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Benabdellah K, Azcón-Aguilar C, Valderas A, Speziga D, Fitzpatrick TB, Ferrol N. GintPDX1 encodes a protein involved in vitamin B6 biosynthesis that is up-regulated by oxidative stress in the arbuscular mycorrhizal fungus Glomus intraradices. THE NEW PHYTOLOGIST 2009; 184:682-693. [PMID: 19674326 DOI: 10.1111/j.1469-8137.2009.02978.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Vitamin B6 is an essential metabolite that has recently been implicated in defense against cellular oxidative stress. In fungi, the de novo biosynthetic pathway of vitamin B6 involves two genes, PDX1 and PDX2. Here, we report a component of the PDX1/PDX2 vitamin B6 biosynthetic pathway in an arbuscular mycorrhizal (AM) fungus. Using rapid amplification of cDNA ends, we isolated the full-length cDNA of a PDX-like gene, GintPDX1, from Glomus intraradices. GintPDX1 expression was analysed by real-time reverse transcription-polymerase chain reaction (RT-PCR). GintPDX1 activity and function were investigated by heterologous complementation of the yeast strainDeltasnz1, which is deficient in vitamin B6 biosynthesis. Sequence data revealed that GintPDX1 is highly homologous to other identified PDX1 proteins. GintPDX1 restores prototrophy to the vitamin B6 auxotrophic yeast mutant and reverts its superoxide sensitivity. GintPDX1 is expressed throughout the fungal life cycle, with the highest transcription levels found in the intraradical fungal structures. GintPDX1 expression was induced in response to hydrogen peroxide, paraquat and copper. The results demonstrate that AM fungi possess at least one component of the machinery necessary for vitamin B6 biosynthesis. Transcriptional regulation of GintPDX1 suggests a role for vitamin B6 as an antioxidant and modulator of reactive oxygen species in G. intraradices.
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Affiliation(s)
- Karim Benabdellah
- Estación Experimental del Zaidín, CSIC, Profesor Albareda 1, Granada 18008, Spain
| | | | - Ascensión Valderas
- Estación Experimental del Zaidín, CSIC, Profesor Albareda 1, Granada 18008, Spain
| | - Davide Speziga
- Institute of Plant Biology, University of Zurich, 8008 Zurich, Switzerland
| | | | - Nuria Ferrol
- Estación Experimental del Zaidín, CSIC, Profesor Albareda 1, Granada 18008, Spain
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Yu S, Luo L. Expression analysis of a novel pyridoxal kinase messenger RNA splice variant, PKL, in oil rape suffering abiotic stress and phytohormones. Acta Biochim Biophys Sin (Shanghai) 2008; 40:1005-14. [PMID: 19089298 DOI: 10.1111/j.1745-7270.2008.00489.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Pyridoxal kinase is key enzyme for the biosynthesis of pyridoxal 5'-phosphate, the biologically active form of vitamin B6, in the salvage pathway. A pyridoxal kinase gene, BnPKL (GenBank accession No. DQ463962), was isolated from oilseed rape (Brassica napus L.) following water stress through rapid amplification of complementary DNA (cDNA) ends. The results showed that the gene had two splice variants: PKL and PKL2. PKL, the long cDNA, encodes a 334 amino acid protein with a complete ATP-binding site, pyridoxal kinase-binding site and dimer interface site of a pyridoxal kinase, while PKL2, the short cDNA, lacked a partial domain. Southern blot showed that there were two copies in Brassica napus. The expression of BnPKL cDNA could rescue the mutant phenotype of Escherichia coli defective in pyridoxal kinase. Real-time reverse transcription-polymerase chain reaction revealed that the relative abundance of two transcripts are modulated by development and environmental stresses. Abscisic acid and NaCl were inclined to decrease PKL expression, but H2O2 and cold temperatures induced the PKL expression. In addition, the PKL expression could be transiently induced by jasmonate acid at an early stage, abscisic acid, salicylic acid and jasmonate acid enhanced the PKL expression in roots. Our results demonstrated that BnPKL was a pyridoxal kinase involved in responses to biotic and abiotic stresses.
