3STU

Crystal Structure of tomato Methylketone Synthase I complexed with methyl-3-hydroxydodecanoate

3STU の概要

• エントリーDOI: 10.2210/pdb3stu/pdb
• 関連するPDBエントリー: 3STT 3STV 3STW 3STX 3STY
• 分子名称: Methylketone synthase 1, DECANOIC ACID, methyl (3S)-3-hydroxydodecanoate, ... (4 entities in total)
• 機能のキーワード: methylketone, alpha/beta hydrolase, decarboxylase, hydrolase
• 由来する生物種: Lycopersicon hirsutum f. glabratum
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 58664.48

構造登録者

Auldridge, M.E.,Austin, M.B.,Noel, J.P. (登録日: 2011-07-11, 公開日: 2012-05-02, 最終更新日: 2023-09-13)

主引用文献

Auldridge, M.E.,Guo, Y.,Austin, M.B.,Ramsey, J.,Fridman, E.,Pichersky, E.,Noel, J.P.
Emergent Decarboxylase Activity and Attenuation of alpha/beta-Hydrolase Activity during the Evolution of Methylketone Biosynthesis in Tomato.
Plant Cell, 24:1596-1607, 2012

PubMed Abstract: Specialized methylketone-containing metabolites accumulate in certain plants, in particular wild tomatoes in which they serve as toxic compounds against chewing insects. In Solanum habrochaites f. glabratum, methylketone biosynthesis occurs in the plastids of glandular trichomes and begins with intermediates of de novo fatty acid synthesis. These fatty-acyl intermediates are converted via sequential reactions catalyzed by Methylketone Synthase2 (MKS2) and MKS1 to produce the n-1 methylketone. We report crystal structures of S. habrochaites MKS1, an atypical member of the α/β-hydrolase superfamily. Sequence comparisons revealed the MKS1 catalytic triad, Ala-His-Asn, as divergent to the traditional α/β-hydrolase triad, Ser-His-Asp. Determination of the MKS1 structure points to a novel enzymatic mechanism dependent upon residues Thr-18 and His-243, confirmed by biochemical assays. Structural analysis further reveals a tunnel leading from the active site consisting mostly of hydrophobic residues, an environment well suited for fatty-acyl chain binding. We confirmed the importance of this substrate binding mode by substituting several amino acids leading to an alteration in the acyl-chain length preference of MKS1. Furthermore, we employ structure-guided mutagenesis and functional assays to demonstrate that MKS1, unlike enzymes from this hydrolase superfamily, is not an efficient hydrolase but instead catalyzes the decarboxylation of 3-keto acids.

PubMed: 22523203
DOI: 10.1105/tpc.111.093997

実験手法

X-RAY DIFFRACTION (1.93 Å)