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Saeki N, Yamamoto C, Eguchi Y, Sekito T, Shigenobu S, Yoshimura M, Yashiroda Y, Boone C, Moriya H. Overexpression profiling reveals cellular requirements in the context of genetic backgrounds and environments. PLoS Genet 2023; 19:e1010732. [PMID: 37115757 PMCID: PMC10171610 DOI: 10.1371/journal.pgen.1010732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 05/10/2023] [Accepted: 04/04/2023] [Indexed: 04/29/2023] Open
Abstract
Overexpression can help life adapt to stressful environments, making an examination of overexpressed genes valuable for understanding stress tolerance mechanisms. However, a systematic study of genes whose overexpression is functionally adaptive (GOFAs) under stress has yet to be conducted. We developed a new overexpression profiling method and systematically identified GOFAs in Saccharomyces cerevisiae under stress (heat, salt, and oxidative). Our results show that adaptive overexpression compensates for deficiencies and increases fitness under stress, like calcium under salt stress. We also investigated the impact of different genetic backgrounds on GOFAs, which varied among three S. cerevisiae strains reflecting differing calcium and potassium requirements for salt stress tolerance. Our study of a knockout collection also suggested that calcium prevents mitochondrial outbursts under salt stress. Mitochondria-enhancing GOFAs were only adaptive when adequate calcium was available and non-adaptive when calcium was deficient, supporting this idea. Our findings indicate that adaptive overexpression meets the cell's needs for maximizing the organism's adaptive capacity in the given environment and genetic context.
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Affiliation(s)
- Nozomu Saeki
- Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan
| | - Chie Yamamoto
- Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan
| | - Yuichi Eguchi
- Biomedical Business Center, RICOH Futures BU, Kanagawa, Japan
| | - Takayuki Sekito
- Graduate School of Agriculture, Ehime University, Matsuyama, Japan
| | | | - Mami Yoshimura
- RIKEN Center for Sustainable Resource Science, Wako, Japan
| | - Yoko Yashiroda
- RIKEN Center for Sustainable Resource Science, Wako, Japan
| | - Charles Boone
- RIKEN Center for Sustainable Resource Science, Wako, Japan
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Hisao Moriya
- Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, Japan
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2
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Maruyama Y, Sadahira T, Nagasaki N, Watanabe T, Sekito T, Iwata T, Ishii A, Watanabe M, Wada K, Araki M. Transition in antimicrobial susceptibility and impact of urease production on urinary stone formation of P. mirabilis and M. morganii isolated from urinary tract infections. Eur Urol 2023. [DOI: 10.1016/s0302-2838(23)00782-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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3
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Ohnishi S, Kawano-Kawada M, Yamamoto Y, Akiyama K, Sekito T. A vacuolar membrane protein Vsb1p contributes to the vacuolar compartmentalization of basic amino acids in Schizosaccharomyces pombe. Biosci Biotechnol Biochem 2022; 86:763-769. [PMID: 35289847 DOI: 10.1093/bbb/zbac041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 03/10/2022] [Indexed: 11/12/2022]
Abstract
Accumulation levels of Arg, Lys, and His in vacuoles of Schizosaccharomyces pombe cells were drastically decreased by the disruption of SPAC24H6.11c (vsb1+) gene identified by a homology search with the VSB1 gene of Saccharomyces cerevisiae. The Vsb1p fused with green fluorescent protein particularly localized at vacuolar membranes in S. pombe cells. Overexpression of vsb1+ markedly increased vacuolar levels of basic amino acids; however, overexpression of the vsb1D174A mutant did not affect the levels of these amino acids. These results suggest that the vsb1+ contributes to the accumulation of basic amino acids into the vacuoles of S. pombe, and the aspartate residue in the putative first transmembrane domain conserved among fungal homologs is crucial for the function of Vsb1p.
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Affiliation(s)
- Shota Ohnishi
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Graduate School of Agriculture, Ehime University, Matsuyama, Japan
| | - Miyuki Kawano-Kawada
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Graduate School of Agriculture, Ehime University, Matsuyama, Japan.,Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama, Japan.,Advanced Research Support Center, Ehime University, Matsuyama, Japan
| | - Yusuke Yamamoto
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Graduate School of Agriculture, Ehime University, Matsuyama, Japan
| | - Koichi Akiyama
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Graduate School of Agriculture, Ehime University, Matsuyama, Japan.,Advanced Research Support Center, Ehime University, Matsuyama, Japan
| | - Takayuki Sekito
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Graduate School of Agriculture, Ehime University, Matsuyama, Japan.,Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama, Japan
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4
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Yoshinaga K, Araki M, Wada K, Sekito T, Watari S, Maruyama Y, Sadahira T, Nishimura S, Sako T, Edamura K, Kobayashi Y, Watanabe M, Watanabe T, Nasu Y. Well controlled patients with diabetes mellitus has the potential to expand the kidney donor pool. Eur Urol 2021. [DOI: 10.1016/s0302-2838(21)00724-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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5
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Kawano-Kawada M, Ichimura H, Ohnishi S, Yamamoto Y, Kawasaki Y, Sekito T. Ygr125w/Vsb1-dependent accumulation of basic amino acids into vacuoles of Saccharomyces cerevisiae. Biosci Biotechnol Biochem 2021; 85:1157-1164. [PMID: 33704406 DOI: 10.1093/bbb/zbab015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 01/20/2021] [Indexed: 01/23/2023]
Abstract
The Ygr125w was previously identified as a vacuolar membrane protein by a proteomic analysis. We found that vacuolar levels of basic amino acids drastically decreased in ygr125wΔ cells. Since N- or C-terminally tagged Ygr125w was not functional, an expression plasmid of YGR125w with HA3-tag inserted in its N-terminal hydrophilic region was constructed. Introduction of this plasmid into ygr125w∆ cells restored the vacuolar levels of basic amino acids. We successfully detected the uptake activity of arginine by the vacuolar membrane vesicles depending on HA3-YGR125w expression. A conserved aspartate residue in the predicted first transmembrane helix (D223) was indispensable for the accumulation of basic amino acids. YGR125w has been recently reported as a gene involved in vacuolar storage of arginine; and it is designated as VSB1. Taken together, our findings indicate that Ygr125w/Vsb1 contributes to the uptake of arginine into vacuoles and vacuolar compartmentalization of basic amino acids.
