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Crystal Structure of Arabidopsis thaliana HCT
Structural highlights
FunctionHST_ARATH Acyltransferase involved in the biosynthesis of lignin. Accepts caffeoyl-CoA and p-coumaroyl-CoA as substrates and transfers the acyl group on both shikimate and quinate acceptors.[1] Publication Abstract from PubMedHydroxycinnamoyl-CoA:shikimate hydroxycinnamoyltransferase (HCT) is an essential acyltransferase that mediates flux through plant phenylpropanoid metabolism by catalyzing a reaction between p-coumaroyl-CoA and shikimate, yet it also exhibits broad substrate permissiveness in vitro. How do enzymes like HCT avoid functional derailment by cellular metabolites that qualify as non-native substrates? Here, we combine X-ray crystallography and molecular dynamics to reveal distinct dynamic modes of HCT under native and non-native catalysis. We find that essential electrostatic and hydrogen-bonding interactions between the ligand and active site residues, permitted by active site plasticity, are elicited more effectively by shikimate than by other non-native substrates. This work provides a structural basis for how dynamic conformational states of HCT favor native over non-native catalysis by reducing the number of futile encounters between the enzyme and shikimate. Dynamic Conformational States Dictate Selectivity toward the Native Substrate in a Substrate-Permissive Acyltransferase.,Levsh O, Chiang YC, Tung CF, Noel JP, Wang Y, Weng JK Biochemistry. 2016 Nov 2. PMID:27805809[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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