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Affiliation(s)
- Shunwu Yu
- Shanghai Agrobiological Gene Center, Shanghai Academy of Agricultural Sciences, Germsperm Resources Division (Shanghai), National Key Laboratory of Crop Genetic Improvement, Shanghai, China
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Filamentous fungi for production of food additives and processing aids. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2008. [PMID: 18253709 DOI: 10.1007/10_2007_094] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Filamentous fungi are metabolically versatile organisms with a very wide distribution in nature. They exist in association with other species, e.g. as lichens or mycorrhiza, as pathogens of animals and plants or as free-living species. Many are regarded as nature's primary degraders because they secrete a wide variety of hydrolytic enzymes that degrade waste organic materials. Many species produce secondary metabolites such as polyketides or peptides and an increasing range of fungal species is exploited commercially as sources of enzymes and metabolites for food or pharmaceutical applications. The recent availability of fungal genome sequences has provided a major opportunity to explore and further exploit fungi as sources of enzymes and metabolites. In this review chapter we focus on the use of fungi in the production of food additives but take a largely pre-genomic, albeit a mainly molecular, view of the topic.
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Fitzpatrick TB, Amrhein N, Kappes B, Macheroux P, Tews I, Raschle T. Two independent routes of de novo vitamin B6 biosynthesis: not that different after all. Biochem J 2007; 407:1-13. [PMID: 17822383 DOI: 10.1042/bj20070765] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Vitamin B6 is well known in its biochemically active form as pyridoxal 5'-phosphate, an essential cofactor of numerous metabolic enzymes. The vitamin is also implicated in numerous human body functions ranging from modulation of hormone function to its recent discovery as a potent antioxidant. Its de novo biosynthesis occurs only in bacteria, fungi and plants, making it an essential nutrient in the human diet. Despite its paramount importance, its biosynthesis was predominantly investigated in Escherichia coli, where it is synthesized from the condensation of deoxyxylulose 5-phosphate and 4-phosphohydroxy-L-threonine catalysed by the concerted action of PdxA and PdxJ. However, it has now become clear that the majority of organisms capable of producing this vitamin do so via a different route, involving precursors from glycolysis and the pentose phosphate pathway. This alternative pathway is characterized by the presence of two genes, Pdx1 and Pdx2. Their discovery has sparked renewed interest in vitamin B6, and numerous studies have been conducted over the last few years to characterize the new biosynthesis pathway. Indeed, enormous progress has been made in defining the nature of the enzymes involved in both pathways, and important insights have been provided into their mechanisms of action. In the present review, we summarize the recent advances in our knowledge of the biosynthesis of this versatile molecule and compare the two independent routes to the biosynthesis of vitamin B6. Surprisingly, this comparison reveals that the key biosynthetic enzymes of both pathways are, in fact, very similar both structurally and mechanistically.
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Webb ME, Marquet A, Mendel RR, Rébeillé F, Smith AG. Elucidating biosynthetic pathways for vitamins and cofactors. Nat Prod Rep 2007; 24:988-1008. [PMID: 17898894 DOI: 10.1039/b703105j] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The elucidation of the pathways to the water-soluble vitamins and cofactors has provided many biochemical and chemical challenges. This is a reflection both of their complex chemical nature, and the fact that they are often made in small amounts, making detection of the enzyme activities and intermediates difficult. Here we present an orthogonal review of how these challenges have been overcome using a combination of methods, which are often ingenious. We make particular reference to some recent developments in the study of biotin, pantothenate, folate, pyridoxol, cobalamin, thiamine, riboflavin and molybdopterin biosynthesis.
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Affiliation(s)
- Michael E Webb
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, UK.
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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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Zhu J, Burgner JW, Harms E, Belitsky BR, Smith JL. A new arrangement of (beta/alpha)8 barrels in the synthase subunit of PLP synthase. J Biol Chem 2005; 280:27914-23. [PMID: 15911615 DOI: 10.1074/jbc.m503642200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pyridoxal 5'-phosphate (PLP, vitamin B6), a cofactor in many enzymatic reactions, has two distinct biosynthetic routes, which do not coexist in any organism. Two proteins, known as PdxS and PdxT, together form a PLP synthase in plants, fungi, archaea, and some eubacteria. PLP synthase is a heteromeric glutamine amidotransferase in which PdxT produces ammonia from glutamine and PdxS combines ammonia with five- and three-carbon phosphosugars to form PLP. In the 2.2-A crystal structure, PdxS is a cylindrical dodecamer of subunits having the classic (beta/alpha)8 barrel fold. PdxS subunits form two hexameric rings with the active sites positioned on the inside. The hexamer and dodecamer forms coexist in solution. A novel phosphate-binding site is suggested by bound sulfate. The sulfate and another bound molecule, methyl pentanediol, were used to model the substrate ribulose 5-phosphate, and to propose catalytic roles for residues in the active site. The distribution of conserved surfaces in the PdxS dodecamer was used to predict a docking site for the glutaminase partner, PdxT.