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Affiliation(s)
- Miyuki Kawano-Kawada
- Laboratory of Molecular Physiology and Genetics, Graduate School of Agriculture, Ehime University, Matsuyama, Japan.,Division of Cell-Free Life Sciences, Proteo-Science Center, Ehime University, Matsuyama, Japan.,Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Japan
| | - Haruka Ichimura
- Laboratory of Molecular Physiology and Genetics, Graduate School of Agriculture, Ehime University, Matsuyama, Japan
| | - Shota Ohnishi
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Yusuke Yamamoto
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Yumi Kawasaki
- Laboratory of Molecular Physiology and Genetics, Graduate School of Agriculture, Ehime University, Matsuyama, Japan
| | - Takayuki Sekito
- Laboratory of Molecular Physiology and Genetics, Graduate School of Agriculture, Ehime University, Matsuyama, Japan.,Division of Cell-Free Life Sciences, Proteo-Science Center, Ehime University, Matsuyama, Japan
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6
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Sato A, Kimura T, Hondo K, Kawano-Kawada M, Sekito T. The vacuolar amino acid transport system is a novel, direct target of GATA transcription factors. Biosci Biotechnol Biochem 2021; 85:587-599. [PMID: 33624780 DOI: 10.1093/bbb/zbaa041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 10/20/2020] [Indexed: 01/21/2023]
Abstract
In Saccharomyces cerevisiae, Avt4 exports neutral and basic amino acids from vacuoles. Previous studies have suggested that the GATA transcription factors, Gln3 and Gat1, which are key regulators that adapt cells in response to changes in amino acid status, are involved in the AVT4 transcription. Here, we show that mutations in the putative GATA-binding sites of the AVT4 promoter reduced AVT4 expression. Consistently, a chromatin immunoprecipitation (ChIP) assay revealed that Gat1-Myc13 binds to the AVT4 promoter. Previous microarray results were confirmed that gln3∆gat1∆ cells showed a decrease in expression of AVT1 and AVT7, which also encode vacuolar amino acid transporters. Additionally, ChIP analysis revealed that the AVT6 encoding vacuolar acidic amino acid exporter represents a new direct target of the GATA transcription factor. The broad effect of the GATA transcription factors on the expression of AVT transporters suggests that vacuolar amino acid transport is integrated into cellular amino acid homeostasis.
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Affiliation(s)
- Akane Sato
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan
| | - Takumi Kimura
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan
| | - Kana Hondo
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan
| | - Miyuki Kawano-Kawada
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan.,Proteo-Science Center (PROS), Ehime University, Matsuyama, Ehime, Japan.,Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Ehime, Japan
| | - Takayuki Sekito
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan.,Proteo-Science Center (PROS), Ehime University, Matsuyama, Ehime, Japan
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7
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Kawano-Kawada M, Ueda T, Mori H, Ichimura H, Takegawa K, Sekito T. Stm1 is a vacuolar PQ-loop protein involved in the transport of basic amino acids in Schizosaccharomyces pombe. Biochim Biophys Acta Biomembr 2020; 1863:183507. [PMID: 33189720 DOI: 10.1016/j.bbamem.2020.183507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 10/21/2020] [Accepted: 11/06/2020] [Indexed: 12/14/2022]
Abstract
The stm1+ (SPAC17C9.10) gene of Schizosaccharomyces pombe is closely related to genes encoding vacuolar PQ-loop proteins, Ypq1, Ypq2, and Ypq3, of Saccharomyces cerevisiae. When stm1+ fused with GFP was expressed in fission or budding yeast, Stm1-GFP localized at the vacuolar membrane. Isolated vacuolar membrane vesicles from S. cerevisiae cells overexpressing stm1+ exhibited stm1+-dependent arginine and lysine uptake activity. Exchange activity of arginine and histidine/arginine, as observed for Ypq2 of S. cerevisiae, was also detected in the vesicles expressing stm1+. The expression levels of stm1+ in S. pombe cells significantly affected the vacuolar contents of lysine, histidine, and arginine. These results suggest that Stm1 is a vacuolar PQ-loop protein involved in the transport of basic amino acids across the vacuolar membrane.
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Affiliation(s)
- Miyuki Kawano-Kawada
- Laboratory of Molecular Physiology and Genetics, Department of Bioscience, Graduate School of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566, Japan; Advanced Research Support Center (ADRES), Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566, Japan; Division of Cell-Free Life Science, Proteo-Science Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan
| | - Taisuke Ueda
- Laboratory of Molecular Physiology and Genetics, Department of Bioscience, Graduate School of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566, Japan
| | - Hikari Mori
- Laboratory of Applied Microbiology, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Haruka Ichimura
- Laboratory of Molecular Physiology and Genetics, Department of Bioscience, Graduate School of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566, Japan
| | - Kaoru Takegawa
- Laboratory of Applied Microbiology, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Takayuki Sekito
- Laboratory of Molecular Physiology and Genetics, Department of Bioscience, Graduate School of Agriculture, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566, Japan; Division of Cell-Free Life Science, Proteo-Science Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
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8
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Kawano-Kawada M, Kakinuma Y, Sekito T. Transport of Amino Acids across the Vacuolar Membrane of Yeast: Its Mechanism and Physiological Role. Biol Pharm Bull 2019; 41:1496-1501. [PMID: 30270317 DOI: 10.1248/bpb.b18-00165] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In yeast cells growing under nutrient-rich condition approximately 50% of total amino acids are accumulated in the vacuoles; however, the composition of amino acids in the cytosol and in the vacuoles is quite different. The vacuoles, like lysosomes, degrade proteins transported into their lumen and produce amino acids. These amino acids should be quickly excreted to the cytosol under nutrient starvation condition and recycled for de novo protein synthesis. These suggest that specific machineries that transport amino acids into and out of the vacuoles operate at the vacuolar membrane. Several families of transporter involved in the vacuolar compartmentalization of amino acids have been identified and characterized using budding yeast Saccharomyces cerevisiae. In this review, we describe the vacuolar amino acid transporters identified so far and introduce recent findings on their activity and physiological function.
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Affiliation(s)
- Miyuki Kawano-Kawada
- Department of Biosicence, Graduate School of Agriculture, Ehime University.,Advanced Research Support Center (ADRES), Ehime University
| | - Yoshimi Kakinuma
- Department of Biosicence, Graduate School of Agriculture, Ehime University
| | - Takayuki Sekito
- Department of Biosicence, Graduate School of Agriculture, Ehime University
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9
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Fujiki Y, Teshima H, Kashiwao S, Kawano-Kawada M, Ohsumi Y, Kakinuma Y, Sekito T. Functional identification ofAtAVT3, a family of vacuolar amino acid transporters, inArabidopsis. FEBS Lett 2016; 591:5-15. [DOI: 10.1002/1873-3468.12507] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 11/15/2016] [Accepted: 11/18/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Yuki Fujiki
- Division of Life Science; Graduate School of Science and Engineering; Saitama University; Japan
| | - Hiromitsu Teshima
- Department of Applied Bioscience; Faculty of Agriculture; Ehime University; Japan
| | - Shinji Kashiwao
- Department of Applied Bioscience; Faculty of Agriculture; Ehime University; Japan
| | - Miyuki Kawano-Kawada
- Department of Applied Bioscience; Faculty of Agriculture; Ehime University; Japan
- Advanced Research Support Center (ADRES); Ehime University; Japan
| | - Yoshinori Ohsumi
- Frontier Research Center; Tokyo Institute of Technology; Yokohama Japan
| | - Yoshimi Kakinuma
- Department of Applied Bioscience; Faculty of Agriculture; Ehime University; Japan
| | - Takayuki Sekito
- Department of Applied Bioscience; Faculty of Agriculture; Ehime University; Japan
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10
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Kawano-Kawada M, Chardwiriyapreecha S, Manabe K, Sekito T, Akiyama K, Takegawa K, Kakinuma Y. The amino-terminal hydrophilic region of the vacuolar transporter Avt3p is dispensable for the vacuolar amino acid compartmentalization of Schizosaccharomyces pombe. Biosci Biotechnol Biochem 2016; 80:2291-2297. [PMID: 27555098 DOI: 10.1080/09168451.2016.1220819] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Avt3p, a vacuolar amino acid exporter (656 amino acid residues) that is important for vacuolar amino acid compartmentalization as well as spore formation in Schizosaccharomyces pombe, has an extremely long hydrophilic region (approximately 290 amino acid residues) at its N-terminus. Because known functional domains have not been found in this region, its functional role was examined with a deletion mutant avt3(∆1-270) expressed in S. pombe avt3∆ cells. The deletion of this region did not affect its intracellular localization or vacuolar contents of basic amino acids as well as neutral ones. The defect of avt3Δ cells in spore formation was rescued by the expression of avt3+ but was not completely rescued by the expression of avt3(∆1-270). The N-terminal region is thus dispensable for the function of Avt3p as an amino acid exporter, but it is likely to be involved in the role of Avt3p under nutritional starvation conditions.
