1
|
Runnebohm AM, Indovina CJ, Turk SM, Bailey CG, Orchard CJ, Wade L, Overton DL, Snow BJ, Rubenstein EM. Methionine Restriction Impairs Degradation of a Protein that Aberrantly Engages the Endoplasmic Reticulum Translocon. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.001021. [PMID: 38021175 PMCID: PMC10667923 DOI: 10.17912/micropub.biology.001021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/01/2023] [Accepted: 11/07/2023] [Indexed: 12/01/2023]
Abstract
Proteins that persistently engage endoplasmic reticulum (ER) translocons are degraded by multiple translocon quality control (TQC) mechanisms. In Saccharomyces cerevisiae , the model translocon-associated protein Deg1 -Sec62 is subject to ER-associated degradation (ERAD) by the Hrd1 ubiquitin ligase and, to a lesser extent, proteolysis mediated by the Ste24 protease. In a recent screen, we identified nine methionine-biosynthetic genes as candidate TQC regulators. Here, we found methionine restriction impairs Hrd1-independent Deg1 -Sec62 degradation. Beyond revealing methionine as a novel regulator of TQC, our results urge caution when working with laboratory yeast strains with auxotrophic mutations, often presumed not to influence cellular processes under investigation.
Collapse
Affiliation(s)
- Avery M. Runnebohm
- Department of Biology, Ball State University, Muncie, Indiana, United States
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | | | - Samantha M. Turk
- Department of Biology, Ball State University, Muncie, Indiana, United States
- St. Jude Graduate School of Biomedical Science, Memphis, Tennessee, United States
| | - Connor G. Bailey
- Department of Biology, Ball State University, Muncie, Indiana, United States
- AllSource PPS, United States
| | - Cade J. Orchard
- Department of Biology, Ball State University, Muncie, Indiana, United States
- Department of Geology, University of Georgia, Athens, Georgia, United States
| | - Lauren Wade
- Department of Biology, Ball State University, Muncie, Indiana, United States
- Flow Cytometry Department, LabCorp, United States
| | - Danielle L. Overton
- Department of Biology, Ball State University, Muncie, Indiana, United States
- Department of Biology, Indiana University – Purdue University Indianapolis, Indianapolis, Indiana, United States
| | - Brian J. Snow
- Department of Biology, Ball State University, Muncie, Indiana, United States
- Department of Pathology and Laboratory Medicine, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Eric M. Rubenstein
- Department of Biology, Ball State University, Muncie, Indiana, United States
| |
Collapse
|
2
|
Hoffert KM, Higginbotham KSP, Gibson JT, Oehrle S, Strome ED. Mutations in the S-Adenosylmethionine Synthetase Genes SAM1 and SAM2 Differentially Affect Genome Stability in Saccharomyces cerevisiae. Genetics 2019; 213:97-112. [PMID: 31320408 PMCID: PMC6727793 DOI: 10.1534/genetics.119.302435] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 07/15/2019] [Indexed: 12/20/2022] Open
Abstract
Maintenance of genome integrity is a crucial cellular focus that involves a wide variety of proteins functioning in multiple processes. Defects in many different pathways can result in genome instability, a hallmark of cancer. Utilizing a diploid Saccharomyces cerevisiae model, we previously reported a collection of gene mutations that affect genome stability in a haploinsufficient state. In this work we explore the effect of gene dosage on genome instability for one of these genes and its paralog; SAM1 and SAM2 These genes encode S-Adenosylmethionine (AdoMet) synthetases, responsible for the creation of AdoMet from methionine and ATP. AdoMet is the universal methyl donor for methylation reactions and is essential for cell viability. It is the second most used cellular enzyme substrate and is exceptionally well-conserved through evolution. Mammalian cells express three genes, MAT1A, MAT2A, and MAT2B, with distinct expression profiles and functions. Alterations to these AdoMet synthetase genes, and AdoMet levels, are found in many cancers, making them a popular target for therapeutic intervention. However, significant variance in these alterations are found in different tumor types, with the cellular consequences of the variation still unknown. By studying this pathway in the yeast system, we demonstrate that losses of SAM1 and SAM2 have different effects on genome stability through distinctive effects on gene expression and AdoMet levels, and ultimately separate effects on the methyl cycle. Thus, this study provides insight into the mechanisms by which differential expression of the SAM genes have cellular consequences that affect genome instability.
Collapse
Affiliation(s)
- Kellyn M Hoffert
- Department of Biological Sciences, Northern Kentucky University, Highland Heights, Kentucky 41099
| | - Kathryn S P Higginbotham
- Department of Biological Sciences, Northern Kentucky University, Highland Heights, Kentucky 41099
| | - Justin T Gibson
- Department of Biological Sciences, Northern Kentucky University, Highland Heights, Kentucky 41099
| | - Stuart Oehrle
- Waters Field Laboratory, Chemistry Department, Northern Kentucky University, Highland Heights, Kentucky 41099
| | - Erin D Strome
- Department of Biological Sciences, Northern Kentucky University, Highland Heights, Kentucky 41099
| |
Collapse
|
3
|
Caslavka Zempel KE, Vashisht AA, Barshop WD, Wohlschlegel JA, Clarke SG. Determining the Mitochondrial Methyl Proteome in Saccharomyces cerevisiae using Heavy Methyl SILAC. J Proteome Res 2016; 15:4436-4451. [PMID: 27696855 DOI: 10.1021/acs.jproteome.6b00521] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Methylation is a common and abundant post-translational modification. High-throughput proteomic investigations have reported many methylation sites from complex mixtures of proteins. The lack of consistency between parallel studies, resulting from both false positives and missed identifications, suggests problems with both over-reporting and under-reporting methylation sites. However, isotope labeling can be used effectively to address the issue of false-positives, and fractionation of proteins can increase the probability of identifying methylation sites in lower abundance. Here we have adapted heavy methyl SILAC to analyze fractions of the budding yeast Saccharomyces cerevisiae under respiratory conditions to allow for the production of mitochondria, an organelle whose proteins are often overlooked in larger methyl proteome studies. We have found 12 methylation sites on 11 mitochondrial proteins as well as an additional 14 methylation sites on 9 proteins that are nonmitochondrial. Of these methylation sites, 20 sites have not been previously reported. This study represents the first characterization of the yeast mitochondrial methyl proteome and the second proteomic investigation of global mitochondrial methylation to date in any organism.
Collapse
Affiliation(s)
- Katelyn E Caslavka Zempel
- Department of Chemistry and Biochemistry and the Molecular Biology Institute and ‡Department of Biological Chemistry and the David Geffen School of Medicine, UCLA , Los Angeles, California 90095, United States
| | - Ajay A Vashisht
- Department of Chemistry and Biochemistry and the Molecular Biology Institute and ‡Department of Biological Chemistry and the David Geffen School of Medicine, UCLA , Los Angeles, California 90095, United States
| | - William D Barshop
- Department of Chemistry and Biochemistry and the Molecular Biology Institute and ‡Department of Biological Chemistry and the David Geffen School of Medicine, UCLA , Los Angeles, California 90095, United States
| | - James A Wohlschlegel
- Department of Chemistry and Biochemistry and the Molecular Biology Institute and ‡Department of Biological Chemistry and the David Geffen School of Medicine, UCLA , Los Angeles, California 90095, United States
| | - Steven G Clarke
- Department of Chemistry and Biochemistry and the Molecular Biology Institute and ‡Department of Biological Chemistry and the David Geffen School of Medicine, UCLA , Los Angeles, California 90095, United States
| |
Collapse
|
4
|
Fagan S, Owens R, Ward P, Connolly C, Doyle S, Murphy R. Biochemical Comparison of Commercial Selenium Yeast Preparations. Biol Trace Elem Res 2015; 166:245-59. [PMID: 25855372 DOI: 10.1007/s12011-015-0242-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Accepted: 01/18/2015] [Indexed: 02/02/2023]
Abstract
The trace mineral selenium (Se) is an essential element for human and animal nutrition. The addition of Se to the diet through dietary supplements or fortified food/feed is increasingly common owing to the often sub-optimal content of standard diets of many countries. Se supplements commercially available include the inorganic mineral salts such as sodium selenite or selenate, and organic forms such as Se-enriched yeast. Today, Se yeast is produced by several manufacturers and has become the most widely used source of Se for human supplementation and is also widely employed in animal nutrition where approval in all species has been granted by regulatory bodies such as the European Food Safety Authority (EFSA). Characterisation and comparison of Se-enriched yeast products has traditionally been made by quantifying total selenomethionine (SeMet) content. A disadvantage of this approach, however, is that it does not consider the effects of Se deposition on subsequent digestive availability. In this study, an assessment was made of the water-soluble extracts of commercially available Se-enriched yeast samples for free, peptide-bound and total water-soluble SeMet. Using LC-MS/MS, a total of 62 Se-containing proteins were identified across four Se yeast products, displaying quantitative/qualitative changes in abundance relative to the certified reference material, SELM-1 (P value <0.05; fold change ≥2). Overall, the study indicates that significant differences exist between Se yeast products in terms of SeMet content, Se-containing protein abundance and associated metabolic pathways.
