1
|
Schenck CA, Busta L. Using interdisciplinary, phylogeny-guided approaches to understand the evolution of plant metabolism. PLANT MOLECULAR BIOLOGY 2022; 109:355-367. [PMID: 34816350 DOI: 10.1007/s11103-021-01220-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 11/05/2021] [Indexed: 06/13/2023]
Abstract
To cope with relentless environmental pressures, plants produce an arsenal of structurally diverse chemicals, often called specialized metabolites. These lineage-specific compounds are derived from the simple building blocks made by ubiquitous core metabolic pathways. Although the structures of many specialized metabolites are known, the underlying metabolic pathways and the evolutionary events that have shaped the plant chemical diversity landscape are only beginning to be understood. However, with the advent of multi-omics data sets and the relative ease of studying pathways in previously intractable non-model species, plant specialized metabolic pathways are now being systematically identified. These large datasets also provide a foundation for comparative, phylogeny-guided studies of plant metabolism. Comparisons of metabolic traits and features like chemical abundances, enzyme activities, or gene sequences from phylogenetically diverse plants provide insights into how metabolic pathways evolved. This review highlights the power of studying evolution through the lens of comparative biochemistry, particularly how placing metabolism into a phylogenetic context can help a researcher identify the metabolic innovations enabling the evolution of structurally diverse plant metabolites.
Collapse
Affiliation(s)
- Craig A Schenck
- Department of Biochemistry, University of Missouri, Columbia, MO, USA.
| | - Lucas Busta
- Department of Chemistry and Biochemistry, University of Minnesota Duluth, Duluth, MN, USA
| |
Collapse
|
2
|
Koper K, Han SW, Pastor DC, Yoshikuni Y, Maeda HA. Evolutionary Origin and Functional Diversification of Aminotransferases. J Biol Chem 2022; 298:102122. [PMID: 35697072 PMCID: PMC9309667 DOI: 10.1016/j.jbc.2022.102122] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 06/06/2022] [Accepted: 06/07/2022] [Indexed: 11/30/2022] Open
Abstract
Aminotransferases (ATs) are pyridoxal 5′-phosphate–dependent enzymes that catalyze the transamination reactions between amino acid donor and keto acid acceptor substrates. Modern AT enzymes constitute ∼2% of all classified enzymatic activities, play central roles in nitrogen metabolism, and generate multitude of primary and secondary metabolites. ATs likely diverged into four distinct AT classes before the appearance of the last universal common ancestor and further expanded to a large and diverse enzyme family. Although the AT family underwent an extensive functional specialization, many AT enzymes retained considerable substrate promiscuity and multifunctionality because of their inherent mechanistic, structural, and functional constraints. This review summarizes the evolutionary history, diverse metabolic roles, reaction mechanisms, and structure–function relationships of the AT family enzymes, with a special emphasis on their substrate promiscuity and multifunctionality. Comprehensive characterization of AT substrate specificity is still needed to reveal their true metabolic functions in interconnecting various branches of the nitrogen metabolic network in different organisms.
Collapse
Affiliation(s)
- Kaan Koper
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Sang-Woo Han
- The US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | | | - Yasuo Yoshikuni
- The US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Global Center for Food, Land, and Water Resources, Research Faculty of Agriculture, Hokkaido University, Hokkaido 060-8589, Japan
| | - Hiroshi A Maeda
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
| |
Collapse
|
3
|
Lopez-Nieves S, El-Azaz J, Men Y, Holland CK, Feng T, Brockington SF, Jez JM, Maeda HA. Two independently evolved natural mutations additively deregulate TyrA enzymes and boost tyrosine production in planta. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 109:844-855. [PMID: 34807484 DOI: 10.1111/tpj.15597] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/29/2021] [Accepted: 11/15/2021] [Indexed: 06/13/2023]
Abstract
l-Tyrosine is an essential amino acid for protein synthesis and is also used in plants to synthesize diverse natural products. Plants primarily synthesize tyrosine via TyrA arogenate dehydrogenase (TyrAa or ADH), which are typically strongly feedback inhibited by tyrosine. However, two plant lineages, Fabaceae (legumes) and Caryophyllales, have TyrA enzymes that exhibit relaxed sensitivity to tyrosine inhibition and are associated with elevated production of tyrosine-derived compounds, such as betalain pigments uniquely produced in core Caryophyllales. Although we previously showed that a single D222N substitution is primarily responsible for the deregulation of legume TyrAs, it is unknown when and how the deregulated Caryophyllales TyrA emerged. Here, through phylogeny-guided TyrA structure-function analysis, we found that functionally deregulated TyrAs evolved early in the core Caryophyllales before the origin of betalains, where the E208D amino acid substitution in the active site, which is at a different and opposite location from D222N found in legume TyrAs, played a key role in the TyrA functionalization. Unlike legumes, however, additional substitutions on non-active site residues further contributed to the deregulation of TyrAs in Caryophyllales. The introduction of a mutation analogous to E208D partially deregulated tyrosine-sensitive TyrAs, such as Arabidopsis TyrA2 (AtTyrA2). Moreover, the combined introduction of D222N and E208D additively deregulated AtTyrA2, for which the expression in Nicotiana benthamiana led to highly elevated accumulation of tyrosine in planta. The present study demonstrates that phylogeny-guided characterization of key residues underlying primary metabolic innovations can provide powerful tools to boost the production of essential plant natural products.
