Bio


Plants have an extraordinary capacity to harvest atmospheric CO2 and sunlight for the production of energy-rich biopolymers, clinically used drugs, and other biologically active small molecules. The metabolic pathways that produce these compounds are key to developing sustainable biofuel feedstocks, protecting crops from pathogens, and discovering new natural-product based therapeutics for human disease. These applications motivate us to find new ways to elucidate and engineer plant metabolism. We use a multidisciplinary approach combining chemistry, enzymology, genetics, and metabolomics to tackle problems that include new methods for delignification of lignocellulosic biomass and the engineering of plant antibiotic biosynthesis.

Academic Appointments


Honors & Awards


  • Allan P. Colburn Award, AlChe (2019)
  • HHMI Investigator, Howard Hughes Medical Institute (2018)
  • Young Faculty Award, DARPA (2018)
  • Chan Zuckerberg Biohub Investigator, Chan Zuckerberg Biohub (2017)
  • Marion Milligan Mason Award for Women in the Chemical Sciences, AAAS (2016)
  • Simons Faculty Scholar Award, Howard Hughes Medical Institute (2016)
  • Early Career Award, DOE (2015)
  • Faculty Scholar Award, Hellman Fellows Fund (2013)
  • New Innovator Award, NIH (2013)
  • Gabilan Fellow, Stanford University (2011)
  • Terman Fellow, Stanford University (2011)
  • Pathway to Independence Award, NIH (2010)
  • Postdoctoral Fellowship, Damon Runyon Cancer Research Foundation (2008)
  • Division of Organic Chemistry Graduate Fellowship, ACS (2003)

Boards, Advisory Committees, Professional Organizations


  • Steering committee for SynBio satellite meeting, American Society of Plant Biology Annual Conference (2018 - 2018)
  • Advisory Committee, Joint Institute for Metrology in Biology (2016 - Present)
  • Synthetic Biology Advisory Board Member, DOE JGI (2016 - Present)
  • Editorial Board Member, Cell Chemical Biology (2015 - Present)
  • Genomes to Natural Products Network (GNPN) Member, NIH (2015 - Present)
  • American Institute of Chemical Engineers (AICHE) Member, AlChe (2013 - Present)
  • Fellow, Stanford ChEM-H Institute (2013 - Present)
  • Faculty advisor, SMASH (Summer Math and Science Honors Academy) (2011 - 2011)

Professional Education


  • PhD, Boston College (2007)

2020-21 Courses


Stanford Advisees


All Publications


  • Rerouting plant terpene biosynthesis enables momilactone pathway elucidation. Nature chemical biology De La Pena, R., Sattely, E. S. 2020

    Abstract

    Momilactones from rice have allelopathic activity, the ability to inhibit growth of competing plants. Transferring momilactone production to other crops is a potential approach to combat weeds, yet a complete momilactone biosynthetic pathway remains elusive. Here, we address this challenge through rapid gene screening in Nicotiana benthamiana, a heterologous plant host. This required us to solve a central problem: diminishing intermediate and product yields remain a bottleneck for multistep diterpene pathways. We increased intermediate and product titers by rerouting diterpene biosynthesis from the chloroplast to the cytosolic, high-flux mevalonate pathway. This enabled the discovery and reconstitution of a complete route to momilactones (>10-fold yield improvement in production versus rice). Pure momilactone B isolated from N. benthamiana inhibited germination and root growth in Arabidopsis thaliana, validating allelopathic activity. We demonstrated the broad utility of this approach by applying it to forskolin, a Hedgehog inhibitor, and taxadiene, an intermediate in taxol biosynthesis (~10-fold improvement in production versus chloroplast expression).

    View details for DOI 10.1038/s41589-020-00669-3

    View details for PubMedID 33106662

  • Engineering Plant Synthetic Pathways for the Biosynthesis of Novel Antifungals. ACS central science Calgaro-Kozina, A., Vuu, K. M., Keasling, J. D., Loque, D., Sattely, E. S., Shih, P. M. 2020; 6 (8): 1394–1400

    Abstract

    Plants produce a wealth of biologically active compounds, many of which are used to defend themselves from various pests and pathogens. We explore the possibility of expanding upon the natural chemical diversity of plants and create molecules that have enhanced properties, by engineering metabolic pathways new to nature. We rationally broaden the set of primary metabolites that can be utilized by the core biosynthetic pathway of the natural biopesticide, brassinin, producing in planta a novel class of compounds that we call crucifalexins. Two of our new-to-nature crucifalexins are more potent antifungals than brassinin and, in some instances, comparable to commercially used fungicides. Our findings highlight the potential to push the boundaries of plant metabolism for the biosynthesis of new biopesticides.