Collapse
Affiliation(s)
- Sheena Fagan
- Alltech Biotechnology Centre, Dunboyne, County Meath, Ireland,
| | | | | | | | | | | |
Collapse
|
5
|
Suomi F, Menger KE, Monteuuis G, Naumann U, Kursu VAS, Shvetsova A, Kastaniotis AJ. Expression and evolution of the non-canonically translated yeast mitochondrial acetyl-CoA carboxylase Hfa1p. PLoS One 2014; 9:e114738. [PMID: 25503745 PMCID: PMC4263661 DOI: 10.1371/journal.pone.0114738] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Accepted: 11/13/2014] [Indexed: 12/16/2022] Open
Abstract
The Saccharomyces cerevisiae genome encodes two sequence related acetyl-CoA carboxylases, the cytosolic Acc1p and the mitochondrial Hfa1p, required for respiratory function. Several aspects of expression of the HFA1 gene and its evolutionary origin have remained unclear. Here, we determined the HFA1 transcription initiation sites by 5' RACE analysis. Using a novel "Stop codon scanning" approach, we mapped the location of the HFA1 translation initiation site to an upstream AUU codon at position -372 relative to the annotated start codon. This upstream initiation leads to production of a mitochondrial targeting sequence preceding the ACC domains of the protein. In silico analyses of fungal ACC genes revealed conserved "cryptic" upstream mitochondrial targeting sequences in yeast species that have not undergone a whole genome duplication. Our Δhfa1 baker's yeast mutant phenotype rescue studies using the protoploid Kluyveromyces lactis ACC confirmed functionality of the cryptic upstream mitochondrial targeting signal. These results lend strong experimental support to the hypothesis that the mitochondrial and cytosolic acetyl-CoA carboxylases in S. cerevisiae have evolved from a single gene encoding both the mitochondrial and cytosolic isoforms. Leaning on a cursory survey of a group of genes of our interest, we propose that cryptic 5' upstream mitochondrial targeting sequences may be more abundant in eukaryotes than anticipated thus far.
Collapse
Affiliation(s)
- Fumi Suomi
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Katja E Menger
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Geoffray Monteuuis
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Uta Naumann
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - V A Samuli Kursu
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Antonina Shvetsova
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| | - Alexander J Kastaniotis
- Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, Oulu, Finland
| |
Collapse
|
6
|
Dato L, Berterame NM, Ricci MA, Paganoni P, Palmieri L, Porro D, Branduardi P. Changes in SAM2 expression affect lactic acid tolerance and lactic acid production in Saccharomyces cerevisiae. Microb Cell Fact 2014; 13:147. [PMID: 25359316 PMCID: PMC4230512 DOI: 10.1186/s12934-014-0147-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 10/08/2014] [Indexed: 01/25/2023] Open
Abstract
Background The great interest in the production of highly pure lactic acid enantiomers comes from the application of polylactic acid (PLA) for the production of biodegradable plastics. Yeasts can be considered as alternative cell factories to lactic acid bacteria for lactic acid production, despite not being natural producers, since they can better tolerate acidic environments. We have previously described metabolically engineered Saccharomyces cerevisiae strains producing high amounts of L-lactic acid (>60 g/L) at low pH. The high product concentration represents the major limiting step of the process, mainly because of its toxic effects. Therefore, our goal was the identification of novel targets for strain improvement possibly involved in the yeast response to lactic acid stress. Results The enzyme S-adenosylmethionine (SAM) synthetase catalyses the only known reaction leading to the biosynthesis of SAM, an important cellular cofactor. SAM is involved in phospholipid biosynthesis and hence in membrane remodelling during acid stress. Since only the enzyme isoform 2 seems to be responsive to membrane related signals (e.g. myo-inositol), Sam2p was tagged with GFP to analyse its abundance and cellular localization under different stress conditions. Western blot analyses showed that lactic acid exposure correlates with an increase in protein levels. The SAM2 gene was then overexpressed and deleted in laboratory strains. Remarkably, in the BY4741 strain its deletion conferred higher resistance to lactic acid, while its overexpression was detrimental. Therefore, SAM2 was deleted in a strain previously engineered and evolved for industrial lactic acid production and tolerance, resulting in higher production. Conclusions Here we demonstrated that the modulation of SAM2 can have different outcomes, from clear effects to no significant phenotypic responses, upon lactic acid stress in different genetic backgrounds, and that at least in one genetic background SAM2 deletion led to an industrially relevant increase in lactic acid production. Further work is needed to elucidate the molecular basis of these observations, which underline once more that strain robustness relies on complex cellular mechanisms, involving regulatory genes and proteins. Our data confirm cofactor engineering as an important tool for cell factory improvement. Electronic supplementary material The online version of this article (doi:10.1186/s12934-014-0147-7) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Laura Dato
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy.
| | - Nadia Maria Berterame
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy.
| | - Maria Antonietta Ricci
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, 70125, Bari, Italy.
| | - Paola Paganoni
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy.
| | - Luigi Palmieri
- Dipartimento di Bioscienze, Biotecnologie e Biofarmaceutica, Università degli Studi di Bari Aldo Moro, Via Orabona 4, 70125, Bari, Italy.
| | - Danilo Porro
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy.
| | - Paola Branduardi
- Dipartimento di Biotecnologie e Bioscienze, Università degli Studi di Milano-Bicocca, Piazza della Scienza 2, 20126, Milan, Italy.
| |
Collapse
|
7
|
The endosymbiont Amoebophilus asiaticus encodes an S-adenosylmethionine carrier that compensates for its missing methylation cycle. J Bacteriol 2013; 195:3183-92. [PMID: 23667233 DOI: 10.1128/jb.00195-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
All organisms require S-adenosylmethionine (SAM) as a methyl group donor and cofactor for various biologically important processes. However, certain obligate intracellular parasitic bacteria and also the amoeba symbiont Amoebophilus asiaticus have lost the capacity to synthesize this cofactor and hence rely on its uptake from host cells. Genome analyses revealed that A. asiaticus encodes a putative SAM transporter. The corresponding protein was functionally characterized in Escherichia coli: import studies demonstrated that it is specific for SAM and S-adenosylhomocysteine (SAH), the end product of methylation. SAM transport activity was shown to be highly dependent on the presence of a membrane potential, and by targeted analyses, we obtained direct evidence for a proton-driven SAM/SAH antiport mechanism. Sequence analyses suggest that SAM carriers from Rickettsiales might operate in a similar way, in contrast to chlamydial SAM transporters. SAM/SAH antiport is of high physiological importance, as it allows for compensation for the missing methylation cycle. The identification of a SAM transporter in A. asiaticus belonging to the Bacteroidetes phylum demonstrates that SAM transport is more widely spread than previously assumed and occurs in bacteria belonging to three different phyla (Proteobacteria, Chlamydiae, and Bacteroidetes).
