joseph jez, ph.d. assistant member
jjez@danforthcenter.org
Plants are amazing chemists and capable of generating an arsenal of small molecules with an array of biological activities. Our research focuses on understanding the biosynthesis of plant- made compounds and how they exert their biological effects.
cysteine and sulfur assimilation. Protein-protein interactions play an essential role in a range of cellular processes. For example, as- sociation of the two enzymes in cysteine biosynthesis (O-acetylserine sulfhydrylase, oass, and serine acetyltransferase, sat) coordinates sulfur assimilation and modulates cysteine synthesis in plants. Bio-physical analysis of this interaction reveals how this macromolecular complex is assembled, and provides new insights into the molecular mechanisms underlying the biochemical regulation of cysteine synthesis in plants.
redox regulation of plant glutathione biosynthesis.Gluta- thione is a key regulator of intracellular environment and provides pro- tection against environmental stresses. Growing evidence indicates that reactive oxygen species act as signaling molecules; however, how changes in redox environment effects critical target proteins is only beginning to be explored. Using a combination of approaches, we showed that Arabidopsis glutamate-cysteine ligase (gcl), the rate-limiting enzyme in glutathione biosynthesis, responds to changes in redox environment both in vitro and in vivo through disulfide bonds (see Figure). Te thiol-based regulation of gcl provides a post-translational mechanism for modulating its activity in response to cellular redox environment and suggests a role for oxidative signaling in protecting plants from a range of environmental stresses.
toward phytoremediation. To optimize plants as tools for envi- ronmental clean-up, it is essential to understand the molecular basis of how plants protect themselves from heavy metal toxicity. Phytochelatin peptides play a pivotal role in heavy metal detoxification in plants. To improve their production in response to heavy metal toxicity, we engi- neered Arabidopsis phytochelatin synthase (pcs) to provide plants with improved tolerance to cadmium toxicity. Tis approach has now worked in yeast, Arabidopsis, and Brassica juncea (Indian mustard), which is a plant used for phytoremediation.
new nematicide targets. Parasitic nematodes of humans, animals, and plants are a major cause of disease worldwide and the development of new nematicides requires the identification of biochemical targets not
recent publications: Alvarex S, Berla BM, Sheffield J, Cahoon RE, Jez JM, Hicks LM. (2009) Comprehensive analysis of the Brassica juncea root proteome in response to cadmium exposure by complementary proteomic approaches. Proteomics 9, 2419-2431 Chen Q, Zhang B, Hicks LM, Wang S, Jez JM. (2009) A liquid chromatography-tandem mass spectrometry-based assay for indole-3-acetic acid-amido synthetases. Anal. Biochem. 390, 149-154 Galant A, Arkus KAJ, Zubieta C, Cahoon RE, Jez JM. (2009) Structural basis for evolution of product diversity in plant glutathione synthesis. Plant Cell 21, 3450-3458 He Y, Mawhinney TP, Preuss ML, Schroeder AC, Chen B, Abraham L, Jez JM, Chen S. (2009) A redox active isopropylmalate dehydrogenase functions in the biosynthesis of glucosinolates and leucine in Arabidopsis. Plant J. 60, 679-690 Higashi Y, Smith TJ, Jez JM, Kutchan TM. (2010) Crystallization and preliminary x-ray diffraction analysis of salutaridine reductase from the opium poppy Papaver somniferum. Acta Cryst. F (in press). Jez JM, Krishnan HB. (2009) Sulfur assimilation and cysteine biosynthesis
page 12 2009 scientific report the donald danforth plant science center
Te interplay between genomes, protein function, and a plant’s environment shapes the evolution of new metabolism. Te three- dimensional structure of soybean homogluathione synthetase reveals the molecular changes that define the substrate preference between evolutionarily related enzymes and reinforces the critical role of active site loops in the adaptation and diversification of enzyme function.
found in host organisms. Nematodes synthesize phosphatidylcholine, a major membrane lipid, by a route that differs from mammals. Tis pathway converts phosphoethanolamine to phosphocholine through the action of phosphoethanolamine methyltransferases (pmt). If the essential role of the pmt is conserved, then inhibition of these enzymes offers a new approach for targeting parasites with compounds of me- dicinal, veterinary, or agronomic value.
lab members: Naveen Bisht, Ph.D., Visiting Scientist nipgr, New Delhi, In- dia / Yamini Bisht, Lab Assistant / Ashley Galant, Graduate Student Washington University/ William Johnston, Summer Intern micds / Matthew Juergens, Lab Assistant Webster University / Naveena Lall, Lab Assistant Washington University Soon Goo Lee, Graduate Student Washington University / Samuel McKinney, Summer Intern Washington University / Alexander Markhov, Summer Intern micds / Akina Nagata, Summer Intern Knox College / Mary L. Preuss, Ph.D., Postdoctoral Associate / Geoff E. Ravilious, Graduate Student Washington Uni- versity/ Amy C. Schroeder, Research Assistant Leia M. Wachsstock, Lab Assistant Corey Westfall, Graduate Student Washington University / Jonathan Wignes, Lab Assistant Washington University / Hankuil Yi, Ph.D., Postdoctoral Associate Chuanmei Zhu, Graduate Student Rotation Washington University
in soybean seeds: towards engineering sulfur amino acid content In Modi- fication of Seed Composition to Promote Health and Nutrition (Krishnan HB, Ed.), pp. 249-262, ASA-CSSA-SSSA Publishing, Madison, WI Kumaran S, Yi H, Krishnan HB, Jez JM. (2009) Assembly of the cysteine synthase complex and the regulatory role of protein-protein interactions. J. Biol. Chem. 284, 10268-10275 Schroeder AC, Zhu C, Yanamadala SR, Cahoon RE, Arkus KAJ, Wachsstock L, Bleeke J, Krishnan HB, Jez JM. (2010) Treonine-insensitive homoserine dehydrogenase from soybean: genomic organization, kinetic characterization, and in vivo activity. J. Biol. Chem. 285, 827-83 Yi H, Preuss ML, Jez JM. (2009) Te devil (and an active jasmonate hormone) is in the details. Nature Chem. Biol. 5, 273-274 Yi H, Galant A, Ravilious GE, Preuss ML, Jez JM. (2010) Simple to complex biochemical regulatory mechanisms in plant thiol metabolism. Molecular Plant (in press). Yi H, Ravilious GE, Galant A, Krishnan HB, Jez JM. (2010) Thiol meta- bolism in soybean: sulfur to homoglutathione. Amino Acids (in press).
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