    View details for DOI 10.1021/acscentsci.0c00241

    View details for PubMedID 32875080

  • Discovery and engineering of colchicine alkaloid biosynthesis. Nature Nett, R. S., Lau, W., Sattely, E. S. 2020

    Abstract

    Few complete pathways have been established for the biosynthesis of medicinal compounds from plants. Accordingly, many plant-derived therapeutics are isolated directly from medicinal plants or plant cell culture1. A lead example is colchicine, a US Food and Drug Administration (FDA)-approved treatment for inflammatory disorders that is sourced from Colchicum and Gloriosa species2-5. Here we use a combination of transcriptomics, metabolic logic and pathway reconstitution to elucidate a near-completebiosynthetic pathway tocolchicine without prior knowledge of biosynthetic genes, a sequenced genome or genetic tools in the native host. We uncovered eight genes from Gloriosa superba for the biosynthesis of N-formyldemecolcine, a colchicine precursor that contains the characteristic tropolone ring and pharmacophore of colchicine6. Notably, we identified a non-canonical cytochrome P450 that catalyses the remarkable ring expansion reaction that is required to produce the distinct carbon scaffold of colchicine. We further used the newly identified genes to engineer a biosynthetic pathway (comprising 16enzymes in total) to N-formyldemecolcine in Nicotiana benthamiana starting from the amino acids phenylalanine and tyrosine. This study establishes a metabolic route to tropolone-containing colchicine alkaloids and provides insights into the unique chemistry that plants use to generate complex, bioactive metabolites from simple amino acids.

    View details for DOI 10.1038/s41586-020-2546-8

    View details for PubMedID 32699417

  • A Metabolic Pathway for Activation of Dietary Glucosinolates by a Human Gut Symbiont. Cell Liou, C. S., Sirk, S. J., Diaz, C. A., Klein, A. P., Fischer, C. R., Higginbottom, S. K., Erez, A., Donia, M. S., Sonnenburg, J. L., Sattely, E. S. 2020; 180 (4): 717

    Abstract

    Consumption of glucosinolates, pro-drug-like metabolites abundant in Brassica vegetables, has been associated with decreased risk of certain cancers. Gut microbiota have the ability to metabolize glucosinolates, generating chemopreventive isothiocyanates. Here, we identify a genetic and biochemical basis for activation of glucosinolates to isothiocyanates by Bacteroides thetaiotaomicron, a prominent gut commensal species. Using a genome-wide transposon insertion screen, we identified an operon required for glucosinolate metabolism in B.thetaiotaomicron. Expression of BT2159-BT2156 in a non-metabolizing relative, Bacteroides fragilis, resulted in gain of glucosinolate metabolism. We show that isothiocyanate formation requires the action of BT2158 and either BT2156 or BT2157 invitro. Monocolonization of mice with mutant BtDelta2157 showed reduced isothiocyanate production in the gastrointestinal tract. These data provide insight into the mechanisms by which a common gut bacterium processes an important dietary nutrient.

    View details for DOI 10.1016/j.cell.2020.01.023

    View details for PubMedID 32084341

  • Root-Secreted Coumarins and the Microbiota Interact to Improve Iron Nutrition in Arabidopsis. Cell host & microbe Harbort, C. J., Hashimoto, M., Inoue, H., Niu, Y., Guan, R., Rombolà, A. D., Kopriva, S., Voges, M. J., Sattely, E. S., Garrido-Oter, R., Schulze-Lefert, P. 2020

    Abstract

    Plants benefit from associations with a diverse community of root-colonizing microbes. Deciphering the mechanisms underpinning these beneficial services are of interest for improving plant productivity. We report a plant-beneficial interaction between Arabidopsis thaliana and the root microbiota under iron deprivation that is dependent on the secretion of plant-derived coumarins. Disrupting this pathway alters the microbiota and impairs plant growth in iron-limiting soil. Furthermore, the microbiota improves iron-limiting plant performance via a mechanism dependent on plant iron import and secretion of the coumarin fraxetin. This beneficial trait is strain specific yet functionally redundant across phylogenetic lineages of the microbiota. Transcriptomic and elemental analyses revealed that this interaction between commensals and coumarins promotes growth by relieving iron starvation. These results show that coumarins improve plant performance by eliciting microbe-assisted iron nutrition. We propose that the bacterial root microbiota, stimulated by secreted coumarins, is an integral mediator of plant adaptation to iron-limiting soils.

    View details for DOI 10.1016/j.chom.2020.09.006

    View details for PubMedID 33027611

  • A Pathogen-Responsive Gene Cluster for Highly Modified Fatty Acids in Tomato. Cell Jeon, J. E., Kim, J. G., Fischer, C. R., Mehta, N., Dufour-Schroif, C., Wemmer, K., Mudgett, M. B., Sattely, E. 2020; 180 (1): 176–87.e19

    Abstract

    In response to biotic stress, plants produce suites of highly modified fatty acids that bear unusual chemical functionalities. Despite their chemical complexity and proposed roles in pathogen defense, little is known about the biosynthesis of decorated fatty acids in plants. Falcarindiol is a prototypical acetylenic lipid present in carrot, tomato, and celery that inhibits growth of fungi and human cancer cell lines. Using a combination of untargeted metabolomics and RNA sequencing, we discovered a biosynthetic gene cluster in tomato (Solanum lycopersicum) required for falcarindiol production. By reconstituting initial biosynthetic steps in a heterologous host and generating transgenic pathway mutants in tomato, we demonstrate a direct role of the cluster in falcarindiol biosynthesis and resistance to fungal and bacterial pathogens in tomato leaves. This work reveals a mechanism by which plants sculpt their lipid pool in response to pathogens and provides critical insight into the complex biochemistry of alkynyl lipid production.

