE SYNTHASE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.09 Å
  • R-Value Free: 0.236 
  • R-Value Work: 0.184 
  • R-Value Observed: 0.184 

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This is version 1.3 of the entry. See complete history


Literature

Structural adaptations of the cold-active citrate synthase from an Antarctic bacterium.

Russell, R.J.Gerike, U.Danson, M.J.Hough, D.W.Taylor, G.L.

(1998) Structure 6: 351-361

  • DOI: https://doi.org/10.1016/s0969-2126(98)00037-9
  • Primary Citation of Related Structures:  
    1A59

  • PubMed Abstract: 

    The structural basis of adaptation of enzymes to low temperature is poorly understood. Dimeric citrate synthase has been used as a model enzyme to study the structural basis of thermostability, the structure of the enzyme from organisms living in habitats at 55 degrees C and 100 degrees C having previously been determined. Here the study is extended to include a citrate synthase from an Antarctic bacterium, allowing us to explore the structural basis of cold activity and thermostability across the whole temperature range over which life is known to exit. We report here the first crystal structure of a cold-active enzyme, citrate synthase, isolated from an Antarctic bacterium, at a resolution of 2.09 A. In comparison with the same enzyme from a hyperthermophilic host, the cold-active enzyme has a much more accessible active site, an unusual electrostatic potential distribution and an increased relative flexibility of the small domain compared to the large domain. Several other features of the cold-active enzyme were also identified: reduced subunit interface interactions with no intersubunit ion-pair networks; loops of increased length carrying more charge and fewer proline residues; an increase in solvent-exposed hydrophobic residues; and an increase in intramolecular ion pairs. Enzymes from organisms living at the temperature extremes of life need to avoid hot or cold denaturation yet maintain sufficient structural integrity to allow catalytic efficiency. For hyperthermophiles, thermal denaturation of the citrate synthase dimer appears to be resisted by complex networks of ion pairs at the dimer interface, a feature common to other hyperthermophilic proteins. For the cold-active citrate synthase, cold denaturation appears to be resisted by an increase in intramolecular ion pairs compared to the hyperthermophilic enzyme. Catalytic efficiency of the cold-active enzyme appears to be achieved by a more accessible active site and by an increase in the relative flexibility of the small domain compared to the large domain.


  • Organizational Affiliation

    Department of Biology and Biochemistry, University of Bath, UK.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
CITRATE SYNTHASE378Antarctic bacterium DS2-3RMutation(s): 0 
UniProt
Find proteins for O34002 (Antarctic bacterium DS2-3R)
Explore O34002 
Go to UniProtKB:  O34002
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO34002
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
COA
Query on COA

Download Ideal Coordinates CCD File 
B [auth A]COENZYME A
C21 H36 N7 O16 P3 S
RGJOEKWQDUBAIZ-IBOSZNHHSA-N
CIT
Query on CIT

Download Ideal Coordinates CCD File 
C [auth A]CITRIC ACID
C6 H8 O7
KRKNYBCHXYNGOX-UHFFFAOYSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.09 Å
  • R-Value Free: 0.236 
  • R-Value Work: 0.184 
  • R-Value Observed: 0.184 
  • Space Group: P 65 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 70.8α = 90
b = 70.8β = 90
c = 307.8γ = 120
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
DENZOdata reduction
SCALEPACKdata scaling
X-PLORphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1999-03-30
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2024-02-07
    Changes: Data collection, Database references, Derived calculations, Other