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Affiliation(s)
- Miyuki Kawano-Kawada
- a Faculty of Agriculture , Ehime University , Matsuyama , Japan.,b Advanced Research Support Center (ADRES) , Ehime University , Matsuyama , Japan
| | | | - Kunio Manabe
- b Advanced Research Support Center (ADRES) , Ehime University , Matsuyama , Japan
| | - Takayuki Sekito
- b Advanced Research Support Center (ADRES) , Ehime University , Matsuyama , Japan
| | - Koichi Akiyama
- a Faculty of Agriculture , Ehime University , Matsuyama , Japan.,b Advanced Research Support Center (ADRES) , Ehime University , Matsuyama , Japan
| | - Kaoru Takegawa
- c Faculty of Agriculture , Kyushu University , Fukuoka , Japan
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11
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Manabe K, Kawano-Kawada M, Ikeda K, Sekito T, Kakinuma Y. Ypq3p-dependent histidine uptake by the vacuolar membrane vesicles of Saccharomyces cerevisiae. Biosci Biotechnol Biochem 2016; 80:1125-30. [PMID: 26928127 DOI: 10.1080/09168451.2016.1141041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
The vacuolar membrane proteins Ypq1p, Ypq2p, and Ypq3p of Saccharomyces cerevisiae are known as the members of the PQ-loop protein family. We found that the ATP-dependent uptake activities of arginine and histidine by the vacuolar membrane vesicles were decreased by ypq2Δ and ypq3Δ mutations, respectively. YPQ1 and AVT1, which are involved in the vacuolar uptake of lysine/arginine and histidine, respectively, were deleted in addition to ypq2Δ and ypq3Δ. The vacuolar membrane vesicles isolated from the resulting quadruple deletion mutant ypq1Δypq2Δypq3Δavt1Δ completely lost the uptake activity of basic amino acids, and that of histidine, but not lysine and arginine, was evidently enhanced by overexpressing YPQ3 in the mutant. These results suggest that Ypq3p is specifically involved in the vacuolar uptake of histidine in S. cerevisiae. The cellular level of Ypq3p-HA(3) was enhanced by depletion of histidine from culture medium, suggesting that it is regulated by the substrate.
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Affiliation(s)
- Kunio Manabe
- a Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture , Ehime University , Matsuyama , Japan
| | - Miyuki Kawano-Kawada
- a Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture , Ehime University , Matsuyama , Japan.,b Advanced Research Support Center (ADRES), Ehime University , Matsuyama , Japan
| | - Koichi Ikeda
- a Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture , Ehime University , Matsuyama , Japan
| | - Takayuki Sekito
- a Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture , Ehime University , Matsuyama , Japan
| | - Yoshimi Kakinuma
- a Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture , Ehime University , Matsuyama , Japan
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Kawano-Kawada M, Pongcharoen P, Kawahara R, Yasuda M, Yamasaki T, Akiyama K, Sekito T, Kakinuma Y. Vba4p, a vacuolar membrane protein, is involved in the drug resistance and vacuolar morphology of Saccharomyces cerevisiae. Biosci Biotechnol Biochem 2016; 80:279-87. [DOI: 10.1080/09168451.2015.1083401] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Abstract
In the vacuolar basic amino acid (VBA) transporter family of Saccharomyces cerevisiae, VBA4 encodes a vacuolar membrane protein with 14 putative transmembrane helices. Transport experiments with isolated vacuolar membrane vesicles and estimation of the amino acid contents in vacuoles showed that Vba4p is not likely involved in the transport of amino acids. We found that the vba4Δ cells, as well as vba1Δ and vba2Δ cells, showed increased susceptibility to several drugs, particularly to azoles. Although disruption of the VBA4 gene did not affect the salt tolerance of the cells, vacuolar fragmentation observed under high salt conditions was less prominent in vba4Δ cells than in wild type, vba1Δ, and vba2Δ cells. Vba4p differs from Vba1p and Vba2p as a vacuolar transporter but is important for the drug resistance and vacuolar morphology of S. cerevisiae.
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Affiliation(s)
- Miyuki Kawano-Kawada
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
- Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Japan
| | - Pongsanat Pongcharoen
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Rieko Kawahara
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Mayu Yasuda
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Takashi Yamasaki
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Koichi Akiyama
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
- Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Japan
| | - Takayuki Sekito
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Yoshimi Kakinuma
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
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Lunprom S, Pongcharoen P, Sekito T, Kawano-Kawada M, Kakinuma Y, Akiyama K. Characterization of vacuolar amino acid transporter from Fusarium oxysporum in Saccharomyces cerevisiae. Biosci Biotechnol Biochem 2015; 79:1972-9. [DOI: 10.1080/09168451.2015.1058703] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Abstract
Fusarium oxysporum causes wilt disease in many plant families, and many genes are involved in its development or growth in host plants. A recent study revealed that vacuolar amino acid transporters play an important role in spore formation in Schizosaccharomyces pombe and Saccharomyces cerevisiae. To investigate the role of vacuolar amino acid transporters of this phytopathogenic fungus, the FOXG_11334 (FoAVT3) gene from F. oxysporum was isolated and its function was characterized. Transcription of FoAVT3 was upregulated after rapamycin treatment. A green fluorescent protein fusion of FoAvt3p was localized to vacuolar membranes in both S. cerevisiae and F. oxysporum. Analysis of the amino acid content of the vacuolar fraction and amino acid transport activities using vacuolar membrane vesicles from S. cerevisiae cells heterologously expressing FoAVT3 revealed that FoAvt3p functions as a vacuolar amino acid transporter, exporting neutral amino acids. We conclude that the FoAVT3 gene encodes a vacuolar neutral amino acid transporter.
