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Hassett K, Muria-Gonzalez MJ, Turner A, McLean MS, Wallwork H, Martin A, Ellwood SR. Widespread genetic heterogeneity and genotypic grouping associated with fungicide resistance among barley spot form net blotch isolates in Australia. G3 (BETHESDA, MD.) 2023; 13:jkad076. [PMID: 37002913 PMCID: PMC10151411 DOI: 10.1093/g3journal/jkad076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 02/13/2023] [Accepted: 03/10/2023] [Indexed: 04/04/2023]
Abstract
Spot form net blotch, caused by Pyrenophora teres f. maculata, is a major foliar disease of barley worldwide. Knowledge of the pathogen's genetic diversity and population structure is critical for a better understanding of inherent evolutionary capacity and for the development of sustainable disease management strategies. Genome-wide, single nucleotide polymorphism data of 254 Australian isolates revealed genotypic diversity and an absence of population structure, either between states, or between fields and cultivars in different agro-ecological zones. This indicates there is little geographical isolation or cultivar directional selection and that the pathogen is highly mobile across the continent. However, two cryptic genotypic groups were found only in Western Australia, predominantly associated with genes involved in fungicide resistance. The findings in this study are discussed in the context of current cultivar resistance and the pathogen's adaptive potential.
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Affiliation(s)
- Kealan Hassett
- Centre for Crop and Disease Management, Curtin University, Bentley, WA 6102, Australia
| | | | - Aleesha Turner
- Centre for Crop and Disease Management, Curtin University, Bentley, WA 6102, Australia
| | - Mark S McLean
- Field Crops Pathology, Agriculture Victoria, Horsham, Victoria 3401, Australia
| | - Hugh Wallwork
- Cereal Pathology Laboratory, South Australian Research and Development Institute, Hartley Grove, Urrbrae, SA 5064, Australia
| | - Anke Martin
- Centre for Crop Health, University of Southern Queensland, Toowoomba, Queensland 4350, Australia
| | - Simon R Ellwood
- Centre for Crop and Disease Management, Curtin University, Bentley, WA 6102, Australia
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Wu Y, Li B, Miao B, Xie C, Tang YQ. Saccharomyces cerevisiae employs complex regulation strategies to tolerate low pH stress during ethanol production. Microb Cell Fact 2022; 21:247. [DOI: 10.1186/s12934-022-01974-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 11/15/2022] [Indexed: 11/25/2022] Open
Abstract
Abstract
Background
Industrial bioethanol production may involve a low pH environment caused by inorganic acids, improving the tolerance of Saccharomyces cerevisiae to a low pH environment is of industrial importance to increase ethanol yield, control bacterial contamination, and reduce production cost. In our previous study, acid tolerance of a diploid industrial Saccharomyces cerevisiae strain KF-7 was chronically acclimatized by continuous ethanol fermentation under gradually increasing low-pH stress conditions. Two haploid strains B3 and C3 having excellent low pH tolerance were derived through the sporulation of an isolated mutant. Diploid strain BC3 was obtained by mating these two haploids. In this study, B3, C3, BC3, and the original strain KF-7 were subjected to comparison transcriptome analysis to investigate the molecular mechanism of the enhanced phenotype.
Result
The comparison transcriptome analysis results suggested that the upregulated vitamin B1 and B6 biosynthesis contributed to the low pH tolerance. Amino acid metabolism, DNA repairment, and general stress response might also alleviate low pH stress.
Conclusion
Saccharomyces cerevisiae seems to employ complex regulation strategies to tolerate low pH during ethanol production. The findings provide guides for the construction of low pH-tolerant industrial strains that can be used in industrial fermentation processes.