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Affiliation(s)
- Jianghai Zhu
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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Stolz J, Wöhrmann HJP, Vogl C. Amiloride uptake and toxicity in fission yeast are caused by the pyridoxine transporter encoded by bsu1+ (car1+). EUKARYOTIC CELL 2005; 4:319-26. [PMID: 15701794 PMCID: PMC549319 DOI: 10.1128/ec.4.2.319-326.2005] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Accepted: 11/29/2004] [Indexed: 11/20/2022]
Abstract
Amiloride, a diuretic drug that acts by inhibition of various sodium transporters, is toxic to the fission yeast Schizosaccharomyces pombe. Previous work has established that amiloride sensitivity is caused by expression of car1+, which encodes a protein with similarity to plasma membrane drug/proton antiporters from the multidrug resistance family. Here we isolated car1+ by complementation of Saccharomyces cerevisiae mutants that are deficient in pyridoxine biosynthesis and uptake. Our data show that Car1p represents a new high-affinity, plasma membrane-localized import carrier for pyridoxine, pyridoxal, and pyridoxamine. We therefore propose the gene name bsu1+ (for vitamin B6 uptake) to replace car1+. Bsu1p displays an acidic pH optimum and is inhibited by various protonophores, demonstrating that the protein works as a proton symporter. The expression of bsu1+ is associated with amiloride sensitivity and pyridoxine uptake in both S. cerevisiae and S. pombe cells. Moreover, amiloride acts as a competitor of pyridoxine uptake, demonstrating that both compounds are substrates of Bsu1p. Taken together, our data show that S. pombe and S. cerevisiae possess unrelated plasma membrane pyridoxine transporters. The S. pombe protein may be structurally related to the unknown human pyridoxine transporter, which is also inhibited by amiloride.
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Affiliation(s)
- Jürgen Stolz
- Lehrstuhl für Zellbiologie und Pflanzenphysiologie, Universität Regensburg, Universitätsstrasse 31, D-93040 Regensburg, Germany.
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Tanaka T, Tateno Y, Gojobori T. Evolution of vitamin B6 (pyridoxine) metabolism by gain and loss of genes. Mol Biol Evol 2004; 22:243-50. [PMID: 15483325 DOI: 10.1093/molbev/msi011] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Vitamin B(6) (VB6) functions as a cofactor of many diverse enzymes in amino acid metabolism. Three metabolic pathways for pyridoxal 5'-phosphate (PLP; the active form of VB6) are known: the de novo pathway, the salvage pathway, and the fungal type pathway. Most unicellular organisms and plants biosynthesize VB6 using one or two of these three biosynthetic pathways. However, animals such as insects and mammals do not possess any of the pathways and, thus, need to intake VB6 in their diet to survive. It is conceivable that breakdowns of these pathways occurred in the evolutionary lineages of insects and mammals, and one of the major reasons for this would be the loss of pertinent genes. We studied the evolution of VB6 biosynthesis from the view of the gain and loss of 10 pertinent genes in 122 species whose genome sequences were completely determined. The results revealed that each gene in the pathways was lost more than once in the entire evolutionary lineages of the 122 species. We also found the following three points regarding the evolution of PLP biosynthesis: (1) the breakdown of the PLP biosynthetic pathways occurred independently at least three times in animal lineages, (2) the de novo pathway was formed by the generation of pdxB in gamma-proteobacteria, and (3) the order of the gene loss in VB6 metabolism was conserved among different evolutionary lineages. These results suggest that the evolution of VB6 metabolism was subject to gains and frequent losses of related genes in the 122 species examined. This dynamic nature of the evolutionary changes must have been responsible for the breakdowns of the pathways, resulting in profound differentiation of heterotrophy among the species.