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Affiliation(s)
| | | | | | - Miyuki Kawano-Kawada
- Faculty of Agriculture, Ehime University, Matsuyama, Japan
- Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Japan
| | | | - Koichi Akiyama
- Faculty of Agriculture, Ehime University, Matsuyama, Japan
- Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Japan
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14
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Chardwiriyapreecha S, Manabe K, Iwaki T, Kawano-Kawada M, Sekito T, Lunprom S, Akiyama K, Takegawa K, Kakinuma Y. Functional Expression and Characterization of Schizosaccharomyces pombe Avt3p as a Vacuolar Amino Acid Exporter in Saccharomyces cerevisiae. PLoS One 2015; 10:e0130542. [PMID: 26083598 PMCID: PMC4471098 DOI: 10.1371/journal.pone.0130542] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 05/22/2015] [Indexed: 11/18/2022] Open
Abstract
In Saccharomyces cerevisiae, Avt3p and Avt4p mediate the extrusion of several amino acids from the vacuolar lumen into the cytosol. SpAvt3p of Schizosaccharomyces pombe, a homologue of these vacuolar amino acid transporters, has been indicated to be involved in spore formation. In this study, we confirmed that GFP-SpAvt3p localized to the vacuolar membrane in S. pombe. The amounts of various amino acids increased significantly in the vacuolar pool of avt3Δ cells, but decreased in that of avt3+-overexpressing avt3Δ cells. These results suggest that SpAvt3p participates in the vacuolar compartmentalization of amino acids in S. pombe. To examine the export activity of SpAvt3p, we expressed the avt3+ gene in S. cerevisiae cells. We found that the heterologously overproduced GFP-SpAvt3p localized to the vacuolar membrane in S. cerevisiae. Using the vacuolar membrane vesicles isolated from avt3+-overexpressing S. cerevisiae cells, we detected the export activities of alanine and tyrosine in an ATP-dependent manner. These activities were inhibited by the addition of a V-ATPase inhibitor, concanamycin A, thereby suggesting that the activity of SpAvt3p is dependent on a proton electrochemical gradient generated by the action of V-ATPase. In addition, the amounts of various amino acids in the vacuolar pools of S. cerevisiae cells were decreased by the overproduction of SpAvt3p, which indicated that SpAvt3p was functional in S. cerevisiae cells. Thus, SpAvt3p is a vacuolar transporter that is involved in the export of amino acids from S. pombe vacuoles.
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Affiliation(s)
- Soracom Chardwiriyapreecha
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan
| | - Kunio Manabe
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan
| | - Tomoko Iwaki
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan
| | - Miyuki Kawano-Kawada
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan; Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Ehime, Japan
| | - Takayuki Sekito
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan
| | - Siriporn Lunprom
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan; Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Ehime, Japan
| | - Koichi Akiyama
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan; Advanced Research Support Center (ADRES), Ehime University, Matsuyama, Ehime, Japan
| | - Kaoru Takegawa
- Laboratory of Applied Microbiology, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Yoshimi Kakinuma
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Ehime, Japan
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15
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Tone J, Yoshimura A, Manabe K, Murao N, Sekito T, Kawano-Kawada M, Kakinuma Y. Characterization of Avt1p as a vacuolar proton/amino acid antiporter in Saccharomyces cerevisiae. Biosci Biotechnol Biochem 2015; 79:782-9. [DOI: 10.1080/09168451.2014.998621] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Abstract
Several genes for vacuolar amino acid transport were reported in Saccharomyces cerevisiae, but have not well been investigated. We characterized AVT1, a member of the AVT vacuolar transporter family, which is reported to be involved in lifespan of yeast. ATP-dependent uptake of isoleucine and histidine by the vacuolar vesicles of an AVT exporter mutant was lost by introducing avt1∆ mutation. Uptake activity was inhibited by the V-ATPase inhibitor: concanamycin A and a protonophore. Isoleucine uptake was inhibited by various neutral amino acids and histidine, but not by γ-aminobutyric acid, glutamate, and aspartate. V-ATPase-dependent acidification of the vesicles was declined by the addition of isoleucine or histidine, depending upon Avt1p. Taken together with the data of the amino acid contents of vacuolar fractions in cells, the results suggested that Avt1p is a proton/amino acid antiporter important for vacuolar compartmentalization of various amino acids.
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Affiliation(s)
- Junichi Tone
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Ayumi Yoshimura
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Kunio Manabe
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Nami Murao
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Takayuki Sekito
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Miyuki Kawano-Kawada
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
- Integrated Center for Sciences (INCS), Ehime University, Matsuyama, Japan
| | - Yoshimi Kakinuma
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
- Integrated Center for Sciences (INCS), Ehime University, Matsuyama, Japan
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16
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Tone J, Yamanaka A, Manabe K, Murao N, Kawano-Kawada M, Sekito T, Kakinuma Y. A vacuolar membrane protein Avt7p is involved in transport of amino acid and spore formation in Saccharomyces cerevisiae. Biosci Biotechnol Biochem 2015; 79:190-5. [DOI: 10.1080/09168451.2014.963501] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Abstract
Active transport systems for various amino acids operate in the vacuolar membrane of Saccharomyces cerevisiae. The gene families for vacuolar amino acid transporters were identified by reverse genetics experiments. In the AVT transporter family, Avt1p works for active uptake of amino acid into vacuole, and Avt3p, Avt4p, and Avt6p for active extrusion of amino acid from vacuole to cytosol. Here, we found green fluorescent protein-tagged Avt7p, an unidentified member of the AVT family, localized to the vacuolar membrane of S. cerevisiae. Disruption of the AVT7 gene enhanced both vacuolar contents of several amino acids and uptake activities of glutamine and proline by vacuolar membrane vesicles. Efficiency of spore formation was impaired by the disruption of the AVT7 gene, suggesting the physiological importance of Avt7p-dependent efflux of amino acid from vacuoles under nutrient-poor condition.
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Affiliation(s)
- Junichi Tone
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Atsushi Yamanaka
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Kunio Manabe
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Nami Murao
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Miyuki Kawano-Kawada
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
- Integrated Center for Sciences (INCS), Ehime University, Matsuyama, Japan
| | - Takayuki Sekito
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
| | - Yoshimi Kakinuma
- Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture, Ehime University, Matsuyama, Japan
- Integrated Center for Sciences (INCS), Ehime University, Matsuyama, Japan
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17
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Sekito T, Onoue K, Dote Y, Sakanakura H, Nakamura K. Variation and correlation of content and leachability of hazardous metals in MSW molten slag. Environ Monit Assess 2015; 187:4193. [PMID: 25504189 DOI: 10.1007/s10661-014-4193-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 11/20/2014] [Indexed: 06/04/2023]
Abstract
To increase the amount of accessible municipal solid waste molten slag (MSWS) for its use in aggregates such as sand, MSWS must be deemed environmentally safe. Municipal solid waste (MSW) is a heterogeneous waste source used in MSWS and varies in chemical composition. Due to its nature, there is great concern about hazardous metal contamination among users of MSWS. In this study, MSWS samples were obtained weekly for 1 year from a typical incineration ash melting facility for municipal solid waste in Japan. Variation in heavy metal contents and the leachability of MSWS were investigated using two content analysis methods and two leaching tests, respectively. There is a weak correlation between metal content and concentration, and the leachability of metals in slag could not be reduced by decreasing its metal content. No measured values of hazardous metal concentration and metal content exceed the regulation levels stipulated in Japanese Industrial Standards A5031 and A5032, respectively, thereby demonstrating that the slag can be safely utilized as road and concrete aggregates. However, metal concentrations varied widely and differed by greater than 1 order of magnitude and Pb concentrations of several MSWS samples approach the regulation level. Therefore, frequent monitoring of lead leachability of MSWS and storing MSWS for several weeks to obtain a high quality that is more homogeneous in chemical composition are demanded. This study provides fundamental information for controlling the quality of MSWS and the contributing factors for achieving a safe slag recycling system.