Collapse
|
8
|
Fungal S-adenosylmethionine synthetase and the control of development and secondary metabolism in Aspergillus nidulans. Fungal Genet Biol 2012; 49:443-54. [DOI: 10.1016/j.fgb.2012.04.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 04/11/2012] [Accepted: 04/12/2012] [Indexed: 12/15/2022]
|
9
|
Pajares MA, Markham GD. Methionine adenosyltransferase (s-adenosylmethionine synthetase). ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2011; 78:449-521. [PMID: 22220481 DOI: 10.1002/9781118105771.ch11] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- María A Pajares
- Instituto de Investigaciones Biomédicas "Alberto Sols" (CSIC-UAM), Madrid Spain
| | | |
Collapse
|
10
|
Mutation of high-affinity methionine permease contributes to selenomethionyl protein production in Saccharomyces cerevisiae. Appl Environ Microbiol 2010; 76:6351-9. [PMID: 20693451 DOI: 10.1128/aem.01026-10] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The production of selenomethionine (SeMet) derivatives of recombinant proteins allows phase determination by single-wavelength or multiwavelength anomalous dispersion phasing in X-ray crystallography, and this popular approach has permitted the crystal structures of numerous proteins to be determined. Although yeast is an ideal host for the production of large amounts of eukaryotic proteins that require posttranslational modification, the toxic effects of SeMet often interfere with the preparation of protein derivatives containing this compound. We previously isolated a mutant strain (SMR-94) of the methylotrophic yeast Pichia pastoris that is resistant to both SeMet and selenate and demonstrated its applicability for the production of proteins suitable for X-ray crystallographic analysis. However, the molecular basis for resistance to SeMet by the SMR-94 strain remains unclear. Here, we report the characterization of SeMet-resistant mutants of Saccharomyces cerevisiae and the identification of a mutant allele of the MUP1 gene encoding high-affinity methionine permease, which confers SeMet resistance. Although the total methionine uptake by the mup1 mutant (the SRY5-7 strain) decreased to 47% of the wild-type level, it was able to incorporate SeMet into the overexpressed epidermal growth factor peptide with 73% occupancy, indicating the importance of the moderate uptake of SeMet by amino acid permeases other than Mup1p for the alleviation of SeMet toxicity. In addition, under standard culture conditions, the mup1 mutant showed higher productivity of the SeMet derivative relative to other SeMet-resistant mutants. Based on these results, we conclude that the mup1 mutant would be useful for the preparation of selenomethionyl proteins for X-ray crystallography.
Collapse
|
11
|
Development of bottom-fermenting saccharomyces strains that produce high SO2 levels, using integrated metabolome and transcriptome analysis. Appl Environ Microbiol 2008; 74:2787-96. [PMID: 18310411 DOI: 10.1128/aem.01781-07] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sulfite plays an important role in beer flavor stability. Although breeding of bottom-fermenting Saccharomyces strains that produce high levels of SO(2) is desirable, it is complicated by the fact that undesirable H(2)S is produced as an intermediate in the same pathway. Here, we report the development of a high-level SO(2)-producing bottom-fermenting yeast strain by integrated metabolome and transcriptome analysis. This analysis revealed that O-acetylhomoserine (OAH) is the rate-limiting factor for the production of SO(2) and H(2)S. Appropriate genetic modifications were then introduced into a prototype strain to increase metabolic fluxes from aspartate to OAH and from sulfate to SO(2), resulting in high SO(2) and low H(2)S production. Spontaneous mutants of an industrial strain that were resistant to both methionine and threonine analogs were then analyzed for similar metabolic fluxes. One promising mutant produced much higher levels of SO(2) than the parent but produced parental levels of H(2)S.
Collapse
|
12
|
Malkowski MG, Quartley E, Friedman AE, Babulski J, Kon Y, Wolfley J, Said M, Luft JR, Phizicky EM, DeTitta GT, Grayhack EJ. Blocking S-adenosylmethionine synthesis in yeast allows selenomethionine incorporation and multiwavelength anomalous dispersion phasing. Proc Natl Acad Sci U S A 2007; 104:6678-83. [PMID: 17426150 PMCID: PMC1850019 DOI: 10.1073/pnas.0610337104] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2006] [Indexed: 11/18/2022] Open
Abstract
Saccharomyces cerevisiae is an ideal host from which to obtain high levels of posttranslationally modified eukaryotic proteins for x-ray crystallography. However, extensive replacement of methionine by selenomethionine for anomalous dispersion phasing has proven intractable in yeast. We report a general method to incorporate selenomethionine into proteins expressed in yeast based on manipulation of the appropriate metabolic pathways. sam1(-) sam2(-) mutants, in which the conversion of methionine to S-adenosylmethionine is blocked, exhibit reduced selenomethionine toxicity compared with wild-type yeast, increased production of protein during growth in selenomethionine, and efficient replacement of methionine by selenomethionine, based on quantitative mass spectrometry and x-ray crystallography. The structure of yeast tryptophanyl-tRNA synthetase was solved to 1.8 A by using multiwavelength anomalous dispersion phasing with protein that was expressed and purified from the sam1(-) sam2(-) strain grown in selenomethionine. Six of eight selenium residues were located in the structure.
Collapse
Affiliation(s)
- Michael G. Malkowski
- *Hauptman-Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203; and
- Department of Structural Biology, State University of New York, 700 Ellicott Street, Buffalo, NY 14203
| | | | | | | | - Yoshiko Kon
- Center for Pediatric Biomedical Research and
- Biochemistry and Biophysics, University of Rochester Medical School, Rochester, NY 14642
| | - Jennifer Wolfley
- *Hauptman-Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203; and
| | - Meriem Said
- *Hauptman-Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203; and
| | - Joseph R. Luft
- *Hauptman-Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203; and
- Department of Structural Biology, State University of New York, 700 Ellicott Street, Buffalo, NY 14203
| | - Eric M. Phizicky
- Center for Pediatric Biomedical Research and
- Biochemistry and Biophysics, University of Rochester Medical School, Rochester, NY 14642
| | - George T. DeTitta
- *Hauptman-Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY 14203; and
- Department of Structural Biology, State University of New York, 700 Ellicott Street, Buffalo, NY 14203
| | - Elizabeth J. Grayhack
- Center for Pediatric Biomedical Research and
- Biochemistry and Biophysics, University of Rochester Medical School, Rochester, NY 14642
| |
Collapse
|
13
|
Tabor CW, Tabor H. Methionine adenosyltransferase (S-adenosylmethionine synthetase) and S-adenosylmethionine decarboxylase. ADVANCES IN ENZYMOLOGY AND RELATED AREAS OF MOLECULAR BIOLOGY 2006; 56:251-82. [PMID: 6364703 DOI: 10.1002/9780470123027.ch4] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
|
14
|
Kuepfer L, Sauer U, Blank LM. Metabolic functions of duplicate genes in Saccharomyces cerevisiae. Genome Res 2006; 15:1421-30. [PMID: 16204195 PMCID: PMC1240085 DOI: 10.1101/gr.3992505] [Citation(s) in RCA: 184] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The roles of duplicate genes and their contribution to the phenomenon of enzyme dispensability are a central issue in molecular and genome evolution. A comprehensive classification of the mechanisms that may have led to their preservation, however, is currently lacking. In a systems biology approach, we classify here back-up, regulatory, and gene dosage functions for the 105 duplicate gene families of Saccharomyces cerevisiae metabolism. The key tool was the reconciled genome-scale metabolic model iLL672, which was based on the older iFF708. Computational predictions of all metabolic gene knockouts were validated with the experimentally determined phenotypes of the entire singleton yeast library of 4658 mutants under five environmental conditions. iLL672 correctly identified 96%-98% and 73%-80% of the viable and lethal singleton phenotypes, respectively. Functional roles for each duplicate family were identified by integrating the iLL672-predicted in silico duplicate knockout phenotypes, genome-scale carbon-flux distributions, singleton mutant phenotypes, and network topology analysis. The results provide no evidence for a particular dominant function that maintains duplicate genes in the genome. In particular, the back-up function is not favored by evolutionary selection because duplicates do not occur more frequently in essential reactions than singleton genes. Instead of a prevailing role, multigene-encoded enzymes cover different functions. Thus, at least for metabolism, persistence of the paralog fraction in the genome can be better explained with an array of different, often overlapping functional roles.
