Abstract
Background: The Archaea constitute a phylogenetically distinct, evolutionary domain and comprise organisms that live under environmental extremes of temperature, salinity and/or anaerobicity. Different members of the thermophilic Archaea tolerate temperatures in the range 55-110 degrees C, and the comparison of the structures of their enzymes with the structurally homogolous enzymes of mesophilic organisms (optimum growth temperature range 15-45 degrees C) may provide important information on the structural basis of protein thermostability. We have chosen citrate synthase, the first enzyme of the citric acid cycle, as a model enzyme for such studies.
Results: We have determined the crystal structure of Thermoplasma acidophilum citrate synthase to 2.5 Angstrom and have compared it with the citrate synthase from pig heart, with which it shares a high degree of structural homology, but little sequence identity (20%).
Conclusions: The three-dimensional structural comparison of thermophilic and mesophilic citrate synthases has permitted catalytic and substrate-binding residues to be tentatively assigned in the archaeal, thermophilic enzyme, and has identified structural features that may be responsible for its thermostability.
Original language | English |
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Pages (from-to) | 1157-1167 |
Number of pages | 11 |
Journal | Structure |
Volume | 2 |
Issue number | 12 |
Publication status | Published - 15 Dec 1994 |
Keywords
- ARCHAEA
- CITRATE SYNTHASE
- CRYSTAL STRUCTURE
- THERMOPHILE
- THERMOPLASMA ACIDOPHILUM
- ALPHA-HELIX STABILITY
- PROTEIN-STRUCTURE
- ESCHERICHIA-COLI
- CRYSTALLOGRAPHIC REFINEMENT
- SECONDARY STRUCTURE
- SEQUENCE
- MUTATIONS
- MODELS
- GENE
- DEHYDROGENASE