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Wangsanut T, Amsri A, Pongpom M. Antibody screening reveals antigenic proteins involved in Talaromyces marneffei and human interaction. Front Cell Infect Microbiol 2023; 13:1118979. [PMID: 37404721 PMCID: PMC10315666 DOI: 10.3389/fcimb.2023.1118979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 05/30/2023] [Indexed: 07/06/2023] Open
Abstract
Talaromycosis is a fungal infection that generally affects immunocompromised hosts and is one of the most frequent systemic mycoses in HIV patients, especially in endemic areas such as Southeast Asia. Talaromyces marneffei, the causative agent of talaromycosis, grows as a mold in the environment but adapts to the human body and host niches by transitioning from conidia to yeast-like cells. Knowledge of the human host and T. marneffei interaction has a direct impact on the diagnosis, yet studies are still lacking. The morbidity and mortality rates are high in taloromycosis patients if the diagnosis and treatments are delayed. Immunogenic proteins are excellent candidates for developing detection tools. Previously, we identified antigenic proteins that were recognized by antibodies from talaromycosis sera. Three of these identified proteins have been previously characterized in detail, while the others have not been explored. To expedite the progress of antigen discovery, the complete list of antigenic proteins and their features was fully reported in this study. Functional annotation and Gene Ontology examination revealed that these proteins showed a high association with membrane trafficking. Further bioinformatics analyses were performed to search for antigenic protein characteristics, including functional domains, critical residues, subcellular localization, secretory signals, and epitope peptide sequences. Expression profiling of these antigenic encoding genes was investigated using quantitative real-time PCR. The results demonstrated that most genes were expressed at low levels in the mold form, but were highly upregulated in the pathogenic yeast phase, consistent with the antigenic role of these genes during the human-host interaction. Most transcripts accumulated in the conidia, suggesting a role during phase transition. The collection of all antigen-encoding DNA sequences described here is freely accessible at GenBank, which could be useful for the research community to develop into biomarkers, diagnostic tests, research detection tools, and even vaccines.
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Tirincsi A, Sicking M, Hadzibeganovic D, Haßdenteufel S, Lang S. The Molecular Biodiversity of Protein Targeting and Protein Transport Related to the Endoplasmic Reticulum. Int J Mol Sci 2021; 23:143. [PMID: 35008565 PMCID: PMC8745461 DOI: 10.3390/ijms23010143] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 12/19/2021] [Accepted: 12/20/2021] [Indexed: 12/15/2022] Open
Abstract
Looking at the variety of the thousands of different polypeptides that have been focused on in the research on the endoplasmic reticulum from the last five decades taught us one humble lesson: no one size fits all. Cells use an impressive array of components to enable the safe transport of protein cargo from the cytosolic ribosomes to the endoplasmic reticulum. Safety during the transit is warranted by the interplay of cytosolic chaperones, membrane receptors, and protein translocases that together form functional networks and serve as protein targeting and translocation routes. While two targeting routes to the endoplasmic reticulum, SRP (signal recognition particle) and GET (guided entry of tail-anchored proteins), prefer targeting determinants at the N- and C-terminus of the cargo polypeptide, respectively, the recently discovered SND (SRP-independent) route seems to preferentially cater for cargos with non-generic targeting signals that are less hydrophobic or more distant from the termini. With an emphasis on targeting routes and protein translocases, we will discuss those functional networks that drive efficient protein topogenesis and shed light on their redundant and dynamic nature in health and disease.
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Affiliation(s)
- Andrea Tirincsi
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Mark Sicking
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Drazena Hadzibeganovic
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
| | - Sarah Haßdenteufel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Sven Lang
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany; (A.T.); (M.S.); (D.H.)
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3
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Kerdsomboon K, Techo T, Limcharoensuk T, Tatip S, Auesukaree C. Low phosphate mitigates cadmium-induced oxidative stress in Saccharomyces cerevisiae by enhancing endogenous antioxidant defence system. Environ Microbiol 2021; 24:707-720. [PMID: 34927334 DOI: 10.1111/1462-2920.15875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/10/2021] [Accepted: 12/11/2021] [Indexed: 11/30/2022]
Abstract
Cadmium is a highly toxic heavy metal that causes many harmful effects on human health and ecosystems. Metal chelation-based techniques have become a common approach for the treatment of metal poisoning and also for the remediation of metal contamination. Phosphate, an essential nutrient required for key cellular functions, has been supposed to be effective in reducing cadmium bioavailability, possibly through its chelating potential. In this study, we explored the effects of phosphate on cadmium toxicity and cellular response to cadmium stress in the eukaryotic model Saccharomyces cerevisiae. Our results reveal that cadmium toxicity is unexpectedly enhanced during phosphate repletion and optimal phosphate levels for yeast growth under cadmium stress conditions decline with increasing cadmium concentrations. The profound cadmium toxicity during phosphate repletion is unlikely to result from either elevated cadmium accumulation or dysregulated homeostasis of essential metals, but rather due to increased production of intracellular reactive oxygen species. We show that, under phosphate-depleted conditions, the activities of antioxidant enzymes, especially Mn-superoxide dismutase and catalase, are significantly promoted through transcriptional upregulation. Our findings highlight the important role of cellular response to phosphate limitation in mitigating cadmium toxicity and endogenous oxidative stress through the enhancement of antioxidant enzyme activity.