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Yamashiro T, Yasujima T, Said HM, Yuasa H. pH-dependent pyridoxine transport by SLC19A2 and SLC19A3: Implications for absorption in acidic microclimates. J Biol Chem 2020; 295:16998-17008. [PMID: 33008889 PMCID: PMC7863892 DOI: 10.1074/jbc.ra120.013610] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 10/01/2020] [Indexed: 11/06/2022] Open
Abstract
SLC19A2 and SLC19A3, also known as thiamine transporters (THTR) 1 and 2, respectively, transport the positively charged thiamine (vitamin B1) into cells to enable its efficient utilization. SLC19A2 and SLC19A3 are also known to transport structurally unrelated cationic drugs, such as metformin, but whether this charge selectivity extends to other molecules, such as pyridoxine (vitamin B6), is unknown. We tested this possibility using Madin-Darby canine kidney II (MDCKII) cells and human embryonic kidney 293 (HEK293) cells for transfection experiments, and also using Caco-2 cells as human intestinal epithelial model cells. The stable expression of SLC19A2 and SLC19A3 in MDCKII cells (as well as their transient expression in HEK293 cells) led to a significant induction in pyridoxine uptake at pH 5.5 compared with control cells. The induced uptake was pH-dependent, favoring acidic conditions over neutral to basic conditions, and protonophore-sensitive. It was saturable as a function of pyridoxine concentration, with an apparent Km of 37.8 and 18.5 μm, for SLC19A2 and SLC19A3, respectively, and inhibited by the pyridoxine analogs pyridoxal and pyridoxamine as well as thiamine. We also found that silencing the endogenous SLC19A3, but not SLC19A2, of Caco-2 cells with gene-specific siRNAs lead to a significant reduction in carrier-mediated pyridoxine uptake. These results show that SLC19A2 and SLC19A3 are capable of recognizing/transporting pyridoxine, favoring acidic conditions for operation, and suggest a possible role for these transporters in pyridoxine transport mainly in tissues with an acidic environment like the small intestine, which has an acidic surface microclimate.
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Affiliation(s)
- Takahiro Yamashiro
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Tomoya Yasujima
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Hamid M Said
- Departments of Medicine and Physiology/Biophysics, University of California, Irvine, California, USA; Department of Veterans Affairs Medical Center, Long Beach, California, USA
| | - Hiroaki Yuasa
- Department of Biopharmaceutics, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan.
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Parra M, Stahl S, Hellmann H. Vitamin B₆ and Its Role in Cell Metabolism and Physiology. Cells 2018; 7:cells7070084. [PMID: 30037155 PMCID: PMC6071262 DOI: 10.3390/cells7070084] [Citation(s) in RCA: 196] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 07/18/2018] [Accepted: 07/20/2018] [Indexed: 12/11/2022] Open
Abstract
Vitamin B6 is one of the most central molecules in cells of living organisms. It is a critical co-factor for a diverse range of biochemical reactions that regulate basic cellular metabolism, which impact overall physiology. In the last several years, major progress has been accomplished on various aspects of vitamin B6 biology. Consequently, this review goes beyond the classical role of vitamin B6 as a cofactor to highlight new structural and regulatory information that further defines how the vitamin is synthesized and controlled in the cell. We also discuss broader applications of the vitamin related to human health, pathogen resistance, and abiotic stress tolerance. Overall, the information assembled shall provide helpful insight on top of what is currently known about the vitamin, along with addressing currently open questions in the field to highlight possible approaches vitamin B6 research may take in the future.
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Affiliation(s)
- Marcelina Parra
- Hellmann Lab, School of Biological Sciences, College of Liberal Arts and Sciences, Washington State University, Pullman, 99164-6234 WA, USA.
| | - Seth Stahl
- Hellmann Lab, School of Biological Sciences, College of Liberal Arts and Sciences, Washington State University, Pullman, 99164-6234 WA, USA.
| | - Hanjo Hellmann
- Hellmann Lab, School of Biological Sciences, College of Liberal Arts and Sciences, Washington State University, Pullman, 99164-6234 WA, USA.
