1H74

CRYSTAL STRUCTURE OF HOMOSERINE KINASE COMPLEXED WITH ILE

1H74 の概要

• エントリーDOI: 10.2210/pdb1h74/pdb
• 関連するPDBエントリー: 1FWK 1FWL 1H72 1H73
• 分子名称: HOMOSERINE KINASE, ISOLEUCINE, ADENOSINE-5'-DIPHOSPHATE, ... (6 entities in total)
• 機能のキーワード: transferase, kinase
• 由来する生物種: METHANOCOCCUS JANNASCHII
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 131647.38

構造登録者

Krishna, S.S.,Zhou, T.,Daugherty, M.,Osterman, A.L.,Zhang, H. (登録日: 2001-07-02, 公開日: 2001-11-28, 最終更新日: 2023-12-13)

主引用文献

Krishna, S.S.,Zhou, T.,Daugherty, M.,Osterman, A.L.,Zhang, H.
Structural Basis for the Catalysis and Substrate Specificity of Homoserine Kinase
Biochemistry, 40:10810-, 2001

PubMed Abstract: Homoserine kinase (HSK), the fourth enzyme in the aspartate pathway of amino acid biosynthesis, catalyzes the phosphorylation of L-homoserine (Hse) to L-homoserine phosphate, an intermediate in the production of L-threonine, L-isoleucine, and in higher plants, L-methionine. The high-resolution structures of Methanococcus jannaschii HSK ternary complexes with its amino acid substrate and ATP analogues have been determined by X-ray crystallography. These structures reveal the structural determinants of the tight and highly specific binding of Hse, which is coupled with local conformational changes that enforce the sequestration of the substrate. The delta-hydroxyl group of bound Hse is only 3.4 A away from the gamma-phosphate of the bound nucleotide, poised for the in-line attack at the gamma-phosphorus. The bound nucleotides are flexible at the triphosphate tail. Nevertheless, a Mg(2+) was located in one of the complexes that binds between the beta- and gamma-phosphates of the nucleotide with good ligand geometry and is coordinated by the side chain of Glu130. No strong nucleophile (base) can be located near the phosphoryl acceptor hydroxyl group. Therefore, we propose that the catalytic mechanism of HSK does not involve a catalytic base for activating the phosphoryl acceptor hydroxyl but instead is mediated via a transition state stabilization mechanism.

PubMed: 11535056
DOI: 10.1021/BI010851Z

実験手法

X-RAY DIFFRACTION (1.9 Å)