1
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Lasok H, Nziengui H, Kochersperger P, Ditengou FA. Arabidopsis Root Development Regulation by the Endogenous Folate Precursor, Para-Aminobenzoic Acid, via Modulation of the Root Cell Cycle. PLANTS (BASEL, SWITZERLAND) 2023; 12:4076. [PMID: 38140403 PMCID: PMC10748309 DOI: 10.3390/plants12244076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/15/2023] [Accepted: 11/30/2023] [Indexed: 12/24/2023]
Abstract
The continuous growth of roots depends on their ability to maintain a balanced ratio between cell production and cell differentiation at the tip. This process is regulated by the hormonal balance of cytokinin and auxin. However, other important regulators, such as plant folates, also play a regulatory role. In this study, we investigated the impact of the folate precursor para-aminobenzoic acid (PABA) on root development. Using pharmacological, genetic, and imaging approaches, we show that the growth of Arabidopsis thaliana roots is repressed by either supplementing the growth medium with PABA or overexpressing the PABA synthesis gene GAT-ADCS. This is associated with a smaller root meristem consisting of fewer cells. Conversely, reducing the levels of free root endogenous PABA results in longer roots with extended meristems. We provide evidence that PABA represses Arabidopsis root growth in a folate-independent manner and likely acts through two mechanisms: (i) the G2/M transition of cell division in the root apical meristem and (ii) promoting premature cell differentiation in the transition zone. These data collectively suggest that PABA plays a role in Arabidopsis root growth at the intersection between cell division and cell differentiation.
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Affiliation(s)
- Hanna Lasok
- Malopolska Centre of Biotechnology, Jagiellonian University, Gronostajowa 7A, 30-387 Kraków, Poland;
- Faculty of Biology, Institute of Biology II, Albert Ludwigs University Freiburg, 79104 Freiburg, Germany
| | - Hugues Nziengui
- Department of Biology, Faculty of Sciences, Science and Technology University of Masuku, Franceville P.O. Box 913, Gabon;
| | - Philip Kochersperger
- Faculty of Biology, Institute of Biology II, Albert Ludwigs University Freiburg, 79104 Freiburg, Germany
| | - Franck Anicet Ditengou
- Faculty of Biology, Institute of Biology II, Albert Ludwigs University Freiburg, 79104 Freiburg, Germany
- Lighthouse Core Facility, Medical Center University of Freiburg, Albert Ludwigs University Freiburg, 79106 Freiburg, Germany
- Bio Imaging Core Light Microscopy (BiMiC), Institute for Disease Modelling and Targeted Medicine (IMITATE), Medical Center University of Freiburg, Albert Ludwigs University Freiburg, 79106 Freiburg, Germany
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2
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Danchin A, Huang JD. SynBio 2.0, a new era for synthetic life: Neglected essential functions for resilience. Environ Microbiol 2023; 25:64-78. [PMID: 36045561 DOI: 10.1111/1462-2920.16140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Accepted: 07/16/2022] [Indexed: 01/21/2023]
Affiliation(s)
- Antoine Danchin
- School of Biomedical Sciences, Li KaShing Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong
| | - Jian Dong Huang
- School of Biomedical Sciences, Li KaShing Faculty of Medicine, University of Hong Kong, Pokfulam, Hong Kong
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3
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Liu Z, Farkas P, Wang K, Kohli M, Fitzpatrick TB. B vitamin supply in plants and humans: the importance of vitamer homeostasis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2022; 111:662-682. [PMID: 35673947 PMCID: PMC9544542 DOI: 10.1111/tpj.15859] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 06/02/2022] [Accepted: 06/06/2022] [Indexed: 05/26/2023]
Abstract
B vitamins are a group of water-soluble micronutrients that are required in all life forms. With the lack of biosynthetic pathways, humans depend on dietary uptake of these compounds, either directly or indirectly, from plant sources. B vitamins are frequently given little consideration beyond their role as enzyme accessory factors and are assumed not to limit metabolism. However, it should be recognized that each individual B vitamin is a family of compounds (vitamers), the regulation of which has dedicated pathways. Moreover, it is becoming increasingly evident that individual family members have physiological relevance and should not be sidelined. Here, we elaborate on the known forms of vitamins B1 , B6 and B9 , their distinct functions and importance to metabolism, in both human and plant health, and highlight the relevance of vitamer homeostasis. Research on B vitamin metabolism over the past several years indicates that not only the total level of vitamins but also the oft-neglected homeostasis of the various vitamers of each B vitamin is essential to human and plant health. We briefly discuss the potential of plant biology studies in supporting human health regarding these B vitamins as essential micronutrients. Based on the findings of the past few years we conclude that research should focus on the significance of vitamer homeostasis - at the organ, tissue and subcellular levels - which could improve the health of not only humans but also plants, benefiting from cross-disciplinary approaches and novel technologies.
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Affiliation(s)
- Zeguang Liu
- Vitamins and Environmental Stress Responses in Plants, Department of Botany and Plant BiologyUniversity of GenevaQuai Ernest‐Ansermet 30CH‐1211Geneva 4Switzerland
| | - Peter Farkas
- Vitamins and Environmental Stress Responses in Plants, Department of Botany and Plant BiologyUniversity of GenevaQuai Ernest‐Ansermet 30CH‐1211Geneva 4Switzerland
| | - Kai Wang
- Vitamins and Environmental Stress Responses in Plants, Department of Botany and Plant BiologyUniversity of GenevaQuai Ernest‐Ansermet 30CH‐1211Geneva 4Switzerland
| | - Morgan‐Océane Kohli
- Vitamins and Environmental Stress Responses in Plants, Department of Botany and Plant BiologyUniversity of GenevaQuai Ernest‐Ansermet 30CH‐1211Geneva 4Switzerland
| | - Teresa B. Fitzpatrick
- Vitamins and Environmental Stress Responses in Plants, Department of Botany and Plant BiologyUniversity of GenevaQuai Ernest‐Ansermet 30CH‐1211Geneva 4Switzerland
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4
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Korbmacher F, Drepper B, Sanderson T, Martin P, Stach T, Maier AG, Matuschewski K, Matz JM. An apicoplast-resident folate transporter is essential for sporogony of malaria parasites. Cell Microbiol 2021; 23:e13266. [PMID: 32975363 PMCID: PMC7616068 DOI: 10.1111/cmi.13266] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 08/14/2020] [Accepted: 09/18/2020] [Indexed: 11/30/2022]
Abstract
Malaria parasites are fast replicating unicellular organisms and require substantial amounts of folate for DNA synthesis. Despite the central role of this critical co-factor for parasite survival, only little is known about intraparasitic folate trafficking in Plasmodium. Here, we report on the expression, subcellular localisation and function of the parasite's folate transporter 2 (FT2) during life cycle progression in the murine malaria parasite Plasmodium berghei. Using live fluorescence microscopy of genetically engineered parasites, we demonstrate that FT2 localises to the apicoplast. In invasive P. berghei stages, a fraction of FT2 is also observed at the apical end. Upon genetic disruption of FT2, blood and liver infection, gametocyte production and mosquito colonisation remain unaltered. But in the Anopheles vector, FT2-deficient parasites develop inflated oocysts with unusual pulp formation consisting of numerous single-membrane vesicles, which ultimately fuse to form large cavities. Ultrastructural analysis suggests that this defect reflects aberrant sporoblast formation caused by abnormal vesicular traffic. Complete sporogony in FT2-deficient oocysts is very rare, and mutant sporozoites fail to establish hepatocyte infection, resulting in a complete block of parasite transmission. Our findings reveal a previously unrecognised organellar folate transporter that exerts critical roles for pathogen maturation in the arthropod vector.
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Affiliation(s)
- Francois Korbmacher
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Benjamin Drepper
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Theo Sanderson
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, UK
| | - Peer Martin
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Thomas Stach
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Alexander G. Maier
- Research School of Biology, The Australian National University, Canberra, Australia
| | - Kai Matuschewski
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Joachim M. Matz
- Department of Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
- Malaria Biochemistry Laboratory, The Francis Crick Institute, London, UK
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5
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Andrade LH, Hornink MM, Lopes AU. Biobased Spiroimides from Itaconic Acid and Formamides: Molecular Targets for a Novel Synthetic Application of Renewable Chemicals. SYNTHESIS-STUTTGART 2021. [DOI: 10.1055/s-0040-1707318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
AbstractSpiroimides exhibit a wide range of biological activities, such as anticonvulsant, antiarrhythmic, and antihyperglycemic activities. Herein, a novel synthetic application of renewable chemicals, itaconic acid and formamides, is described. Proper exploitation of the reactivity of itaconic acid and formamide allows for the development of an efficient synthetic approach for the production of several new biobased spiroimides, spiro[dihydroquinolin-2-one-succinimides] and spiro[indolin-2-one-glutarimides], in excellent overall yields (up to 98%).