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Global Fitness Profiling Identifies Arsenic and Cadmium Tolerance Mechanisms in Fission Yeast. G3-GENES GENOMES GENETICS 2016; 6:3317-3333. [PMID: 27558664 PMCID: PMC5068951 DOI: 10.1534/g3.116.033829] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Heavy metals and metalloids such as cadmium [Cd(II)] and arsenic [As(III)] are widespread environmental toxicants responsible for multiple adverse health effects in humans. However, the molecular mechanisms underlying metal-induced cytotoxicity and carcinogenesis, as well as the detoxification and tolerance pathways, are incompletely understood. Here, we use global fitness profiling by barcode sequencing to quantitatively survey the Schizosaccharomyces pombe haploid deletome for genes that confer tolerance of cadmium or arsenic. We identified 106 genes required for cadmium resistance and 110 genes required for arsenic resistance, with a highly significant overlap of 36 genes. A subset of these 36 genes account for almost all proteins required for incorporating sulfur into the cysteine-rich glutathione and phytochelatin peptides that chelate cadmium and arsenic. A requirement for Mms19 is explained by its role in directing iron–sulfur cluster assembly into sulfite reductase as opposed to promoting DNA repair, as DNA damage response genes were not enriched among those required for cadmium or arsenic tolerance. Ubiquinone, siroheme, and pyridoxal 5′-phosphate biosynthesis were also identified as critical for Cd/As tolerance. Arsenic-specific pathways included prefoldin-mediated assembly of unfolded proteins and protein targeting to the peroxisome, whereas cadmium-specific pathways included plasma membrane and vacuolar transporters, as well as Spt–Ada–Gcn5-acetyltransferase (SAGA) transcriptional coactivator that controls expression of key genes required for cadmium tolerance. Notable differences are apparent with corresponding screens in the budding yeast Saccharomyces cerevisiae, underscoring the utility of analyzing toxic metal defense mechanisms in both organisms.
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Candida Efflux ATPases and Antiporters in Clinical Drug Resistance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 892:351-376. [PMID: 26721282 DOI: 10.1007/978-3-319-25304-6_15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
An enhanced expression of genes encoding ATP binding cassette (ABC) and major facilitator superfamily (MFS) transport proteins are known to contribute to the development of tolerance to antifungals in pathogenic yeasts. For example, the azole resistant (AR) clinical isolates of the opportunistic human fungal pathogen Candida albicans show an overexpression of CDR1 and/or CaMDR1 belonging to ABC and MFS, superfamilies, respectively. The reduced accumulation (due to rapid efflux) of drugs in AR isolates confirms the role of efflux pump proteins in the development of drug tolerance. Considering the importance of major multidrug transporters, the focus of recent research has been to understand the structure and function of these proteins which could help to design inhibitors/modulators of these pump proteins. This chapter focuses on some aspects of the structure and function of yeast transporter proteins particularly in relation to MDR in Candida.
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7
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Abstract
Two observations stimulated the interest in vitamin B-6 and alkaline phosphatase in brain: the marked increase in plasma pyridoxal phosphate and the occurrence of pyridoxine responsive seizures in hypophosphatasia. The increase in plasma pyridoxal phosphate indicates the importance of tissue non-specific alkaline phosphatase (TNAP) in transferring vitamin B-6 into the tissues. Vitamin B-6 is involved in the biosynthesis of most of the neurotransmitters. Decreased gamma-aminobutyrate (GABA) appears to be most directly related to the development of seizures in vitamin B-6 deficiency. Cytosolic pyridoxal phosphatase/chronophin may interact with vitamin B-6 metabolism and neuronal development and function. Ethanolaminephosphate phospholyase interacts with phosphoethanolamine metabolism. Extracellular pyridoxal phosphate may interact with purinoceptors and calcium channels. In conclusion, TNAP clearly influences extracellular and intracellular metabolism of vitamin B-6 in brain, particularly during developmental stages. While effects on GABA metabolism appear to be the major contributor to seizures, multiple other intra- and extra-cellular metabolic systems may be affected directly and/or indirectly by altered vitamin B-6 hydrolysis and uptake resulting from variations in alkaline phosphatase activity.
