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L-Carnitine in Drosophila: A Review. Antioxidants (Basel) 2020; 9:antiox9121310. [PMID: 33371457 PMCID: PMC7767417 DOI: 10.3390/antiox9121310] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 12/12/2022] Open
Abstract
L-Carnitine is an amino acid derivative that plays a key role in the metabolism of fatty acids, including the shuttling of long-chain fatty acyl CoA to fuel mitochondrial β-oxidation. In addition, L-carnitine reduces oxidative damage and plays an essential role in the maintenance of cellular energy homeostasis. L-carnitine also plays an essential role in the control of cerebral functions, and the aberrant regulation of genes involved in carnitine biosynthesis and mitochondrial carnitine transport in Drosophila models has been linked to neurodegeneration. Drosophila models of neurodegenerative diseases provide a powerful platform to both unravel the molecular pathways that contribute to neurodegeneration and identify potential therapeutic targets. Drosophila can biosynthesize L-carnitine, and its carnitine transport system is similar to the human transport system; moreover, evidence from a defective Drosophila mutant for one of the carnitine shuttle genes supports the hypothesis of the occurrence of β-oxidation in glial cells. Hence, Drosophila models could advance the understanding of the links between L-carnitine and the development of neurodegenerative disorders. This review summarizes the current knowledge on L-carnitine in Drosophila and discusses the role of the L-carnitine pathway in fly models of neurodegeneration.
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Kazaks A, Makrecka-Kuka M, Kuka J, Voronkova T, Akopjana I, Grinberga S, Pugovics O, Tars K. Expression and purification of active, stabilized trimethyllysine hydroxylase. Protein Expr Purif 2014; 104:1-6. [PMID: 25220864 DOI: 10.1016/j.pep.2014.09.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 09/01/2014] [Accepted: 09/03/2014] [Indexed: 11/24/2022]
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Distinguishing between genotoxic and non-genotoxic hepatocarcinogens by gene expression profiling and bioinformatic pathway analysis. Sci Rep 2013; 3:2783. [PMID: 24089152 PMCID: PMC6505678 DOI: 10.1038/srep02783] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 09/06/2013] [Indexed: 01/09/2023] Open
Abstract
A rapid and sensitive method to determine the characteristics of carcinogens is needed. In this study, we used a microarray-based genomics approach, with a short-term in vivo model, in combination with insights from statistical and mechanistic analyses to determine the characteristics of carcinogens. Carcinogens were evaluated based on the different mechanisms involved in the responses to genotoxic carcinogens and non-genotoxic carcinogens. Gene profiling was performed at two time points after treatment with six training and four test carcinogens. We mapped the DEG (differentially expressed gene)-related pathways to analyze cellular processes, and we discovered significant mechanisms that involve critical cellular components. Classification results were further supported by Comet and Micronucleus assays. Mechanistic studies based on gene expression profiling enhanced our understanding of the characteristics of different carcinogens. Moreover, the efficiency of this study was demonstrated by the short-term nature of the animal experiments that were conducted.
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Ngamskulrungroj P, Chang Y, Roh J, Kwon-Chung KJ. Differences in nitrogen metabolism between Cryptococcus neoformans and C. gattii, the two etiologic agents of cryptococcosis. PLoS One 2012; 7:e34258. [PMID: 22479580 PMCID: PMC3313984 DOI: 10.1371/journal.pone.0034258] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 02/24/2012] [Indexed: 12/23/2022] Open
Abstract
Two members of the Cryptococcus neoformans-gattii species complex, the etiologic agents of cryptococcosis, can be differentiated by biological, biochemical, serological and molecular typing techniques. Based on their differences in carbon and nitrogen utilization patterns, cost effective and very specific diagnostic tests using D-proline and canvanine-glycine-bromthymol blue (CGB) media have been formulated and are widely used for identification of the two species. However, these methods have yet to be tested for strains with confirmed molecular types to assess the degree of specificity for each molecular type in the two species. We collected global isolates of every major molecular type available and tested their patterns of nitrogen utilization. We confirmed specificity of the CGB test to be 100% regardless of molecular type while the D-proline test yielded 8–38% false negative results in three of the four C. gattii molecular types, VGI–VGIII. The utilization pattern of a new set of amino acids: D-alanine, L-tryptophan and L-phenylalanine, showed species specificity comparable to that of D-proline. We discovered that the transcription factor Gat1 (Are1) regulates the utilization of nitrogen differently between C. neoformans and C. gattii strains. Unlike in C. neoformans, expression of the genes encoding glycine decarboxylase complex in C. gatti was only partially suppressed by nitrogen catabolite repression in the presence of ammonium. GAT1 in C. neoformans controlled the induction of three of the four genes encoding the glycine decarboxylase complex when glycine was used as the sole nitrogen source while in C. gattii its regulation of these genes was less stringent. Moreover, while virulence of C. neoformans strains in mice was not affected by Gat1, the transcription factor positively influenced the virulence of C. gattii strain.
