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Journal of Integrative plant Biology 2011年第1期53卷 35-43页

作者： Cai-Ling Wang Hai-Ling Yang College of Life Sciences and Biotechnology Beijing Forestry University Beijing 100083 China

The tau class glutathione S-transferases （GSTs） have important roles in stress tolerance and the detoxification of herbicides in crops and weeds. Structural investigations of a wheat tau GST （TaGSTU4） show two subunit interactions： a hydrogen bond between the Tyr93 and Pro65 from another subunit of the dimer, and two salt bridges between residues Glu78 and side chains of Arg95 and Arg99 in the opposite subunit. By investigating enzyme activities, kinetic parameters and structural characterizations, this study showed the following results：（i） the hydrogen bond interaction between the Tyr93 and Pro65 was not essential for dimerization, but contributed to the enzyme＇s catalytic activity, thermal stability and affinity towards substrates glutathione and 1-chloro-2, 4-dinitrobenzene; and （ii） two salt bridges mainly contributed to the protein structure stability and catalysis. The results of this study form a structural and functional basis for rational design of more selective and environmentally friendly herbicides.

关键词： GLUTATHIONE transferase CROP residues plantS -- Herbicide tolerance plant enzymes ENZYME activation HYDROGEN bonding HERBICIDES -- Toxicology

Allelic Analyses of the Arabidopsis YUC1 Locus Reveal Residues and Domains Essential for the Functions of YUC Family of Flavin Monooxygenases

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Journal of Integrative plant Biology 2011年第1期53卷 54-62页

作者： Xianhui Hou Sainan Liu Florencia Pierri Xinhua Dai Li-Jia Qu Yunde Zhao National Laboratory for Protein Engineering and plant Genetic Engineering Peking-Yale Joint Research Center for Plant Molecular Genetics and AgroBiotechnology College of Life Sciences Peking University Beijing 100871 China Section of Cell and Developmental Biology University of California at San Diego La Jolla California 92093-0116 USA

Flavin monooxygenases （FMOs） play critical roles in plant growth and development by synthesizing auxin and other signaling molecules. However, the structure and function relationship within plant FMOs is not understood. Here we defined the important residues and domains of the Arabidopsis YUC1 FMO, a key enzyme in auxin biosynthesis. We previously showed that simultaneous inactivation of YUC1 and its homologue YUC4 caused severe defects in vascular and floral development. We mutagenized the yuc4 mutant and screened for mutants with phenotypes similar to those of yucl yuc4 double mutants. Among the isolated mutants, five of them contained mutations in the YUC1 gene. Interestingly, the mutations identified in the new yucl alleles were concentrated in the two GXGXXG motifs that are highly conserved among the plant FMOs. One such motif presumably binds to flavin adenine dinucleotide （FAD） cofactor and the other binds to nicotinamide adenine dinucleotide phosphate （NADPH）. We also identified the Ser139 to Phe conversion in yucl, a mutation that is located between the two nucleotide-binding sites. By analyzing a series of yucl mutants, we identified key residues and motifs essential for the functions of YUC1 FMO.

关键词： ARABIDOPSIS FLAVINS MONOOXYGENASES plant enzymes PHOTOSYNTHESIS NAD (Coenzyme) plant mutation NUCLEOTIDES AUXIN

Characterization of a Novel β-thioglucosidase CpTGG1 in Carica papaya and its Substrate-dependent and Ascorbic Acid-independent O-β-glucosidase Activity

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Journal of Integrative plant Biology 2010年第10期52卷 879-890页

作者： Han Nong Jia-Ming Zhang Ding-Qin Li Meng Wang Xue-Piao Sun Yun Judy Zhu Johan Meijer Qin-Huang Wang National Center for Tropical Crops Engineering and Technology Research Spice and Beverage Crops Research Institute ChineseAcademy of Tropical Agricultural Sciences (CATAS) Wannin 571533 China MOA Key Biotechnology Laboratory for Tropical Crops Institute of Tropical Bioscience and Biotechnology CATAS Haikou 571101 China College of Agriculture Hainan University H'aikou 571101 China Institute of Biotechnology Yunnan Acaclemy of Agricultural Sciences Kunming 650205 China Department of plant Biology and Forest Genetics BioCenter Swedish University of Agricultural Sciences SE-750 07 Uppsala Sweden