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8
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Yagi T, Iwamoto S, Mizuseki R, Furuya M, Nakayama K. Contents of all forms of vitamin B6, pyridoxine-β-glucoside and 4-pyridoxic acid in mature milk of Japanese women according to 4-pyridoxolactone-conversion high performance liquid chromatography. J Nutr Sci Vitaminol (Tokyo) 2013; 59:9-15. [PMID: 23535534 DOI: 10.3177/jnsv.59.9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The contents of six vitamin B6 forms, pyridoxine-β-glucoside, and 4-pyridoxic acid in mature milk of 20 Japanese lactating women consuming ordinary Japanese foods were determined by a 4-pyridoxolactone-conversion HPLC method. These compounds were determined with the average recovery rate of 83.9% or more. The average total content of vitamin B6 forms was 1.01 ± 0.32 (µmol/L). Pyridoxal and pyridoxal 5'-phosphate were found in all of the samples, and their average contents were 0.71 ± 0.28 (µmol/L) and 0.16 ± 0.07 (µmol/L), respectively. Pyridoxamine, pyridoxine, pyridoxamine 5'-phosphate, pyridoxine 5'-phosphate, and pyridoxine-β-glucoside were found in 15, 14, 13, 9, and 7 samples, respectively. The presence of pyridoxine 5'-phosphate was for the first time found in human milk. A method for the determination of 4-pyridoxic acid, which is the excretion form of vitamin B6, was modified to quantitate it by isocratic HPLC. 4-Pyridoxic acid was found in all samples, and its average content was 0.094 ± 0.040 (µmol/L), which was only 12% of its content in cow (Holstein) milk. The total content of vitamin B6 forms, and predominant presence of pyridoxal among other vitamin B6 forms in the Japanese women's milk samples shared similar characteristics with American women's milk samples.
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Affiliation(s)
- Toshiharu Yagi
- Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Kochi, Japan.
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9
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Hediger MA, Clémençon B, Burrier RE, Bruford EA. The ABCs of membrane transporters in health and disease (SLC series): introduction. Mol Aspects Med 2013; 34:95-107. [PMID: 23506860 PMCID: PMC3853582 DOI: 10.1016/j.mam.2012.12.009] [Citation(s) in RCA: 399] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Accepted: 12/18/2012] [Indexed: 01/19/2023]
Abstract
The field of transport biology has steadily grown over the past decade and is now recognized as playing an important role in manifestation and treatment of disease. The SLC (solute carrier) gene series has grown to now include 52 families and 395 transporter genes in the human genome. A list of these genes can be found at the HUGO Gene Nomenclature Committee (HGNC) website (see www.genenames.org/genefamilies/SLC). This special issue features mini-reviews for each of these SLC families written by the experts in each field. The existing online resource for solute carriers, the Bioparadigms SLC Tables (www.bioparadigms.org), has been updated and significantly extended with additional information and cross-links to other relevant databases, and the nomenclature used in this database has been validated and approved by the HGNC. In addition, the Bioparadigms SLC Tables functionality has been improved to allow easier access by the scientific community. This introduction includes: an overview of all known SLC and “non-SLC” transporter genes; a list of transporters of water soluble vitamins; a summary of recent progress in the structure determination of transporters (including GLUT1/SLC2A1); roles of transporters in human diseases and roles in drug approval and pharmaceutical perspectives.
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Affiliation(s)
- Matthias A Hediger
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.
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10
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Szydlowski N, Bürkle L, Pourcel L, Moulin M, Stolz J, Fitzpatrick TB. Recycling of pyridoxine (vitamin B6) by PUP1 in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:40-52. [PMID: 23551747 DOI: 10.1111/tpj.12195] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 03/26/2013] [Accepted: 03/29/2013] [Indexed: 05/06/2023]
Abstract
Vitamin B6 is a cofactor for more than 140 essential enzymatic reactions and was recently proposed as a potent antioxidant, playing a role in the photoprotection of plants. De novo biosynthesis of the vitamin has been described relatively recently and is derived from simple sugar precursors as well as glutamine. In addition, the vitamin can be taken up from exogenous sources in a broad range of organisms, including plants. However, specific transporters have been identified only in yeast. Here we assess the ability of the family of Arabidopsis purine permeases (PUPs) to transport vitamin B6. Several members of the family complement the growth phenotype of a Saccharomyces cerevisiae mutant strain impaired in both de novo biosynthesis of vitamin B6 as well as its uptake. The strongest activity was observed with PUP1 and was confirmed by direct measurement of uptake in yeast as well as in planta, defining PUP1 as a high affinity transporter for pyridoxine. At the tissue level the protein is localised to hydathodes and here we use confocal microscopy to illustrate that at the cellular level it is targeted to the plasma membrane. Interestingly, we observe alterations in pyridoxine recycling from the guttation sap upon overexpression of PUP1 and in a pup1 mutant, consistent with the role of the protein in retrieval of pyridoxine. Furthermore, combining the pup1 mutant with a vitamin B6 de novo biosynthesis mutant (pdx1.3) corroborates that PUP1 is involved in the uptake of the vitamin.
