Russell RJ, Hough DW, Danson MJ, Taylor GL. The crystal structure of citrate synthase from the thermophilic archaeon, Thermoplasma acidophilum.
Structure 1994;
2:1157-67. [PMID:
7704526 DOI:
10.1016/s0969-2126(94)00118-9]
[Citation(s) in RCA: 149] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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 A 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.
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