2HDB

HMG-CoA synthase from Enterococcus faecalis. Mutation alanine 110 to glycine

2HDB の概要

• エントリーDOI: 10.2210/pdb2hdb/pdb
• 関連するPDBエントリー: 1TVZ 1TXT 1X9E 1XPK 1XPM 1YSL
• 分子名称: HMG-CoA synthase, SULFATE ION, 2-(N-MORPHOLINO)-ETHANESULFONIC ACID, ... (4 entities in total)
• 機能のキーワード: thiolase fold, synthase, protein, mutant, lyase
• 由来する生物種: Enterococcus faecalis
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 85033.75

構造登録者

Steussy, C.N.,Sutherlin, A.,Stauffacher, C.V. (登録日: 2006-06-20, 公開日: 2007-03-20, 最終更新日: 2023-08-30)

主引用文献

Steussy, C.N.,Robison, A.D.,Tetrick, A.M.,Knight, J.T.,Rodwell, V.W.,Stauffacher, C.V.,Sutherlin, A.L.
A structural limitation on enzyme activity: the case of HMG-CoA synthase.
Biochemistry, 45:14407-14414, 2006

PubMed Abstract: Recent structural studies of the HMG-CoA synthase members of the thiolase superfamily have shown that the catalytic loop containing the nucleophilic cysteine follows the phi and psi angle pattern of a II' beta turn. However, the i + 1 residue is conserved as an alanine, which is quite unusual in this position as it must adopt a strained positive phi angle to accommodate the geometry of the turn. To assess the effect of the conserved strain in the catalytic loop, alanine 110 of Enterococcus faecalis 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) synthase was mutated to a glycine. Subsequent enzymatic studies showed that the overall reaction rate of the enzyme was increased 140-fold. An X-ray crystallographic study of the Ala110Gly mutant enzyme demonstrated unanticipated adjustments in the active site that resulted in additional stabilization of all three steps of the reaction pathway. The rates of acetylation and hydrolysis of the mutant enzyme increased because the amide nitrogen of Ser308 shifts 0.4 A toward the catalytic cysteine residue. This motion positions the nitrogen to better stabilize the intermediate negative charge that develops on the carbonyl oxygen of the acetyl group during both the formation of the acyl-enzyme intermediate and its hydrolysis. In addition, the hydroxyl of Ser308 rotates 120 degrees to a position where it is able to stabilize the carbanion intermediate formed by the methyl group of the acetyl-S-enzyme during its condensation with acetoacetyl-CoA.

PubMed: 17128980
DOI: 10.1021/bi061505q

実験手法

X-RAY DIFFRACTION (2.2 Å)