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Affiliation(s)
- Nicolas Szydlowski
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Lukas Bürkle
- ETH Zurich, Institute of Agricultural Sciences, 8092, Zurich, Switzerland
| | - Lucille Pourcel
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Michael Moulin
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
| | - Jürgen Stolz
- Lehrstuhl für Ernährungsphysiologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung (ZIEL) - Abteilung Biochemie, Wissenschaftszentrum Weihenstephan, Technische Universität München, 85350, Freising, Germany
| | - Teresa B Fitzpatrick
- Department of Botany and Plant Biology, University of Geneva, 1211, Geneva, Switzerland
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Rueschhoff EE, Gillikin JW, Sederoff HW, Daub ME. The SOS4 pyridoxal kinase is required for maintenance of vitamin B6-mediated processes in chloroplasts. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 63:281-91. [PMID: 23321022 DOI: 10.1016/j.plaphy.2012.12.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 12/14/2012] [Indexed: 05/01/2023]
Abstract
Vitamin B(6) (pyridoxal 5'-phosphate and its vitamers) is an important cofactor in numerous enzymatic reactions. In spite of its importance, the consequences of altering vitamin B(6) content on plant growth and development are not well understood. This study compares two mutants for vitamin B(6)-metabolizing enzymes in Arabidopsis thaliana: a pdx1.3 mutant in the de novo synthesis pathway and a salvage pathway sos4 mutant that accumulates more vitamin B(6). We show that despite a difference in total B(6) content in leaf tissue, both mutants share similar phenotypes, including chlorosis, decreased size, altered chloroplast ultrastructure, and root sensitivity to sucrose. Assay of B(6) vitamer content from isolated chloroplasts showed that, despite differing B(6) vitamer content in whole leaf tissue, both mutants share a common deficiency in total and phosphorylated vitamers in chloroplasts. One of the splice variants of the SOS4 proteins was shown to be located in the chloroplast. Our data indicate that some of the phenotypic consequences shared between the pdx1.3 and sos4 mutants are due to B(6) deficiency in chloroplasts, and show that SOS4 is required for maintenance of phosphorylated B(6) vitamer concentrations in chloroplasts. Further, our data are consistent with a diffusion model for transport of vitamin B(6) into chloroplasts.
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Affiliation(s)
- Elizabeth E Rueschhoff
- Department of Plant Biology, North Carolina State University, Raleigh, NC 27695-7612, USA.
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12
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Comparisons of uptake and cell surface binding among pyridoxal, pyridoxine, and pyridoxamine in RAW264.7 cells. Nutrition 2010; 26:648-52. [DOI: 10.1016/j.nut.2009.08.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 08/04/2009] [Accepted: 08/11/2009] [Indexed: 11/23/2022]
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13
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Mooney S, Hellmann H. Vitamin B6: Killing two birds with one stone? PHYTOCHEMISTRY 2010; 71:495-501. [PMID: 20089286 DOI: 10.1016/j.phytochem.2009.12.015] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 12/23/2009] [Accepted: 12/30/2009] [Indexed: 05/24/2023]
Abstract
Vitamin B6 comprises a group of compounds that are involved in a surprisingly high diversity of biochemical reactions. Actually, most of these reactions are co-catalyzed by a single B6 vitamer, pyridoxal 5'-phosphate, making it a crucial and versatile co-factor in many metabolic processes in the cell. In addition, it has been demonstrated in recent years that vitamin B6 has a second important function by being an effective antioxidant. Because of these two characteristics the vitamin is an interesting compound to study in plants. This review provides a brief overview and update on such important aspects like vitamin B6-dependent enzymes and known biosynthetic pathways in plants, phenotypes of plant mutants affected in vitamin B6 biosynthesis, and the potential benefits of modifying vitamin B6 content in plants.
