Dynamic Conformational States Dictate Selectivity toward the Native Substrate in a Substrate-Permissive Acyltransferase.
Hydroxycinnamoyl-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.
Whitehead Institute for Biomedical Research , 9 Cambridge Center, Cambridge, Massachusetts 02142, United States.|Department of Biology, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
Olesya
O
Levsh
Department of Physics, The Chinese University of Hong Kong , Shatin, Hong Kong.
Ying-Chih
YC
Chiang
Department of Physics, The Chinese University of Hong Kong , Shatin, Hong Kong.
Chun Fai
CF
Tung
Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology & Proteomics, The Salk Institute for Biological Studies , La Jolla, California 92037, United States.
Joseph P
JP
Noel
Department of Physics, The Chinese University of Hong Kong , Shatin, Hong Kong.
Yi
Y
Wang
Whitehead Institute for Biomedical Research , 9 Cambridge Center, Cambridge, Massachusetts 02142, United States.|Department of Biology, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
Jing-Ke
JK
Weng
D000217:Acyltransferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D055162:Biocatalysis; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D009154:Mutation; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D012765:Shikimic Acid / Q000737:chemistry / Q000378:metabolism; D055672:Static Electricity; D013379:Substrate Specificity
D029681:Arabidopsis Proteins; D012765:Shikimic Acid; D000217:Acyltransferases; C519874:HCT protein, Arabidopsis