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Affiliation(s)
- Popchai Ngamskulrungroj
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- Department of Microbiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Yun Chang
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Jamin Roh
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Kyung J. Kwon-Chung
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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Serine hydroxymethyltransferase: A model enzyme for mechanistic, structural, and evolutionary studies. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:1489-96. [DOI: 10.1016/j.bbapap.2010.10.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Revised: 10/25/2010] [Accepted: 10/29/2010] [Indexed: 11/18/2022]
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Zheng C, Choquer M, Zhang B, Ge H, Hu S, Ma H, Chen S. LongSAGE gene-expression profiling of Botrytis cinerea germination suppressed by resveratrol, the major grapevine phytoalexin. Fungal Biol 2011; 115:815-32. [PMID: 21872179 DOI: 10.1016/j.funbio.2011.06.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 06/13/2011] [Accepted: 06/15/2011] [Indexed: 12/11/2022]
Abstract
The ascomycetes Botrytis cinerea is one of the most studied necrotrophic phytopathogens and one of the main fungal parasites of grapevine. As a defense mechanism, grapevine produces a phytoalexin compound, resveratrol, which inhibits germination of the fungal conidium before it can penetrate the plant barriers and lead to host cell necrotrophy. To elucidate the effect of resveratrol on transcriptional regulation in B. cinerea germlings, two LongSAGE (long serial analysis of gene expression) libraries were generated in vitro for gene-expression profiling: 41 428 tags and among them, 15 665 unitags were obtained from resveratrol-treated B. cinerea germlings and 41 358 tags, among them, 16 362 unitags were obtained from non-treated B. cinerea germlings. In-silico analysis showed that about half of these unitags match known genes in the complete B. cinerea genome sequence. Comparison of unitag frequencies between libraries highlighted 110 genes that were transcriptionally regulated in the presence of resveratrol: 53 and 57 genes were significantly down- and upregulated, respectively. Manual curation of their putative functional categories showed that primary metabolism of germinating conidia appears to be markedly affected under resveratrol treatment, along with changes in other putative metabolic pathways, such as resveratrol detoxification and virulence-effector secretion, in B. cinerea germlings. We propose a hypothetical model of cross talk between B. cinerea germinating conidia and resveratrol-producing grapevine at the very early steps of infection.
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Affiliation(s)
- Chuanlin Zheng
- College of Agriculture and Biotechnology, China Agricultural University, Beijing
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Chooi YH, Cacho R, Tang Y. Identification of the viridicatumtoxin and griseofulvin gene clusters from Penicillium aethiopicum. ACTA ACUST UNITED AC 2010; 17:483-94. [PMID: 20534346 DOI: 10.1016/j.chembiol.2010.03.015] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 03/26/2010] [Accepted: 03/30/2010] [Indexed: 10/19/2022]
Abstract
Penicillium aethiopicum produces two structurally interesting and biologically active polyketides: the tetracycline-like viridicatumtoxin 1 and the classic antifungal agent griseofulvin 2. Here, we report the concurrent discovery of the two corresponding biosynthetic gene clusters (vrt and gsf) by 454 shotgun sequencing. Gene deletions confirmed that two nonreducing PKSs (NRPKSs), vrtA and gsfA, are required for the biosynthesis of 1 and 2, respectively. Both PKSs share similar domain architectures and lack a C-terminal thioesterase domain. We identified gsfI as the chlorinase involved in the biosynthesis of 2, because deletion of gsfI resulted in the accumulation of decholorogriseofulvin 3. Comparative analysis with the P. chrysogenum genome revealed that both clusters are embedded within conserved syntenic regions of P. aethiopicum chromosomes. Discovery of the vrt and gsf clusters provided the basis for genetic and biochemical studies of the pathways.