Collapse
Affiliation(s)
- Lars Kuepfer
- Institute of Molecular Systems Biology, ETH Zurich, 8093 Zurich, Switzerland
| | | | | |
Collapse
|
15
|
Rodrigues PH, Progulske-Fox A. Gene expression profile analysis of Porphyromonas gingivalis during invasion of human coronary artery endothelial cells. Infect Immun 2005; 73:6169-73. [PMID: 16113342 PMCID: PMC1231123 DOI: 10.1128/iai.73.9.6169-6173.2005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Microarrays were used to identify genes of Porphyromonas gingivalis W83 differentially expressed during invasion of primary human coronary artery endothelial cells. Analyses of microarray images indicated that 62 genes were differentially regulated. Of these, 11 genes were up-regulated and 51 were down-regulated. The differential expression of 16 selected genes was confirmed by real-time PCR.
Collapse
Affiliation(s)
- Paulo H Rodrigues
- Department of Oral Biology, University of Florida, P.O. Box 100424, Gainesville, FL 32610-0424, USA
| | | |
Collapse
|
16
|
Larsen HH, Kovacs JA, Stock F, Vestereng VH, Lundgren B, Fischer SH, Gill VJ. Development of a rapid real-time PCR assay for quantitation of Pneumocystis carinii f. sp. carinii. J Clin Microbiol 2002; 40:2989-93. [PMID: 12149363 PMCID: PMC120631 DOI: 10.1128/jcm.40.8.2989-2993.2002] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A method for reliable quantification of Pneumocystis carinii in research models of P. carinii pneumonia (PCP) that is more convenient and reproducible than microscopic enumeration of organisms would greatly facilitate investigations of this organism. We developed a rapid quantitative touchdown (QTD) PCR assay for detecting P. carinii f. sp. carinii, the subspecies of P. carinii commonly used in research models of PCP. The assay was based on the single-copy dihydrofolate reductase gene and was able to detect <5 copies of a plasmid standard per tube. It was reproducibly quantitative (r = 0.99) over 6 log values for standards containing > or =5 copies/tube. Application of the assay to a series of 10-fold dilutions of P. carinii organisms isolated from rat lung demonstrated that it was reproducibly quantitative over 5 log values (r = 0.99). The assay was applied to a recently reported in vitro axenic cultivation system for P. carinii and confirmed our microscopy findings that no organism multiplication had occurred during culture. For all cultures analyzed, QTD PCR assays showed a decrease in P. carinii DNA that exceeded the expected decrease due to dilution of the inoculum upon transfer. In conclusion, a rapid, sensitive, and reproducible quantitative PCR assay for P. carinii f. sp. carinii has been developed and is applicable to in vivo as well as in vitro systems. The assay should prove useful for conducting studies in which quantification of organism burden or growth assessment is critical, such as in vitro antimicrobic susceptibility testing or in vivo immunopathological experiments.
Collapse
Affiliation(s)
- Hans Henrik Larsen
- Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, Maryland, USA.
| | | | | | | | | | | | | |
Collapse
|
17
|
Abstract
We previously reported that S-adenosylmethionine (AdoMet), a key molecule in methylation reactions and polyamine biosynthesis, enhances axenic culture of the AIDS-associated opportunistic fungal pathogen Pneumocystis carinii. Here we report that AdoMet is absolutely required for continuous growth. Two transporters are present, one high affinity, K(m) = 4.5 microm, and one low affinity, K(m) = 333 microm. The physiologically relevant high affinity transporter has a pH optimum of 7.5 and no related natural compounds compete for uptake. Transport is 98% inhibited at 4 degrees C, 24% inhibited by 20 mm sodium azide, and 95% inhibited by the combination of 20 mm sodium azide and 1 mm salicylhydroxamic acid; thus transport is active and dependent on both a cytochrome chain and an alternative oxidase. In vitro, AdoMet is used at a rate of 1. 40 x 10(7) molecules cell(-1) min(-1). AdoMet synthetase activity was not detected by a sensitive radiolabel incorporation assay capable of detecting 0.1% of the activity in rat liver. In addition, the AdoMet plasma concentration of rats is inversely correlated with the number of P. carinii in the lungs. These findings demonstrate that P. carinii is an AdoMet auxotroph. The uptake and metabolism of this compound are rational chemotherapeutic targets.
Collapse
Affiliation(s)
- S Merali
- Department of Medical and Molecular Parasitology, New York University School of Medicine, New York, New York 10010, USA.
| | | | | | | |
Collapse
|
18
|
Hilti N, Gräub R, Jörg M, Arnold P, Schweingruber AM, Schweingruber ME. Gene sam1 encoding adenosylmethionine synthetase: effects of its expression in the fission yeast Schizosaccharomyces pombe. Yeast 2000; 16:1-10. [PMID: 10620770 DOI: 10.1002/(sici)1097-0061(20000115)16:1<1::aid-yea501>3.0.co;2-k] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
By screening gene libraries of Schizosaccharomyces pombe with a DNA fragment encoding part of the Saccharomyces cerevisiae S-adenosylmethionine synthetase (SAMS), we isolated the fission yeast sam1 gene. Its sequence exhibits good homology to SAMSs of other organisms and reveals the motifs characteristic for SAMSs. SAMS activity and sam1 mRNA levels decrease when cells enter stationary phase. In haploid strains, gene sam1 is essential for growth; if weakly expressed, cells mate and sporulate at a reduced rate. Strains overexpressing sam1 exhibit methionine-sensitive growth. This methionine-induced growth inhibition is partially relieved by adenine. We assume that methionine reduces the level of one or several adenine nucleotides by a SAMS-mediated mechanism. Intracellular SAM levels increase drastically by exogenously added methionine. This increase predicts that mutants exhibiting methionine revertible phenotypes can be indicative for mutations in proteins exhibiting SAM-dependent functions. In agreement with this prediction, we show that mutant pmt2-5 has this phenotype and that gene pmt2 encodes a potential SAM-dependent enzyme.
Collapse
Affiliation(s)
- N Hilti
- Institute of General Microbiology, University of Berne, CH-3012 Berne, Switzerland
| | | | | | | | | | | |
Collapse
|
19
|
Bawa S, Xiao W. Methionine reduces spontaneous and alkylation-induced mutagenesis in Saccharomyces cerevisiae cells deficient in O6-methylguanine-DNA methyltransferase. Mutat Res 1999; 430:99-107. [PMID: 10592321 DOI: 10.1016/s0027-5107(99)00163-3] [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: 12/25/2022]
Abstract
The exposure of DNA to reactive intracellular metabolites is thought to be a major cause of spontaneous mutagenesis. DNA alkylation is implicated in the above process by the fact that bacterial and yeast cells lacking DNA alkylation-specific repair genes exhibit elevated spontaneous mutation rates. The origin of the intracellular alkylating molecules is not clear; however, S-adenosylmethionine (SAM) has been proposed as one source because it has a reactive methyl group known to methylate proteins and DNA. We supplemented yeast cultures with excess methionine and examined the effects of increased endogenous SAM concentration on spontaneous and alkylation-induced mutagenesis in the absence of various DNA repair pathways. Our results show that either the excess methionine, or the increased SAM produced as a result of this treatment, is able to protect yeast cells from mutagenesis, and that this effect is alkylation-damage-specific. The protective effect was observed only in the mgt1 mutant deficient in the O(6)-methylguanine-DNA repair methyltransferase, but not in the wild type or other DNA repair-deficient strains, indicating that the protection is specific for O-methyl lesions. Thus, our results may lend support to the recently reported chemopreventive effect of SAM in rodents and further suggest that the observed tumor prevention by SAM may be, in part, due to its suppression of spontaneous mutagenesis in mammals. Given that a strong correlation has been established between O(6)-methylguanine and carcinogenicity, this study may offer a novel approach to preventing carcinogenesis.