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Affiliation(s)
- T Sekito
- Department of Civil and Environmental Engineering, University of Miyazaki, 889-2192, 1-1 Gakuen Kibanadai Nishi, Miyazaki City, Japan,
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18
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Sekito T, Sugimoto N, Ishimoto M, Kawano-Kawada M, Akiyama K, Nishimoto S, Sugahara T, Kakinuma Y. Tributyltin induces cell cycle arrest at G1 phase in the yeast Saccharomyces cerevisiae. J Toxicol Sci 2014; 39:311-7. [PMID: 24646713 DOI: 10.2131/jts.39.311] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Tributyltin (TBT) has long been recognized as a major environmental pollutant that can cause significant damage to the cellular functions as well as disruption of endocrine homeostasis. TBT induces apoptosis accompanied by production of reactive oxygen species (ROS) in mammalian and yeast cells. We observed that the budding yeast cells exposed to this compound at low concentrations exhibited cell growth arrest, but not cell death. Flow cytometric analysis of yeast cells without synchronization and morphological assessment of cells synchronized at M phase by nocodazole treatment indicated that TBT-exposed Saccharomyces cerevisiae cells were arrested at G1 phase of the cell cycle. This arrest was recovered by the addition of N-acetylcysteine, suggesting the involvement of ROS production by TBT. This is the first study to evaluate the action of TBT on cell cycle events.
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Sekito T, Dote Y, Onoue K, Sakanakura H, Nakamura K. Characteristics of element distributions in an MSW ash melting treatment system. Waste Manag 2014; 34:1637-1643. [PMID: 24863626 DOI: 10.1016/j.wasman.2014.04.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 01/10/2014] [Accepted: 04/10/2014] [Indexed: 06/03/2023]
Abstract
Thermal treatment of municipal solid waste (MSW) has become a common practice in waste volume reduction and resource recovery. For the utilization of molten slag for construction materials and metal recovery, it is important to understand the behavior of heavy metals in the melting process. In this study, the correlation between the contents of elements in feed materials and MSW molten slag and their distributions in the ash melting process, including metal residues, are investigated. The hazardous metal contents in the molten slag were significantly related to the contents of metals in the feed materials. Therefore, the separation of products containing these metals in waste materials could be an effective means of producing environmentally safe molten slag with a low hazardous metals content. The distribution ratios of elements in the ash melting process were also determined. The elements Zn and Pb were found to have a distribution ratio of over 60% in fly ash from the melting furnace and the contents of these metals were also high; therefore, Zn and Pb could be potential target metals for recycling from fly ash from the melting furnace. Meanwhile, Cu, Ni, Mo, Sn, and Sb were found to have distribution ratios of over 60% in the metal residue. Therefore, metal residue could be a good resource for these metals, as the contents of Cu, Ni, Mo, Sn, and Sb in metal residue are higher than those in other output materials.
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Affiliation(s)
- T Sekito
- Department of Civil and Environmental Engineering, University of Miyazaki, Japan.
| | - Y Dote
- Department of Civil and Environmental Engineering, University of Miyazaki, Japan
| | - K Onoue
- Department of Civil and Environmental Engineering, University of Miyazaki, Japan
| | - H Sakanakura
- Research Center for Material Cycles and Waste Management, National Institute for Environmental Studies, Japan
| | - K Nakamura
- Department of Environmental Science, Miyazaki Prefectural Institute for Public Health and Environment, Japan
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20
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Sekito T, Nakamura K, Manabe K, Tone J, Sato Y, Murao N, Kawano-Kawada M, Kakinuma Y. Loss of ATP-dependent lysine uptake in the vacuolar membrane vesicles of Saccharomyces cerevisiae ypq1∆ mutant. Biosci Biotechnol Biochem 2014; 78:1199-202. [PMID: 25229858 DOI: 10.1080/09168451.2014.918489] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Saccharomyces cerevisiae Ypq1p is a vacuolar membrane protein of the PQ-loop protein family. We found that ATP-dependent uptake activities of amino acids by vacuolar membrane vesicles were impaired by ypq1∆ mutation. Loss of lysine uptake was most remarkable, and the uptake was recovered by overproduction of Ypq1p. Ypq1p is thus involved in transport of amino acids into vacuoles.
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Affiliation(s)
- Takayuki Sekito
- a Faculty of Agriculture, Department of Applied Bioresource Science , Ehime University , Matsuyama , Japan
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21
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Sekito T, Chardwiriyapreecha S, Sugimoto N, Ishimoto M, Kawano-Kawada M, Kakinuma Y. Vacuolar transporter Avt4 is involved in excretion of basic amino acids from the vacuoles of Saccharomyces cerevisiae. Biosci Biotechnol Biochem 2014; 78:969-75. [PMID: 25036121 DOI: 10.1080/09168451.2014.910095] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Basic amino acids (lysine, histidine and arginine) accumulated in Saccharomyces cerevisiae vacuoles should be mobilized to cytosolic nitrogen metabolism under starvation. We found that the decrease of vacuolar basic amino acids in response to nitrogen starvation was impaired by the deletion of AVT4 gene encoding a vacuolar transporter. In addition, overexpression of AVT4 reduced the accumulation of basic amino acids in vacuoles under nutrient-rich condition. In contrast to AVT4, the deletion and overexpression of AVT3, which encodes the closest homologue of Avt4p, did not affect the contents of vacuolar basic amino acids. Consistent with these, arginine uptake into vacuolar membrane vesicles was decreased by Avt4p-, but not by Avt3p-overproduction, whereas various neutral amino acids were excreted from vacuolar membrane vesicles in a manner dependent on either Avt4p or Avt3p. These results suggest that Avt4p is a vacuolar amino acid exporter involving in the recycling of basic amino acids.
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Affiliation(s)
- Takayuki Sekito
- a Laboratory of Molecular Physiology and Genetics, Faculty of Agriculture , Ehime University , Matsuyama , Japan
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22
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Yamamoto H, Kakuta S, Watanabe TM, Kitamura A, Sekito T, Kondo-Kakuta C, Ichikawa R, Kinjo M, Ohsumi Y. Atg9 vesicles are an important membrane source during early steps of autophagosome formation. ACTA ACUST UNITED AC 2012; 198:219-33. [PMID: 22826123 PMCID: PMC3410421 DOI: 10.1083/jcb.201202061] [Citation(s) in RCA: 454] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
During the process of autophagy, cytoplasmic materials are sequestered by double-membrane structures, the autophagosomes, and then transported to a lytic compartment to be degraded. One of the most fundamental questions about autophagy involves the origin of the autophagosomal membranes. In this study, we focus on the intracellular dynamics of Atg9, a multispanning membrane protein essential for autophagosome formation in yeast. We found that the vast majority of Atg9 existed on cytoplasmic mobile vesicles (designated Atg9 vesicles) that were derived from the Golgi apparatus in a process involving Atg23 and Atg27. We also found that only a few Atg9 vesicles were required for a single round of autophagosome formation. During starvation, several Atg9 vesicles assembled individually into the preautophagosomal structure, and eventually, they are incorporated into the autophagosomal outer membrane. Our findings provide conclusive linkage between the cytoplasmic Atg9 vesicles and autophagosomal membranes and offer new insight into the requirement for Atg9 vesicles at the early step of autophagosome formation.