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Affiliation(s)
- Yit-Heng Chooi
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
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Abstract
The water-soluble zwitterion carnitine is an essential metabolite in eukaryotes required for fatty acid oxidation as it functions as a carrier during transfer of activated acyl and acetyl groups across intracellular membranes. Most eukaryotes are able to synthesize carnitine endogenously, besides their capacity to take up carnitine from the diet or extracellular medium through plasma membrane transporters. This review discusses the current knowledge on carnitine homeostasis with special emphasis on the enzymology of the four steps of the carnitine biosynthesis pathway.
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Affiliation(s)
- Karin Strijbis
- Department of Medical Biochemistry, Academic Medical Center, Amsterdam, The Netherlands
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Strijbis K, Van Roermund CWT, Hardy GP, Van den Burg J, Bloem K, Haan J, Van Vlies N, Wanders RJA, Vaz FM, Distel B. Identification and characterization of a complete carnitine biosynthesis pathway in
Candida albicans. FASEB J 2009; 23:2349-59. [DOI: 10.1096/fj.08-127985] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Karin Strijbis
- Department of Medical BiochemistryAcademic Medical CenterUniversity of AmsterdamAmsterdamThe Netherlands
| | - Carlo W. T. Van Roermund
- Department of Genetic Metabolic DiseasesAcademic Medical CenterUniversity of AmsterdamAmsterdamThe Netherlands
| | - Guy P. Hardy
- Department of Medical BiochemistryAcademic Medical CenterUniversity of AmsterdamAmsterdamThe Netherlands
| | - Janny Van den Burg
- Department of Medical BiochemistryAcademic Medical CenterUniversity of AmsterdamAmsterdamThe Netherlands
| | - Karien Bloem
- Department of Medical BiochemistryAcademic Medical CenterUniversity of AmsterdamAmsterdamThe Netherlands
| | - Jolanda Haan
- Department of Medical BiochemistryAcademic Medical CenterUniversity of AmsterdamAmsterdamThe Netherlands
| | - Naomi Van Vlies
- Department of Genetic Metabolic DiseasesAcademic Medical CenterUniversity of AmsterdamAmsterdamThe Netherlands
| | - Ronald J. A. Wanders
- Department of Genetic Metabolic DiseasesAcademic Medical CenterUniversity of AmsterdamAmsterdamThe Netherlands
| | - Frédéric M. Vaz
- Department of Genetic Metabolic DiseasesAcademic Medical CenterUniversity of AmsterdamAmsterdamThe Netherlands
| | - Ben Distel
- Department of Medical BiochemistryAcademic Medical CenterUniversity of AmsterdamAmsterdamThe Netherlands
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Misono H, Maeda H, Tuda K, Ueshima S, Miyazaki N, Nagata S. Characterization of an inducible phenylserine aldolase from Pseudomonas putida 24-1. Appl Environ Microbiol 2005; 71:4602-9. [PMID: 16085854 PMCID: PMC1183316 DOI: 10.1128/aem.71.8.4602-4609.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An inducible phenylserine aldolase (L-threo-3-phenylserine benzaldehyde-lyase, EC 4.1.2.26), which catalyzes the cleavage of L-3-phenylserine to yield benzaldehyde and glycine, was purified to homogeneity from a crude extract of Pseudomonas putida 24-1 isolated from soil. The enzyme was a hexamer with the apparent subunit molecular mass of 38 kDa and contained 0.7 mol of pyridoxal 5' phosphate per mol of the subunit. The enzyme exhibited absorption maxima at 280 and 420 nm. The maximal activity was obtained at about pH 8.5. The enzyme acted on L-threo-3-phenylserine (Km, 1.3 mM), l-erythro-3-phenylserine (Km, 4.6 mM), l-threonine (Km, 29 mM), and L-allo-threonine (Km, 22 mM). In the reverse reaction, threo- and erythro- forms of L-3-phenylserine were produced from benzaldehyde and glycine. The optimum pH for the reverse reaction was 7.5. The structural gene coding for the phenylserine aldolase from Pseudomonas putida 24-1 was cloned and overexpressed in Escherichia coli cells. The nucleotide sequence of the phenylserine aldolase gene encoded a peptide containing 357 amino acids with a calculated molecular mass of 37.4 kDa. The recombinant enzyme was purified and characterized. Site-directed mutagenesis experiments showed that replacement of K213 with Q resulted in a loss of the enzyme activity, with a disappearance of the absorption maximum at 420 nm. Thus, K213 of the enzyme probably functions as an essential catalytic residue, forming a Schiff base with pyridoxal 5'-phosphate.