    View details for DOI 10.1016/j.cell.2019.11.037

    View details for PubMedID 31923394

  • Total Biosynthesis for Milligram-Scale Production of Etoposide Intermediates in a Plant Chassis JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Schultz, B. J., Kim, S., Lau, W., Sattely, E. S. 2019; 141 (49): 19231–35

    Abstract

    Etoposide is a plant-derived drug used clinically to treat several forms of cancer. Recent shortages of etoposide demonstrate the need for a more dependable production method to replace the semisynthetic method currently in place, which relies on extraction of a precursor natural product from Himalayan mayapple. Here we report milligram-scale production of (-)-deoxypodophyllotoxin, a late-stage biosynthetic precursor to the etoposide aglycone, using an engineered biosynthetic pathway in tobacco. Our strategy relies on engineering the supply of coniferyl alcohol, an endogenous tobacco metabolite and monolignol precursor to the etoposide aglycone. We show that transient expression of 16 genes, encoding both coniferyl alcohol and main etoposide aglycone pathway enzymes from mayapple, in tobacco leaves results in the accumulation of up to 4.3 mg/g dry plant weight (-)-deoxypodophyllotoxin, and enables isolation of high-purity (-)-deoxypodophyllotoxin after chromatography at levels up to 0.71 mg/g dry plant weight. Our work reveals that long (>10 step) pathways can be efficiently transferred from difficult-to-cultivate medicinal plants to a tobacco plant production chassis, and demonstrates mg-scale total biosynthesis for access to valuable precursors of the chemotherapeutic etoposide.

    View details for DOI 10.1021/jacs.9b10717

    View details for Web of Science ID 000502687800008

    View details for PubMedID 31755709

  • An engineered pathway for N-hydroxy-pipecolic acid synthesis enhances systemic acquired resistance in tomato. Science signaling Holmes, E. C., Chen, Y., Sattely, E. S., Mudgett, M. B. 2019; 12 (604)

    Abstract

    Systemic acquired resistance (SAR) is a powerful immune response that triggers broad-spectrum disease resistance throughout a plant. In the model plant Arabidopsis thaliana, long-distance signaling and SAR activation in uninfected tissues occur without circulating immune cells and instead rely on the metabolite N-hydroxy-pipecolic acid (NHP). Engineering SAR in crop plants would enable external control of a plant's ability to mount a global defense response upon sudden changes in the environment. Such a metabolite-engineering approach would require the molecular machinery for producing and responding to NHP in the crop plant. Here, we used heterologous expression in Nicotiana benthamiana leaves to identify a minimal set of Arabidopsis genes necessary for the biosynthesis of NHP. Local expression of these genes in tomato leaves triggered SAR in distal tissues in the absence of a pathogen, suggesting that the SAR trait can be engineered to enhance a plant's endogenous ability to respond to pathogens. We also showed tomato produces endogenous NHP in response to a bacterial pathogen and that NHP is present across the plant kingdom, raising the possibility that an engineering strategy to enhance NHP-induced defenses could be possible in many crop plants.

    View details for DOI 10.1126/scisignal.aay3066

    View details for PubMedID 31641079

  • The alkynes we eat: Where do they come from and how do we identify them? Fischer, C., Jeon, J., Smith, K., Sattely, E. AMER CHEMICAL SOC. 2019
  • Developing Plant Synthetic Biology Tools for Complex Metabolic Engineering. Shih, P. M., Calgaro-Kozina, A., Khanh Vuu, Keasling, J. D., Loque, D., Sattely, E. S. SPRINGER. 2019: S2
  • Identification of key enzymes responsible for protolimonoid biosynthesis in plants: Opening the door to azadirachtin production. Proceedings of the National Academy of Sciences of the United States of America Hodgson, H., De La Peña, R., Stephenson, M. J., Thimmappa, R., Vincent, J. L., Sattely, E. S., Osbourn, A. 2019