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Affiliation(s)
- Tsuyoshi Tanaka
- Center for Information Biology and DNA Data Bank of Japan, National Institute of Genetics, Mishima, Japan
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Borkovich KA, Alex LA, Yarden O, Freitag M, Turner GE, Read ND, Seiler S, Bell-Pedersen D, Paietta J, Plesofsky N, Plamann M, Goodrich-Tanrikulu M, Schulte U, Mannhaupt G, Nargang FE, Radford A, Selitrennikoff C, Galagan JE, Dunlap JC, Loros JJ, Catcheside D, Inoue H, Aramayo R, Polymenis M, Selker EU, Sachs MS, Marzluf GA, Paulsen I, Davis R, Ebbole DJ, Zelter A, Kalkman ER, O'Rourke R, Bowring F, Yeadon J, Ishii C, Suzuki K, Sakai W, Pratt R. Lessons from the genome sequence of Neurospora crassa: tracing the path from genomic blueprint to multicellular organism. Microbiol Mol Biol Rev 2004; 68:1-108. [PMID: 15007097 PMCID: PMC362109 DOI: 10.1128/mmbr.68.1.1-108.2004] [Citation(s) in RCA: 434] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We present an analysis of over 1,100 of the approximately 10,000 predicted proteins encoded by the genome sequence of the filamentous fungus Neurospora crassa. Seven major areas of Neurospora genomics and biology are covered. First, the basic features of the genome, including the automated assembly, gene calls, and global gene analyses are summarized. The second section covers components of the centromere and kinetochore complexes, chromatin assembly and modification, and transcription and translation initiation factors. The third area discusses genome defense mechanisms, including repeat induced point mutation, quelling and meiotic silencing, and DNA repair and recombination. In the fourth section, topics relevant to metabolism and transport include extracellular digestion; membrane transporters; aspects of carbon, sulfur, nitrogen, and lipid metabolism; the mitochondrion and energy metabolism; the proteasome; and protein glycosylation, secretion, and endocytosis. Environmental sensing is the focus of the fifth section with a treatment of two-component systems; GTP-binding proteins; mitogen-activated protein, p21-activated, and germinal center kinases; calcium signaling; protein phosphatases; photobiology; circadian rhythms; and heat shock and stress responses. The sixth area of analysis is growth and development; it encompasses cell wall synthesis, proteins important for hyphal polarity, cytoskeletal components, the cyclin/cyclin-dependent kinase machinery, macroconidiation, meiosis, and the sexual cycle. The seventh section covers topics relevant to animal and plant pathogenesis and human disease. The results demonstrate that a large proportion of Neurospora genes do not have homologues in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe. The group of unshared genes includes potential new targets for antifungals as well as loci implicated in human and plant physiology and disease.
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Affiliation(s)
- Katherine A Borkovich
- Department of Plant Pathology, University of California, Riverside, California 92521, USA. Katherine/
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Luo ZW, Zhang RM, Kearsey MJ. Theoretical basis for genetic linkage analysis in autotetraploid species. Proc Natl Acad Sci U S A 2004; 101:7040-5. [PMID: 15100415 PMCID: PMC406462 DOI: 10.1073/pnas.0304482101] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2003] [Accepted: 03/15/2004] [Indexed: 11/18/2022] Open
Abstract
Linkage analysis in autotetraploid species has been an historical challenge in quantitative genetics theory and is a stumbling block that urgently needs to be removed in the rapidly emerging genome research on this species, such as cultivated potato. This article presents theory of a full model of tetrasomic linkage and develops a statistical framework for the linkage analysis. The model considers both double reduction and recombination, the most essential features of tetrasomic inheritance with linked loci, whereas the statistical method takes appropriate account of the major complexities in analyzing both dominant and codominant molecular marker data during map reconstruction in tetraploid species. These complexities include the problems arising from multiple dosage of allelic inheritance, the null allele, allelic segregation distortion, mixed bivalent and quadrivalent pairing in meiosis, and incomplete information of marker phenotype data. The theoretical analysis established the relationship between the coefficients of double reduction at linked loci, which is essential in the present tetrasomic linkage analysis and in assessing the impact of double reduction on the evolution of tetraploid populations. The statistical method, based on the combination of theoretical analysis and a computer-based algorithm, provided analytical tools for predicting the maximum-likelihood estimates of the model parameters. A simulation study showed the feasibility of a practical implementation of the method, detailed the procedure of the analysis, validated the power and reliability in the parameter estimation, and compared the present method with those proposed in the current literature.
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Affiliation(s)
- Z W Luo
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom.