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Affiliation(s)
- Haruo Misono
- Department of Bioresources Science, Kochi University, Nankoku, Kochi 783-8502, Japan.
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Edgar AJ. Mice have a transcribed L-threonine aldolase/GLY1 gene, but the human GLY1 gene is a non-processed pseudogene. BMC Genomics 2005; 6:32. [PMID: 15757516 PMCID: PMC555945 DOI: 10.1186/1471-2164-6-32] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2004] [Accepted: 03/09/2005] [Indexed: 11/24/2022] Open
Abstract
Background There are three pathways of L-threonine catabolism. The enzyme L-threonine aldolase (TA) has been shown to catalyse the conversion of L-threonine to yield glycine and acetaldehyde in bacteria, fungi and plants. Low levels of TA enzymatic activity have been found in vertebrates. It has been suggested that any detectable activity is due to serine hydroxymethyltransferase and that mammals lack a genuine threonine aldolase. Results The 7-exon murine L-threonine aldolase gene (GLY1) is located on chromosome 11, spanning 5.6 kb. The cDNA encodes a 400-residue protein. The protein has 81% similarity with the bacterium Thermotoga maritima TA. Almost all known functional residues are conserved between the two proteins including Lys242 that forms a Schiff-base with the cofactor, pyridoxal-5'-phosphate. The human TA gene is located at 17q25. It contains two single nucleotide deletions, in exons 4 and 7, which cause frame-shifts and a premature in-frame stop codon towards the carboxy-terminal. Expression of human TA mRNA was undetectable by RT-PCR. In mice, TA mRNA was found at low levels in a range of adult tissues, being highest in prostate, heart and liver. In contrast, serine/threonine dehydratase, another enzyme that catabolises L-threonine, is expressed very highly only in the liver. Serine dehydratase-like 1, also was most abundant in the liver. In whole mouse embryos TA mRNA expression was low prior to E-15 increasing more than four-fold by E-17. Conclusion Mice, the western-clawed frog and the zebrafish have transcribed threonine aldolase/GLY1 genes, but the human homolog is a non-transcribed pseudogene. Serine dehydratase-like 1 is a putative L-threonine catabolising enzyme.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Chromosome Mapping
- Cloning, Molecular
- Codon, Terminator
- Computational Biology
- Crystallography, X-Ray
- DNA, Complementary/metabolism
- Embryo, Mammalian/metabolism
- Exons
- Gene Deletion
- Gene Expression Regulation, Developmental
- Glycine Hydroxymethyltransferase/genetics
- Glycine Hydroxymethyltransferase/metabolism
- Humans
- Liver/metabolism
- Lysine/chemistry
- Mice
- Molecular Sequence Data
- Open Reading Frames
- Protein Structure, Tertiary
- Pseudogenes
- Pyridoxal Phosphate/chemistry
- RNA, Messenger/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Homology, Amino Acid
- Species Specificity
- Time Factors
- Tissue Distribution
- Transcription, Genetic
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Affiliation(s)
- Alasdair J Edgar
- Department of Craniofacial Development, King's College, London, UK.