    Abstract

    Limonoids are natural products made by plants belonging to the Meliaceae (Mahogany) and Rutaceae (Citrus) families. They are well known for their insecticidal activity, contribution to bitterness in citrus fruits, and potential pharmaceutical properties. The best known limonoid insecticide is azadirachtin, produced by the neem tree (Azadirachta indica). Despite intensive investigation of limonoids over the last half century, the route of limonoid biosynthesis remains unknown. Limonoids are classified as tetranortriterpenes because the prototypical 26-carbon limonoid scaffold is postulated to be formed from a 30-carbon triterpene scaffold by loss of 4 carbons with associated furan ring formation, by an as yet unknown mechanism. Here we have mined genome and transcriptome sequence resources for 3 diverse limonoid-producing species (A. indica, Melia azedarach, and Citrus sinensis) to elucidate the early steps in limonoid biosynthesis. We identify an oxidosqualene cyclase able to produce the potential 30-carbon triterpene scaffold precursor tirucalla-7,24-dien-3β-ol from each of the 3 species. We further identify coexpressed cytochrome P450 enzymes from M. azedarach (MaCYP71CD2 and MaCYP71BQ5) and C. sinensis (CsCYP71CD1 and CsCYP71BQ4) that are capable of 3 oxidations of tirucalla-7,24-dien-3β-ol, resulting in spontaneous hemiacetal ring formation and the production of the protolimonoid melianol. Our work reports the characterization of protolimonoid biosynthetic enzymes from different plant species and supports the notion of pathway conservation between both plant families. It further paves the way for engineering crop plants with enhanced insect resistance and producing high-value limonoids for pharmaceutical and other applications by expression in heterologous hosts.

    View details for DOI 10.1073/pnas.1906083116

    View details for PubMedID 31371503

  • Plant-derived coumarins shape the composition of an Arabidopsis synthetic root microbiome. Proceedings of the National Academy of Sciences of the United States of America Voges, M. J., Bai, Y., Schulze-Lefert, P., Sattely, E. S. 2019

    Abstract

    The factors that contribute to the composition of the root microbiome and, in turn, affect plant fitness are not well understood. Recent work has highlighted a major contribution of the soil inoculum in determining the composition of the root microbiome. However, plants are known to conditionally exude a diverse array of unique secondary metabolites, that vary among species and environmental conditions and can interact with the surrounding biota. Here, we explore the role of specialized metabolites in dictating which bacteria reside in the rhizosphere. We employed a reduced synthetic community (SynCom) of Arabidopsis thaliana root-isolated bacteria to detect community shifts that occur in the absence of the secreted small-molecule phytoalexins, flavonoids, and coumarins. We find that lack of coumarin biosynthesis in f6'h1 mutant plant lines causes a shift in the root microbial community specifically under iron deficiency. We demonstrate a potential role for iron-mobilizing coumarins in sculpting the A. thaliana root bacterial community by inhibiting the proliferation of a relatively abundant Pseudomonas species via a redox-mediated mechanism. This work establishes a systematic approach enabling elucidation of specific mechanisms by which plant-derived molecules mediate microbial community composition. Our findings expand on the function of conditionally exuded specialized metabolites and suggest avenues to effectively engineer the rhizosphere with the aim of improving crop growth in iron-limited alkaline soils, which make up a third of the world's arable soils.

    View details for DOI 10.1073/pnas.1820691116

    View details for PubMedID 31152139

  • N-hydroxy-pipecolic acid is a mobile metabolite that induces systemic disease resistance in Arabidopsis PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Chen, Y., Holmes, E. C., Rajniak, J., Kim, J., Tang, S., Fischer, C. R., Mudgett, M., Sattely, E. S. 2018; 115 (21): E4920–E4929

    Abstract

    Systemic acquired resistance (SAR) is a global response in plants induced at the site of infection that leads to long-lasting and broad-spectrum disease resistance at distal, uninfected tissues. Despite the importance of this priming mechanism, the identity and complexity of defense signals that are required to initiate SAR signaling is not well understood. In this paper, we describe a metabolite, N-hydroxy-pipecolic acid (N-OH-Pip) and provide evidence that this mobile molecule plays a role in initiating SAR signal transduction in Arabidopsis thaliana We demonstrate that FLAVIN-DEPENDENT MONOOXYGENASE 1 (FMO1), a key regulator of SAR-associated defense priming, can synthesize N-OH-Pip from pipecolic acid in planta, and exogenously applied N-OH-Pip moves systemically in Arabidopsis and can rescue the SAR-deficiency of fmo1 mutants. We also demonstrate that N-OH-Pip treatment causes systemic changes in the expression of pathogenesis-related genes and metabolic pathways throughout the plant and enhances resistance to a bacterial pathogen. This work provides insight into the chemical nature of a signal for SAR and also suggests that the N-OH-Pip pathway is a promising target for metabolic engineering to enhance disease resistance.

