5dhk | pdb_00005dhk

Nicotiana tabacum 5-epi-aristolochene synthase mutant W273E - alkylated

spinqualitylabelsall models 5dhk, resolution 2.43Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5dhk is a 1 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: FAR, MG Related: 5dhi Activity: 5-epiaristolochene synthase, with EC number 4.2.3.61 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum Function [5EAS_TOBAC] Catalyzes the cyclization of trans,trans-farnesyl diphosphate (FPP) to the bicyclic intermediate 5-epi-aristolochene, initial step in the conversion of FPP to the sesquiterpenoid antifungal phytoalexin capsidiol. Produces germacrene A as an enzyme-bound intermediate that is not released by the enzyme, but is further cyclized to produce the bicyclic 5-epi-aristolochene. Publication Abstract from PubMed Terpenes are ubiquitous natural chemicals with diverse biological functions spanning all three domains of life. In specialized metabolism, the active sites of terpene synthases (TPSs) evolve in shape and reactivity to direct the biosynthesis of a myriad of chemotypes for organismal fitness. As most terpene biosynthesis mechanistically involves highly reactive carbocationic intermediates, the protein surfaces catalyzing these cascade reactions possess reactive regions possibly prone to premature carbocation capture and potentially enzyme inactivation. Here, we show using proteomic and X-ray crystallographic analyses that cationic intermediates undergo capture by conserved active site residues leading to inhibitory self-alkylation. Moreover, the level of cation-mediated inactivation increases with mutation of the active site, upon changes in the size and structure of isoprenoid diphosphate substrates, and alongside increases in reaction temperatures. TPSs that individually synthesize multiple products are less prone to self-alkylation then TPSs possessing relatively high product specificity. In total, the results presented suggest that mechanism-based alkylation represents an overlooked mechanistic pressure during the evolution of cation-derived terpene biosynthesis. Mechanism-Based Post-Translational Modification and Inactivation in Terpene Synthases.,Kersten RD, Diedrich JK, Yates JR 3rd, Noel JP ACS Chem Biol. 2015 Sep 17. PMID:26378620 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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