Collapse
Affiliation(s)
- S Bawa
- Department of Microbiology and Immunology, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada
| | | |
Collapse
|
20
|
Newman EB, Budman LI, Chan EC, Greene RC, Lin RT, Woldringh CL, D'Ari R. Lack of S-adenosylmethionine results in a cell division defect in Escherichia coli. J Bacteriol 1998; 180:3614-9. [PMID: 9658005 PMCID: PMC107330 DOI: 10.1128/jb.180.14.3614-3619.1998] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The enzyme S-adenosylmethionine (SAM) synthetase, the Escherichia coli metK gene product, produces SAM, the cell's major methyl donor. We show here that SAM synthetase activity is induced by leucine and repressed by Lrp, the leucine-responsive regulatory protein. When SAM synthetase activity falls below a certain critical threshold, the cells produce long filaments with regularly distributed nucleoids. Expression of a plasmid-carried metK gene prevents filamentation and restores normal growth to the metK mutant. This indicates that lack of SAM results in a division defect.
Collapse
Affiliation(s)
- E B Newman
- Biology Department, Concordia University Montreal, Quebec H3G 1M8.
| | | | | | | | | | | | | |
Collapse
|
21
|
Abstract
Sulfur amino acid biosynthesis in Saccharomyces cerevisiae involves a large number of enzymes required for the de novo biosynthesis of methionine and cysteine and the recycling of organic sulfur metabolites. This review summarizes the details of these processes and analyzes the molecular data which have been acquired in this metabolic area. Sulfur biochemistry appears not to be unique through terrestrial life, and S. cerevisiae is one of the species of sulfate-assimilatory organisms possessing a larger set of enzymes for sulfur metabolism. The review also deals with several enzyme deficiencies that lead to a nutritional requirement for organic sulfur, although they do not correspond to defects within the biosynthetic pathway. In S. cerevisiae, the sulfur amino acid biosynthetic pathway is tightly controlled: in response to an increase in the amount of intracellular S-adenosylmethionine (AdoMet), transcription of the coregulated genes is turned off. The second part of the review is devoted to the molecular mechanisms underlying this regulation. The coordinated response to AdoMet requires two cis-acting promoter elements. One centers on the sequence TCACGTG, which also constitutes a component of all S. cerevisiae centromeres. Situated upstream of the sulfur genes, this element is the binding site of a transcription activation complex consisting of a basic helix-loop-helix factor, Cbf1p, and two basic leucine zipper factors, Met4p and Met28p. Molecular studies have unraveled the specific functions for each subunit of the Cbf1p-Met4p-Met28p complex as well as the modalities of its assembly on the DNA. The Cbf1p-Met4p-Met28p complex contains only one transcription activation module, the Met4p subunit. Detailed mutational analysis of Met4p has elucidated its functional organization. In addition to its activation and bZIP domains, Met4p contains two regulatory domains, called the inhibitory region and the auxiliary domain. When the level of intracellular AdoMet increases, the transcription activation function of Met4 is prevented by Met30p, which binds to the Met4 inhibitory region. In addition to the Cbf1p-Met4p-Met28p complex, transcriptional regulation involves two zinc finger-containing proteins, Met31p and Met32p. The AdoMet-mediated control of the sulfur amino acid pathway illustrates the molecular strategies used by eucaryotic cells to couple gene expression to metabolic changes.
Collapse
Affiliation(s)
- D Thomas
- Centre de Génétique Moléculaire, CNRS, Gif sur Yvette, France
| | | |
Collapse
|
22
|
Park J, Tai J, Roessner CA, Scott AI. Enzymatic synthesis of S-adenosyl-L-methionine on the preparative scale. Bioorg Med Chem 1996; 4:2179-85. [PMID: 9022980 DOI: 10.1016/s0968-0896(96)00228-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The problems inherent in the enzymatic and chemical synthesis of S-adenosyl-L-methionine (SAM) led us to develop an efficient, simple method for the synthesis of large amounts of labeled SAM. Previously, we reported that the problem of product inhibition of E. coli SAM synthetase encoded by the metK gene was successfully overcome in the presence of sodium p-toluenesulfonate (pTsONa). This research has now been expanded to demonstrate that product inhibition of this enzyme can also be overcome by adding a high concentration of beta-mercaptoethanol (beta ME), acetonitrile, or urea. In addition a recombinant strain of E. coli has been constructed that expresses the yeast SAM synthetase encoded by the sam2 gene. The yeast enzyme does not have the problem of product inhibition seen with the E. coli enzyme. Complete conversion of 10 mM methionine to SAM was achieved in incubations with either the recombinant yeast enzyme and 1 molar potassium ion or the E. coli enzyme in the presence of additives such as beta ME, acetonitrile, urea, or pTsONa. The recombinant yeast SAM synthetase was used to generate SAM in situ for use in the multi-enzymatic synthesis of precorrin 2.
Collapse
Affiliation(s)
- J Park
- Center for Biological NMR, Department of Chemistry, Texas A&M University, College Station 77843-3255, USA
| | | | | | | |
Collapse
|
23
|
Barra JL, Mautino MR, Rosa AL. A dominant negative effect of eth-1r, a mutant allele of the Neurospora crassa S-adenosylmethionine synthetase-encoding gene conferring resistance to the methionine toxic analogue ethionine. Genetics 1996; 144:1455-62. [PMID: 8978034 PMCID: PMC1207698 DOI: 10.1093/genetics/144.4.1455] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
eth-1r, a thermosensitive allele of the Neurospora crassa S-adenosylmethionine (AdoMet) synthetase gene that confers ethionine resistance, has been cloned and sequenced. Replacement of an aspartic amino acid residue (D48-->N48), perfectly conserved in prokaryotic, fungal and higher eukaryotic AdoMet synthetases, was found responsible for both thermosensitivity and ethionine resistance conferred by eth-1r. Gene fusion constructs, designed to overexpress eth-1r in vivo, render transformant cells resistant to ethionine. Dominance of ethionine resistance was further demonstrated in eth-1+/eth-1r partial diploids carrying identical gene doses of both alleles. Heterozygous eth-1+/eth-1r cells have, at the same time, both the thermotolerance conferred by eth-1+ and the ethionine-resistant phenotype conferred by eth-1r. AdoMet levels and AdoMet synthetase activities were dramatically decreased in heterozygous eth-1+/ eth-1r cells. We propose that this negative effect exerted by eth-1r results from the in vivo formation of heteromeric eth-1+/eth-1r AdoMet synthetase molecules.
Collapse
Affiliation(s)
- J L Barra
- Departamento de Química Biológica (CIQUIBIC-CONICET), Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina
| | | | | |
Collapse
|
24
|
Yocum RR, Perkins JB, Howitt CL, Pero J. Cloning and characterization of the metE gene encoding S-adenosylmethionine synthetase from Bacillus subtilis. J Bacteriol 1996; 178:4604-10. [PMID: 8755891 PMCID: PMC178230 DOI: 10.1128/jb.178.15.4604-4610.1996] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The metE gene, encoding S-adenosylmethionine synthetase (EC 2.5.1.6) from Bacillus subtilis, was cloned in two steps by normal and inverse PCR. The DNA sequence of the metE gene contains an open reading frame which encodes a 400-amino-acid sequence that is homologous to other known S-adenosylmethionine synthetases. The cloned gene complements the metE1 mutation and integrates at or near the chromosomal site of metE1. Expression of S-adenosylmethionine synthetase is reduced by only a factor of about 2 by exogenous methioinine. Overproduction of S-adenosylmethionine synthetase from a strong constitutive promoter leads to methionine auxotrophy in B. subtilis, suggesting that S-adenosylmethionine is a corepressor of methionine biosynthesis in B. subtilis, as others have already shown for Escherichia coli.