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6
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Dahlhausen KE, Jospin G, Coil DA, Eisen JA, Wilkins LG. Isolation and sequence-based characterization of a koala symbiont: Lonepinella koalarum. PeerJ 2020; 8:e10177. [PMID: 33150080 PMCID: PMC7583611 DOI: 10.7717/peerj.10177] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 09/22/2020] [Indexed: 11/23/2022] Open
Abstract
Koalas (Phascolarctos cinereus) are highly specialized herbivorous marsupials that feed almost exclusively on Eucalyptus leaves, which are known to contain varying concentrations of many different toxic chemical compounds. The literature suggests that Lonepinella koalarum, a bacterium in the Pasteurellaceae family, can break down some of these toxic chemical compounds. Furthermore, in a previous study, we identified L. koalarum as the most predictive taxon of koala survival during antibiotic treatment. Therefore, we believe that this bacterium may be important for koala health. Here, we isolated a strain of L. koalarum from a healthy koala female and sequenced its genome using a combination of short-read and long-read sequencing. We placed the genome assembly into a phylogenetic tree based on 120 genome markers using the Genome Taxonomy Database (GTDB), which currently does not include any L. koalarum assemblies. Our genome assembly fell in the middle of a group of Haemophilus, Pasteurella and Basfia species. According to average nucleotide identity and a 16S rRNA gene tree, the closest relative of our isolate is L. koalarum strain Y17189. Then, we annotated the gene sequences and compared them to 55 closely related, publicly available genomes. Several genes that are known to be involved in carbohydrate metabolism could exclusively be found in L. koalarum relative to the other taxa in the pangenome, including glycoside hydrolase families GH2, GH31, GH32, GH43 and GH77. Among the predicted genes of L. koalarum were 79 candidates putatively involved in the degradation of plant secondary metabolites. Additionally, several genes coding for amino acid variants were found that had been shown to confer antibiotic resistance in other bacterial species against pulvomycin, beta-lactam antibiotics and the antibiotic efflux pump KpnH. In summary, this genetic characterization allows us to build hypotheses to explore the potentially beneficial role that L. koalarum might play in the koala intestinal microbiome. Characterizing and understanding beneficial symbionts at the whole genome level is important for the development of anti- and probiotic treatments for koalas, a highly threatened species due to habitat loss, wildfires, and high prevalence of Chlamydia infections.
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Affiliation(s)
| | - Guillaume Jospin
- Genome and Biomedical Sciences Facility, University of California, Davis, Davis, CA, USA
| | - David A. Coil
- Genome and Biomedical Sciences Facility, University of California, Davis, Davis, CA, USA
| | - Jonathan A. Eisen
- Genome and Biomedical Sciences Facility, University of California, Davis, Davis, CA, USA
- Department of Evolution and Ecology, University of California, Davis, Davis, CA, USA
- Department of Medical Microbiology and Immunology, University of California, Davis, Davis, CA, USA
| | - Laetitia G.E. Wilkins
- Genome and Biomedical Sciences Facility, University of California, Davis, Davis, CA, USA
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7
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Nambiar D, Sharma O, Duff MR, Howell EE. Effects of Osmolytes on Ligand Binding to Dihydropteroate Synthase from Bacillus anthracis. J Phys Chem B 2020; 124:6212-6224. [PMID: 32580556 DOI: 10.1021/acs.jpcb.0c03311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Osmolyte interactions with ligands can affect their affinity for proteins and are dependent upon the cosolute and the functional groups of the ligand. Here, we explored ligand binding to Bacillus anthracis dihydropteroate synthase (BaDHPS) under osmotic stress conditions. Osmolyte effects were specific to the cosolute and ligand, suggesting interaction of the osmolytes with the free ligands in solution. The association rates of pterin pyrophosphate were mostly unaffected by the osmolytes, except for a 2-fold decrease in the presence of 1 M trehalose, while the dissociation rates decreased in most osmolyte solutions. The viscosity and dielectric constant of the solution did not correlate with the effects of the osmolytes. Experimental results were compared with predicted preferential interaction coefficients (Δμ23/RT) between the osmolytes and ligands. The Δμ23/RT were able to predict the experimental data for most of the osmolytes. Trehalose and proline effects did not correlate with the predicted values, indicating that these two osmolytes may affect binding in more complex ways than simple preferential interactions. Additionally, osmolytes weakly interacted with the sulfa drug sulfathiazole, which altered its affinity for BaDHPS, suggesting that these types of weak interactions can also impact drug binding. As osmolytes affect ligands binding to two different folate cycle enzymes (DHFRs and DHPS), we predicted how ligand binding to other folate cycle enzymes will be altered by the presence of osmolytes.
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Affiliation(s)
- Deepika Nambiar
- Department of Biochemistry & Cellular and Molecular Biology Department, University of Tennessee-Knoxville, Knoxville, Tennessee 37996, United States
| | - Ojaswini Sharma
- Department of Biochemistry & Cellular and Molecular Biology Department, University of Tennessee-Knoxville, Knoxville, Tennessee 37996, United States
| | - Michael R Duff
- Department of Biochemistry & Cellular and Molecular Biology Department, University of Tennessee-Knoxville, Knoxville, Tennessee 37996, United States
| | - Elizabeth E Howell
- Department of Biochemistry & Cellular and Molecular Biology Department, University of Tennessee-Knoxville, Knoxville, Tennessee 37996, United States
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8
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De Lepeleire J, Strobbe S, Verstraete J, Blancquaert D, Ambach L, Visser RGF, Stove C, Van Der Straeten D. Folate Biofortification of Potato by Tuber-Specific Expression of Four Folate Biosynthesis Genes. MOLECULAR PLANT 2018; 11:175-188. [PMID: 29277427 DOI: 10.1016/j.molp.2017.12.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 12/08/2017] [Accepted: 12/08/2017] [Indexed: 05/24/2023]
Abstract
Insufficient dietary intake of micronutrients, known as "hidden hunger", is a devastating global burden, affecting two billion people. Deficiency of folates (vitamin B9), which are known to play a central role in C1 metabolism, causes birth defects in at least a quarter million people annually. Biofortification to enhance the level of naturally occurring folates in crop plants, proves to be an efficient and cost-effective tool in fighting folate deficiency. Previously, introduction of folate biosynthesis genes GTPCHI and ADCS, proven to be a successful biofortification strategy in rice and tomato, turned out to be insufficient to adequately increase folate levels in potato tubers. Here, we provide a proof of concept that additional introduction of HPPK/DHPS and/or FPGS, downstream genes in mitochondrial folate biosynthesis, enables augmentation of folates to satisfactory levels (12-fold) and ensures folate stability upon long-term storage of tubers. In conclusion, this engineering strategy can serve as a model in the creation of folate-accumulating potato cultivars, readily applicable in potato-consuming populations suffering from folate deficiency.
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Affiliation(s)
- Jolien De Lepeleire
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
| | - Simon Strobbe
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
| | - Jana Verstraete
- Laboratory of Toxicology, Department of Bioanalysis, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Dieter Blancquaert
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
| | - Lars Ambach
- Laboratory of Toxicology, Department of Bioanalysis, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Richard G F Visser
- Plant Breeding, Wageningen University & Research, Droevendaalsesteeg 1, 6700 Wageningen, the Netherlands
| | - Christophe Stove
- Plant Breeding, Wageningen University & Research, Droevendaalsesteeg 1, 6700 Wageningen, the Netherlands
| | - Dominique Van Der Straeten
- Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, 9000 Ghent, Belgium.
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9
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Gorelova V, Ambach L, Rébeillé F, Stove C, Van Der Straeten D. Folates in Plants: Research Advances and Progress in Crop Biofortification. Front Chem 2017; 5:21. [PMID: 28424769 PMCID: PMC5372827 DOI: 10.3389/fchem.2017.00021] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 03/09/2017] [Indexed: 11/13/2022] Open
Abstract
Folates, also known as B9 vitamins, serve as donors and acceptors in one-carbon (C1) transfer reactions. The latter are involved in synthesis of many important biomolecules, such as amino acids, nucleic acids and vitamin B5. Folates also play a central role in the methyl cycle that provides one-carbon groups for methylation reactions. The important functions fulfilled by folates make them essential in all living organisms. Plants, being able to synthesize folates de novo, serve as an excellent dietary source of folates for animals that lack the respective biosynthetic pathway. Unfortunately, the most important staple crops such as rice, potato and maize are rather poor sources of folates. Insufficient folate consumption is known to cause severe developmental disorders in humans. Two approaches are employed to fight folate deficiency: pharmacological supplementation in the form of folate pills and biofortification of staple crops. As the former approach is considered rather costly for the major part of the world population, biofortification of staple crops is viewed as a decent alternative in the struggle against folate deficiency. Therefore, strategies, challenges and recent progress of folate enhancement in plants will be addressed in this review. Apart from the ever-growing need for the enhancement of nutritional quality of crops, the world population faces climate change catastrophes or environmental stresses, such as elevated temperatures, drought, salinity that severely affect growth and productivity of crops. Due to immense diversity of their biochemical functions, folates take part in virtually every aspect of plant physiology. Any disturbance to the plant folate metabolism leads to severe growth inhibition and, as a consequence, to a lower productivity. Whereas today's knowledge of folate biochemistry can be considered very profound, evidence on the physiological roles of folates in plants only starts to emerge. In the current review we will discuss the implication of folates in various aspects of plant physiology and development.
