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Subfunctionalization of a monolignol to a phytoalexin glucosyltransferase is accompanied by substrate inhibition

Plant Communications 2023年第3期4卷 151-170页

作者： Jieren Liao Guangxin Sun Elisabeth Kurze Wieland Steinchen Timothy D.Hoffmann Chuankui Song Zhiwei Zou Thomas Hoffmann Wilfried G.Schwab Biotechnology of Natural Products Technische University at MüunchenLiesel-Beckmann-Str.185354 FreisingGermany Center for Synthetic Microbiology(SYNMIKRO)&Faculty of Chemistry Philipps-University MarburgKarl-von-Frisch-Straße 1435043 MarburgGermany State Key Laboratory of Tea Plant Biology and Utilization International Joint Laboratory on Tea Chemistry and Health EffectsAnhui Agricultural University230036 HefeiAnhuiP.R.China Present address:Department of Molecular Biophysics and Biochemistry Yale UniversityNew HavenCTUSA

Uridine diphosphate-dependent glycosyltransferases(UGTs)mediate the glycosylation of plant metabolites,thereby altering their physicochemical properties and *** possess numerous UGT genes,with the encoded enzymes often glycosylating multiple substrates and some exhibiting substrate inhibition kinetics,but the biological function and molecular basis of these phenomena are not fully *** promiscuous monolignol/phytoalexin glycosyltransferase NbUGT72AY1 exhibits substrate inhibition(Ki)at 4 mM scopoletin,whereas the highly homologous monolignol StUGT72AY2 is inhibited at 190 *** therefore used hydrogen/deuterium exchange mass spectrometry and structure-based mutational analyses of both proteins and introduced NbUGT72AY1 residues into StUGT72AY2 and vice versa to study promiscuity and substrate inhibition of UGTs.A single F87I and chimeric mutant of NbUGT72AY1 showed significantly reducedscopoletin substrate inhibition,whereas its monolignolgly cosylation activity was almost *** mutations in StUGT72AY2 resulted in increased scopoletin glycosylation,leading to enhanced promiscuity,which was accompanied by substrate *** of 3D structures identified open and closed UGT conformers,allowing visualization of the dynamics of conformational changes that occur during *** postulated substrate access tunnels likely serve as drainage *** results suggest a two-site model in which the second substrate molecule binds near the catalytic site and blocks product *** studies showed that minor changes in amino acid sequence can enhance the promiscuity of the enzyme and add new capabilities such as substrate inhibition without affecting existing *** proposed subfunctionalization mechanism of expanded promiscuity may play a role in enzyme evolution and highlights the importance of promiscuous enzymes in providing new functions.

关键词： glycosyltransferase substrate inhibition hydrogen/deuterium exchange mass spectrometry protein morphing protein conformer scopoletin

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Microbial Degradation of Quinoline: Kinetics Study With Burkholderia picekttii

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Biomedical and Environmental Sciences 2004年第1期17卷 21-26页

作者： JIAN-LONGWANG WEI-ZHONG XUANZHAO LaboratoryofEnvironmentalTechnology INETTsinghuaUniversityBeijing100084China SchoolofEnvironmentalScience PekingUniversityBeijing100871China

Objective To investigate the kinetics of quinoline biodegradation by Burkholderia pickttii, a Gram negative rod-shaped aerobe, isolated in our laboratory. Methods HPLC (Hewlett-Packard model 5050 with an UV detector) was used for the analysis of quinoline concentration. GC/MS method was used to identify the intermediate metabolites of quinoline degradation. Results The biodegradation of quinoline was inhibited by quinoline at a high concentration, and the degradation process could be described by the Haldane model. The kinetic parameters based on Haldane substrate inhibition were evaluated. The values were v = 0.44 h-1,Ks=166.7 mg/L, Ki= 650 mg/L, respectively. The quinoline concentration to avoid substrate inhibition was inferred theoretically and determined to be 329 mg/L. Conclusion The biodegradation of quinoline conforms to the Haldane inhibition model and the main intermediate metabolite of quinoline biodegradation is 2-hydroxy-quinoline.

关键词： Quinoline Microbial degradation Burkholderia pickttii Kinetics substrate inhibition Intermediate metabolite

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Kinetics of Asymmetric Reduction of Phenylglyoxylic Acid to R-(-)-Mandelic Acid by Saccharomyces Cerevisiae FD11b

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Chinese Journal of Chemical Engineering 2006年第1期14卷 73-80页

作者：肖美添黄雅燕孟春郭养浩 Institute of Pharmaceutical Biotechnology and Engineering Fuzhou University Fuzhou 350001 China Institute of Pharmaceutical Engineering Huaqiao University Quanzhou 362021 China

The kinetics of asymmetric production of R-（-）-mandelic acid （R-MA） from phenylglyoxylic acid （PGA） catalyzed by Saccharomyces cerevisiae sp. strain FD11b was studied by fed-batch cultures. The concentrations of glucose and PGA were controlled respectively with a dual feeding system. When the electron donor glucose was supplied at the rate of 0.0833mmol·gdw^-1·h^-1, the specific production rate （qp） and the enantiomeric excess of R-MA reached the maximum 0.353mmol·gdw^-1·h^-1 and 97.1%, respectively. The apparent reduction activity of yeast FD 11 b was obviously affected by both substrate PGA and product MA. The qp value reached the maximum 0.36-0.38mmol·gdw^-1·h^-1 when the PGA concentration was controlled between 25 and 35mmol·L^-1. The obvious substrate inhibition of bioconversion was observed at the PGA concentrations higher than 40mmol·L^-1. The accumulation of product MA also caused a severe feed-back inhibition for its production when the product concentration was above 60mmol·L^-1. The kinetic model with the inhibition effect of both substrate and product was simulated by a computer-based least-square arithrnatic. The established kinetic model was in good agreement with the experimental data.

关键词： Saccharomyces cerevisiae asymmetric reduction R-(-)-mandelic acid substrate inhibition product inhibi- tion kinetic model

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