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Belitsky BR. Physical and enzymological interaction of Bacillus subtilis proteins required for de novo pyridoxal 5'-phosphate biosynthesis. J Bacteriol 2004; 186:1191-6. [PMID: 14762015 PMCID: PMC344226 DOI: 10.1128/jb.186.4.1191-1196.2004] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus subtilis synthesizes pyridoxal 5'-phosphate, the active form of vitamin B(6), by a poorly characterized pathway involving the yaaD and yaaE genes. The pdxS (yaaD) mutant was confirmed to be a strict B(6) auxotroph, but the pdxT (yaaE) mutant turned out to be a conditional auxotroph depending on the availability of ammonium in the growth medium. The PdxS and PdxT proteins copurified during affinity chromatography and apparently form a complex that has glutaminase activity. PdxS and PdxT appear to encode the synthase and glutaminase subunits, respectively, of a glutamine amidotransferase of as-yet-unknown specificity essential for B(6) biosynthesis.
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Affiliation(s)
- Boris R Belitsky
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
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Abstract
This chapter describes the metabolic pathways for Neurospora crassa in the biosynthesis of amino acids, purines, pyrimidines, vitamins, and cofactors, and for glycolysis, the TCA and glyoxylate cycles and the initial stages of the pentose phosphate pathway. For each step in metabolism, the gene or genes within the genome sequence of the species is identified, correlations are made with previously identified genes, and new gene designations are assigned to others. For each gene, details given are the function of the gene product, contig location, comparison of the genetic and physical map location, Saccharomyces cerevisiae homolog, and perhaps others, and the level of similarity.
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Affiliation(s)
- Alan Radford
- School of Biology, University of Leeds, Leeds LS2 9JT, England, UK
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Bauer JA, Bennett EM, Begley TP, Ealick SE. Three-dimensional structure of YaaE from Bacillus subtilis, a glutaminase implicated in pyridoxal-5'-phosphate biosynthesis. J Biol Chem 2003; 279:2704-11. [PMID: 14585832 DOI: 10.1074/jbc.m310311200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The structure of YaaE from Bacillus subtilis was determined at 2.5-A resolution. YaaE is a member of the triad glutamine aminotransferase family and functions in a recently identified alternate pathway for the biosynthesis of vitamin B(6). Proposed active residues include conserved Cys-79, His-170, and Glu-172. YaaE shows similarity to HisH, a glutaminase involved in histidine biosynthesis. YaaD associates with YaaE. A homology model of this protein was constructed. YaaD is predicted to be a (beta/alpha)(8) barrel on the basis of sequence comparisons. The predicted active site includes highly conserved residues 211-216 and 233-235. Finally, a homology model of a putative YaaD-YaaE complex was prepared using the structure of HisH-F as a model. This model predicts that the ammonia molecule generated by YaaE is channeled through the center of the YaaD barrel to the putative YaaD active site.
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Affiliation(s)
- Jacob A Bauer
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, USA
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Stolz J, Vielreicher M. Tpn1p, the plasma membrane vitamin B6 transporter of Saccharomyces cerevisiae. J Biol Chem 2003; 278:18990-6. [PMID: 12649274 DOI: 10.1074/jbc.m300949200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pyridoxine (PN) is a metabolic precursor of pyridoxal phosphate that functions as a cofactor of many enzymes in amino acid metabolism. PN, pyridoxal, and pyridoxamine are collectively referred to as vitamin B6, and mammalian organisms depend on its uptake from the diet. In addition to the ability to use extracellular vitamin B6, most unicellular organisms are also capable of synthesizing PN to generate pyridoxal phosphate. Here, we report the isolation of Saccharomyces cerevisiae mutants that have lost the ability to transport PN across the plasma membrane. We used these mutants to isolate TPN1, the first known gene encoding a transport protein for vitamin B6. Tpn1p is a member of the purine-cytosine permease family within the major facilitator superfamily. The protein functions as a proton symporter, localizes to the plasma membrane, and has high affinity for PN. TPN1 mutants lost the ability to utilize extracellular PN, pyridoxal, and pyridoxamine, showing that there is no other transporter for vitamin B6 encoded in the genome. Amino acid substitutions that led to a loss of Tpn1p function localized to transmembrane domain 4 within the 12-transmembrane domain protein. Moreover, expression of TPN1 was regulated and increased with decreasing concentrations of vitamin B6 in the medium. We also provide evidence that of the highly conserved SNZ and SNO genes in S. cerevisiae, only the protein encoded by SNZ1 is required for vitamin B6 biosynthesis.