Collapse
Affiliation(s)
- R R Yocum
- OmniGene Bioproducts, Inc. Cambridge, Massachusetts 02138, USA
| | | | | | | |
Collapse
|
25
|
Park J, Tai J, Roessner CA, Scott A. Overcoming product inhibition of S-Adenosyl-L-methionine (SAM) synthetase: Preparation of SAM on the 30 mM scale. Bioorg Med Chem Lett 1995. [DOI: 10.1016/0960-894x(95)00384-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
|
26
|
TheSAM2 gene product catalyzes the formation of S-adenosyl-ethionine from ethionine inSaccharomyces cerevisiae. Curr Microbiol 1994. [DOI: 10.1007/bf01570198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
27
|
Mathur M, Sharma N, Sachar RC. Differential regulation of S-adenosylmethionine synthetase isozymes by gibberellic acid in dwarf pea epicotyls. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1162:283-90. [PMID: 8457592 DOI: 10.1016/0167-4838(93)90292-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Dwarf pea epicotyls contained a single activity peak of S-adenosylmethionine (AdoMet) synthetase (isozyme I). Gibberellic acid (GA3, 1 microM) induced two additional isozymes (II and III). Cycloheximide (20 microgram/ml) blocked the appearance of GA3-induced isozymes, suggesting that it is dependent on de novo protein synthesis. Conclusive proof was obtained by labelling the isozymes II and III with [35S]SO2-(4) in vivo. The purified 35S-labelled AdoMet synthetase isozymes (II, III) showed a single protein band that coincided with the single radioactive peak on SDS-PAGE. Molecular-sieve chromatography of the isozyme I from control dwarf pea epicotyls and three isozymes of GA3-treated epicotyls on Sepharose CL-6B showed a single activity peak with an identical molecular mass of 174 kDa for each isozyme. Analysis of purified AdoMet synthetase isozymes (I, II, III) on SDS-PAGE showed a single silver-stained protein band with a molecular mass of 87 kDa. This proved the dimeric nature of all the isozymes of AdoMet synthetase which could be physically separated by ion-exchange chromatography on DE-52. In vitro molecular hybridization of physically separated isozymes by NaCl-freeze-thaw treatment method revealed that the three isozymes (I, II, III) in GA3-treated dwarf pea epicotyls are formed through the random dimerization of two different species of enzyme subunits that differ in their net charge. Thus, the two flanking activity peaks (isozymes I, III) represent homodimers, while the middle activity peak (isozyme II) is a heterodimer. Apparently, the single isozyme I in control epicotyls is a product of one gene of AdoMet synthetase (SAM 1), while three isozymes in GA3-treated epicotyls are the product of two genes of AdoMet synthetase. We speculate that the differential regulation of AdoMet synthetase in GA3-treated epicotyls is achieved by the expression of an alternate gene of AdoMet synthetase (SAM 2).
Collapse
Affiliation(s)
- M Mathur
- Department of Botany, University of Delhi, India
| | | | | |
Collapse
|
28
|
Heiland PC, Hill FF. Accumulation of S-adenosylhomocysteine and S-adenosylmethionine by an ethionine-resistant mutant of bakers' yeast. Process Biochem 1993. [DOI: 10.1016/0032-9592(93)80004-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
29
|
Ozier-Kalogeropoulos O, Fasiolo F, Adeline MT, Collin J, Lacroute F. Cloning, sequencing and characterization of the Saccharomyces cerevisiae URA7 gene encoding CTP synthetase. MOLECULAR & GENERAL GENETICS : MGG 1991; 231:7-16. [PMID: 1753946 DOI: 10.1007/bf00293815] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The URA7 gene of Saccharomyces cerevisiae encodes CTP synthetase (EC 6.3.4.2) which catalyses the conversion of uridine 5'-triphosphate to cytidine 5'-triphosphate, the last step of the pyrimidine biosynthetic pathway. We have cloned and sequenced the URA7 gene. The coding region is 1710 bp long and the deduced protein sequence shows a strong degree of homology with bacterial and human CTP synthetases. Gene disruption shows that URA7 is not an essential gene: the level of the intracellular CTP pool is roughly the same in the deleted and the wild-type strains, suggesting that an alternative pathway for CTP synthesis exists in yeast. This could involve either a divergent duplicated gene or a different route beginning with the amination of uridine mono- or diphosphate.
Collapse
Affiliation(s)
- O Ozier-Kalogeropoulos
- Centre de Génétique Moléculaire du C.N.R.S. Université Pierre et Marie Curie, Gif-sur-Yvette, France
| | | | | | | | | |
Collapse
|
30
|
De La Rosa J, Kotb M, Kredich NM. Regulation of S-adenosylmethionine synthetase activity in cultured human lymphocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1077:225-32. [PMID: 1849748 DOI: 10.1016/0167-4838(91)90062-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
S-Adenosylmethionine (AdoMet), inorganic pyrophosphate (PPi) and inorganic phosphate (Pi) are potent product inhibitors of AdoMet synthetase and have been postulated to play a role in increasing AdoMet levels and turnover in peripheral blood mononuclear cells (PBM) after stimulation with phytohemagglutinin (PHA). Measurements of these metabolites in PHA-stimulated PBM showed the expected 2- to 3-fold increases in AdoMet after 8 h, and smaller increases in PPi and Pi. Since the kinetic model requires substantial decreases in PPi and Pi in response to PHA, product inhibition cannot explain the observed changes in AdoMet metabolism in this system. A 2.5-fold increase in AdoMet synthetase catalytic activity was found in crude extracts of PBM within 8 h of PHA-stimulation and probably accounts for increased cellular levels and utilization of AdoMet. Immunochemical analyses with a monoclonal antibody specific for the alpha/alpha' subunits of human lymphocyte AdoMet synthetase showed that these increases in catalytic activity were not associated with increases in immunoreactive protein. The ratio of catalytic activity to immunoreactivity in stimulated cells was 4-fold higher than in unstimulated controls and almost identical to that found in extracts from the human B-lymphocyte line WI-L2. Unstimulated PBM appear to contain substantial amounts of AdoMet synthetase alpha/alpha' subunit with reduced or absent catalytic activity, which can be activated by PHA-stimulation.
Collapse
Affiliation(s)
- J De La Rosa
- Department of Medicine, Duke University Medical Center, Durham, NC 27710
| | | | | |
Collapse
|
31
|
Thomas D, Surdin-Kerjan Y. The synthesis of the two S-adenosyl-methionine synthetases is differently regulated in Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1991; 226:224-32. [PMID: 1903502 DOI: 10.1007/bf00273607] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
S-adenosyl-L-methionine (AdoMet) is synthesized by transfer of the adenosyl moiety of ATP to the sulfur atom of methionine. This reaction is catalysed by AdoMet synthetase. In all eukaryotic organisms studied so far, multiple forms of AdoMet synthetases have been reported and from their recent study, it appears that AdoMet synthetase is an exceptionally well conserved enzyme through evolution. In Saccharomyces cerevisiae, we have demonstrated the existence of two AdoMet synthetases encoded by genes SAM1 and SAM2. Yeast, which is able to concentrate exogenously added AdoMet, is thus a particularly useful biological system to understand the role and the physiological significance of the preservation of two almost identical AdoMet synthetases. The analysis of the expression of the two SAM genes in different genetic backgrounds during growth under different conditions shows that the expression of SAM1 and SAM2 is regulated differently. The regulation of SAM1 expression is identical to that of other genes implicated in AdoMet metabolism, whereas SAM2 shows a specific pattern of regulation. A careful analysis of the expression of the two genes and of the variations in the methionine and AdoMet intracellular pools during the growth of different strains lead us to postulate the existence of two different AdoMet pools, each one supplied by a different AdoMet synthetase but in equilibrium with each other. This could be a means of storing AdoMet whenever this metabolite is overproduced, thus avoiding the degradation of a metabolite the synthesis of which is energetically expensive.