Collapse
Affiliation(s)
- Samuel Lopez-Nieves
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| | - Jorge El-Azaz
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Yusen Men
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Cynthia K Holland
- Department of Biology, Williams College, Williamstown, MA, 01267, USA
| | - Tao Feng
- Department of Plant Sciences, University of Cambridge, Cambridge, CB2 3EA, UK
| | | | - Joseph M Jez
- Department of Biology, Washington University in St Louis, St Louis, MO, 63130, USA
| | - Hiroshi A Maeda
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
| |
Collapse
|
4
|
Lynch JH, Dudareva N. Aromatic Amino Acids: A Complex Network Ripe for Future Exploration. TRENDS IN PLANT SCIENCE 2020; 25:670-681. [PMID: 32526172 DOI: 10.1016/j.tplants.2020.02.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 02/06/2020] [Accepted: 02/07/2020] [Indexed: 05/28/2023]
Abstract
In plants, high carbon flux is committed to the biosynthesis of phenylalanine, tyrosine, and tryptophan, owing to their roles not only in the production of proteins, but also as precursors to thousands of primary and specialized metabolites. The core plastidial pathways that supply the majority of aromatic amino acids (AAAs) have previously been described in detail. More recently, the discovery of cytosolic enzymes contributing to overall AAA biosynthesis, as well as the identification of intracellular transporters and the continuing elucidation of transcriptional and post-transcriptional regulatory mechanisms, have revealed the complexity of this intercompartmental metabolic network. Here, we review the latest breakthroughs in AAA production and use the newest findings to highlight both longstanding and newly developed questions.
Collapse
Affiliation(s)
- Joseph H Lynch
- Department of Biochemistry, Purdue University, 175 South University St., West Lafayette, IN 47907-2063, USA
| | - Natalia Dudareva
- Purdue Center for Plant Biology, Purdue University, West Lafayette, IN 47907, USA.
| |
Collapse
|
5
|
Schenck CA, Westphal J, Jayaraman D, Garcia K, Wen J, Mysore KS, Ané J, Sumner LW, Maeda HA. Role of cytosolic, tyrosine-insensitive prephenate dehydrogenase in Medicago truncatula. PLANT DIRECT 2020; 4:e00218. [PMID: 32368714 PMCID: PMC7196213 DOI: 10.1002/pld3.218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 03/21/2020] [Accepted: 03/25/2020] [Indexed: 05/26/2023]
Abstract
l-Tyrosine (Tyr) is an aromatic amino acid synthesized de novo in plants and microbes downstream of the shikimate pathway. In plants, Tyr and a Tyr pathway intermediate, 4-hydroxyphenylpyruvate (HPP), are precursors to numerous specialized metabolites, which are crucial for plant and human health. Tyr is synthesized in the plastids by a TyrA family enzyme, arogenate dehydrogenase (ADH/TyrAa), which is feedback inhibited by Tyr. Additionally, many legumes possess prephenate dehydrogenases (PDH/TyrAp), which are insensitive to Tyr and localized to the cytosol. Yet the role of PDH enzymes in legumes is currently unknown. This study isolated and characterized Tnt1-transposon mutants of MtPDH1 (pdh1) in Medicago truncatula to investigate PDH function. The pdh1 mutants lacked PDH transcript and PDH activity, and displayed little aberrant morphological phenotypes under standard growth conditions, providing genetic evidence that MtPDH1 is responsible for the PDH activity detected in M. truncatula. Though plant PDH enzymes and activity have been specifically found in legumes, nodule number and nitrogenase activity of pdh1 mutants were not significantly reduced compared with wild-type (Wt) during symbiosis with nitrogen-fixing bacteria. Although Tyr levels were not significantly different between Wt and mutants under standard conditions, when carbon flux was increased by shikimate precursor feeding, mutants accumulated significantly less Tyr than Wt. These data suggest that MtPDH1 is involved in Tyr biosynthesis when the shikimate pathway is stimulated and possibly linked to unidentified legume-specific specialized metabolism.
