4N6B

Soybean Serine Acetyltransferase Complexed with CoA

4N6B の概要

• エントリーDOI: 10.2210/pdb4n6b/pdb
• 関連するPDBエントリー: 4N69 4N6A
• 分子名称: Serine Acetyltransferase Apoenzyme, COENZYME A (2 entities in total)
• 機能のキーワード: acetyltransferase, transferase
• 由来する生物種: Glycine max (soybeans)
• タンパク質・核酸の鎖数: 6
• 化学式量合計: 186247.30

構造登録者

Yi, H.,Dey, S.,Kumaran, S.,Krishnan, H.B.,Jez, J.M. (登録日: 2013-10-11, 公開日: 2013-11-13, 最終更新日: 2024-02-28)

主引用文献

Yi, H.,Dey, S.,Kumaran, S.,Lee, S.G.,Krishnan, H.B.,Jez, J.M.
Structure of soybean serine acetyltransferase and formation of the cysteine regulatory complex as a molecular chaperone.
J.Biol.Chem., 288:36463-36472, 2013

PubMed Abstract: Serine acetyltransferase (SAT) catalyzes the limiting reaction in plant and microbial biosynthesis of cysteine. In addition to its enzymatic function, SAT forms a macromolecular complex with O-acetylserine sulfhydrylase. Formation of the cysteine regulatory complex (CRC) is a critical biochemical control feature in plant sulfur metabolism. Here we present the 1.75-3.0 Å resolution x-ray crystal structures of soybean (Glycine max) SAT (GmSAT) in apoenzyme, serine-bound, and CoA-bound forms. The GmSAT-serine and GmSAT-CoA structures provide new details on substrate interactions in the active site. The crystal structures and analysis of site-directed mutants suggest that His(169) and Asp(154) form a catalytic dyad for general base catalysis and that His(189) may stabilize the oxyanion reaction intermediate. Glu(177) helps to position Arg(203) and His(204) and the β1c-β2c loop for serine binding. A similar role for ionic interactions formed by Lys(230) is required for CoA binding. The GmSAT structures also identify Arg(253) as important for the enhanced catalytic efficiency of SAT in the CRC and suggest that movement of the residue may stabilize CoA binding in the macromolecular complex. Differences in the effect of cold on GmSAT activity in the isolated enzyme versus the enzyme in the CRC were also observed. A role for CRC formation as a molecular chaperone to maintain SAT activity in response to an environmental stress is proposed for this multienzyme complex in plants.

PubMed: 24225955
DOI: 10.1074/jbc.M113.527143

実験手法

X-RAY DIFFRACTION (3.005 Å)