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Affiliation(s)
- Vera Gorelova
- Laboratory of Functional Plant Biology, Department of Biology, Ghent UniversityGhent, Belgium
| | - Lars Ambach
- Laboratory of Toxicology, Department of Bioanalysis, Ghent UniversityGhent, Belgium
| | - Fabrice Rébeillé
- Laboratoire de Physiologie Cellulaire Végétale, Bioscience and Biotechnologies Institute of Grenoble, CEA-GrenobleGrenoble, France
| | - Christophe Stove
- Laboratory of Toxicology, Department of Bioanalysis, Ghent UniversityGhent, Belgium
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10
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Ramírez Rivera NG, García-Salinas C, Aragão FJL, Díaz de la Garza RI. Metabolic engineering of folate and its precursors in Mexican common bean (Phaseolus vulgaris L.). PLANT BIOTECHNOLOGY JOURNAL 2016; 14:2021-32. [PMID: 26997331 PMCID: PMC5043471 DOI: 10.1111/pbi.12561] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 03/05/2016] [Accepted: 03/12/2016] [Indexed: 05/24/2023]
Abstract
Folate (vitamin B9) deficiency causes several health problems globally. However, folate biofortification of major staple crops is one alternative that can be used to improve vitamin intakes in populations at risk. We increased the folate levels in common bean by engineering the pteridine branch required for their biosynthesis. GTP cyclohydrolase I from Arabidopsis (AtGchI) was stably introduced into three common bean Pinto cultivars by particle bombardment. Seed-specific overexpression of AtGCHI caused significant increases of up to 150-fold in biosynthetic pteridines in the transformed lines. The pteridine boost enhanced folate levels in raw desiccated seeds by up to threefold (325 μg in a 100 g portion), which would represent 81% of the adult recommended daily allowance. Unexpectedly, the engineering also triggered a general increase in PABA levels, the other folate precursor. This was not observed in previous engineering studies and was probably caused by a feedforward mechanism that remains to be elucidated. Results from this work also show that common bean grains accumulate considerable amounts of oxidized pteridines that might represent products of folate degradation in desiccating seeds. Our study uncovers a probable different regulation of folate homoeostasis in these legume grains than that observed in other engineering works. Legumes are good sources of folates, and this work shows that they can be engineered to accumulate even greater amounts of folate that, when consumed, can improve folate status. Biofortification of common bean with folates and other micronutrients represents a promising strategy to improve the nutritional status of populations around the world.
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Affiliation(s)
- Naty G Ramírez Rivera
- Tecnologico de Monterrey, Escuela de Ingeniería y Ciencias, Monterrey, Nuevo León, México
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11
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Widhalm JR, Dudareva N. A familiar ring to it: biosynthesis of plant benzoic acids. MOLECULAR PLANT 2015; 8:83-97. [PMID: 25578274 DOI: 10.1016/j.molp.2014.12.001] [Citation(s) in RCA: 199] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 10/19/2014] [Indexed: 05/20/2023]
Abstract
Plant benzoic acids (BAs) are building blocks or important structural elements for numerous primary and specialized metabolites, including plant hormones, cofactors, defense compounds, and attractants for pollinators and seed dispersers. Many natural products derived from plant BAs or containing benzoyl/benzyl moieties are also of medicinal or nutritional value to humans. Biosynthesis of BAs in plants is a network involving parallel and intersecting pathways spread across multiple subcellular compartments. In this review, a current overview on the metabolism of plant BAs is presented with a focus on the recent progress made on isolation and functional characterization of genes encoding biosynthetic enzymes and intracellular transporters. In addition, approaches for deciphering the complex interactions between pathways of the BAs network are discussed.
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Affiliation(s)
- Joshua R Widhalm
- Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, IN 47907-2063, USA
| | - Natalia Dudareva
- Department of Biochemistry, Purdue University, 175 South University Street, West Lafayette, IN 47907-2063, USA.
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12
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Ivanov VP, Marchenko SI, Nartov DI, Ivanov YV. Growth status of Scots pine artificial stands under the influence of para-aminobenzoic acid. CONTEMP PROBL ECOL+ 2015. [DOI: 10.1134/s1995425515010059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Block A, Widhalm JR, Fatihi A, Cahoon RE, Wamboldt Y, Elowsky C, Mackenzie SA, Cahoon EB, Chapple C, Dudareva N, Basset GJ. The Origin and Biosynthesis of the Benzenoid Moiety of Ubiquinone (Coenzyme Q) in Arabidopsis. THE PLANT CELL 2014; 26:1938-1948. [PMID: 24838974 PMCID: PMC4079360 DOI: 10.1105/tpc.114.125807] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 04/15/2014] [Accepted: 04/24/2014] [Indexed: 05/18/2023]
Abstract
It is not known how plants make the benzenoid ring of ubiquinone, a vital respiratory cofactor. Here, we demonstrate that Arabidopsis thaliana uses for that purpose two separate biosynthetic branches stemming from phenylalanine and tyrosine. Gene network modeling and characterization of T-DNA mutants indicated that acyl-activating enzyme encoded by At4g19010 contributes to the biosynthesis of ubiquinone specifically from phenylalanine. CoA ligase assays verified that At4g19010 prefers para-coumarate, ferulate, and caffeate as substrates. Feeding experiments demonstrated that the at4g19010 knockout cannot use para-coumarate for ubiquinone biosynthesis and that the supply of 4-hydroxybenzoate, the side-chain shortened version of para-coumarate, can bypass this blockage. Furthermore, a trans-cinnamate 4-hydroxylase mutant, which is impaired in the conversion of trans-cinnamate into para-coumarate, displayed similar defects in ubiquinone biosynthesis to that of the at4g19010 knockout. Green fluorescent protein fusion experiments demonstrated that At4g19010 occurs in peroxisomes, resulting in an elaborate biosynthetic architecture where phenylpropanoid intermediates have to be transported from the cytosol to peroxisomes and then to mitochondria where ubiquinone is assembled. Collectively, these results demonstrate that At4g19010 activates the propyl side chain of para-coumarate for its subsequent β-oxidative shortening. Evidence is shown that the peroxisomal ABCD transporter (PXA1) plays a critical role in this branch.
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Affiliation(s)
- Anna Block
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
| | - Joshua R Widhalm
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | - Abdelhak Fatihi
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
| | - Rebecca E Cahoon
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
| | - Yashitola Wamboldt
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
| | - Christian Elowsky
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
| | - Sally A Mackenzie
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
| | - Edgar B Cahoon
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
| | - Clint Chapple
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | - Natalia Dudareva
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907
| | - Gilles J Basset
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska 68588
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14
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Para-aminobenzoic acid (PABA) synthase enhances thermotolerance of mushroom Agaricus bisporus. PLoS One 2014; 9:e91298. [PMID: 24614118 PMCID: PMC3948851 DOI: 10.1371/journal.pone.0091298] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 02/11/2014] [Indexed: 12/03/2022] Open
Abstract
Most mushrooms are thermo-sensitive to temperatures over 23°C, which greatly restricts their agricultural cultivation. Understanding mushroom’s innate heat-tolerance mechanisms may facilitate genetic improvements of their thermotolerance. Agaricus bisporus strain 02 is a relatively thermotolerant mushroom strain, while strain 8213 is quite thermo-sensitive. Here, we compared their responses at proteomic level to heat treatment at 33°C. We identified 73 proteins that are differentially expressed between 02 and 8213 or induced upon heat stress in strain 02 itself, 48 of which with a known identity. Among them, 4 proteins are constitutively more highly expressed in 02 than 8213; and they can be further upregulated in response to heat stress in 02, but not in 8213. One protein is encoded by the para-aminobenzoic acid (PABA) synthase gene Pabs, which has been shown to scavenge the reactive oxygen species in vitro. Pabs mRNA and its chemical product PABA show similar heat stress induction pattern as PABA synthase protein and are more abundant in 02, indicating transcriptional level upregulation of Pabs upon heat stress. A specific inhibitor of PABA synthesis impaired thermotolerance of 02, while exogenous PABA or transgenic overexpression of 02 derived PABA synthase enhanced thermotolerance of 8213. Furthermore, compared to 8213, 02 accumulated less H2O2 but more defense-related proteins (e.g., HSPs and Chitinase) under heat stress. Together, these results demonstrate a role of PABA in enhancing mushroom thermotolerance by removing H2O2 and elevating defense-related proteins.