plant thioglucosidases are the only known S-glycosidases in the large superfamily of glycosidases. These enzymes evolved more recently and are distributed mainly in Brassicales. Thioglucosidase research has focused mainly on the cruciferous crops due to their economic importance and cancer preventive benefits. In this study, we cloned a novel myrosinase gene, CpTGG1, from Carica papaya Linnaeus. and showed that it was expressed in the aboveground tissues in planta. The recombinant CpTGG1 expressed in Pichia pastoris catalyzed the hydrolysis of both sinigrin and glucotropaeolin （the only thioglucoside present in papaya）, showing that CpTGG1 was indeed a functional myrosinase gene. Sequence alignment analysis indicated that CpTGG1 contained all the motifs conserved in functional myrosinases from crucifers, except for two aglycon-binding motifs, suggesting substrate priority varia- tion of the non-cruciferous myrosinases. Using sinigrin as substrate, the apparent Km and Vmax values of recombinant CpTGG1 were 2.82 mM and 59.9 μmoI min-1 mg protein-1, respectively. The KcatlKm value was 23 s-1 mM-1, O-β-glucosidase activity towards a variety of substrates were tested, CpTGG1 displayed substrate-dependent and ascorbic acid-independent O-β-glucosidase activity towards 2-nitrophenyl-β- D-glucopyranoside and 4-nitrophenyl-β-D-glucopyranoside, but was inactive towards glucovanillin and n-octyl-β-D-glucopyranoside. Phylogenetic analysis indicated CpTGG1 belongs to the MYR II subfamily of myrosinases.

关键词： GLUCOSIDASES plant enzymes PAPAYA VITAMIN C plant gene expression CANCER prevention plant phylogeny plant cells & tissues

Regulation of Thermogenesis in plants:The Interaction of Alternative Oxidase and plant Uncoupling Mitochondrial Protein

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Journal of Integrative plant Biology 2011年第1期53卷 7-13页

作者： Yan Zhu Jianfei Lu Jing Wang Fu Chen Feifan Leng Hongyu Li MOE Key Laboratory of Arid and Grassland Ecology School of Life Sciences Lanz-hou University Lanzhou 730000 China College of Food Science and Engineering Gansu Agriculture University Lanzhou 730070 China Institute of Potato Gansu Academy of Agricultural Sciences Lanzhou 730070 China

Thermogenesis is a process of heat production in living organisms. It is rare in plants, but it does occur in some species of angiosperm. The heat is generated via plant mitochondrial respiration. As possible involvement in thermogenesis of mitochondrial factors, alternative ox- idases （AOXs） and plant uncoupling mitochondrial proteins （PUMPs） have been well studied. AOXs and PUMPs are ubiquitously present in the inner membrane of plant mitochondria. They serve as two major energy dissipation systems that balance mitochondrial respiration and uncoupled phosphorylation by dissipating the H~ redox energy and proton electrochemical gradient （A#H~） as heat, respectively. AOXs and PUMPs exert similar physiological functions during homeothermic heat production in thermogenic plants. AOXs have five isoforms, while PUMPs have six. Both AOXs and PUMPs are encoded by small nuclear multigene families. Multiple isoforms are expressed in different tissues or *** studies have been done in the area of thermogenesis in higher plants. In this review, we focus on the involvement and regulation of AOXs and PUMPs in thermogenesis.

关键词： plant enzymes EFFECT of temperature on plants OXIDASES plantS -- Phosphorylation plant mitochondria MITOCHONDRIAL membranes GENETIC code

Is There a Metabolic Requirement for Photorespiratory Enzyme Activities in Heterotrophic Tissues？

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Molecular plant 2014年第1期7卷 248-251页

作者： Adriano Nunes-Nesi Alexandra Florian Andrew Howden Kathrin Jahnke Stefan Timm Hermann Bauwe Lee Sweetlove Alisdair R. Fernie Max Planck Partner Group Departamento de Biologia Vegetal Universidade Federal de Vicosa 36570-000 Vicosa Minas Gerais Brazil Central Metabolism Group Max Planck Institute of Molecular Plant Physiology Am Muehlenberg 1 D-14476 Potsdam-Golm Germany Department of plant Sciences University of Oxford South Parks Road Oxford OX2 3RB UK Department of plant Physiology University of Rostock D-18051 Rostock Germany

Photorespiration is an essential metabolic process in leaves that facilitates recovery of carbon lost by the oxygenase reaction of Rubisco and avoids the accumulation of the toxic product, 2-phosphoglycolate （2PG） of this reaction （Bauwe et al., 2012）. However, there is also evidence to suggest that photorespiration has a more complex role during normal growth than the mere detoxification of 2PG and the recovery of 3-phosphoglycerate （3PGA）（Bauwe et al., 2012）.

关键词： HETEROTROPHIC bacteria RESEARCH TISSUES plant photorespiration GLYCOLATES plant enzymes plant enzymes -- Regulation