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Affiliation(s)
- Jürgen Stolz
- Lehrstuhl für Zellbiologie und Pflanzenphysiologie, Universität Regensburg, Universitätsstrasse 31, D-93040 Regensburg, Germany.
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Zeke T, Kókai E, Szöor B, Yatzkan E, Yarden O, Szirák K, Fehér Z, Bagossi P, Gergely P, Dombrádi V. Expression of protein phosphatase 1 during the asexual development of Neurospora crassa. Comp Biochem Physiol B Biochem Mol Biol 2003; 134:161-70. [PMID: 12524044 DOI: 10.1016/s1096-4959(02)00188-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We cloned and sequenced the cDNA and the gene encoding the catalytic subunit of protein phosphatase 1 from the filamentous fungus Neurospora crassa. The gene, designated ppp-1 (phosphoprotein phosphatase 1), was mapped by restriction fragment length polymorphism to linkage group III, in the vicinity of con-7 and trp-1. The expression of the gene was monitored by reverse transcriptase and polymerase chain reactions, by Western blotting, and by protein phosphatase activity assays in synchronized cultures. Transcripts of ppp-1 were detected in the dormant conidia. The abundance of ppp-1 mRNA, Ppp-1 protein, and the activity of protein phosphatase 1 increased during germination and subsequent hyphal elongation as well as during the early stages of aerial mycelium formation.
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Affiliation(s)
- Tamás Zeke
- Department of Medical Chemistry, Medical and Health Sciences Center, University of Debrecen, H-4026 Debrecen, Hungary
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Dettman JR, Jacobson DJ, Taylor JW. A MULTILOCUS GENEALOGICAL APPROACH TO PHYLOGENETIC SPECIES RECOGNITION IN THE MODEL EUKARYOTE NEUROSPORA. Evolution 2003. [DOI: 10.1554/03-073] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Abstract
Eukaryotic cell proliferation is controlled by specific growth factors and the availability of essential nutrients. If either of these signals is lacking, cells may enter into a specialized nondividing resting state, known as stationary phase or G(0). The entry into such resting states is typically accompanied by a dramatic decrease in the overall growth rate and an increased resistance to a variety of environmental stresses. Since most cells spend most of their life in these quiescent states, it is important that we develop a full understanding of the biology of the stationary phase/G(0) cell. This knowledge would provide important insights into the control of two of the most fundamental aspects of eukaryotic cell biology: cell proliferation and long-term cell survival. This review will discuss some recent advances in our understanding of the stationary phase of growth in the budding yeast, Saccharomyces cerevisiae.
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Affiliation(s)
- Paul K Herman
- Department of Molecular Genetics, The Ohio State University, 484 West Twelfth Avenue, Room 984, Columbus, Ohio 43210, USA.
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Rodríguez-Navarro S, Llorente B, Rodríguez-Manzaneque MT, Ramne A, Uber G, Marchesan D, Dujon B, Herrero E, Sunnerhagen P, Pérez-Ortín JE. Functional analysis of yeast gene families involved in metabolism of vitamins B1and B6. Yeast 2002; 19:1261-76. [PMID: 12271461 DOI: 10.1002/yea.916] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In order to clarify their physiological functions, we have undertaken a characterization of the three-membered gene families SNZ1-3 and SNO1-3. In media lacking vitamin B(6), SNZ1 and SNO1 were both required for growth in certain conditions, but neither SNZ2, SNZ3, SNO2 nor SNO3 were required. Copies 2 and 3 of the gene products have, in spite of their extremely close sequence similarity, slightly different functions in the cell. We have also found that copies 2 and 3 are activated by the lack of thiamine and that the Snz proteins physically interact with the thiamine biosynthesis Thi5 protein family. Whereas copy 1 is required for conditions in which B(6) is essential for growth, copies 2 and 3 seem more related with B(1) biosynthesis during the exponential phase.