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Blancquaert D, De Steur H, Gellynck X, Van Der Straeten D. Present and future of folate biofortification of crop plants. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:895-906. [PMID: 24574483 DOI: 10.1093/jxb/ert483] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Improving nutritional health is one of the major socio-economic challenges of the 21st century, especially with the continuously growing and ageing world population. Folate deficiency is an important and underestimated problem of micronutrient malnutrition affecting billions of people worldwide. More and more countries are adapting policies to fight folate deficiency, mostly by fortifying foods with folic acid. However, there is growing concern about this practice, calling for alternative or complementary strategies. In addition, fortification programmes are often inaccessible to remote and poor populations where folate deficiency is most prevalent. Enhancing folate content in staple crops by metabolic engineering is a promising, cost-effective strategy to eradicate folate malnutrition worldwide. Over the last decade, major progress has been made in this field. Nevertheless, engineering strategies have thus far been implemented on a handful of plant species only and need to be transferred to highly consumed staple crops to maximally reach target populations. Moreover, successful engineering strategies appear to be species-dependent, hence the need to adapt them in order to biofortify different staple crops with folate.
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Affiliation(s)
- Dieter Blancquaert
- Laboratory of Functional Plant Biology, Department of Physiology, Ghent University, K.L. Ledeganckstraat 35, 9000 Gent, Belgium
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16
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Blancquaert D, Storozhenko S, Van Daele J, Stove C, Visser RGF, Lambert W, Van Der Straeten D. Enhancing pterin and para-aminobenzoate content is not sufficient to successfully biofortify potato tubers and Arabidopsis thaliana plants with folate. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:3899-909. [PMID: 23956417 DOI: 10.1093/jxb/ert224] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Folates are important cofactors in one-carbon metabolism in all living organisms. Since only plants and micro- organisms are capable of biosynthesizing folates, humans depend entirely on their diet as a folate source. Given the low folate content of several staple crop products, folate deficiency affects regions all over the world. Folate biofortification of staple crops through enhancement of pterin and para-aminobenzoate levels, precursors of the folate biosynthesis pathway, was reported to be successful in tomato and rice. This study shows that the same strategy is not sufficient to enhance folate content in potato tubers and Arabidopsis thaliana plants and concludes that other steps in folate biosynthesis and/or metabolism need to be engineered to result in substantial folate accumulation. The findings provide a plausible explanation why, more than half a decade after the proof of concept in rice and tomato, successful folate biofortification of other food crops through enhancement of para-aminobenzoate and pterin content has not been reported thus far. A better understanding of the folate pathway is required in order to determine an engineering strategy that can be generalized to most staple crops.
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Affiliation(s)
- Dieter Blancquaert
- Laboratory of Functional Plant Biology, Department of Physiology, Ghent University, K.L. Ledeganckstraat 35, 9000 Gent, Belgium
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17
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Gutensohn M, Orlova I, Nguyen TTH, Davidovich-Rikanati R, Ferruzzi MG, Sitrit Y, Lewinsohn E, Pichersky E, Dudareva N. Cytosolic monoterpene biosynthesis is supported by plastid-generated geranyl diphosphate substrate in transgenic tomato fruits. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:351-63. [PMID: 23607888 DOI: 10.1111/tpj.12212] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 04/11/2013] [Accepted: 04/16/2013] [Indexed: 05/20/2023]
Abstract
Geranyl diphosphate (GPP), the precursor of most monoterpenes, is synthesized in plastids from dimethylallyl diphosphate and isopentenyl diphosphate by GPP synthases (GPPSs). In heterodimeric GPPSs, a non-catalytic small subunit (GPPS-SSU) interacts with a catalytic large subunit, such as geranylgeranyl diphosphate synthase, and determines its product specificity. Here, snapdragon (Antirrhinum majus) GPPS-SSU was over-expressed in tomato fruits under the control of the fruit ripening-specific polygalacturonase promoter to divert the metabolic flux from carotenoid formation towards GPP and monoterpene biosynthesis. Transgenic tomato fruits produced monoterpenes, including geraniol, geranial, neral, citronellol and citronellal, while exhibiting reduced carotenoid content. Co-expression of the Ocimum basilicum geraniol synthase (GES) gene with snapdragon GPPS-SSU led to a more than threefold increase in monoterpene formation in tomato fruits relative to the parental GES line, indicating that the produced GPP can be used by plastidic monoterpene synthases. Co-expression of snapdragon GPPS-SSU with the O. basilicum α-zingiberene synthase (ZIS) gene encoding a cytosolic terpene synthase that has been shown to possess both sesqui- and monoterpene synthase activities resulted in increased levels of ZIS-derived monoterpene products compared to fruits expressing ZIS alone. These results suggest that re-direction of the metabolic flux towards GPP in plastids also increases the cytosolic pool of GPP available for monoterpene synthesis in this compartment via GPP export from plastids.
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Affiliation(s)
- Michael Gutensohn
- Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA
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18
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Eisenhut M, Pick TR, Bordych C, Weber APM. Towards closing the remaining gaps in photorespiration--the essential but unexplored role of transport proteins. PLANT BIOLOGY (STUTTGART, GERMANY) 2013. [PMID: 23199026 DOI: 10.1111/j.1438-8677.2012.00690.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Photorespiration is an essential prerequisite for all autotrophic organisms performing oxygenic photosynthesis. In contrast to the well-characterised enzymes accomplishing photorespiratory metabolism, current knowledge on the involved transport processes and the respective proteins is still quite limited. In this review, we focus on the status quo of translocators involved in photorespiratory metabolism. Although the transport of some of the photorespiratory intermediates could be characterised biochemically, using isolated organelles, the genes encoding these transporters have to date not been identified in most cases. Here, we describe the postulated transport processes, present information on established or hypothetical photorespiratory transporters, depict strategies on how to identify the transport proteins on the molecular level and, finally, discuss strategies for how to find the remaining candidates.
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Affiliation(s)
- M Eisenhut
- Center of Excellence on Plant Sciences (CEPLAS), Institute of Plant Biochemistry, Heinrich-Heine-University, Düsseldorf, Germany
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19
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Camara D, Bisanz C, Barette C, Van Daele J, Human E, Barnard B, Van der Straeten D, Stove CP, Lambert WE, Douce R, Maréchal E, Birkholtz LM, Cesbron-Delauw MF, Dumas R, Rébeillé F. Inhibition of p-aminobenzoate and folate syntheses in plants and apicomplexan parasites by natural product rubreserine. J Biol Chem 2012; 287:22367-76. [PMID: 22577137 DOI: 10.1074/jbc.m112.365833] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Glutamine amidotransferase/aminodeoxychorismate synthase (GAT-ADCS) is a bifunctional enzyme involved in the synthesis of p-aminobenzoate, a central component part of folate cofactors. GAT-ADCS is found in eukaryotic organisms autonomous for folate biosynthesis, such as plants or parasites of the phylum Apicomplexa. Based on an automated screening to search for new inhibitors of folate biosynthesis, we found that rubreserine was able to inhibit the glutamine amidotransferase activity of the plant GAT-ADCS with an apparent IC(50) of about 8 μM. The growth rates of Arabidopsis thaliana, Toxoplasma gondii, and Plasmodium falciparum were inhibited by rubreserine with respective IC(50) values of 65, 20, and 1 μM. The correlation between folate biosynthesis and growth inhibition was studied with Arabidopsis and Toxoplasma. In both organisms, the folate content was decreased by 40-50% in the presence of rubreserine. In both organisms, the addition of p-aminobenzoate or 5-formyltetrahydrofolate in the external medium restored the growth for inhibitor concentrations up to the IC(50) value, indicating that, within this range of concentrations, rubreserine was specific for folate biosynthesis. Rubreserine appeared to be more efficient than sulfonamides, antifolate drugs known to inhibit the invasion and proliferation of T. gondii in human fibroblasts. Altogether, these results validate the use of the bifunctional GAT-ADCS as an efficient drug target in eukaryotic cells and indicate that the chemical structure of rubreserine presents interesting anti-parasitic (toxoplasmosis, malaria) potential.
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Affiliation(s)
- Djeneb Camara
- Laboratoire de Physiologie Cellulaire Végétale, Commissariat à l'Energie Atomique/CNRS UMR5168/INRA USC1200/Université Joseph Fourier Grenoble I, Institut de Recherches en Technologies et Sciences pour le Vivant, F-38054 Grenoble, France
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20
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Navarrete O, Van Daele J, Stove C, Lambert W, Van Der Straeten D, Storozhenko S. A folate independent role for cytosolic HPPK/DHPS upon stress in Arabidopsis thaliana. PHYTOCHEMISTRY 2012; 73:23-33. [PMID: 21996493 DOI: 10.1016/j.phytochem.2011.09.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 09/17/2011] [Accepted: 09/20/2011] [Indexed: 05/24/2023]
Abstract
Cytosolic HPPK/DHPS (cytHPPK/DHPS) in Arabidopsis is a functional enzyme with activity similar to its mitochondrial isoform. Genomic complementation of the cytHPPK/DHPS knockout mutant with the wild type gene led to a complete rescue of the stress sensitive mutant phenotype in seed germination tests under abiotic stress conditions. Moreover, over-expression of the gene resulted in higher germination rate under stress as compared to the wild-type, confirming its role in stress resistance. Analysis of folates in seedlings, inflorescence and dry seeds showed unchanged levels in the wild-type, mutant and over-expressor line, upon stress and normal conditions, suggesting a role for cytHPPK/DHPS distinct from folate biosynthesis and a folate-independent stress resistance mechanism. This apparently folate-independent mechanism of stress resistance points towards a possible role of pterins, since the product of HPPK/DHPS is dihydropteroate.