    View details for PubMedID 29735713

  • Biosynthesis of redox-active metabolites in response to iron deficiency in plants NATURE CHEMICAL BIOLOGY Rajniak, J., Giehl, R. H., Chang, E., Murgia, I., von Wiren, N., Sattely, E. S. 2018; 14 (5): 442-+

    Abstract

    Iron is an essential but poorly bioavailable nutrient because of its low solubility, especially in alkaline soils. Here, we describe the discovery of a previously undescribed redox-active catecholic metabolite, termed sideretin, which derives from the coumarin fraxetin and is the primary molecule exuded by Arabidopsis thaliana roots in response to iron deficiency. We identified two enzymes that complete the biosynthetic pathway of fraxetin and sideretin. Chemical characterization of fraxetin and sideretin, and biological assays with pathway mutants, suggest that these coumarins are critical for iron nutrition in A. thaliana. Further, we show that sideretin production also occurs in eudicot species only distantly related to A. thaliana. Untargeted metabolomics of the root exudates of various eudicots revealed production of structurally diverse redox-active molecules in response to iron deficiency. Our results indicate that secretion of small-molecule reductants by roots may be a widespread and previously underappreciated component of reduction-based iron uptake.

    View details for PubMedID 29581584

  • A lignin-epoxy resin derived from biomass as an alternative to formaldehyde-based wood adhesives GREEN CHEMISTRY Li, R., Gutierrez, J., Chung, Y., Frank, C. W., Billington, S. L., Sattely, E. S. 2018; 20 (7): 1459–66

    View details for DOI 10.1039/c7gc03026f

    View details for Web of Science ID 000432567300005

  • HEx: A heterologous expression platform for the discovery of fungal natural products SCIENCE ADVANCES Harvey, C. B., Tang, M., Schlecht, U., Horecka, J., Fischer, C. R., Lin, H., Li, J., Naughton, B., Cherry, J., Miranda, M., Li, Y., Chu, A. M., Hennessy, J. R., Vandova, G. A., Inglis, D., Aiyar, R. S., Steinmetz, L. M., Davis, R. W., Medema, M. H., Sattely, E., Khosla, C., St Onge, R. P., Tang, Y., Hillenmeyer, M. E. 2018; 4 (4): eaar5459

    Abstract

    For decades, fungi have been a source of U.S. Food and Drug Administration-approved natural products such as penicillin, cyclosporine, and the statins. Recent breakthroughs in DNA sequencing suggest that millions of fungal species exist on Earth, with each genome encoding pathways capable of generating as many as dozens of natural products. However, the majority of encoded molecules are difficult or impossible to access because the organisms are uncultivable or the genes are transcriptionally silent. To overcome this bottleneck in natural product discovery, we developed the HEx (Heterologous EXpression) synthetic biology platform for rapid, scalable expression of fungal biosynthetic genes and their encoded metabolites in Saccharomyces cerevisiae. We applied this platform to 41 fungal biosynthetic gene clusters from diverse fungal species from around the world, 22 of which produced detectable compounds. These included novel compounds with unexpected biosynthetic origins, particularly from poorly studied species. This result establishes the HEx platform for rapid discovery of natural products from any fungal species, even those that are uncultivable, and opens the door to discovery of the next generation of natural products.

    View details for PubMedID 29651464

  • D2O Labeling to Measure Active Biosynthesis of Natural Products in Medicinal Plants. AIChE journal. American Institute of Chemical Engineers Nett, R. S., Guan, X., Smith, K., Faust, A. M., Sattely, E. S., Fischer, C. R. 2018; 64 (12): 4319–30

    Abstract

    Plant natural products have served as a prominent source of medicines throughout human history, and are still used today as clinically-approved pharmaceuticals. However, many medicinal plants that produce useful compounds are slow-growing or recalcitrant to cultivation, making it difficult to investigate the underlying genetic/enzymatic machinery responsible for biosynthesis. To better understand the metabolism of bioactive natural products in slow-growing medicinal plants, we used D2O labeling and LC-MS-based metabolomics to explore the biosynthesis of medically-relevant alkaloids in three plant species. Our results provide evidence for sites of active biosynthesis for these alkaloids, and demonstrate that D2O labeling can be used as a general method to determine sites of active secondary metabolism over relatively short time scales. We anticipate that these results will facilitate discovery of complete metabolic pathways for plant natural products of medicinal importance, especially for approaches that rely upon transcriptomics and knowledge of active metabolism to identify biosynthetic enzymes.

    View details for DOI 10.1002/aic.16413

    View details for PubMedID 31235979

    View details for PubMedCentralID PMC6590064

  • Biosynthesis of cabbage phytoalexins from indole glucosinolate. Proceedings of the National Academy of Sciences of the United States of America Klein, A. P., Sattely, E. S. 2017; 114 (8): 1910-1915

    Abstract

    Brassica crop species are prolific producers of indole-sulfur phytoalexins that are thought to have an important role in plant disease resistance. These molecules are conspicuously absent in the model plant Arabidopsis thaliana, and little is known about the enzymatic steps that assemble the key precursor brassinin. Here, we report the minimum set of biosynthetic genes required to generate cruciferous phytoalexins starting from the well-studied glucosinolate pathway. In vitro biochemical characterization revealed an additional role for the previously described carbon-sulfur lyase SUR1 in processing cysteine-isothiocyanate conjugates, as well as the S-methyltransferase DTCMT that methylates the resulting dithiocarbamate, together completing a pathway to brassinin. Additionally, the β-glucosidase BABG that is present in Brassica rapa but absent in Arabidopsis was shown to act as a myrosinase and may be a determinant of plants that synthesize phytoalexins from indole glucosinolate. Transient expression of the entire pathway in Nicotiana benthamiana yields brassinin, demonstrating that the biosynthesis of indole-sulfur phytoalexins can be engineered into noncruciferous plants. The identification of these biosynthetic enzymes and the heterologous reconstitution of the indole-sulfur phytoalexin pathway sheds light on an important pathway in an edible plant and opens the door to using metabolic engineering to systematically quantify the impact of cruciferous phytoalexins on plant disease resistance and human health.

