3STV
Crystal Structure of tomato Methylketone Synthase I complexed with 3-hydroxyoctanoate
Summary for 3STV
| Entry DOI | 10.2210/pdb3stv/pdb |
| Related | 3STT 3STU 3STW 3STX 3STY |
| Descriptor | Methylketone synthase 1, (3S)-3-hydroxyoctanoic acid, BROMIDE ION, ... (4 entities in total) |
| Functional Keywords | methylketone, alpha/beta hydrolase, decarboxylase, hydrolase |
| Biological source | Lycopersicon hirsutum f. glabratum |
| Total number of polymer chains | 2 |
| Total formula weight | 58501.99 |
| Authors | Auldridge, M.E.,Austin, M.B.,Noel, J.P. (deposition date: 2011-07-11, release date: 2012-05-02, Last modification date: 2023-09-13) |
| Primary citation | 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 Cited by 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: 22523203DOI: 10.1105/tpc.111.093997 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (2.2 Å) |
Structure validation
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