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Affiliation(s)
- Oscar Navarrete
- Laboratory of Functional Plant Biology, Department of Physiology, Ghent University, KL Ledeganckstraat 35, B-9000 Gent, Belgium.
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21
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Hanson AD, Gregory JF. Folate biosynthesis, turnover, and transport in plants. ANNUAL REVIEW OF PLANT BIOLOGY 2011; 62:105-25. [PMID: 21275646 DOI: 10.1146/annurev-arplant-042110-103819] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Folates are essential cofactors for one-carbon transfer reactions and are needed in the diets of humans and animals. Because plants are major sources of dietary folate, plant folate biochemistry has long been of interest but progressed slowly until the genome era. Since then, genome-enabled approaches have brought rapid advances: We now know (a) all the plant folate synthesis genes and some genes of folate turnover and transport, (b) certain mechanisms governing folate synthesis, and (c) the subcellular locations of folate synthesis enzymes and of folates themselves. Some of this knowledge has been applied, simply and successfully, to engineer folate-enriched food crops (i.e., biofortification). Much remains to be discovered about folates, however, particularly in relation to homeostasis, catabolism, membrane transport, and vacuolar storage. Understanding these processes, which will require both biochemical and -omics research, should lead to improved biofortification strategies based on transgenic or conventional approaches.
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Affiliation(s)
- Andrew D Hanson
- Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611, USA
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22
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Marbois B, Xie LX, Choi S, Hirano K, Hyman K, Clarke CF. para-Aminobenzoic acid is a precursor in coenzyme Q6 biosynthesis in Saccharomyces cerevisiae. J Biol Chem 2010; 285:27827-38. [PMID: 20592037 DOI: 10.1074/jbc.m110.151894] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Coenzyme Q (ubiquinone or Q) is a crucial mitochondrial lipid required for respiratory electron transport in eukaryotes. 4-Hydroxybenozoate (4HB) is an aromatic ring precursor that forms the benzoquinone ring of Q and is used extensively to examine Q biosynthesis. However, the direct precursor compounds and enzymatic steps for synthesis of 4HB in yeast are unknown. Here we show that para-aminobenzoic acid (pABA), a well known precursor of folate, also functions as a precursor for Q biosynthesis. A hexaprenylated form of pABA (prenyl-pABA) is normally present in wild-type yeast crude lipid extracts but is absent in yeast abz1 mutants starved for pABA. A stable (13)C(6)-isotope of pABA (p- amino[aromatic-(13)C(6)]benzoic acid ([(13)C(6)]pABA)), is prenylated in either wild-type or abz1 mutant yeast to form prenyl-[(13)C(6)]pABA. We demonstrate by HPLC and mass spectrometry that yeast incubated with either [(13)C(6)]pABA or [(13)C(6)]4HB generate both (13)C(6)-demethoxy-Q (DMQ), a late stage Q biosynthetic intermediate, as well as the final product (13)C(6)-coenzyme Q. Pulse-labeling analyses show that formation of prenyl-pABA occurs within minutes and precedes the synthesis of Q. Yeast utilizing pABA as a ring precursor produce another nitrogen containing intermediate, 4-imino-DMQ(6). This intermediate is produced in small quantities in wild-type yeast cultured in standard media and in abz1 mutants supplemented with pABA. We suggest a mechanism where Schiff base-mediated deimination forms DMQ(6) quinone, thereby eliminating the nitrogen contributed by pABA. This scheme results in the convergence of the 4HB and pABA pathways in eukaryotic Q biosynthesis and has implications regarding the action of pABA-based antifolates.
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Affiliation(s)
- Beth Marbois
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569, USA
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23
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Waller JC, Akhtar TA, Lara-Núñez A, Gregory JF, McQuinn RP, Giovannoni JJ, Hanson AD. Developmental and feedforward control of the expression of folate biosynthesis genes in tomato fruit. MOLECULAR PLANT 2010; 3:66-77. [PMID: 20085893 DOI: 10.1093/mp/ssp057] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Little is known about how plants regulate their folate content, including whether the expression of folate biosynthesis genes is orchestrated during development or modulated by folate levels. Nor is much known about how folate levels impact the expression of other genes. These points were addressed using wild-type tomato fruit and fruit engineered for high folate content. In wild-type fruit, the expression of genes specifying early steps in folate biosynthesis declined during development but that of other genes did not. In engineered fruit overexpressing foreign GTP cyclohydrolase I and aminodeoxychorismate synthase genes, the expression of the respective endogenous genes did not change, but that of three downstream pathway genes-aminodeoxychorismate lyase, dihydroneopterin aldolase, and mitochondrial folylpolyglutamate synthase-respectively increased by up to 7.8-, 2.8-, and 1.7-fold, apparently in response to the build-up of specific folate pathway metabolites. These results indicate that, in fruit, certain folate pathway genes are developmentally regulated and that certain others are subject to feedforward control by pathway intermediates. Microarray analysis showed that only 14 other transcripts (of 11 000 surveyed) increased in abundance by two-fold or more in high-folate fruit, demonstrating that the induction of folate pathway genes is relatively specific.
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Affiliation(s)
- Jeffrey C Waller
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
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24
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Sandoval FJ, Zhang Y, Roje S. Flavin nucleotide metabolism in plants: monofunctional enzymes synthesize fad in plastids. J Biol Chem 2008; 283:30890-900. [PMID: 18713732 PMCID: PMC2662166 DOI: 10.1074/jbc.m803416200] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 07/30/2008] [Indexed: 11/06/2022] Open
Abstract
FAD synthetases (EC 2.7.7.2) catalyze biosynthesis of FAD from FMN and ATP. Monofunctional FAD synthetases are known to exist in mammals and yeast; bifunctional enzymes also catalyzing phosphorylation of riboflavin to FMN are known to exist in bacteria. Previously known eukaryotic enzymes with FAD synthetase activity have no sequence similarity to prokaryotic enzymes with riboflavin kinase and FAD synthetase activities. Proteins homologous to bacterial bifunctional FAD synthetases, yet shorter and lacking amino acid motifs at the C terminus, were found by bioinformatic analyses in vascular plant genomes, suggesting that plants contain a type of FAD synthetase previously known to exist only in prokaryotes. The Arabidopsis thaliana genome encodes two of such proteins. Both proteins, which we named AtRibF1 and AtRibF2, carry N-terminal extensions with characteristics of organellar targeting peptides. AtRibF1 and AtRibF2 cDNAs were cloned by reverse transcription-PCR. Only FAD synthetase activity was detected in the recombinant enzymes produced in Escherichia coli. FMN and ATP inhibited both enzymes. Kinetic parameters of AtRibF1 and AtRibF2 for the two substrates were similar. Confocal microscopy of protoplasts transformed with enhanced green fluorescence protein-fused proteins showed that AtRibF1 and AtRibF2 are targeted to plastids. In agreement with subcellular localization to plastids, Percoll-isolated chloroplasts from pea (Pisum sativum) synthesized FAD from imported riboflavin. Riboflavin kinase, FMN hydrolase, and FAD pyrophosphatase activities were detected in Percoll-isolated chloroplasts and mitochondria from pea. We propose from these new findings a model for subcellular distribution of enzymes that synthesize and hydrolyze flavin nucleotides in plants.
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Affiliation(s)
- Francisco J Sandoval
- Institute of Biological Chemistry, Washingon State University, Pullman, WA 99164, USA
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25
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Eudes A, Bozzo GG, Waller JC, Naponelli V, Lim EK, Bowles DJ, Gregory JF, Hanson AD. Metabolism of the folate precursor p-aminobenzoate in plants: glucose ester formation and vacuolar storage. J Biol Chem 2008; 283:15451-9. [PMID: 18385129 PMCID: PMC2397476 DOI: 10.1074/jbc.m709591200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 03/07/2008] [Indexed: 11/06/2022] Open
Abstract
Plants produce p-aminobenzoate (pABA) in chloroplasts and use it for folate synthesis in mitochondria. In plant tissues, however, pABA is known to occur predominantly as its glucose ester (pABA-Glc), and the role of this metabolite in folate synthesis has not been defined. In this study, the UDP-glucose:pABA acyl-glucosyltransferase (pAGT) activity in Arabidopsis extracts was found to reside principally (95%) in one isoform with an apparent K(m) for pABA of 0.12 mm. Screening of recombinant Arabidopsis UDP-glycosyltransferases identified only three that recognized pABA. One of these (UGT75B1) exhibited a far higher k(cat)/K(m) value than the others and a far lower apparent K(m) for pABA (0.12 mm), suggesting its identity with the principal enzyme in vivo. Supporting this possibility, ablation of UGT75B1 reduced extractable pAGT activity by 95%, in vivo [(14)C]pABA glucosylation by 77%, and the endogenous pABA-Glc/pABA ratio by 9-fold. The K(eq) for the pABA esterification reaction was found to be 3 x 10(-3). Taken with literature data on the cytosolic location of pAGT activity and on cytosolic UDP-glucose/UDP ratios, this K(eq) value allowed estimation that only 4% of cytosolic pABA is esterified. That pABA-Glc predominates in planta therefore implies that it is sequestered away from the cytosol and, consistent with this possibility, vacuoles isolated from [(14)C]pABA-fed pea leaves were estimated to contain> or =88% of the [(14)C]pABA-Glc formed. In total, these data and the fact that isolated mitochondria did not take up [(3)H]pABA-Glc, suggest that the glucose ester represents a storage form of pABA that does not contribute directly to folate synthesis.
