1AJ8

CITRATE SYNTHASE FROM PYROCOCCUS FURIOSUS

1AJ8 の概要

• エントリーDOI: 10.2210/pdb1aj8/pdb
• 分子名称: CITRATE SYNTHASE, COENZYME A, CITRIC ACID, ... (4 entities in total)
• 機能のキーワード: hyperthermostable, lyase
• 由来する生物種: Pyrococcus furiosus
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 86599.29

構造登録者

Russell, R.J.M.,Ferguson, J.M.C.,Hough, D.W.,Danson, M.J.,Taylor, G.L. (登録日: 1997-05-16, 公開日: 1997-11-19, 最終更新日: 2024-02-07)

主引用文献

Russell, R.J.,Ferguson, J.M.,Hough, D.W.,Danson, M.J.,Taylor, G.L.
The crystal structure of citrate synthase from the hyperthermophilic archaeon pyrococcus furiosus at 1.9 A resolution,.
Biochemistry, 36:9983-9994, 1997

PubMed Abstract: The crystal structure of the closed form of citrate synthase, with citrate and CoA bound, from the hyperthermophilic Archaeon Pyrococcus furiosus has been determined to 1.9 A. This has allowed direct structural comparisons between the same enzyme from organisms growing optimally at 37 degrees C (pig), 55 degrees C (Thermoplasma acidophilum) and now 100 degrees C (Pyrococcus furiosus). The three enzymes are homodimers and share a similar overall fold, with the dimer interface comprising primarily an eight alpha-helical sandwich of four antiparallel pairs of helices. The active sites show similar modes of substrate binding; moreover, the structural equivalence of the amino acid residues implicated in catalysis implies that the mechanism proceeds via the same acid-base catalytic process. Given the overall structural and mechanistic similarities, it has been possible to make detailed structural comparisons between the three citrate synthases, and a number of differences can be identified in passing from the mesophilic to thermophilic to hyperthermophilic citrate synthases. The most significant of these are an increased compactness of the enzyme, a more intimate association of the subunits, an increase in intersubunit ion pairs, and a reduction in thermolabile residues. Compactness is achieved by the shortening of a number of loops, an increase in the number of atoms buried from solvent, an optimized packing of side chains in the interior, and an absence of cavities. The intimate subunit association in the dimeric P. furiosus enzyme is achieved by greater complementarity of the monomers and by the C-terminal region of each monomer folding over the surface of the other monomer, in contrast to the pig enzyme where the C-terminus has a very different fold. The increased number of intersubunit ion pairs is accompanied by an increase in the number involved in networks. Interestingly, all loop regions in the P. furiosus enzyme either are shorter or contain additional ion pairs compared with the pig enzyme. The possible relevance of these structural features to enzyme hyperthermostability is discussed.

PubMed: 9254593
DOI: 10.1021/bi9705321

実験手法

X-RAY DIFFRACTION (1.9 Å)