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Affiliation(s)
- Hayashi Yamamoto
- Frontier Research Center, Tokyo Institute of Technology, Yokohama 226-8503, Japan
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23
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Akiyama K, Iwaki T, Sugimoto N, Chardwiriyapreecha S, Kawano M, Nishimoto S, Sugahara T, Sekito T, Kakinuma Y. Bfr1p is responsible for tributyltin resistance in Schizosaccharomyces pombe. J Toxicol Sci 2011; 36:117-20. [PMID: 21297349 DOI: 10.2131/jts.36.117] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
ATP-binding cassette (ABC) transporter plays an important role for resistance against xenobiotics. There are eleven ABC transporter genes in the genome of fission yeast Schizosaccharomyces pombe. We examined the role of ABC transporter against the toxicity of tributyltin chloride (TBT), a widespread environmental pollutant, in cell growth. Among individual ABC transporter mutants, the growth of a mutant deficient in Bfr1p, a plasma membrane-embedded transporter, was extremely sensitive to TBT. The lethal TBT concentration inducing 50% of cell death (LC(50)) was 25 µM for the parent strain and 10.2 µM for the bfr1∆ mutant. Thus, Bfr1p was responsible for TBT resistance in S. pombe.
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Chardwiriyapreecha S, Mukaiyama H, Sekito T, Iwaki T, Takegawa K, Kakinuma Y. Avt5p is required for vacuolar uptake of amino acids in the fission yeastSchizosaccharomycespombe. FEBS Lett 2010; 584:2339-45. [DOI: 10.1016/j.febslet.2010.04.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Accepted: 04/06/2010] [Indexed: 10/19/2022]
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25
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Chahomchuen T, Akiyama K, Sekito T, Sugimoto N, Okabe M, Nishimoto S, Sugahara T, Kakinuma Y. Tributyltin induces Yca1p-dependent cell death of yeast Saccharomyces cerevisiae. J Toxicol Sci 2010; 34:541-5. [PMID: 19797862 DOI: 10.2131/jts.34.541] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Tributyltin chloride (TBT), an environmental pollutant, is toxic to a variety of eukaryotic and prokaryotic organisms. Although it has been reported that TBT induces apoptotic cell death in mammalian, the action of TBT on eukaryotic microorganisms has not yet been fully investigated. In this study we examined the mechanism involved in cell death caused by TBT exposure in Saccharomyces cerevisiae. The median lethal concentration of TBT was 10 microM for the parent strain BY4741 and 3 microM for the pdr5Delta mutant defective in a major multidrug transporter, respectively. Fluorescence microscopic observations revealed nuclear condensation and chromatin fragmentation in cells treated with TBT indicating that cells underwent an apoptosis-like cell dearth. TBT-induced cell death was suppressed by deletion of the yca1 gene encoding a homologue of the mammalian caspase. In parallel, reactive oxygen species (ROS) were produced by TBT. These results suggest that TBT induces apoptosis-like cell death in yeast via an Yca1p-dependent pathway possibly downstream of the ROS production. This is the first report on TBT-induced apoptotic cell death in yeast.
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26
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Chardwiriyapreecha S, Inoue T, Sugimoto N, Sekito T, Yamato I, Murata T, Homma M, Kakinuma Y. Tributyltin sensitivity of vacuolar-type Na(+)-transporting ATPase from Enterococcus hirae. J Toxicol Sci 2010; 34:575-9. [PMID: 19797867 DOI: 10.2131/jts.34.575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Tributyltin chloride (TBT), an environmental pollutant, is toxic to a variety of eukaryotic and prokaryotic organisms. Some members of F-ATP synthase (F-ATPase)/vacuolar type ATPase (V-ATPase) superfamily have been identified as the molecular target of this compound. TBT inhibited the activities of H(+)-transporting or Na(+)-transporting F-ATPase as well as H(+)-transporting V-ATPase originated from various organisms. However, the sensitivity to TBT of Na(+)-transporting V-ATPase has not been investigated. We examined the effect of TBT on Na(+)-transporting V-ATPase from an eubacterium Enterococus hirae. The ATP hydrolytic activity of E. hirae V-ATPase in purified form as well as in membrane-bound form was little inhibited by less than 10 microM TBT; IC50 for TBT inhibition of purified enzyme was estimated to be about 35 microM. Active sodium transport by E. hirae cells, indicating the in vivo activity of this V-ATPase, was not inhibited by 20 microM TBT. By contrast, IC50 of H(+)-transporting V-ATPase of the vacuolar membrane vesicles from Saccharomyces cerevisiae was about 0.2 microM. E. hirae V-ATPase is thus extremely less sensitive to TBT.
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27
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Suzuki Y, Kubota A, Furukawa T, Sugamoto K, Asano Y, Takahashi H, Sekito T, Dote Y, Sugimoto Y. Residual of 17beta-estradiol in digestion liquid generated from a biogas plant using livestock waste. J Hazard Mater 2009; 165:677-682. [PMID: 19042081 DOI: 10.1016/j.jhazmat.2008.10.057] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 10/09/2008] [Accepted: 10/09/2008] [Indexed: 05/27/2023]
Abstract
A biogas plant using livestock waste in which a methane fermentation process is applied is a useful facility for generating energy. The digestion liquid generated from the biogas plant as a residue has high potential for use as a crop fertilizer. However, high-density estrogens such as 17beta-estradiol (E2) are included in livestock waste, and there is little information on the behavior of E2 in the digestion liquid. In this study, a survey of E2 concentration at each process in a biogas plant using livestock waste was carried out. In addition, the efficiencies of E2 removal from the digestion liquid by activated carbon adsorption and soil infiltration were examined. The total concentration of E2 in raw livestock waste was reduced to 2 microg/l after treatment, and the removal efficiency of E2 was about 80% for the plant. The methane fermentation process is important not only for the generation of methane but also for the removal of E2. The proportion of E2 conjugates comprising the total E2 concentration was 10% or less in all treated samples. In the plant, there is no likelihood of an increase in estrogen activity by the cleaving of E2 conjugates. By carrying out activated carbon adsorption to remove E2 from the digestion liquid, a large portion of E2 was removed from the digestion liquid, but an E2 concentration of 0.5 microg/l still remained in the treated digestion liquid. In contrast, it was possible to purify the digestion liquid to an E2 concentration of less than 0.002-0.011 microg/l by soil infiltration. It is thus possible to utilize the digestion liquid as a fertilizer without causing aquatic environmental pollution, but factors such as application rate, soil characteristics, and the E2 concentration of digestion liquid should be considered first.
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Affiliation(s)
- Y Suzuki
- Department of Civil and Environmental Engineering, Faculty of Engineering, University of Miyazaki, Miyazaki, Japan.
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Abstract
Autophagy is a degradation system of cytoplasmic proteins and organelles via formation of double-membrane vesicles called autophagosomes. In the yeast Saccharomyces cerevisiae, autophagosomes are formed via the pre-autophagosomal structure (PAS) in a manner dependent on Atg proteins. Under nutrient-rich condition, Atg9 is recruited to the PAS by binding to Atg11 for the Cvt pathway. However, because Atg9 is recruited to the PAS in atg11Delta cells in starved condition and autophagy is induced, autophagy-specific mechanism for the Atg9 recruitment to the PAS has been assumed. Here, we demonstrate that, in autophagy-inducing condition, Atg9 is recruited to the PAS in a manner dependent on Atg17. Atg9 physically interacts with Atg17 in the presence of rapamycin. This interaction requires Atg1, a protein kinase essential for autophagy. Consistently, the Atg17-dependent PAS localization of Atg9 requires Atg1. However, its kinase activity is dispensable for this process. It rather regulates the equilibrium of assembly and disassembly of Atg9 at the PAS.