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Affiliation(s)
- Aymerick Eudes
- Departments of Horticultural Sciences and Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611 and the Centre for Novel Agricultural Products, Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Gale G. Bozzo
- Departments of Horticultural Sciences and Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611 and the Centre for Novel Agricultural Products, Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Jeffrey C. Waller
- Departments of Horticultural Sciences and Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611 and the Centre for Novel Agricultural Products, Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Valeria Naponelli
- Departments of Horticultural Sciences and Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611 and the Centre for Novel Agricultural Products, Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Eng-Kiat Lim
- Departments of Horticultural Sciences and Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611 and the Centre for Novel Agricultural Products, Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Dianna J. Bowles
- Departments of Horticultural Sciences and Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611 and the Centre for Novel Agricultural Products, Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Jesse F. Gregory
- Departments of Horticultural Sciences and Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611 and the Centre for Novel Agricultural Products, Department of Biology, University of York, York YO10 5DD, United Kingdom
| | - Andrew D. Hanson
- Departments of Horticultural Sciences and Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611 and the Centre for Novel Agricultural Products, Department of Biology, University of York, York YO10 5DD, United Kingdom
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Kim HU, van Oostende C, Basset GJC, Browse J. The AAE14 gene encodes the Arabidopsis o-succinylbenzoyl-CoA ligase that is essential for phylloquinone synthesis and photosystem-I function. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 54:272-83. [PMID: 18208520 DOI: 10.1111/j.1365-313x.2008.03416.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Phylloquinone is the one-electron carrier at the A(1) site of photosystem I, and is essential for photosynthesis. Arabidopsis mutants deficient in early steps of phylloquinone synthesis do not become autotrophic and are seedling lethals, even when grown on sucrose-supplemented media. Here, we identify acyl-activating enzyme 14 (AAE14, At1g30520) as the o-succinylbenzoyl-coenzyme A (OSB-CoA) ligase acting in phylloquinone synthesis. Three aae14 mutant alleles, identified by reverse genetics, were found to be seedling lethal, to contain no detectable phylloquinone (< 0.1 pmol mg(-1) fresh weight) compared with 10 pmol mg(-1) fresh weight in wild-type leaves, and to accumulate OSB. AAE14 was able to restore menaquinone biosynthesis when expressed in an Escherichia coli mutant disrupted in the menE gene that encodes the bacterial OSB-CoA ligase. Weak expression of an AAE14 transgene in mutant plants (controlled by the uninduced XVE promoter) resulted in chlorotic, slow-growing plants that accumulated an average of 4.7 pmol mg(-1) fresh weight of phylloquinone. Inducing the XVE promoter in these plants, or expressing an AAE14 transgene under the control of the CaMV 35S promoter, led to full complementation of the mutant phenotype. aae14-mutant plants were also able to synthesize phylloquinone when provided with 1,4-dihydroxy-2-naphthoate, an intermediate in phylloquinone synthesis downstream of the OSB-CoA ligase reaction. Expression of an AAE14:GFP reporter construct indicated that the protein accumulated in discrete foci within the chloroplasts. This and other evidence suggests that the enzymes of phylloquinone synthesis from isochorismate may form a complex in the chloroplast stroma to facilitate the efficient channeling of intermediates through the pathway.
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Affiliation(s)
- Hyun Uk Kim
- Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340, USA
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27
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Bekaert S, Storozhenko S, Mehrshahi P, Bennett MJ, Lambert W, Gregory JF, Schubert K, Hugenholtz J, Van Der Straeten D, Hanson AD. Folate biofortification in food plants. TRENDS IN PLANT SCIENCE 2008; 13:28-35. [PMID: 18083061 DOI: 10.1016/j.tplants.2007.11.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 10/27/2007] [Accepted: 11/05/2007] [Indexed: 05/10/2023]
Abstract
Folate deficiency is a global health problem affecting many people in the developing and developed world. Current interventions (industrial food fortification and supplementation by folic acid pills) are effective if they can be used but might not be possible in less developed countries. Recent advances demonstrate that folate biofortification of food crops is now a feasible complementary strategy to fight folate deficiency worldwide. The genes and enzymes of folate synthesis are sufficiently understood to enable metabolic engineering of the pathway, and results from pilot engineering studies in plants (and bacteria) are encouraging. Here, we review the current status of investigations in the field of folate enhancement on the eve of a new era in food fortification.
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Affiliation(s)
- Samir Bekaert
- Department of Molecular Genetics, Ghent University, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium
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Botet J, Mateos L, Revuelta JL, Santos MA. A chemogenomic screening of sulfanilamide-hypersensitive Saccharomyces cerevisiae mutants uncovers ABZ2, the gene encoding a fungal aminodeoxychorismate lyase. EUKARYOTIC CELL 2007; 6:2102-11. [PMID: 17873082 PMCID: PMC2168415 DOI: 10.1128/ec.00266-07] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Large-scale phenotypic analyses have proved to be useful strategies in providing functional clues about the uncharacterized yeast genes. We used here a chemogenomic profiling of yeast deletion collections to identify the core of cellular processes challenged by treatment with the p-aminobenzoate/folate antimetabolite sulfanilamide. In addition to sulfanilamide-hypersensitive mutants whose deleted genes can be categorized into a number of groups, including one-carbon related metabolism, vacuole biogenesis and vesicular transport, DNA metabolic and cell cycle processes, and lipid and amino acid metabolism, two uncharacterized open reading frames (YHI9 and YMR289w) were also identified. A detailed characterization of YMR289w revealed that this gene was required for growth in media lacking p-aminobenzoic or folic acid and encoded a 4-amino-4-deoxychorismate lyase, which is the last of the three enzymatic activities required for p-aminobenzoic acid biosynthesis. In light of these results, YMR289w was designated ABZ2, in accordance with the accepted nomenclature. ABZ2 was able to rescue the p-aminobenzoate auxotrophy of an Escherichia coli pabC mutant, thus demonstrating that ABZ2 and pabC are functional homologues. Phylogenetic analyses revealed that Abz2p is the founder member of a new group of fungal 4-amino-4-deoxychorismate lyases that have no significant homology to its bacterial or plant counterparts. Abz2p appeared to form homodimers and dimerization was indispensable for its catalytic activity.
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Affiliation(s)
- Javier Botet
- Departamento de Microbiología y Genética, Instituto de Microbiología Bioquímica, Universidad de Salamanca/CSIC, Campus Miguel de Unamuno, 37007 Salamanca, Spain
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Abstract
We investigated the metabolism of L-lactate in mitochondria isolated from potato tubers grown and saved after harvest in the absence of any chemical agents. Immunologic analysis by western blot using goat polyclonal anti-lactate dehydrogenase showed the existence of a mitochondrial lactate dehydrogenase, the activity of which could be measured photometrically only in mitochondria solubilized with Triton X-100. The addition of L-lactate to potato tuber mitochondria caused: (a) a minor reduction of intramitochondrial pyridine nucleotides, whose measured rate of change increased in the presence of the inhibitor of the alternative oxidase salicyl hydroxamic acid; (b) oxygen consumption not stimulated by ADP, but inhibited by salicyl hydroxamic acid; and (c) activation of the alternative oxidase as polarographically monitored in a manner prevented by oxamate, an L-lactate dehydrogenase inhibitor. Potato tuber mitochondria were shown to swell in isosmotic solutions of ammonium L-lactate in a stereospecific manner, thus showing that L-lactate enters mitochondria by a proton-compensated process. Externally added L-lactate caused the appearance of pyruvate outside mitochondria, thus contributing to the oxidation of extramitochondrial NADH. The rate of pyruvate efflux showed a sigmoidal dependence on L-lactate concentration and was inhibited by phenylsuccinate. Hence, potato tuber mitochondria possess a non-energy-competent L-lactate/pyruvate shuttle. We maintain, therefore, that mitochondrial metabolism of L-lactate plays a previously unsuspected role in the response of potato to hypoxic stress.