Collapse
Affiliation(s)
- Craig A. Schenck
- Department of BotanyUniversity of Wisconsin‐MadisonMadisonWIUSA
- Present address:
Department of Biochemistry and Molecular BiologyMichigan State UniversityEast LansingMIUSA
| | - Josh Westphal
- Department of BotanyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | | | - Kevin Garcia
- Department of BacteriologyUniversity of Wisconsin‐MadisonMadisonWIUSA
- Department of Crop and Soil SciencesNorth Carolina State UniversityRaleighNCUSA
| | | | | | - Jean‐Michel Ané
- Department of BacteriologyUniversity of Wisconsin‐MadisonMadisonWIUSA
- Department of AgronomyUniversity of Wisconsin‐MadisonMadisonWIUSA
| | - Lloyd W. Sumner
- Department of BiochemistryUniversity of MissouriColumbiaMOUSA
- Metabolomics and Bond Life Sciences CentersUniversity of MissouriColumbiaMOUSA
| | | |
Collapse
|
6
|
Maeda HA. Harnessing evolutionary diversification of primary metabolism for plant synthetic biology. J Biol Chem 2019; 294:16549-16566. [PMID: 31558606 DOI: 10.1074/jbc.rev119.006132] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Plants produce numerous natural products that are essential to both plant and human physiology. Recent identification of genes and enzymes involved in their biosynthesis now provides exciting opportunities to reconstruct plant natural product pathways in heterologous systems through synthetic biology. The use of plant chassis, although still in infancy, can take advantage of plant cells' inherent capacity to synthesize and store various phytochemicals. Also, large-scale plant biomass production systems, driven by photosynthetic energy production and carbon fixation, could be harnessed for industrial-scale production of natural products. However, little is known about which plants could serve as ideal hosts and how to optimize plant primary metabolism to efficiently provide precursors for the synthesis of desirable downstream natural products or specialized (secondary) metabolites. Although primary metabolism is generally assumed to be conserved, unlike the highly-diversified specialized metabolism, primary metabolic pathways and enzymes can differ between microbes and plants and also among different plants, especially at the interface between primary and specialized metabolisms. This review highlights examples of the diversity in plant primary metabolism and discusses how we can utilize these variations in plant synthetic biology. I propose that understanding the evolutionary, biochemical, genetic, and molecular bases of primary metabolic diversity could provide rational strategies for identifying suitable plant hosts and for further optimizing primary metabolism for sizable production of natural and bio-based products in plants.