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Affiliation(s)
- Kittikhun Kerdsomboon
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Chulabhorn International College of Medicine, Thammasat University, Pathum Thani, 12120, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry of Education, Bangkok, 10400, Thailand.,Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Todsapol Techo
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry of Education, Bangkok, 10400, Thailand.,Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Tossapol Limcharoensuk
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry of Education, Bangkok, 10400, Thailand.,Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Supinda Tatip
- Department of Biology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Center of Excellence on Environmental Health and Toxicology, CHE, Ministry of Education, Bangkok, 10400, Thailand.,Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Choowong Auesukaree
- Center of Excellence on Environmental Health and Toxicology, CHE, Ministry of Education, Bangkok, 10400, Thailand.,Mahidol University-Osaka University Collaborative Research Center for Bioscience and Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.,Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
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4
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Aviram N, Ast T, Costa EA, Arakel EC, Chuartzman SG, Jan CH, Haßdenteufel S, Dudek J, Jung M, Schorr S, Zimmermann R, Schwappach B, Weissman JS, Schuldiner M. The SND proteins constitute an alternative targeting route to the endoplasmic reticulum. Nature 2017; 540:134-138. [PMID: 27905431 DOI: 10.1038/nature20169] [Citation(s) in RCA: 148] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 10/18/2016] [Indexed: 12/19/2022]
Abstract
In eukaryotes, up to one-third of cellular proteins are targeted to the endoplasmic reticulum, where they undergo folding, processing, sorting and trafficking to subsequent endomembrane compartments. Targeting to the endoplasmic reticulum has been shown to occur co-translationally by the signal recognition particle (SRP) pathway or post-translationally by the mammalian transmembrane recognition complex of 40 kDa (TRC40) and homologous yeast guided entry of tail-anchored proteins (GET) pathways. Despite the range of proteins that can be catered for by these two pathways, many proteins are still known to be independent of both SRP and GET, so there seems to be a critical need for an additional dedicated pathway for endoplasmic reticulum relay. We set out to uncover additional targeting proteins using unbiased high-content screening approaches. To this end, we performed a systematic visual screen using the yeast Saccharomyces cerevisiae, and uncovered three uncharacterized proteins whose loss affected targeting. We suggest that these proteins work together and demonstrate that they function in parallel with SRP and GET to target a broad range of substrates to the endoplasmic reticulum. The three proteins, which we name Snd1, Snd2 and Snd3 (for SRP-independent targeting), can synthetically compensate for the loss of both the SRP and GET pathways, and act as a backup targeting system. This explains why it has previously been difficult to demonstrate complete loss of targeting for some substrates. Our discovery thus puts in place an essential piece of the endoplasmic reticulum targeting puzzle, highlighting how the targeting apparatus of the eukaryotic cell is robust, interlinked and flexible.