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Affiliation(s)
- Gianluca Paventi
- Dipartimento di Scienze per la Salute, Università del Molise, Via De Sanctis, 86100 Campobasso, Italy
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30
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Díaz de la Garza RI, Gregory JF, Hanson AD. Folate biofortification of tomato fruit. Proc Natl Acad Sci U S A 2007; 104:4218-22. [PMID: 17360503 PMCID: PMC1810332 DOI: 10.1073/pnas.0700409104] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Folate deficiency leads to neural tube defects and other human diseases, and is a global health problem. Because plants are major folate sources for humans, we have sought to enhance plant folate levels (biofortification). Folates are synthesized from pteridine, p-aminobenzoate (PABA), and glutamate precursors. Previously, we increased pteridine production in tomato fruit up to 140-fold by overexpressing GTP cyclohydrolase I, the first enzyme of pteridine synthesis. This strategy increased folate levels 2-fold, but engineered fruit were PABA-depleted. We report here the engineering of fruit-specific overexpression of aminodeoxychorismate synthase, which catalyzes the first step of PABA synthesis. The resulting fruit contained an average of 19-fold more PABA than controls. When transgenic PABA- and pteridine-overproduction traits were combined by crossing, vine-ripened fruit accumulated up to 25-fold more folate than controls. Folate accumulation was almost as high (up to 15-fold) in fruit harvested green and ripened by ethylene-gassing, as occurs in commerce. The accumulated folates showed normal proportions of one-carbon forms, with 5-methyltetrahydrofolate the most abundant, but were less extensively polyglutamylated than controls. Folate concentrations in developing fruit did not change in controls, but increased continuously throughout ripening in transgenic fruit. Pteridine and PABA levels in transgenic fruit were >20-fold higher than in controls, but the pathway intermediates dihydropteroate and dihydrofolate did not accumulate, pointing to a flux constraint at the dihydropteroate synthesis step. The folate levels we achieved provide the complete adult daily requirement in less than one standard serving.
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Affiliation(s)
| | - Jesse F. Gregory
- Food Science and Human Nutrition, University of Florida, Gainesville, FL 32611
| | - Andrew D. Hanson
- Departments of *Horticultural Sciences and
- To whom correspondence should be addressed. E-mail:
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31
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Orsomando G, Bozzo GG, de la Garza RD, Basset GJ, Quinlivan EP, Naponelli V, Rébeillé F, Ravanel S, Gregory JF, Hanson AD. Evidence for folate-salvage reactions in plants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2006; 46:426-35. [PMID: 16623903 DOI: 10.1111/j.1365-313x.2006.02685.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Folates in vivo undergo oxidative cleavage, giving pterin and p-aminobenzoylglutamate (pABAGlu) moieties. These breakdown products are excreted in animals, but their fate is unclear in microorganisms and unknown in plants. As indirect evidence from this and previous studies strongly suggests that plants can have high folate-breakdown rates (approximately 10% per day), salvage of the cleavage products seems likely. Four sets of observations support this possibility. First, cleavage products do not normally accumulate: pools of pABAGlu (including its polyglutamyl forms) are equivalent to, at most, 4-14% of typical total folate pools in Arabidopsis thaliana, Lycopersicon esculentum and Pisum sativum tissues. Pools of the pterin oxidation end-product pterin-6-carboxylate are, likewise, fairly small (3-37%) relative to total folate pools. Second, little pABAGlu built up in A. thaliana plantlets when net folate breakdown was induced by blocking folate synthesis with sulfanilamide. Third, A. thaliana and L. esculentum tissues readily converted supplied breakdown products to folate synthesis precursors: pABAGlu was hydrolysed to p-aminobenzoate and glutamate, and dihydropterin-6-aldehyde was reduced to 6-hydroxymethyldihydropterin. Fourth, both these reactions were detected in vitro; the reduction used NADPH as cofactor. An alternative salvage route for pABAGlu, direct reincorporation into dihydrofolate via the action of dihydropteroate synthase, appears implausible from the properties of this enzyme. We conclude that plants are excellent organisms in which to explore the biochemistry of folate salvage.
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Affiliation(s)
- Giuseppe Orsomando
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
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32
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Klaus SMJ, Kunji ERS, Bozzo GG, Noiriel A, de la Garza RD, Basset GJC, Ravanel S, Rébeillé F, Gregory JF, Hanson AD. Higher plant plastids and cyanobacteria have folate carriers related to those of trypanosomatids. J Biol Chem 2005; 280:38457-63. [PMID: 16162503 DOI: 10.1074/jbc.m507432200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cyanobacterial and plant genomes encode proteins with some similarity to the folate and biopterin transporters of the trypanosomatid parasite Leishmania. The Synechocystis slr0642 gene product and its closest Arabidopsis homolog, the At2g32040 gene product, are representative examples. Both have 12 probable transmembrane domains, and the At2g32040 protein has a predicted chloroplast transit peptide. When expressed in Escherichia coli pabA pabB or folE, mutants, which are unable to produce or take up folates, the slr0642 protein and a modified At2g32040 protein (truncated and fused to the N terminus of slr0642) enabled growth on 5-formyltetrahydrofolate or folic acid but not on 5-formyltetrahydrofolate triglutamate, demonstrating that both proteins mediate folate monoglutamate transport. Both proteins also mediate transport of the antifolate analogs methotrexate and aminopterin, as evidenced by their ability to greatly increase the sensitivity of E. coli to these inhibitors. The full-length At2g32040 polypeptide was translocated into isolated pea chloroplasts and, when fused to green fluorescent protein, directed the passenger protein to the envelope of Arabidopsis chloroplasts in transient expression experiments. At2g32040 transcripts were present at similar levels in roots and aerial organs, indicating that the protein occurs in non-green plastids as well as chloroplasts. Insertional inactivation of At2g32040 significantly raised the total folate content of chloroplasts and lowered the proportion of 5-methyltetrahydrofolate but did not discernibly affect growth. These findings establish conservation of function among folate and biopterin transporter family proteins from three kingdoms of life.
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Affiliation(s)
- Sebastian M J Klaus
- Horticultural Sciences, University of Florida, Gainesville, Florida 32611, USA
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33
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Quinlivan EP, Hanson AD, Gregory JF. The analysis of folate and its metabolic precursors in biological samples. Anal Biochem 2005; 348:163-84. [PMID: 16266679 DOI: 10.1016/j.ab.2005.09.017] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Revised: 09/09/2005] [Accepted: 09/13/2005] [Indexed: 10/25/2022]
Affiliation(s)
- Eoin P Quinlivan
- Department of Food Science and Human Nutrition, University of Florida, Gainesville, FL 32611, USA
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34
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Traditional and accelerator mass spectrometry for quantitation of human folate pools. Trends Food Sci Technol 2005. [DOI: 10.1016/j.tifs.2005.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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35
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Storozhenko S, Ravanel S, Zhang GF, Rébeillé F, Lambert W, Van Der Straeten D. Folate enhancement in staple crops by metabolic engineering. Trends Food Sci Technol 2005. [DOI: 10.1016/j.tifs.2005.03.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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36
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Hasumura M, Imai T, Takizawa T, Ueda M, Onose J, Hirose M. Promotion of Thyroid Carcinogenesis by para-aminobenzoic Acid in Rats Initiated with N-bis(2-hydroxypropyl)nitrosamine. Toxicol Sci 2005; 86:61-7. [PMID: 15843508 DOI: 10.1093/toxsci/kfi173] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Sulfonamide analogues of para-aminobenzoic acid (PABA), a precursor of folate synthesis, have beneficial effects as antifolate, but thyroid peroxidase inhibition has been reported as a side effect that results in promotion of rat thyroid carcinogenesis. In the present study, effects of PABA itself on F344 rat thyroid carcinogenesis after initiation with N-bis(2-hydroxypropyl)nitrosamine (DHPN) were evaluated. In experiment 1, rats in groups 1-4 received a single subcutaneous injection of DHPN at 2800 mg/kg, and groups 5 and 6 received vehicle saline alone. From 1 week after DHPN initiation, rats in groups 2, 3, 4, and 6 were fed basal diet containing 0.25%, 0.5%, 1.0%, and 1.0% PABA, respectively, for 40 weeks. Rats in groups 1 and 5 received basal diet alone throughout the experiment. The final incidence of thyroid follicular cell adenomas and adenocarcinomas was significantly (p < 0.05 or 0.01) increased in groups 3 and 4 as compared to group 1. No thyroid tumors were found in groups 5 and 6. In experiment 2, animals in group 1 were fed basal diet alone, while groups 2 and 3 were given 0.5% and 1.0% PABA in the diet, respectively, for 2 weeks. Thyroid weights in group 3, and serum thyroid stimulating hormone level and proliferative activity of follicular cells in groups 2 and 3 were significantly (p < 0.05 or 0.01) elevated. In addition, the serum thyroxine level in group 3 was significantly (p < 0.05) depressed. These results clearly indicate that PABA exerts promotion/progression effects on rat thyroid carcinogenesis as a result of hypothyroidism followed by negative-feedback via the thyroid-pituitary axis.