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Affiliation(s)
- Takayuki Sekito
- Division of Molecular Cell Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki 444-8585, Japan
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Chahomchuen T, Hondo K, Ohsaki M, Sekito T, Kakinuma Y. Evidence for Avt6 as a vacuolar exporter of acidic amino acids in Saccharomyces cerevisiae cells. J GEN APPL MICROBIOL 2009; 55:409-17. [DOI: 10.2323/jgam.55.409] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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30
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Abstract
Amino acids are compartmentalized in the vacuoles of microorganisms and plants. In Saccharomyces cerevisiae, basic amino acids accumulate preferentially into vacuoles but acidic amino acids are almost excluded from them. This indicates that selective machineries operate at the vacuolar membrane. The members of the amino acid/auxin permease family and the major facilitator superfamily involved in the vacuolar compartmentalization of amino acids have been recently identified in studies using S. cerevisiae. Homologous genes for these transporters are also found in plant and mammalian genomes. The physiological significance in response to nitrogen starvation can now be discussed.
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Affiliation(s)
- Takayuki Sekito
- Department of Applied Bioscience, Faculty of Agriculture, Tarumi 3-5-7, Ehime University, Matsuyama, Ehime, Japan.
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Obara K, Sekito T, Niimi K, Ohsumi Y. The Atg18-Atg2 complex is recruited to autophagic membranes via phosphatidylinositol 3-phosphate and exerts an essential function. J Biol Chem 2008; 283:23972-80. [PMID: 18586673 DOI: 10.1074/jbc.m803180200] [Citation(s) in RCA: 237] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Atg18 is essential for both autophagy and the regulation of vacuolar morphology. The latter process is mediated by phosphatidylinositol 3,5-bisphosphate binding, which is dispensable for autophagy. Atg18 also binds to phosphatidylinositol 3-phosphate (PtdIns(3)P) in vitro. Here, we investigate the relationship between PtdIns(3)P-binding of Atg18 and autophagy. Using an Atg18 variant, Atg18(FTTG), which is unable to bind phosphoinositides, we found that PtdIns(3)P binding of Atg18 is essential for full activity in both selective and nonselective autophagy. Atg18(FTTG) formed a complex with Atg2 in a normal manner, and Atg18-Atg2 complex formation occurred in cells in the absence of PtdIns(3)P, indicating that Atg18-Atg2 complex formation is independent of PtdIns(3)P-binding of Atg18. Atg18 localized to endosomes, the vacuolar membrane, and autophagic membranes, whereas Atg18(FTTG) did not localize to these structures. The localization of Atg2 to autophagic membranes was also lost in Atg18(FTTG) cells. These data indicate that PtdIns(3)P-binding of Atg18 is involved in directing the Atg18-Atg2 complex to autophagic membranes. Connection of a 2xFYVE domain, a specific PtdIns(3)P-binding domain, to the C terminus of Atg18(FTTG) restored the localization of Atg18-Atg2 to autophagic membranes and full autophagic activity, indicating that PtdIns(3)P-binding by Atg18 is dispensable for the function of the Atg18-Atg2 complex but is required for its localization. This also suggests that PtdIns(3)P does not act allosterically on Atg18. Taken together, Atg18 forms a complex with Atg2 irrespective of PtdIns(3)P binding, associates tightly to autophagic membranes by interacting with PtdIns(3)P, and plays an essential role.
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Affiliation(s)
- Keisuke Obara
- Department of Cell Biology, National Institute for Basic Biology, Nishigonaka 38, Myodaiji-cho, Okazaki 444-8585, Japan
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Chardwiriyapreecha S, Shimazu M, Morita T, Sekito T, Akiyama K, Takegawa K, Kakinuma Y. Identification of thefnx1+andfnx2+genes for vacuolar amino acid transporters inSchizosaccharomyces pombe. FEBS Lett 2008; 582:2225-30. [DOI: 10.1016/j.febslet.2008.05.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 05/12/2008] [Accepted: 05/15/2008] [Indexed: 10/22/2022]
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Kawamata T, Kamada Y, Kabeya Y, Sekito T, Ohsumi Y. Organization of the pre-autophagosomal structure responsible for autophagosome formation. Mol Biol Cell 2008; 19:2039-50. [PMID: 18287526 DOI: 10.1091/mbc.e07-10-1048] [Citation(s) in RCA: 197] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Autophagy induced by nutrient depletion is involved in survival during starvation conditions. In addition to starvation-induced autophagy, the yeast Saccharomyces cerevisiae also has a constitutive autophagy-like system, the Cvt pathway. Among 31 autophagy-related (Atg) proteins, the function of Atg17, Atg29, and Atg31 is required specifically for autophagy. In this study, we investigated the role of autophagy-specific (i.e., non-Cvt) proteins under autophagy-inducing conditions. For this purpose, we used atg11Delta cells in which the Cvt pathway is abrogated. The autophagy-unique proteins are required for the localization of Atg proteins to the pre-autophagosomal structure (PAS), the putative site for autophagosome formation, under starvation condition. It is likely that these Atg proteins function as a ternary complex, because Atg29 and Atg31 bind to Atg17. The Atg1 kinase complex (Atg1-Atg13) is also essential for recruitment of Atg proteins to the PAS. The assembly of Atg proteins to the PAS is observed only under autophagy-inducing conditions, indicating that this structure is specifically involved in autophagosome formation. Our results suggest that Atg1 complex and the autophagy-unique Atg proteins cooperatively organize the PAS in response to starvation signals.
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Affiliation(s)
- Tomoko Kawamata
- Department of Cell Biology, National Institute for Basic Biology, and School of Life Science, The Graduate University for Advanced Studies, Okazaki 444-8585, Japan
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Abstract
Autophagy is a bulk degradation process that is conserved in eukaryotic cells and functions in the turnover of cytoplasmic materials and organelles. When eukaryotic cells face nutrient starvation, the autophagosome, a double-membraned organelle, is generated from the pre-autophagosomal structure (PAS). In the yeast Saccharomyces cerevisiae, 16 ATG (autophagy-related) genes are essential for autophagosome formation. Most of the Atg proteins are involved in the PAS, leading to autophagosome production. However, the mechanism of PAS organization remains to be elucidated. Here, we performed a systematic and quantitative analysis by fluorescence microscopy to develop a hierarchy map of Atg proteins involved in PAS organization. This analysis suggests that Atg17p is the most basic protein in PAS organization: when it is specifically targeted to the plasma membrane, other Atg proteins are recruited to that location, suggesting that Atg17p acts as a scaffold protein to organize Atg proteins to the PAS.
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Affiliation(s)
- Kuninori Suzuki
- Department of Cell Biology, Division of Molecular Cell Biology, National Institute for Basic Biology, Nishigonaka 38, Okazaki, 444-8585 Japan
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Abstract
To update sequenced data, we determined the 5' and 3' termini of yeast Hansenula wingei (Pichia canadensis) mitochondrial (mt) large subunit ribosomal RNA (LSU) which is encoded in the mt genome. The 5' end position was mapped downstream from a putative transcription starting site which is homologous to a Saccharomyces cerevisiae mitochondrial promoter sequence. This suggests that the primary transcript of LSU is processed from 5' end and then mature transcript is formed. This processing is different from that of S. cerevisiae mt LSU in which processing on its 5' end does not occur. Based on the sequence data of H. wingei mt LSU, we constructed its secondary structure, and compared it with those of the other fungal organisms. Conserved regions of H. wingei LSU were identified and used for subsequent phylogenetic analysis. In genome structure and gene content, H. wingei mt genome has several characteristics similar to those in filamentous fungi, but the phylogenetic analysis indicates closer kinship to yeast S. cerevisiae. This agrees with previous non-sequencing phylogenies and suggests that extraordinary rearrangements have occurred in yeast mt genomes during divergent evolution.