Collapse
Affiliation(s)
- Hiroshi A Maeda
- Department of Botany, University of Wisconsin-Madison, Madison, Wisconsin 53706
| |
Collapse
|
7
|
Li Z, Wu J, Jia L. Analysis of amino acids in blood by combining zeolitic imidazolate framework-8-based solid phase extraction and capillary electrophoresis. J Pharm Biomed Anal 2019; 168:30-37. [DOI: 10.1016/j.jpba.2019.02.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 02/11/2019] [Accepted: 02/12/2019] [Indexed: 02/05/2023]
|
8
|
de Oliveira MVV, Jin X, Chen X, Griffith D, Batchu S, Maeda HA. Imbalance of tyrosine by modulating TyrA arogenate dehydrogenases impacts growth and development of Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 97:901-922. [PMID: 30457178 DOI: 10.1111/tpj.14169] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 11/09/2018] [Accepted: 11/13/2018] [Indexed: 06/09/2023]
Abstract
l-Tyrosine is an essential aromatic amino acid required for the synthesis of proteins and a diverse array of plant natural products; however, little is known on how the levels of tyrosine are controlled in planta and linked to overall growth and development. Most plants synthesize tyrosine by TyrA arogenate dehydrogenases, which are strongly feedback-inhibited by tyrosine and encoded by TyrA1 and TyrA2 genes in Arabidopsis thaliana. While TyrA enzymes have been extensively characterized at biochemical levels, their in planta functions remain uncertain. Here we found that TyrA1 suppression reduces seed yield due to impaired anther dehiscence, whereas TyrA2 knockout leads to slow growth with reticulate leaves. The tyra2 mutant phenotypes were exacerbated by TyrA1 suppression and rescued by the expression of TyrA2, TyrA1 or tyrosine feeding. Low-light conditions synchronized the tyra2 and wild-type growth, and ameliorated the tyra2 leaf reticulation. After shifting to normal light, tyra2 transiently decreased tyrosine and subsequently increased aspartate before the appearance of the leaf phenotypes. Overexpression of the deregulated TyrA enzymes led to hyper-accumulation of tyrosine, which was also accompanied by elevated aspartate and reticulate leaves. These results revealed that TyrA1 and TyrA2 have distinct and overlapping functions in flower and leaf development, respectively, and that imbalance of tyrosine, caused by altered TyrA activity and regulation, impacts growth and development of Arabidopsis. The findings provide critical bases for improving the production of tyrosine and its derived natural products, and further elucidating the coordinated metabolic and physiological processes to maintain tyrosine levels in plants.
Collapse
Affiliation(s)
- Marcos V V de Oliveira
- Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Xing Jin
- Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Xuan Chen
- Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Daniel Griffith
- Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Sai Batchu
- Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI, 53706, USA
- Department of Biology, The College of New Jersey, Biology Building, 2000 Pennington Road, Ewing, NJ, 08628, USA
| | - Hiroshi A Maeda
- Department of Botany, University of Wisconsin-Madison, 430 Lincoln Drive, Madison, WI, 53706, USA
| |
Collapse
|
9
|
Lopez-Nieves S, Pringle A, Maeda HA. Biochemical characterization of TyrA dehydrogenases from Saccharomyces cerevisiae (Ascomycota) and Pleurotus ostreatus (Basidiomycota). Arch Biochem Biophys 2019; 665:12-19. [PMID: 30771296 DOI: 10.1016/j.abb.2019.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 02/06/2019] [Accepted: 02/12/2019] [Indexed: 12/30/2022]
Abstract
L-Tyrosine is an aromatic amino acid necessary for protein synthesis in all living organisms and a precursor of secondary (specialized) metabolites. In fungi, tyrosine-derived compounds are associated with virulence and defense (i.e. melanin production). However, how tyrosine is produced in fungi is not fully understood. Generally, tyrosine can be synthesized via two pathways: by prephenate dehydrogenase (TyrAp/PDH), a pathway found in most bacteria, or by arogenate dehydrogenase (TyrAa/ADH), a pathway found mainly in plants. Both enzymes require the cofactor NAD+ or NADP+ and typically are strongly feedback inhibited by tyrosine. Here, we biochemically characterized two TyrA enzymes from two distantly related fungi in the Ascomycota and Basidiomycota, Saccharomyces cerevisiae (ScTyrA/TYR1) and Pleurotus ostreatus (PoTyrA), respectively. We found that both enzymes favor the prephenate substrate and NAD+ cofactor in vitro. Interestingly, while PoTyrA was strongly inhibited by tyrosine, ScTyrA exhibited relaxed sensitivity to tyrosine inhibition. We further mutated ScTyrA at the amino acid residue that was previously shown to be involved in the substrate specificity of plant TyrAs; however, no changes in its substrate specificity were observed, suggesting that a different mechanism is involved in the TyrA substrate specificity of fungal TyrAs. The current findings provide foundational knowledge to further understand and engineer tyrosine-derived specialized pathways in fungi.