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Affiliation(s)
- Sutton Mooney
- Washington State University, Pullman, Abelson Hall, WA 99164, USA
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14
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Mooney S, Leuendorf JE, Hendrickson C, Hellmann H. Vitamin B6: a long known compound of surprising complexity. Molecules 2009; 14:329-51. [PMID: 19145213 PMCID: PMC6253932 DOI: 10.3390/molecules14010329] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 01/07/2009] [Accepted: 01/09/2009] [Indexed: 12/31/2022] Open
Abstract
In recent years vitamin B6 has become a focus of research describing the compound’s critical function in cellular metabolism and stress response. For many years the sole function of vitamin B6 was considered to be that of an enzymatic cofactor. However, recently it became clear that it is also a potent antioxidant that effectively quenches reactive oxygen species and is thus of high importance for cellular well-being. In view of the recent findings, the current review takes a look back and summarizes the discovery of vitamin B6 and the elucidation of its structure and biosynthetic pathways. It provides a detailed overview on vitamin B6 both as a cofactor and a protective compound. Besides these general characteristics of the vitamin, the review also outlines the current literature on vitamin B6 derivatives and elaborates on recent findings that provide new insights into transport and catabolism of the compound and on its impact on human health.
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Affiliation(s)
- Sutton Mooney
- School of Biological Sciences, Washington State University, Pullman, WA, USA; E-mail: (S. M.), (C. H.)
| | - Jan-Erik Leuendorf
- Angewandte Genetik, Freie Universität Berlin, 14195 Berlin, Germany E-mail: (J-E. L.)
| | - Christopher Hendrickson
- School of Biological Sciences, Washington State University, Pullman, WA, USA; E-mail: (S. M.), (C. H.)
| | - Hanjo Hellmann
- School of Biological Sciences, Washington State University, Pullman, WA, USA; E-mail: (S. M.), (C. H.)
- Author to whom correspondence should be addressed; E-Mail:
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15
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Said ZM, Subramanian VS, Vaziri ND, Said HM. Pyridoxine uptake by colonocytes: a specific and regulated carrier-mediated process. Am J Physiol Cell Physiol 2008; 294:C1192-7. [PMID: 18353902 DOI: 10.1152/ajpcell.00015.2008] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The water-soluble vitamin B6 (pyridoxine) is important for normal cellular functions, growth, and development. The vitamin is obtained from two exogenous sources: a dietary source, which is absorbed in the small intestine, and a bacterial source, where the vitamin is synthesized in significant quantities by the normal microflora of the large intestine. Evidence exists to suggest the bioavailability of the latter source of the vitamin, but nothing is known about the mechanism involved and its regulation. In this study, we addressed these issues using young adult mouse colonic epithelial (YAMC) cells and human colonic apical membrane vesicles (AMV) as models and using [3H]pyridoxine as the uptake substrate. The results showed the initial rate of [3H]pyridoxine uptake by YAMC cells to be 1) energy- and temperature- (but not Na-) dependent and to occur without metabolic alteration in the transported substrate; 2) saturable as a function of concentration with an apparent Km and Vmax of 2.1 +/- 0.5 muM and 53.4 +/- 4.3 pmol.mg protein(-1).3 min(-1), respectively; 3) cis-inhibited by unlabeled pyridoxine and its structural analogs, but not by the unrelated compounds theophylline, penicillamine, and isoniazid; 4) trans-stimulated by unlabeled pyridoxine; 5) amiloride sensitive; and 6) regulated by extracellular and intracellular factors. Uptake of pyridoxine by native human colonic AMV was also found to involve a carrier-mediated process. These studies demonstrate, for the first time, the functional existence of a specific and regulatable carrier-mediated process for pyridoxine uptake by mammalian colonocytes.