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Affiliation(s)
- Susana Rodríguez-Navarro
- Departamento de Bioquímica y Biología Molecular, Universitat de València, C/Dr Moliner 50, E-46100, Burjassot, Spain
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Hamer L, Pan H, Adachi K, Orbach MJ, Page A, Ramamurthy L, Woessner JP. Regions of microsynteny in Magnaporthe grisea and Neurospora crassa. Fungal Genet Biol 2001; 33:137-43. [PMID: 11456466 DOI: 10.1006/fgbi.2001.1286] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A bacterial artificial chromosome (BAC) clone containing 110,467 bp of genomic DNA from Magnaporthe grisea was sequenced, annotated, and compared to the genomes of Neurospora crassa, Candida albicans, and Saccharomyces cerevisiae. Twenty-six open reading frames (ORFs), involved in multiple biochemical pathways, were identified in the BAC sequence. A region of 53 kb, containing 18 of the 26 ORFs, was found to be syntenic to a portion of the N. crassa genome. Subregions of complete colinearity as well as interrupted colinearity were present. No synteny was evident with either C. albicans or S. cerevisiae. The identification of syntenic regions containing highly conserved genes across two genera that have been evolutionarily separated for approximately 200 million years elicits many biological questions as to the function and identity of these genes.
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Affiliation(s)
- L Hamer
- Paradigm Genetics, Inc., 108 Alexander Drive, Research Triangle Park, NC 27709, USA.
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Ehrenshaft M, Daub ME. Isolation of PDX2, a second novel gene in the pyridoxine biosynthesis pathway of eukaryotes, archaebacteria, and a subset of eubacteria. J Bacteriol 2001; 183:3383-90. [PMID: 11344146 PMCID: PMC99636 DOI: 10.1128/jb.183.11.3383-3390.2001] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
In this paper we describe the isolation of a second gene in the newly identified pyridoxine biosynthesis pathway of archaebacteria, some eubacteria, fungi, and plants. Although pyridoxine biosynthesis has been thoroughly examined in Escherichia coli, recent characterization of the Cercospora nicotianae biosynthesis gene PDX1 led to the discovery that most organisms contain a pyridoxine synthesis gene not found in E. coli. PDX2 was isolated by a degenerate primer strategy based on conserved sequences of a gene specific to PDX1-containing organisms. The role of PDX2 in pyridoxine biosynthesis was confirmed by complementation of two C. nicotianae pyridoxine auxotrophs not mutant in PDX1. Also, targeted gene replacement of PDX2 in C. nicotianae results in pyridoxine auxotrophy. Comparable to PDX1, PDX2 homologues are not found in any of the organisms with homologues to the E. coli pyridoxine genes, but are found in the same archaebacteria, eubacteria, fungi, and plants that contain PDX1 homologues. PDX2 proteins are less well conserved than their PDX1 counterparts but contain several protein motifs that are conserved throughout all PDX2 proteins.
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Affiliation(s)
- M Ehrenshaft
- Department of Plant Pathology, North Carolina State University, Raleigh, NC 27695, USA.
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Kelkar HS, Griffith J, Case ME, Covert SF, Hall RD, Keith CH, Oliver JS, Orbach MJ, Sachs MS, Wagner JR, Weise MJ, Wunderlich JK, Arnold J. The Neurospora crassa genome: cosmid libraries sorted by chromosome. Genetics 2001; 157:979-90. [PMID: 11238388 PMCID: PMC1461552 DOI: 10.1093/genetics/157.3.979] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A Neurospora crassa cosmid library of 12,000 clones (at least nine genome equivalents) has been created using an improved cosmid vector pLorist6Xh, which contains a bacteriophage lambda origin of replication for low-copy-number replication in bacteria and the hygromycin phosphotransferase marker for direct selection in fungi. The electrophoretic karyotype of the seven chromosomes comprising the 42.9-Mb N. crassa genome was resolved using two translocation strains. Using gel-purified chromosomal DNAs as probes against the new cosmid library and the commonly used medium-copy-number pMOcosX N. crassa cosmid library in two independent screenings, the cosmids were assigned to chromosomes. Assignments of cosmids to linkage groups on the basis of the genetic map vs. the electrophoretic karyotype are 93 +/- 3% concordant. The size of each chromosome-specific subcollection of cosmids was found to be linearly proportional to the size of the particular chromosome. Sequencing of an entire cosmid containing the qa gene cluster indicated a gene density of 1 gene per 4 kbp; by extrapolation, 11,000 genes would be expected to be present in the N. crassa genome. By hybridizing 79 nonoverlapping cosmids with an average insert size of 34 kbp against cDNA arrays, the density of previously characterized expressed sequence tags (ESTs) was found to be slightly <1 per cosmid (i.e., 1 per 40 kbp), and most cosmids, on average, contained an identified N. crassa gene sequence as a starting point for gene identification.
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Affiliation(s)
- H S Kelkar
- Department of Genetics, University of Georgia, Athens, Georgia 30602, USA
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