2QUV

Phosphate ions in fructose-1,6-bisphosphate aldolase from rabbit muscle

2QUV の概要

• エントリーDOI: 10.2210/pdb2quv/pdb
• 関連するPDBエントリー: 1ZAH 2QUT 2QUU
• 分子名称: Fructose-bisphosphate aldolase A, PHOSPHATE ION (3 entities in total)
• 機能のキーワード: aldolase, phosphate ions, acetylation, glycolysis, lyase, phosphorylation, schiff base
• 由来する生物種: Oryctolagus cuniculus (rabbit)
• 細胞内の位置: Cytoplasm, myofibril, sarcomere, I band : P00883
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 157719.48

構造登録者

St-Jean, M.,Sygusch, J. (登録日: 2007-08-06, 公開日: 2007-08-28, 最終更新日: 2023-08-30)

主引用文献

St-Jean, M.,Sygusch, J.
Stereospecific proton transfer by a mobile catalyst in mammalian fructose-1,6-bisphosphate aldolase
J.Biol.Chem., 282:31028-31037, 2007

PubMed Abstract: Class I fructose-1,6-bisphosphate aldolases catalyze the interconversion between the enamine and iminium covalent enzymatic intermediates by stereospecific exchange of the pro(S) proton of the dihydroxyacetone-phosphate C3 carbon, an obligatory reaction step during substrate cleavage. To investigate the mechanism of stereospecific proton exchange, high resolution crystal structures of native and a mutant Lys(146) --> Met aldolase were solved in complex with dihydroxyacetone phosphate. The structural analysis revealed trapping of the enamine intermediate at Lys(229) in native aldolase. Mutation of conserved active site residue Lys(146) to Met drastically decreased activity and enabled trapping of the putative iminium intermediate in the crystal structure showing active site attachment by C-terminal residues 360-363. Attachment positions the conserved C-terminal Tyr(363) hydroxyl within 2.9A of the C3 carbon in the iminium in an orientation consistent with incipient re face proton transfer. We propose a catalytic mechanism by which the mobile C-terminal Tyr(363) is activated by the iminium phosphate via a structurally conserved water molecule to yield a transient phenate, whose developing negative charge is stabilized by a Lys(146) positive charge, and which abstracts the C3 pro(S) proton forming the enamine. An identical C-terminal binding mode observed in the presence of phosphate in the native structure corroborates Tyr(363) interaction with Lys(146) and is consistent with transient C terminus binding in the enamine. The absence of charge stabilization and of a mobile C-terminal catalyst explains the extraordinary stability of enamine intermediates in transaldolases.

PubMed: 17728250
DOI: 10.1074/jbc.M704968200

実験手法

X-RAY DIFFRACTION (2.22 Å)