Collapse
Affiliation(s)
- D Thomas
- Laboratoire d'Enzymologie du CNRS, Gif-sur-Yvette, France
| | | |
Collapse
|
32
|
The role of cysteine-150 in the structure and activity of rat liver S-adenosyl-L-methionine synthetase. Biochem J 1991; 274 ( Pt 1):225-9. [PMID: 2001237 PMCID: PMC1150192 DOI: 10.1042/bj2740225] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The present paper reports the tryptic digestion of N-ethylmaleimide-treated S-adenosyl-L-methionine synthetase (high- and low-Mr forms) and the isolation of the modified peptides by h.p.l.c. There is only one site modified after 5 min incubation, and the modification at this site correlates with the main activity decrease. The amino acid composition of this peptide was determined, and its localization in the sequence shows the modified residue as cysteine-150, which is located close to the putative ATP-binding site. Modification of the enzyme for 20 min led to the appearance of a second labelled peptide, which seems to be responsible for about a further 10% of the activity loss. The modification by N-ethylmaleimide of the enzyme was partially prevented in the presence of adenosine 5'-[beta gamma-imido]triphosphate and methionine, further supporting the hypothesis that the modified residues lie within the active site. Urea treatment of the enzyme, followed by modification with N-ethylmaleimide, produces the modification of 7 of the 10 cysteine residues present in the sequence. The results obtained were the same for either of the isoforms.
Collapse
|
33
|
Nucleotide sequence and characterization of a Gene conferring resistance to ethionine in yeast Saccharomyces cerevisiae. ACTA ACUST UNITED AC 1991. [DOI: 10.1016/0922-338x(91)90269-m] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
34
|
Old IG, Phillips SE, Stockley PG, Saint Girons I. Regulation of methionine biosynthesis in the Enterobacteriaceae. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1991; 56:145-85. [PMID: 1771231 DOI: 10.1016/0079-6107(91)90012-h] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- I G Old
- Département de Bactériologie et Mycologie, Institut Pasteur, Paris, France
| | | | | | | |
Collapse
|
35
|
Peleman J, Saito K, Cottyn B, Engler G, Seurinck J, Van Montagu M, Inzé D. Structure and expression analyses of the S-adenosylmethionine synthetase gene family in Arabidopsis thaliana. Gene 1989; 84:359-69. [PMID: 2482229 DOI: 10.1016/0378-1119(89)90510-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The plant, Arabidopsis thaliana, contains two S-adenosylmethionine synthetase-encoding genes (sam). Here, we analyze the structure and expression of the sam-2 gene and compare it with the previously described sam-1 gene. Northern-blot analysis using gene-specific probes shows that both sam-1 and sam-2 are highly expressed in stem, root, and callus tissue. This similar expression pattern might be mediated by the presence of three highly conserved sequences in the 5' region of both sam genes. Using a chimeric beta-glucuronidase (GUS)-encoding gene, we show that in transgenic tobacco plants, 748 bp of 5' sam-1 sequences generate high GUS activity in the same type of tissues as previously observed in transgenic A. thaliana plants. A deletion analysis of these 5' sam-1 sequences indicates that 224 bp of 5' sam-1 sequences can still induce higher expression of the gene in stem and root relative to leaf. However, the level of expression is reduced when compared to the expression level obtained with the full-length promoter.
Collapse
Affiliation(s)
- J Peleman
- Laboratorium voor Genetica, Rijksuniversiteit Gent, Belgium
| | | | | | | | | | | | | |
Collapse
|
36
|
Lobet Y, Lhoest J, Colson C. Partial purification and characterization of the specific protein-lysine N-methyltransferase of YL32, a yeast ribosomal protein. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 997:224-31. [PMID: 2504290 DOI: 10.1016/0167-4838(89)90191-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
YL23 and YL32 are two of the three most heavily methylated ribosomal proteins of Saccharomyces cerevisiae. Using an in vitro assay, it was determined that they are methylated by two distinct enzymes. The protein-lysine N-methyltransferase that methylates YL32 was partially purified by affinity and ion-exchange chromatography. Its molecular mass was estimated to be 82 kDa, and its isoelectric point to be 4.45. Optimum activity was expressed at pH 7.5, and the enzyme was irreversibly inactivated at pH lower than 5.0. The Km of the enzyme for AdoMet is 1.7 +/- 0.4 microM, and the Ki toward AdoHcy was 0.71 microM. Formation of epsilon-N-dimethyllysine was observed to occur in two steps via epsilon-N-monomethyllysine. Like other protein-lysine N-methyltransferases, the methylase of YL32 exhibits a high substrate specificity.
Collapse
Affiliation(s)
- Y Lobet
- Unité de Génétique, Université Catholique de Louvain, Belgium
| | | | | |
Collapse
|
37
|
SAM2 encodes the second methionine S-adenosyl transferase in Saccharomyces cerevisiae: physiology and regulation of both enzymes. Mol Cell Biol 1989. [PMID: 3072475 DOI: 10.1128/mcb.8.12.5132] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Saccharomyces cerevisiae the SAM1 and SAM2 genes encode two distinct forms of S-adenosylmethionine (AdoMet) synthetase. In a previous study we cloned and sequenced the SAM1 gene (D. Thomas and Y. Surdin-Kerjan, J. Biol. Chem. 262:16704-16709, 1987). In this work, the SAM2 gene was isolated by functional complementation of a yeast double-mutant strain, and its identity was ascertained by gene disruption. It has been sequenced and compared with the SAM1 gene. The degree of homology found between the two genes shows that SAM1 and SAM2 are duplicated genes. Using strains disrupted in one or the other SAM gene, we have studied the regulation of their expression by measuring the steady-state level of mRNA after growth under different conditions. The results show that the expression of the two SAM genes is regulated differently, SAM2 being induced by the presence of excess methionine in the growth medium and SAM1 being repressed under the same conditions. The level of mRNA in the parental strain shows that it is not the sum of the levels found in the two disrupted strains. This raises the question of how the two AdoMet synthetases in S. cerevisiae interact to control AdoMet synthesis.
Collapse
|
38
|
Thomas D, Rothstein R, Rosenberg N, Surdin-Kerjan Y. SAM2 encodes the second methionine S-adenosyl transferase in Saccharomyces cerevisiae: physiology and regulation of both enzymes. Mol Cell Biol 1988; 8:5132-9. [PMID: 3072475 PMCID: PMC365615 DOI: 10.1128/mcb.8.12.5132-5139.1988] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
In Saccharomyces cerevisiae the SAM1 and SAM2 genes encode two distinct forms of S-adenosylmethionine (AdoMet) synthetase. In a previous study we cloned and sequenced the SAM1 gene (D. Thomas and Y. Surdin-Kerjan, J. Biol. Chem. 262:16704-16709, 1987). In this work, the SAM2 gene was isolated by functional complementation of a yeast double-mutant strain, and its identity was ascertained by gene disruption. It has been sequenced and compared with the SAM1 gene. The degree of homology found between the two genes shows that SAM1 and SAM2 are duplicated genes. Using strains disrupted in one or the other SAM gene, we have studied the regulation of their expression by measuring the steady-state level of mRNA after growth under different conditions. The results show that the expression of the two SAM genes is regulated differently, SAM2 being induced by the presence of excess methionine in the growth medium and SAM1 being repressed under the same conditions. The level of mRNA in the parental strain shows that it is not the sum of the levels found in the two disrupted strains. This raises the question of how the two AdoMet synthetases in S. cerevisiae interact to control AdoMet synthesis.