    View details for DOI 10.1073/pnas.1615625114

    View details for PubMedID 28154137

    View details for PubMedCentralID PMC5338394

  • Plant Assimilation Kinetics and Metabolism of 2-Mercaptobenzothiazole Tire Rubber Vulcanizers by Arabidopsis ENVIRONMENTAL SCIENCE & TECHNOLOGY Lefevre, G. H., Portmann, A. C., Muller, C. E., Sattely, E. S., Luthy, R. G. 2016; 50 (13): 6762-6771

    Abstract

    2-Mercaptobenzothiazole (MBT) is a tire rubber vulcanizer found in potential sources of reclaimed water where it may come in contact with vegetation. In this work, we quantified the plant assimilation kinetics of MBT using Arabidopsis under hydroponic conditions. MBT depletion kinetics in the hydroponic medium with plants were second order (t1/2 = 0.52 to 2.4 h) and significantly greater than any abiotic losses (>18 times faster; p = 0.0056). MBT depletion rate was related to the initial exposure concentration with higher rates at greater concentrations from 1.6 μg/L to 147 μg/L until a potentially inhibitory level (1973 μg/L) lowered the assimilation rate. 9.8% of the initial MBT mass spike was present in the plants after 3 h and decreased through time. In-source LC-MS/MS fragmentation revealed that MBT was converted by Arabidopsis seedlings to multiple conjugated-MBT metabolites of differential polarity that accumulate in both the plant tissue and hydroponic medium; metabolite representation evolved temporally. Multiple novel MBT-derived plant metabolites were detected via LC-QTOF-MS analysis; proposed transformation products include glucose and amino acid conjugated MBT metabolites. Elucidating plant transformation products of trace organic contaminants has broad implications for water reuse because plant assimilation could be employed advantageously in engineered natural treatment systems, and plant metabolites in food crops could present an unintended exposure route to consumers.

    View details for DOI 10.1021/acs.est.5b04716

    View details for Web of Science ID 000379366300022

    View details for PubMedID 26698834

  • Competing mechanisms for perfluoroalkyl acid accumulation in plants revealed using an Arabidopsis model system. Environmental toxicology and chemistry Müller, C. E., Lefevre, G. H., Timofte, A. E., Hussain, F. A., Sattely, E. S., Luthy, R. G. 2016; 35 (5): 1138-1147

    Abstract

    Perfluoroalkyl acids (PFAAs) bioaccumulate in plants, presenting a human exposure route if present in irrigation water. Curiously, accumulation of PFAAs in plant tissues is greatest for both the short-chain and long-chain PFAAs, generating a U-shaped relationship with chain length. In the present study, the authors decouple competing mechanisms of PFAA accumulation using a hydroponic model plant system (Arabidopsis thaliana) exposed to a suite of 10 PFAAs to determine uptake, depuration, and translocation kinetics. Rapid saturation of root concentrations occurred for all PFAAs except perfluorobutanoate, the least-sorptive (shortest-chain) PFAA. Shoot concentrations increased continuously, indicating that PFAAs are efficiently transported and accumulate in shoots. Tissue concentrations of PFAAs during depuration rapidly declined in roots but remained constant in shoots, demonstrating irreversibility of the translocation process. Root and shoot concentration factors followed the U-shaped trend with perfluoroalkyl chain length; however, when normalized to dead-tissue sorption, this relationship linearized. The authors therefore introduce a novel term, the "sorption normalized concentration factor," to describe PFAA accumulation in plants; because of their hydrophobicity, sorption is the determining factor for long-chain PFAAs, whereas the shortest-chain PFAAs are most effectively transported in the plant. The present study provides a mechanistic explanation for previously unexplained PFAA accumulation trends in plants and suggests that shorter-chained PFAAs may bioaccumulate more readily in edible portions.

    View details for DOI 10.1002/etc.3251

    View details for PubMedID 26383989

  • Two cytochromes P450 catalyze S-heterocyclizations in cabbage phytoalexin biosynthesis. Nature chemical biology Klein, A. P., Sattely, E. S. 2015; 11 (11): 837-839

    Abstract

    Phytoalexins are abundant in edible crucifers and have important biological activities, yet no dedicated gene for their biosynthesis is known. Here, we report two new cytochromes P450 from Brassica rapa (Chinese cabbage) that catalyze unprecedented S-heterocyclizations in cyclobrassinin and spirobrassinin biosynthesis. Our results provide genetic and biochemical insights into the biosynthesis of a prominent pair of dietary metabolites and have implications for pathway discovery across >20 recently sequenced crucifers.