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Affiliation(s)
- Zainab M Said
- Department of Medicine and Physiology, University of California, Irvine, California, USA
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16
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Vogl C, Klein CM, Batke AF, Schweingruber ME, Stolz J. Characterization of Thi9, a Novel Thiamine (Vitamin B1) Transporter from Schizosaccharomyces pombe. J Biol Chem 2008; 283:7379-89. [DOI: 10.1074/jbc.m708275200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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17
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Gospe SM. Pyridoxine-dependent seizures: new genetic and biochemical clues to help with diagnosis and treatment. Curr Opin Neurol 2006; 19:148-53. [PMID: 16538088 DOI: 10.1097/01.wco.0000218230.81301.12] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
PURPOSE OF REVIEW Pyridoxine dependency is an uncommon but important cause of intractable seizures presenting in infancy and early childhood. This paper discusses recent clinical, biochemical and genetic studies and how the findings should change our approach in evaluating young patients with antiepileptic drug-resistant seizures. RECENT FINDINGS Originally thought to be due to abnormal binding of pyridoxal phosphate to glutamic acid decarboxylase resulting in decreased gamma-aminobutyric acid, mutations in the gene encoding this enzyme have been ruled out. While linkage to 5q31 has been demonstrated, a disease-causing gene in that region has not been identified. Further haplotype analysis of six affected kindreds has demonstrated genetic heterogeneity for this rare disorder. Other studies demonstrate that some children with intractable seizures respond to pyridoxal phosphate rather than pyridoxine, including a rare form of neonatal epileptic encephalopathy shown to be due to mutations in the PNPO gene for pyridox(am)ine 5'-phosphate oxidase. While the biochemical explanation for this finding is not clear, elevated pipecolic acid levels may serve as a diagnostic marker for patients with pyridoxine-dependent seizures. SUMMARY The results of these studies should prompt clinicians to adopt new strategies for diagnosis and therapy for young patients with intractable seizures. Levels of both pipecolic acid and certain metabolites shown to be elevated in patients with PNPO mutations should be measured, and therapeutic trials of pyridoxal phosphate as well as pyridoxine should be considered early in the course of the management of infants and young children with intractable seizures.
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Affiliation(s)
- Sidney M Gospe
- Division of Pediatric Neurology, Departments of Neurology and Pediatrics, University of Washington, Seattle, WA 98105, USA.
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Gengenbacher M, Fitzpatrick TB, Raschle T, Flicker K, Sinning I, Müller S, Macheroux P, Tews I, Kappes B. Vitamin B6 biosynthesis by the malaria parasite Plasmodium falciparum: biochemical and structural insights. J Biol Chem 2005; 281:3633-41. [PMID: 16339145 DOI: 10.1074/jbc.m508696200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vitamin B6 is one of nature's most versatile cofactors. Most organisms synthesize vitamin B6 via a recently discovered pathway employing the proteins Pdx1 and Pdx2. Here we present an in-depth characterization of the respective orthologs from the malaria parasite, Plasmodium falciparum. Expression profiling of Pdx1 and -2 shows that blood-stage parasites indeed possess a functional vitamin B6 de novo biosynthesis. Recombinant Pdx1 and Pdx2 form a complex that functions as a glutamine amidotransferase with Pdx2 as the glutaminase and Pdx1 as pyridoxal-5 '-phosphate synthase domain. Complex formation is required for catalytic activity of either domain. Pdx1 forms a chimeric bi-enzyme with the bacterial YaaE, a Pdx2 ortholog, both in vivo and in vitro, although this chimera does not attain full catalytic activity, emphasizing that species-specific structural features govern the interaction between the protein partners of the PLP synthase complexes in different organisms. To gain insight into the activation mechanism of the parasite bi-enzyme complex, the three-dimensional structure of Pdx2 was determined at 1.62 A. The obstruction of the oxyanion hole indicates that Pdx2 is in a resting state and that activation occurs upon Pdx1-Pdx2 complex formation.
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Affiliation(s)
- Martin Gengenbacher
- Abteilung für Parasitologie, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany
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Current awareness on yeast. Yeast 2005; 22:919-26. [PMID: 16201058 DOI: 10.1002/yea.1167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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