Collapse
Affiliation(s)
- D Thomas
- Laboratoire d'Enzymologie du Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | | | | | | |
Collapse
|
39
|
Shiomi N, Fukuda H, Morikawa H, Fukuda Y, Kimura A. Cloning of a gene for S-adenosylmethionine synthesis in Saccharomyces cerevisiae. Appl Microbiol Biotechnol 1988. [DOI: 10.1007/bf00251721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
40
|
Cloning of a gene for S-adenosylmethionine synthesis inSaccharomyces cerevisiae. Appl Microbiol Biotechnol 1988. [DOI: 10.1007/bf01982921] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
41
|
Markham GD, Satishchandran C. Identification of the reactive sulfhydryl groups of S-adenosylmethionine synthetase. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68356-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
|
42
|
Wabiko H, Ochi K, Nguyen DM, Allen ER, Freese E. Genetic mapping and physiological consequences of metE mutations of Bacillus subtilis. J Bacteriol 1988; 170:2705-10. [PMID: 3131307 PMCID: PMC211192 DOI: 10.1128/jb.170.6.2705-2710.1988] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Three metE mutations of Bacillus subtilis, which cause cells to have a 25- to 200-fold decrease in L-methionine S-adenosyltransferase (EC 2.5.1.6) activity, were mapped between bioB and thr. The corresponding three metE mutants contained three- to fourfold less intracellular S-adenosylmethionine (SAM) but at least sevenfold more methionine than the metE+ strain when grown in synthetic medium. This indicates a strong feedback control of SAM on its synthesis. However, only the metE2 strain, with the lowest SAM concentration, grew at a slightly lower rate than the parent, which showed that an intracellular concentration of about 25 microM SAM was critical for growth at the normal rate. Neither DNA methylation (measured by bacteriophage luminal diameter 105 restriction) nor sporulation was affected at this low SAM concentration. Addition of methionine to the growth medium caused an increase in the pool of SAM in some but not all metE mutants. Coaddition of adenine did not change this result. However, the extent of sporulation (induced by mycophenolic acid) was decreased 50-fold in all mutants by the addition of methionine and adenine. Therefore, the combination of methionine and adenine suppresses sporulation regardless of whether it causes an increase in the level of SAM.
Collapse
Affiliation(s)
- H Wabiko
- Laboratory of Molecular Biology, National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, Maryland 20892
| | | | | | | | | |
Collapse
|
43
|
SAM1, the structural gene for one of the S-adenosylmethionine synthetases in Saccharomyces cerevisiae. Sequence and expression. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)49312-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
|
44
|
Locht C, Delcour J. In vitro methylation of undermethylated yeast poly(A)-rich RNA using mRNA(guanine-7-)-methyltransferase purified from wheat germ or yeast. EUROPEAN JOURNAL OF BIOCHEMISTRY 1985; 152:247-51. [PMID: 2414101 DOI: 10.1111/j.1432-1033.1985.tb09190.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
By crossing two strains of Saccharomyces cerevisiae deficient for each of the two methionine adenosyltransferase isoenzymes (ATP: L-methionine S-adenosyltransferase EC 2.5.1.6) respectively, we have constructed a strain strictly auxotrophic for S-adenosylmethionine and used it as a source of undermethylated mRNA suitable for in vitro transmethylation studies. RNA has been phenol-extracted from yeast cells shifted down to S-adenosylmethionine-free medium for 90 min and poly(A)-rich RNA has been prepared by oligo(dT)-cellulose chromatography. Upon incubation in vitro in the presence of methyl-labeled S-adenosylmethionine and mRNA (guanine-7-)-methyltransferase purified from wheat germ or yeast, undermethylated poly(A)-rich RNA became significantly labeled as compared to non-starved cells from the same strain, or from a wild-type control. Cap structures were resolved by paper chromatography afer T2 and P1 RNase digestion, and shown to be a mixture of m7G5'ppp5'G and m7G5'ppp5'A, irrespective of the enzyme source, in agreement with earlier in vivo studies in yeast mRNA capping and methylation.
Collapse
|
45
|
|
46
|
Lhoest J, Lobet Y, Costers E, Colson C. Methylated proteins and amino acids in the ribosomes of Saccharomyces cerevisiae. EUROPEAN JOURNAL OF BIOCHEMISTRY 1984; 141:585-90. [PMID: 6378633 DOI: 10.1111/j.1432-1033.1984.tb08233.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The occurrence of methylated proteins in the ribosomes of Saccharomyces cerevisiae was investigated by tracing the transfer of radioactive methyl groups from S-adenosyl methionine, taken up by growing cells, into the protein moiety of ribosomes. It was estimated that the large subunit contained about 10 protein-bound methyl groups distributed mainly among proteins YL23, YL32 and YL1. The small subunit contained at most 2-4 methyl groups in proteins. Methyl groups could be transferred in vitro to proteins YL23 and YL32 in extracts from cultures of an S-adenosyl methionine auxotroph deprived of the methyl-group donor. In the most heavily methylated proteins the methylated amino acids formed in vitro were the same as those found in vivo (monomethyllysine and dimethyllysine in YL32; dimethyl and trimethyllsine in YL23). It is concluded that the enzymatic reaction in vitro faithfully saturates with methyl groups the target amino acids which are normally fully methylated in vivo.
Collapse
|
47
|
Locht C, Beaudart JL, Delcour J. Partial purification and characterization of mRNA (guanine-7-) methyltransferase from the yeast Saccharomyces cerevisiae. EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 134:117-21. [PMID: 6345158 DOI: 10.1111/j.1432-1033.1983.tb07539.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
As a tool for the study of the capping-methylation process of yeast mRNA, we developed a procedure for the purification of the mRNA (guanine-7-)methyltransferase using the commercial cap analog guanosine(5')triphospho(5')guanosine as a substrate and radioactive S-adenosylmethionine (AdoMet) as the methyl group donor. The osmotic-sensitive yeast strain VY 1160 was used as the enzyme source. Little methyltransferase activity was detectable in a crude lysate obtained after osmotic shock. We showed that this was due to the presence of a low-molecular-weight inhibitor which could easily be eliminated by Sephadex G-25 gel filtration. The 10000 X g supernatant from the crude lysate was submitted to DEAE-cellulose and DNA-agarose chromatography. The resulting preparation was enriched about 450-fold in specific activity. Under standard assay conditions, the incorporation rate remained constant for at least 6 h at 30 degrees C. Transmethylation was not stimulated by KCl nor NaCl. Divalent cations were strong inhibitors. The partially purified enzyme was able to methylate undermethylated poly(A)-rich mRNA isolated from an AdoMet auxotrophic yeast strain briefly exposed to AdoMet-free medium.
Collapse
|
48
|
Lombardini JB, Sufrin JR. Chemotherapeutic potential of methionine analogue inhibitors of tumor-derived methionine adenosyltransferases. Biochem Pharmacol 1983; 32:489-95. [PMID: 6847699 DOI: 10.1016/0006-2952(83)90528-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Two isozymes of ATP:L-methionine S-adenosyltransferase (MAT) were fractionated from rat Novikoff solid hepatoma. Their Km values for L-methionine and/or their inhibition constants for various L-methionine analogues were significantly different from the kinetic constants obtained for three isozymes fractionated from normal rat liver. Ki values for cycloleucine and (+/-)-2-aminobicyclo[2.1.1]hexane-2-carboxylic acid, presented for each tumor and liver isozyme, indicate that (+/-)-2-aminobicyclo[2.1.1]hexane-2-carboxylic acid was the more potent inhibitor. Dixon plots were also used to test a series of amino acid analogues [cycloleucine, 1-aminocyclobutanecarboxylic acid, 1-aminocyclohexanecarboxylic acid, (+/-)-2-aminobicyclo[2.1.1]hexane-2-carboxylic acid, L-2-amino-4-hexynoic acid, (Z)-L-2-amino-5-chloro-trans-4-hexenoic acid, L-ethionine, S-n-propyl-DL-homocysteine, S-n-butyl-DL-homocysteine, and seleno-DL-ethionine] of methionine for inhibitory potency. Fixed L-methionine concentrations were used to determine the concentration of inhibitor necessary to inhibit the MAT reaction by 50%. Differential inhibitory activities of the amino acid analogues were noted between the tumor and rat liver isozymes thus supporting the suggestion that tumor-derived MAT isozymes may provide an exploitable target for cancer chemotherapy.
Collapse
|
49
|
Middelhoven WJ, Hoogkamer-te Niet MC. Nitrogen metabolite repression of arginase, ornithine transaminase and allantoinase in a conditional ethionine-resistant mutant of Saccharomyces cerevisiae with low activity of catabolic NAD-specific glutamate dehydrogenase. Antonie Van Leeuwenhoek 1982; 48:417-32. [PMID: 6762146 DOI: 10.1007/bf00448414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|
50
|
Alix JH. Molecular aspects of the in vivo and in vitro effects of ethionine, an analog of methionine. Microbiol Rev 1982; 46:281-95. [PMID: 6752686 PMCID: PMC281545 DOI: 10.1128/mr.46.3.281-295.1982] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
|