    View details for DOI 10.1038/nchembio.1914

    View details for PubMedID 26389737

  • A new cyanogenic metabolite in Arabidopsis required for inducible pathogen defence. Nature Rajniak, J., Barco, B., Clay, N. K., Sattely, E. S. 2015; 525 (7569): 376-379

    View details for DOI 10.1038/nature14907

    View details for PubMedID 26352477

  • Rapid Phytotransformation of Benzotriazole Generates Synthetic Tryptophan and Auxin Analogs in Arabidopsis. Environmental science & technology Lefevre, G. H., Müller, C. E., Li, R. J., Luthy, R. G., Sattely, E. S. 2015; 49 (18): 10959-10968

    Abstract

    Benzotriazoles (BTs) are xenobiotic contaminants widely distributed in aquatic environments and of emerging concern due to their polarity, recalcitrance, and common use. During some water reclamation activities, such as stormwater bioretention or crop irrigation with recycled water, BTs come in contact with vegetation, presenting a potential exposure route to consumers. We discovered that BT in hydroponic systems was rapidly (approximately 1-log per day) assimilated by Arabidopsis plants and metabolized to novel BT metabolites structurally resembling tryptophan and auxin plant hormones; <1% remained as parent compound. Using LC-QTOF-MS untargeted metabolomics, we identified two major types of BT transformation products: glycosylation and incorporation into the tryptophan biosynthetic pathway. BT amino acid metabolites are structurally analogous to tryptophan and the storage forms of auxin plant hormones. Critical intermediates were synthesized (authenticated by (1)H/(13)C NMR) for product verification. In a multiple-exposure temporal mass balance, three major metabolites accounted for >60% of BT. Glycosylated BT was excreted by the plants into the hydroponic medium, a phenomenon not observed previously. The observed amino acid metabolites are likely formed when tryptophan biosynthetic enzymes substitute synthetic BT for native indolic molecules, generating potential phytohormone mimics. These results suggest that BT metabolism by plants could mask the presence of BT contamination in the environment. Furthermore, BT-derived metabolites are structurally related to plant auxin hormones and should be evaluated for undesirable biological effects.

    View details for DOI 10.1021/acs.est.5b02749

    View details for PubMedID 26301449

  • Six enzymes from mayapple that complete the biosynthetic pathway to the etoposide aglycone. Science Lau, W., Sattely, E. S. 2015; 349 (6253): 1224-1228

    Abstract

    Podophyllotoxin is the natural product precursor of the chemotherapeutic etoposide, yet only part of its biosynthetic pathway is known. We used transcriptome mining in Podophyllum hexandrum (mayapple) to identify biosynthetic genes in the podophyllotoxin pathway. We selected 29 candidate genes to combinatorially express in Nicotiana benthamiana (tobacco) and identified six pathway enzymes, including an oxoglutarate-dependent dioxygenase that closes the core cyclohexane ring of the aryltetralin scaffold. By coexpressing 10 genes in tobacco-these 6 plus 4 previously discovered-we reconstitute the pathway to (-)-4'-desmethylepipodophyllotoxin (the etoposide aglycone), a naturally occurring lignan that is the immediate precursor of etoposide and, unlike podophyllotoxin, a potent topoisomerase inhibitor. Our results enable production of the etoposide aglycone in tobacco and circumvent the need for cultivation of mayapple and semisynthetic epimerization and demethylation of podophyllotoxin.

    View details for DOI 10.1126/science.aac7202

    View details for PubMedID 26359402

  • Key applications of plant metabolic engineering. PLoS biology Lau, W., Fischbach, M. A., Osbourn, A., Sattely, E. S. 2014; 12 (6)

    Abstract

    Great strides have been made in plant metabolic engineering over the last two decades, with notable success stories including Golden rice. Here, we discuss the field's progress in addressing four long-standing challenges: creating plants that satisfy their own nitrogen requirement, so reducing or eliminating the need for nitrogen fertilizer; enhancing the nutrient content of crop plants; engineering biofuel feed stocks that harbor easy-to-access fermentable saccharides by incorporating self-destructing lignin; and increasing photosynthetic efficiency. We also look to the future at emerging areas of research in this field.

    View details for DOI 10.1371/journal.pbio.1001879

    View details for PubMedID 24915445

    View details for PubMedCentralID PMC4051588

  • The chemical logic of plant natural product biosynthesis. Current opinion in plant biology Anarat-Cappillino, G., Sattely, E. S. 2014; 19: 51-58

    Abstract

    Understanding the logic of plant natural product biosynthesis is important for three reasons: it guides the search for new natural products and pathways, illuminates the function of existing pathways in the context of host biology, and builds an enabling 'parts list' for plant and microbial metabolic engineering. In this review, we highlight the chemical themes that underlie a broad range of plant pathways, dividing pathways into two parts: scaffold-generating steps that draw on a limited set of chemistries, and tailoring reactions that produce a wide range of end products from a small number of common scaffolds.