Collapse
Affiliation(s)
- Samuel Lopez-Nieves
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA.
| | - Anne Pringle
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA; Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Hiroshi A Maeda
- Department of Botany, University of Wisconsin-Madison, Madison, WI, 53706, USA
| |
Collapse
|
10
|
Maeda HA. Evolutionary Diversification of Primary Metabolism and Its Contribution to Plant Chemical Diversity. FRONTIERS IN PLANT SCIENCE 2019; 10:881. [PMID: 31354760 PMCID: PMC6635470 DOI: 10.3389/fpls.2019.00881] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 06/20/2019] [Indexed: 05/05/2023]
Abstract
Plants produce a diverse array of lineage-specific specialized (secondary) metabolites, which are synthesized from primary metabolites. Plant specialized metabolites play crucial roles in plant adaptation as well as in human nutrition and medicine. Unlike well-documented diversification of plant specialized metabolic enzymes, primary metabolism that provides essential compounds for cellular homeostasis is under strong selection pressure and generally assumed to be conserved across the plant kingdom. Yet, some alterations in primary metabolic pathways have been reported in plants. The biosynthetic pathways of certain amino acids and lipids have been altered in specific plant lineages. Also, two alternative pathways exist in plants for synthesizing primary precursors of the two major classes of plant specialized metabolites, terpenoids and phenylpropanoids. Such primary metabolic diversities likely underlie major evolutionary changes in plant metabolism and chemical diversity by acting as enabling or associated traits for the evolution of specialized metabolic pathways.
Collapse
|
11
|
Schenck CA, Maeda HA. Tyrosine biosynthesis, metabolism, and catabolism in plants. PHYTOCHEMISTRY 2018; 149:82-102. [PMID: 29477627 DOI: 10.1016/j.phytochem.2018.02.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 01/26/2018] [Accepted: 02/02/2018] [Indexed: 05/22/2023]
Abstract
L-Tyrosine (Tyr) is an aromatic amino acid (AAA) required for protein synthesis in all organisms, but synthesized de novo only in plants and microorganisms. In plants, Tyr also serves as a precursor of numerous specialized metabolites that have diverse physiological roles as electron carriers, antioxidants, attractants, and defense compounds. Some of these Tyr-derived plant natural products are also used in human medicine and nutrition (e.g. morphine and vitamin E). While the Tyr biosynthesis and catabolic pathways have been extensively studied in microbes and animals, respectively, those of plants have received much less attention until recently. Accumulating evidence suggest that the Tyr biosynthetic pathways differ between microbes and plants and even within the plant kingdom, likely to support the production of lineage-specific plant specialized metabolites derived from Tyr. The interspecies variations of plant Tyr pathway enzymes can now be used to enhance the production of Tyr and Tyr-derived compounds in plants and other synthetic biology platforms.
Collapse
Affiliation(s)
- Craig A Schenck
- Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Hiroshi A Maeda
- Department of Botany, University of Wisconsin-Madison, Madison, WI 53706, USA.
| |
Collapse
|
12
|
Holland CK, Jez JM. Reaction Mechanism of Prephenate Dehydrogenase from the Alternative Tyrosine Biosynthesis Pathway in Plants. Chembiochem 2018; 19:1132-1136. [PMID: 29601138 DOI: 10.1002/cbic.201800085] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Indexed: 01/27/2023]
Abstract
Unlike metazoans, plants, bacteria, and fungi retain the enzymatic machinery necessary to synthesize the three aromatic amino acids l-phenylalanine, l-tyrosine, and l-tryptophan de novo. In legumes, such as soybean, alfalfa, and common bean, prephenate dehydrogenase (PDH) catalyzes the tyrosine-insensitive biosynthesis of 4-hydroxyphenylpyruvate, a precursor to tyrosine. The three-dimensional structure of soybean PDH1 was recently solved in complex with the NADP+ cofactor. This structure allowed for the identification of both the cofactor- and ligand-binding sites. Here, we present steady-state kinetic analysis of twenty site-directed active-site mutants of soybean (Glycine max) PDH compared to wild-type. Molecular docking of the substrate, prephenate, into the active site of the enzyme revealed its potential interactions with the active site residues and made a case for the importance of each residue in substrate recognition and/or catalysis, most likely through transition state stabilization. Overall, these results suggested that the active site of the enzyme is highly sensitive to any changes, as even subtle alterations substantially reduced the catalytic efficiency of the enzyme.
Collapse
Affiliation(s)
- Cynthia K Holland
- Department of Biology, Washington University in St. Louis, Brookings Drive, St. Louis, MO, 63112, USA
| | - Joseph M Jez
- Department of Biology, Washington University in St. Louis, Brookings Drive, St. Louis, MO, 63112, USA
| |
Collapse
|