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Affiliation(s)
- Naama Aviram
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Tslil Ast
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Elizabeth A Costa
- Department of Cellular and Molecular Pharmacology, UCSF California Institute for Quantitative Biomedical Research and Howard Hughes Medical Institute, San Francisco, California 94158-2330, USA
| | - Eric C Arakel
- Department of Molecular Biology, University Medical Center Göttingen, 37073 Göttingen, Germany
| | - Silvia G Chuartzman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Calvin H Jan
- Department of Cellular and Molecular Pharmacology, UCSF California Institute for Quantitative Biomedical Research and Howard Hughes Medical Institute, San Francisco, California 94158-2330, USA
| | - Sarah Haßdenteufel
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany
| | - Johanna Dudek
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany
| | - Martin Jung
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany
| | - Stefan Schorr
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany
| | - Richard Zimmermann
- Department of Medical Biochemistry and Molecular Biology, Saarland University, 66421 Homburg, Germany
| | - Blanche Schwappach
- Department of Molecular Biology, University Medical Center Göttingen, 37073 Göttingen, Germany.,Max-Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - Jonathan S Weissman
- Department of Cellular and Molecular Pharmacology, UCSF California Institute for Quantitative Biomedical Research and Howard Hughes Medical Institute, San Francisco, California 94158-2330, USA
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel
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5
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Gjuvsland AB, Zörgö E, Samy JK, Stenberg S, Demirsoy IH, Roque F, Maciaszczyk-Dziubinska E, Migocka M, Alonso-Perez E, Zackrisson M, Wysocki R, Tamás MJ, Jonassen I, Omholt SW, Warringer J. Disentangling genetic and epigenetic determinants of ultrafast adaptation. Mol Syst Biol 2016; 12:892. [PMID: 27979908 PMCID: PMC5199126 DOI: 10.15252/msb.20166951] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
A major rationale for the advocacy of epigenetically mediated adaptive responses is that they facilitate faster adaptation to environmental challenges. This motivated us to develop a theoretical-experimental framework for disclosing the presence of such adaptation-speeding mechanisms in an experimental evolution setting circumventing the need for pursuing costly mutation-accumulation experiments. To this end, we exposed clonal populations of budding yeast to a whole range of stressors. By growth phenotyping, we found that almost complete adaptation to arsenic emerged after a few mitotic cell divisions without involving any phenotypic plasticity. Causative mutations were identified by deep sequencing of the arsenic-adapted populations and reconstructed for validation. Mutation effects on growth phenotypes, and the associated mutational target sizes were quantified and embedded in data-driven individual-based evolutionary population models. We found that the experimentally observed homogeneity of adaptation speed and heterogeneity of molecular solutions could only be accounted for if the mutation rate had been near estimates of the basal mutation rate. The ultrafast adaptation could be fully explained by extensive positive pleiotropy such that all beneficial mutations dramatically enhanced multiple fitness components in concert. As our approach can be exploited across a range of model organisms exposed to a variety of environmental challenges, it may be used for determining the importance of epigenetic adaptation-speeding mechanisms in general.
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Affiliation(s)
- Arne B Gjuvsland
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Enikö Zörgö
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway.,Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Jeevan Ka Samy
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Simon Stenberg
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Ibrahim H Demirsoy
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Francisco Roque
- Computational Biology Unit, University of Bergen, Bergen, Norway
| | | | - Magdalena Migocka
- Institute of Experimental Biology, University of Wroclaw, Wroclaw, Poland
| | - Elisa Alonso-Perez
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Martin Zackrisson
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Robert Wysocki
- Institute of Experimental Biology, University of Wroclaw, Wroclaw, Poland
| | - Markus J Tamás
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Inge Jonassen
- Computational Biology Unit, University of Bergen, Bergen, Norway
| | - Stig W Omholt
- Centre for Biodiversity Dynamics, Department of Biology, NTNU - Norwegian University of Science and Technology, Trondheim, Norway
| | - Jonas Warringer
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway .,Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
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6
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Maciaszczyk-Dziubinska E, Wawrzycka D, Wysocki R. Arsenic and antimony transporters in eukaryotes. Int J Mol Sci 2012; 13:3527-3548. [PMID: 22489166 PMCID: PMC3317726 DOI: 10.3390/ijms13033527] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 02/29/2012] [Accepted: 03/07/2012] [Indexed: 12/27/2022] Open
Abstract
Arsenic and antimony are toxic metalloids, naturally present in the environment and all organisms have developed pathways for their detoxification. The most effective metalloid tolerance systems in eukaryotes include downregulation of metalloid uptake, efflux out of the cell, and complexation with phytochelatin or glutathione followed by sequestration into the vacuole. Understanding of arsenic and antimony transport system is of high importance due to the increasing usage of arsenic-based drugs in the treatment of certain types of cancer and diseases caused by protozoan parasites as well as for the development of bio- and phytoremediation strategies for metalloid polluted areas. However, in contrast to prokaryotes, the knowledge about specific transporters of arsenic and antimony and the mechanisms of metalloid transport in eukaryotes has been very limited for a long time. Here, we review the recent advances in understanding of arsenic and antimony transport pathways in eukaryotes, including a dual role of aquaglyceroporins in uptake and efflux of metalloids, elucidation of arsenic transport mechanism by the yeast Acr3 transporter and its role in arsenic hyperaccumulation in ferns, identification of vacuolar transporters of arsenic-phytochelatin complexes in plants and forms of arsenic substrates recognized by mammalian ABC transporters.