    View details for DOI 10.1016/j.pbi.2014.03.007

    View details for PubMedID 24727074

  • Minimum set of cytochromes p450 for reconstituting the biosynthesis of camalexin, a major Arabidopsis antibiotic. Angewandte Chemie (International ed. in English) Klein, A. P., Anarat-Cappillino, G., Sattely, E. S. 2013; 52 (51): 13625-13628

    Abstract

    Bringing it all together: The missing key step in the biosynthesis of camalexin was uncovered by in vitro biochemical characterization. The coupling of Trp- and Cys-derived fragments through CS bond formation is promoted by an unusual cytochrome P450 CYP71A13. The in vitro reconstitution of the camalexin biosynthesis (left) from Trp and Cys was achieved using just three cytochromes P450. IAN=indole-3-acetonitrile.

    View details for DOI 10.1002/anie.201307454

    View details for PubMedID 24151049

    View details for PubMedCentralID PMC3867539

  • A Renewable Lignin-Lactide Copolymer and Application in Biobased Composites ACS SUSTAINABLE CHEMISTRY & ENGINEERING Chung, Y., Olsson, J. V., Li, R. J., Frank, C. W., Waymouth, R. M., Billington, S. L., Sattely, E. S. 2013; 1 (10): 1231-1238

    View details for DOI 10.1021/sc4000835

    View details for Web of Science ID 000325512000004

  • Three Cytochromes P450 are Sufficient to Reconstitute the Biosynthesis of Camalexin, a Major Arabidopsis Antibiotic Angew. Chem. Int. Ed. Klein, A., P., Anarat-Cappillino, G., Sattely, E., S. 2013; 52: 13625-13628
  • Design and Stereoselective Preparation of a New Class of Chiral Olefin Metathesis Catalysts and Application to Enantioselective Synthesis of Quebrachamine: Catalyst Development Inspired by Natural Product Synthesis J. Am. Chem. Soc. Sattely, E., S., Meek, S., J., Malcolmson, S., J., Schrock, R., R., Hoveyda, A., H. 2009; 131: 943- 953
  • Three Siderophores from One Assembly Line Enzyme J. Am. Chem. Soc. Wuest, W., M., Sattely, E., S., Walsh, C., T. 2009; 131: 5056-5057
  • Enzymatic Tailoring of Ornithine in the Biosynthesis of the Rhizobium Cyclic Trihydroxamate Siderophore Vicibactin J. Am. Chem. Soc. Heemstra Jr., J., R., Walsh, C., T., Sattely, E., S. 2009; 131: 15317-15329
  • A Latent Oxazoline Electrophile for N-O-C Bond Formation in Pseudomonine Biosynthesis J. Am. Chem. Soc. Sattely, E., S., Walsh, C., T. 2008; 130: 12282-12284
  • Total Biosynthesis: in vitro Reconstitution of Polyketide and Nonribosomal Peptide Pathways Nat. Prod. Rep. Sattely, E., S., Fischbach, M., A., Walsh, C., T. 2008; 25: 757-793
  • Highly Efficient Molybdenum-Based Catalysts for Enantioselective Alkene Metathesis Nature Malcolmson, S., J., Meek, S., J., Sattely, E., S., Schrock, R., R., Hoveyda, A., H. 2008; 456: 933-937
  • Enantioselective Synthesis of Cyclic Amines and Amides through Mo-Catalyzed Asymmetric Ring-Closing Metathesis J. Am. Chem. Soc. Sattely, E., S., Cortez, G., A., Moebius, D., C., Schrock, R., R., Hoveyda, A., H. 2005; 127: 8526-8533
  • Efficient Catalytic Enantioselective Synthesis of Unsaturated Amines: Preparation of Small- and Medium- Ring Cyclic Amines through Mo-Catalyzed Asymmetric Ring-Closing Metathesis in the Absence of Solvent J. Am. Chem. Soc. Dolman, S., J., Sattely, E., S., Hoveyda, A., H., Schrock, R., R. 2002; 124: 6991-6997
  • Catalytic Asymmetric Ring-Opening Metathesis/Cross Metathesis (AROM/CM) Reactions. Mechanism and Application to Enantioselective Synthesis of Functionalized Cyclopentanes J. Am. Chem. Soc. La, D., S., Sattely, E., S., Ford, J., G., Schrock, R., R., Hoveyda, A., H. 2001; 123: 7767-7778
  • Tandem Catalytic Asymmetric Ring-Opening Metathesis/Cross Metathesis J. Am. Chem. Soc. La, D., S., Ford, J., G., Sattely, E., S., Bonitatebus, P., J., Schrock, R., R., Hoveyda, A., H. 1999; 121: 11603-11604