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Selmecki A, Bergmann S, Berman J. Comparative genome hybridization reveals widespread aneuploidy in Candida albicans laboratory strains. Mol Microbiol 2005; 55:1553-65. [PMID: 15720560 DOI: 10.1111/j.1365-2958.2005.04492.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Clinical strains of Candida albicans are highly tolerant of aneuploidies and other genome rearrangements. We have used comparative genome hybridization (CGH), in an array format, to analyse the copy number of over 6000 open reading frames (ORFs) in the genomic DNA of C. albicans laboratory strains carrying one (CAI-4) to three (BWP17) auxotrophies. We find that during disruption of the HIS1 locus all genes telomeric to HIS1 were deleted and telomeric repeats were added to a 9 nt sequence within the transforming DNA. This deletion occurred in approximately 10% of transformants analysed and was stably maintained through two additional rounds of transformation and counterselection of the transformation marker. In one example, the deletion was repaired, apparently via break-induced replication. Furthermore, all CAI-4 strains tested were trisomic for chromosome 2 although this trisomy appears to be unstable, as it is not detected in strains subsequently derived from CAI-4. Our data indicate CGH arrays can be used to detect monosomies and trisomies, to predict the sites of chromosome breaks, and to identify chromosomal aberrations that have not been detected with other approaches in C. albicans strains. Furthermore, they highlight the high level of genome instability in C. albicans laboratory strains exposed to the stress of transformation and counterselection on 5-fluoro-orotic acid.
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Affiliation(s)
- Anna Selmecki
- Department of Genetics, Cell Biology and Development, University of Minnesota, MN, USA
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Chen X, Magee BB, Dawson D, Magee PT, Kumamoto CA. Chromosome 1 trisomy compromises the virulence of Candida albicans. Mol Microbiol 2004; 51:551-65. [PMID: 14756793 DOI: 10.1046/j.1365-2958.2003.03852.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Although increases in chromosome copy number typically have devastating developmental consequences in mammals, fungal cells such as Saccharomyces cerevisiae seem to tolerate trisomies without obvious impairment of growth. Here, we demonstrate that two commonly used laboratory strains of the yeast Candida albicans, CAI-4 and SGY-243, can carry three copies of chromosome 1. Although the trisomic strains grow well in the laboratory, Ura+ derivatives of CAI-4, carrying three copies of chromosome 1, are avirulent in the intravenously inoculated mouse model, unlike closely related strains carrying two copies of chromosome 1. Furthermore, changes in chromosome copy number occur during growth in an animal host and during growth in the presence of growth-inhibiting drugs. These results suggest that chromosome copy number variation provides a mechanism for genetic variation in this asexual organism.
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Affiliation(s)
- Xi Chen
- Department of Molecular Biology and Microbiology and Genetics Program, Tufts University School of Medicine, 136 Harrison Ave., Boston, MA 02111, USA
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Schlüpen C, Santos MA, Weber U, de Graaf A, Revuelta JL, Stahmann KP. Disruption of the SHM2 gene, encoding one of two serine hydroxymethyltransferase isoenzymes, reduces the flux from glycine to serine in Ashbya gossypii. Biochem J 2003; 369:263-73. [PMID: 12350229 PMCID: PMC1223077 DOI: 10.1042/bj20021224] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2002] [Revised: 09/23/2002] [Accepted: 09/26/2002] [Indexed: 11/17/2022]
Abstract
Riboflavin overproduction in the ascomycete Ashbya gossypii is limited by glycine, a precursor of purine biosynthesis, and therefore an indicator of glycine metabolism. Disruption of the SHM 2 gene, encoding a serine hydroxymethyltransferase, resulted in a significant increase in riboflavin productivity. Determination of the enzyme's specific activity revealed a reduction from 3 m-units/mg of protein to 0.5 m-unit/mg protein. The remaining activity was due to an isoenzyme encoded by SHM 1, which is probably mitochondrial. A hypothesis proposed to account for the enhanced riboflavin overproduction of SHM 2-disrupted mutants was that the flux from glycine to serine was reduced, thus leading to an elevated supply with the riboflavin precursor glycine. Evidence for the correctness of that hypothesis was obtained from (13)C-labelling experiments. When 500 microM 99% [1-(13)C]threonine was fed, more than 50% of the label was detected in C-1 of glycine resulting from threonine aldolase activity. More than 30% labelling determined in C-1 of serine can be explained by serine synthesis via serine hydroxymethyltransferase. Knockout of SHM 1 had no detectable effect on serine labelling, but disruption of SHM 2 led to a decrease in serine (2-5%) and an increase in glycine (59-67%) labelling, indicating a changed carbon flux.
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Affiliation(s)
- Christina Schlüpen
- Institut für Biotechnologie 1, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany
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