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Affiliation(s)
- M Hasumura
- Division of Pathology, National Institute of Health Sciences, Kamiyoga, Tokyo 158-8501, Japan
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37
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Zhang GF, Mortier KA, Storozhenko S, Van De Steene J, Van Der Straeten D, Lambert WE. Free and total para-aminobenzoic acid analysis in plants with high-performance liquid chromatography/tandem mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2005; 19:963-9. [PMID: 15759312 DOI: 10.1002/rcm.1878] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
para-Aminobenzoic acid (PABA), a precursor in the synthesis of folates in plants, is determined by liquid chromatography/tandem mass spectrometry (LC/MS/MS). In plants PABA can be converted into its beta-D-glucopyranosyl ester (PABA-Glc) and can also exist in its free form. In this work, we developed and validated a quantitative method to study free and total PABA in plants. The total PABA (free PABA plus PABA-Glc) can be evaluated after acid hydrolysis at 80 degrees C for 2 hours. The plant material is homogenized and the PABA content is quantified using the standard addition procedure. The validated method is selective, sensitive, simple, accurate, has a recovery between 99.6 to 102.5%, is reproducible (RSD between 1.4 and 4.4%), and is linear between 2.5 and 1538 ng/mL. Free and total PABA determinations in five vegetables showed that different plant species had different amounts of free and total PABA, and that the ratios of total versus free PABA were also variable. This new method could be valuable for studies of folate synthesis in plants.
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Affiliation(s)
- Guo-Fang Zhang
- Laboratory of Toxicology, Ghent University, Harelbekestraat 72, B-9000 Ghent, Belgium
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38
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Basset GJC, Ravanel S, Quinlivan EP, White R, Giovannoni JJ, Rébeillé F, Nichols BP, Shinozaki K, Seki M, Gregory JF, Hanson AD. Folate synthesis in plants: the last step of the p-aminobenzoate branch is catalyzed by a plastidial aminodeoxychorismate lyase. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2004; 40:453-461. [PMID: 15500462 DOI: 10.1111/j.1365-313x.2004.02231.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In plants, the last step in the synthesis of p-aminobenzoate (PABA) moiety of folate remains to be elucidated. In Escherichia coli, this step is catalyzed by the PabC protein, a beta-lyase that converts 4-amino-4-deoxychorismate (ADC)--the reaction product of the PabA and PabB enzymes--to PABA and pyruvate. So far, the only known plant enzyme involved in PABA synthesis is ADC synthase, which has fused domains homologous to E. coli PabA and PabB and is located in plastids. ADC synthase has no lyase activity, implying that plants have a separate ADC lyase. No such lyase is known in any eukaryote. Genomic and phylogenetic approaches identified Arabidopsis and tomato cDNAs encoding PabC homologs with putative chloroplast-targeting peptides. These cDNAs were shown to encode functional enzymes by complementation of an E. coli pabC mutant, and by demonstrating that the partially purified recombinant proteins convert ADC to PABA. Plant ADC lyase is active as dimer and is not feedback inhibited by physiologic concentrations of PABA, its glucose ester, or folates. The full-length Arabidopsis ADC lyase polypeptide was translocated into isolated pea chloroplasts and, when fused to green fluorescent protein, directed the passenger protein to Arabidopsis chloroplasts in transient expression experiments. These data indicate that ADC lyase, like ADC synthase, is present in plastids. As shown previously for the ADC synthase transcript, the level of ADC lyase mRNA in the pericarp of tomato fruit falls sharply as ripening advances, suggesting that the expression of these two enzymes is coregulated.
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Affiliation(s)
- Gilles J C Basset
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
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39
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Díaz de la Garza R, Quinlivan EP, Klaus SMJ, Basset GJC, Gregory JF, Hanson AD. Folate biofortification in tomatoes by engineering the pteridine branch of folate synthesis. Proc Natl Acad Sci U S A 2004; 101:13720-5. [PMID: 15365185 PMCID: PMC518823 DOI: 10.1073/pnas.0404208101] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plants are the main source of folate in human diets, but many fruits, tubers, and seeds are poor in this vitamin, and folate deficiency is a worldwide problem. Plants synthesize folate from pteridine, p-aminobenzoate (PABA), and glutamate moieties. Pteridine synthesis capacity is known to drop in ripening tomato fruit; therefore, we countered this decline by fruit-specific overexpression of GTP cyclohydrolase I, the first enzyme of pteridine synthesis. We used a synthetic gene based on mammalian GTP cyclohydrolase I, because this enzyme is predicted to escape feedback control in planta. This engineering maneuver raised fruit pteridine content by 3- to 140-fold and fruit folate content by an average of 2-fold among 12 independent transformants, relative to vector-alone controls. Most of the folate increase was contributed by 5-methyltetrahydrofolate polyglutamates and 5,10-methenyltetrahydrofolate polyglutamates, which were also major forms of folate in control fruit. The accumulated pteridines included neopterin, monapterin, and hydroxymethylpterin; their reduced forms, which are folate biosynthesis intermediates; and pteridine glycosides not previously found in plants. Engineered fruit with intermediate levels of pteridine overproduction attained the highest folate levels. PABA pools were severely depleted in engineered fruit that were high in folate, and supplying such fruit with PABA by means of the fruit stalk increased their folate content by up to 10-fold. These results demonstrate that engineering a moderate increase in pteridine production can significantly enhance the folate content in food plants and that boosting the PABA supply can produce further gains.
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40
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Hossain T, Rosenberg I, Selhub J, Kishore G, Beachy R, Schubert K. Enhancement of folates in plants through metabolic engineering. Proc Natl Acad Sci U S A 2004; 101:5158-63. [PMID: 15044686 PMCID: PMC387390 DOI: 10.1073/pnas.0401342101] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Humans depend on plants as a major source of dietary folates. Inadequate dietary levels of the vitamin folate can lead to megaloblastic anemia, birth defects, impaired cognitive development, and increased risk of cardiovascular disease and cancer. The biofortification of folate levels in food crops is a target for metabolic engineering. Folates are synthesized de novo from pterins and para-amino benzoic acid, which are subsequently combined to form dihydropteroate, the direct precursor to dihydrofolate. We postulated that GTP cyclohydrolase-1, which catalyzes the first committed step in pterin biosynthesis, was a rate-limiting step in pterin synthesis in plants and, therefore, in folate synthesis. On this basis, we proposed that the expression of an unregulated bacterial GTP cyclohydrolase-1 in plants would increase pterin biosynthesis with a concomitant enhancement of folate levels. The folE gene encoding GTP cyclohydrolase-1 was cloned from Escherichia coli and introduced into Arabidopsis thaliana through plant transformation. The expression of bacterial GTP cyclohydrolase-1 in transgenic Arabidopsis resulted in a 1,250-fold and 2- to 4-fold enhancement of pterins and folates, respectively. These results helped to identify other potential factors regulating folate synthesis, suggesting ways to further enhance folate levels in food crops.
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Affiliation(s)
- Tahzeeba Hossain
- Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, USA
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41
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Basset GJC, Quinlivan EP, Ravanel S, Rébeillé F, Nichols BP, Shinozaki K, Seki M, Adams-Phillips LC, Giovannoni JJ, Gregory JF, Hanson AD. Folate synthesis in plants: the p-aminobenzoate branch is initiated by a bifunctional PabA-PabB protein that is targeted to plastids. Proc Natl Acad Sci U S A 2004; 101:1496-501. [PMID: 14745019 PMCID: PMC341757 DOI: 10.1073/pnas.0308331100] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It is not known how plants synthesize the p-aminobenzoate (PABA) moiety of folates. In Escherichia coli, PABA is made from chorismate in two steps. First, the PabA and PabB proteins interact to catalyze transfer of the amide nitrogen of glutamine to chorismate, forming 4-amino-4-deoxychorismate (ADC). The PabC protein then mediates elimination of pyruvate and aromatization to give PABA. Fungi, actinomycetes, and Plasmodium spp. also synthesize PABA but have proteins comprising fused domains homologous to PabA and PabB. These bipartite proteins are commonly called "PABA synthases," although it is unclear whether they produce PABA or ADC. Genomic approaches identified Arabidopsis and tomato cDNAs encoding bipartite proteins containing fused PabA and PabB domains, plus a putative chloroplast targeting peptide. These cDNAs encode functional enzymes, as demonstrated by complementation of an E. coli pabA pabB double mutant and a yeast PABA-synthase deletant. The partially purified recombinant Arabidopsis protein did not produce PABA unless the E. coli PabC enzyme was added, indicating that it forms ADC, not PABA. The enzyme behaved as a monomer in size-exclusion chromatography and was not inhibited by physiological concentrations of PABA, its glucose ester, or folates. When the putative targeting peptide was fused to GFP and expressed in protoplasts, the fusion protein appeared only in chloroplasts, indicating that PABA synthesis is plastidial. In the pericarp of tomato fruit, the PabA-PabB mRNA level fell drastically as ripening advanced, but there was no fall in total PABA content, which stayed between 0.7 and 2.3 nmol.g(-1) fresh weight.
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Affiliation(s)
- Gilles J C Basset
- Department of Horticultural Sciences, University of Florida, Gainesville, FL 32611, USA
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