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Affiliation(s)
- Ewa Maciaszczyk-Dziubinska
- Department of Genetics and Cell Physiology, Institute of Plant Biology, University of Wroclaw, Kanonia 6/8, 50-328 Wroclaw, Poland; E-Mail:
| | - Donata Wawrzycka
- Department of Genetics and Cell Physiology, Institute of Plant Biology, University of Wroclaw, Kanonia 6/8, 50-328 Wroclaw, Poland; E-Mail:
| | - Robert Wysocki
- Department of Genetics and Cell Physiology, Institute of Plant Biology, University of Wroclaw, Kanonia 6/8, 50-328 Wroclaw, Poland; E-Mail:
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7
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Hurto RL, Tong AHY, Boone C, Hopper AK. Inorganic phosphate deprivation causes tRNA nuclear accumulation via retrograde transport in Saccharomyces cerevisiae. Genetics 2007; 176:841-52. [PMID: 17409072 PMCID: PMC1894612 DOI: 10.1534/genetics.106.069732] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nuclear export of tRNA is an essential eukaryotic function, yet the one known yeast tRNA nuclear exporter, Los1, is nonessential. Moreover recent studies have shown that tRNAs can move retrograde from the cytosol to the nucleus by an undefined process. Therefore, additional gene products involved in tRNA nucleus-cytosol dynamics have yet to be identified. Synthetic genetic array (SGA) analysis was employed to identify proteins involved in Los1-independent tRNA transport and in regulating tRNA nucleus-cytosol distribution. These studies uncovered synthetic interactions between los1Delta and pho88Delta involved in inorganic phopsphate uptake. Further analysis revealed that inorganic phosphate deprivation causes transient, temperature-dependent nuclear accumulation of mature cytoplasmic tRNA within nuclei via a Mtr10- and retrograde-dependent pathway, providing a novel connection between tRNA subcellular dynamics and phosphate availability.
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Affiliation(s)
- Rebecca L. Hurto
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210 and Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario M5G 1L6, Canada
| | - Amy Hin Yan Tong
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210 and Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario M5G 1L6, Canada
| | - Charles Boone
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210 and Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario M5G 1L6, Canada
| | - Anita K. Hopper
- Department of Molecular Genetics, Ohio State University, Columbus, Ohio 43210 and Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario M5G 1L6, Canada
- Corresponding author: Department of Molecular Genetics, Ohio State University, 484 W. 12th Ave., Columbus, OH 43210. E-mail:
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8
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Miller JP, Lo RS, Ben-Hur A, Desmarais C, Stagljar I, Noble WS, Fields S. Large-scale identification of yeast integral membrane protein interactions. Proc Natl Acad Sci U S A 2005; 102:12123-8. [PMID: 16093310 PMCID: PMC1189342 DOI: 10.1073/pnas.0505482102] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We carried out a large-scale screen to identify interactions between integral membrane proteins of Saccharomyces cerevisiae by using a modified split-ubiquitin technique. Among 705 proteins annotated as integral membrane, we identified 1,985 putative interactions involving 536 proteins. To ascribe confidence levels to the interactions, we used a support vector machine algorithm to classify interactions based on the assay results and protein data derived from the literature. Previously identified and computationally supported interactions were used to train the support vector machine, which identified 131 interactions of highest confidence, 209 of the next highest confidence, 468 of the next highest, and the remaining 1,085 of low confidence. This study provides numerous putative interactions among a class of proteins that have been difficult to analyze on a high-throughput basis by other approaches. The results identify potential previously undescribed components of established biological processes and roles for integral membrane proteins of ascribed functions.
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Affiliation(s)
- John P Miller
- Department of Genome Sciences, Howard Hughes Medical Institute, University of Washington, Seattle, WA 98195, USA
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9
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Almaguer C, Mantella D, Perez E, Patton-Vogt J. Inositol and phosphate regulate GIT1 transcription and glycerophosphoinositol incorporation in Saccharomyces cerevisiae. EUKARYOTIC CELL 2003; 2:729-36. [PMID: 12912892 PMCID: PMC178388 DOI: 10.1128/ec.2.4.729-736.2003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glycerophosphoinositol is produced through deacylation of the essential phospholipid phosphatidylinositol. In Saccharomyces cerevisiae, the glycerophosphoinositol produced is excreted from the cell but is recycled for phosphatidylinositol synthesis when inositol is limiting. To be recycled, glycerophosphoinositol enters the cell through the permease encoded by GIT1. The transport of exogenous glycerophosphoinositol through Git1p is sufficiently robust to support the growth of an inositol auxotroph (ino1Delta). We now report that S. cerevisiae also uses exogenous phosphatidylinositol as an inositol source. Evidence suggests that phosphatidylinositol is deacylated to glycerophosphoinositol extracellularly before being transported across the plasma membrane by Git1p. A genetic screen identified Pho86p, which is required for targeting of the major phosphate transporter (Pho84p) to the plasma membrane, as affecting the utilization of phosphatidylinositol and glycerophosphoinositol. Deletion of PHO86 in an ino1Delta strain resulted in faster growth when either phosphatidylinositol or glycerophosphoinositol was supplied as the sole inositol source. The incorporation of radiolabeled glycerophosphoinositol into an ino1Delta pho86Delta mutant was higher than that into wild-type, ino1Delta, and pho86Delta strains. All strains accumulated the most GIT1 transcript when incubated in media limited for inositol and phosphate in combination. However, the ino1Delta pho86Delta mutant accumulated approximately threefold more GIT1 transcript than did the other strains when incubated in inositol-free media containing either high or low concentrations of P(i). Deletion of PHO4 abolished GIT1 transcription in a wild-type strain. These results indicate that the transport of glycerophosphoinositol by Git1p is regulated by factors affecting both inositol and phosphate availabilities and suggest a regulatory connection between phosphate metabolism and phospholipid metabolism.
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Affiliation(s)
- C Almaguer
- Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania 15282, USA
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10
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Persson BL, Lagerstedt JO, Pratt JR, Pattison-Granberg J, Lundh K, Shokrollahzadeh S, Lundh F. Regulation of phosphate acquisition in Saccharomyces cerevisiae. Curr Genet 2003; 43:225-44. [PMID: 12740714 DOI: 10.1007/s00294-003-0400-9] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2003] [Revised: 04/05/2003] [Accepted: 04/08/2003] [Indexed: 01/08/2023]
Abstract
Membrane transport systems active in cellular inorganic phosphate (P(i)) acquisition play a key role in maintaining cellular P(i) homeostasis, independent of whether the cell is a unicellular microorganism or is contained in the tissue of a higher eukaryotic organism. Since unicellular eukaryotes such as yeast interact directly with the nutritious environment, regulation of P(i) transport is maintained solely by transduction of nutrient signals across the plasma membrane. The individual yeast cell thus recognizes nutrients that can act as both signals and sustenance. The present review provides an overview of P(i) acquisition via the plasma membrane P(i) transporters of Saccharomyces cerevisiae and the regulation of internal P(i) stores under the prevailing P(i) status.
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Affiliation(s)
- Bengt L Persson
- Department of Chemistry and Biomedical Science, Kalmar University, P.O. Box 905, 39182, Kalmar, Sweden.
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11
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Lau WT, Howson RW, Malkus P, Schekman R, O'Shea EK. Pho86p, an endoplasmic reticulum (ER) resident protein in Saccharomyces cerevisiae, is required for ER exit of the high-affinity phosphate transporter Pho84p. Proc Natl Acad Sci U S A 2000; 97:1107-12. [PMID: 10655492 PMCID: PMC15537 DOI: 10.1073/pnas.97.3.1107] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the budding yeast Saccharomyces cerevisiae, PHO84 and PHO86 are among the genes that are most highly induced in response to phosphate starvation. They are essential for growth when phosphate is limiting, and they function in the high-affinity phosphate uptake system. PHO84 encodes a high-affinity phosphate transporter, and mutations in PHO86 cause many of the same phenotypes as mutations in PHO84, including a phosphate uptake defect and constitutive expression of the secreted acid phosphatase, Pho5p. Here, we show that the subcellular localization of Pho84p is regulated in response to extracellular phosphate levels; it is localized to the plasma membrane in low-phosphate medium but quickly endocytosed and transported to the vacuole upon addition of phosphate to the medium. Moreover, Pho84p is localized to the endoplasmic reticulum (ER) and fails to be targeted to the plasma membrane in the absence of Pho86p. Utilizing an in vitro vesicle budding assay, we demonstrate that Pho86p is required for packaging of Pho84p into COPII vesicles. Pho86p is an ER resident protein, which itself is not transported out of the ER. Interestingly, the requirement of Pho86p for ER exit is specific to Pho84p, because other members of the hexose transporter family to which Pho84 belongs are not mislocalized in the absence of Pho86p.
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Affiliation(s)
- W T Lau
- Program in Biophysics, University of California, San Francisco, CA 94143-0448, USA
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