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Affiliation(s)
- Takayuki Sekito
- Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
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Nakatogawa H, Hanada T, Kamada Y, Obara K, Sekito T. [Characterization of yeast Atg proteins]. Tanpakushitsu Kakusan Koso 2006; 51:1457-63. [PMID: 16922419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
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Obara K, Sekito T, Ohsumi Y. Assortment of phosphatidylinositol 3-kinase complexes--Atg14p directs association of complex I to the pre-autophagosomal structure in Saccharomyces cerevisiae. Mol Biol Cell 2006; 17:1527-39. [PMID: 16421251 PMCID: PMC1415304 DOI: 10.1091/mbc.e05-09-0841] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In the yeast Saccharomyces cerevisiae, two similar phosphatidylinositol 3-kinase complexes (complexes I and II) function in distinct biological processes, complex I in autophagy and complex II in the vacuolar protein sorting via endosomes. Atg14p is only integrated into complex I, likely facilitating the function of complex I in autophagy. Deletion analysis of Atg14p revealed that N-terminal region containing the coiled-coil structures was essential and sufficient for autophagy. Atg14p localized to pre-autophagosomal structure (PAS) and vacuolar membranes, whereas Vps38p, a component specific to complex II, localized to endosomes and vacuolar membranes. Vps34p and Vps30p, components shared by the two complexes, localized to the PAS, vacuolar membranes, and several punctate structures that included endosomes. The localization of these components to the PAS was Atg14p dependent but not dependent on Vps38p. Conversely, localization of these proteins to endosomes required Vps38p but not Atg14p. Vps15p, regulatory subunit of the Vps34p complexes, localized to the PAS, vacuolar membranes, and punctate structures independent of both Atg14p and Vps38p. Together, these results indicate that complexes I and II function in distinct biological processes by localizing to specific compartments in a manner mediated by specific components of each complex, Atg14p and Vps38p, respectively.
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Affiliation(s)
- Keisuke Obara
- Division of Molecular Cell Biology, National Institute for Basic Biology, Myodaiji, Okazaki 444-8585, Japan
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Sekito T, Matsuto T, Tanaka N. Application of a gas-solid fluidized bed separator for shredded municipal bulky solid waste separation. Waste Manag 2006; 26:1422-9. [PMID: 16380247 DOI: 10.1016/j.wasman.2005.10.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2004] [Revised: 09/14/2005] [Accepted: 10/27/2005] [Indexed: 05/05/2023]
Abstract
A laboratory-scale gas-solid fluidized bed separator able to separate fractions of 5.6-50mm was used for separation of shredded municipal bulky waste (SBW) into combustibles and incombustibles. In batch-scale tests, it was found that accumulation of SBW in the bottom of the bed significantly reduced the separation efficiency. In this study, stirring was shown to be effective in preventing this accumulation. Flexible sheet materials such as paper and film plastics also significantly decreased the separation efficiency. In batch-scale tests, an overall efficiency of 90% was obtained when flexible materials such as film plastics and paper were excluded from the feed SBW. In continuous feeding tests, purities of the float and sink fractions attained 95% and 86% efficiencies, respectively, with an overall efficiency of 79%. The effect of feedstock shape on separation efficiency was also investigated. This study revealed that large particles can be properly separated on the basis of density, while the shape of the material significantly influenced behavior in the fluidizing bed.
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Affiliation(s)
- T Sekito
- Civil and Environmental Engineering Department, University of Miyazaki, 1-1, Gakuen Kibanadai Nishi, Miyazaki 889-2192, Japan.
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Shimazu M, Sekito T, Akiyama K, Ohsumi Y, Kakinuma Y. A family of basic amino acid transporters of the vacuolar membrane from Saccharomyces cerevisiae. J Biol Chem 2004; 280:4851-7. [PMID: 15572352 DOI: 10.1074/jbc.m412617200] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Among the members of the major facilitator superfamily of Saccharomyces cerevisiae, we identified genes involved in the transport into vacuoles of the basic amino acids histidine, lysine, and arginine. ATP-dependent uptake of histidine and lysine by isolated vacuolar membrane vesicles was impaired in YMR088c, a vacuolar basic amino acid transporter 1 (VBA1)-deleted strain, whereas uptake of tyrosine or calcium was little affected. This defect in histidine and lysine uptake was complemented fully by introducing the VBA1 gene and partially by a gene encoding Vba1p fused with green fluorescent protein, which was determined to localize exclusively to the vacuolar membrane. A defect in the uptake of histidine, lysine, or arginine was also observed in the vacuolar membrane vesicles of mutants YBR293w (VBA2) and YCL069w (VBA3). These three VBA genes are closely related phylogenetically and constitute a new family of basic amino acid transporters in the yeast vacuole.
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Affiliation(s)
- Masamitsu Shimazu
- Department of Applied Chemistry, Muroran Institute of Technology, Muroran 050-8585, Japan
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Abstract
TOR plays a key role in cell growth and cell-cycle progression, but in addition recent studies have shown that TOR is also involved in the regulation of a number of molecular processes associated with nutrient deprivation, such as autophagy. In budding yeast, TOR negatively regulates activation of Apg1 protein kinase, which is essential for the induction of autophagy. This review describes recent research in this field and the mechanism by which TOR mediates induction of autophagy.
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Affiliation(s)
- Y Kamada
- Department of Cell Biology, National Institute for Basic Biology, 444-8585, Okazaki, Japan
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Abstract
Activation of retrograde signaling (RS) by mitochondrial dysfunction or by inhibition of TOR kinases in yeast results in nuclear accumulation of the transcription factors, Rtg1p and Rtg3p. This process requires Rtg2p, a novel cytoplasmic protein with an N-terminal ATP binding domain. We show that Rtg2p controls RS by reversibly binding a negative regulator, Mks1p. The inhibitory form of Mks1p is phosphorylated and complexed with the 14-3-3 proteins, Bmh1p and Bmh2p, which are also negative regulators of RS. A hypophosphorylated form of Mks1p bound to Rtg2p is inactive. Point mutations in the Rtg2p ATP binding domain simultaneously block RS and Mks1p-Rtg2p interaction. We propose that activation of RS via mitochondrial dysfunction and TOR inhibition intersect at the Rtg2p-Mks1p switch.
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Affiliation(s)
- Zhengchang Liu
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
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Sekito T, Liu Z, Thornton J, Butow RA. RTG-dependent Mitochondria-to-Nucleus Signaling Is Regulated by MKS1and Is Linked to Formation of Yeast Prion [URE3]. Mol Biol Cell 2002. [DOI: 10.1091/mbc.01-10-0473] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
An important function of the RTG signaling pathway is maintenance of intracellular glutamate supplies in yeast cells with dysfunctional mitochondria. Herein, we report that MKS1is a negative regulator of the RTG pathway, acting between Rtg2p, a proximal sensor of mitochondrial function, and the bHLH transcription factors Rtg1p and Rtg3p. In mks1Δcells, RTG target gene expression is constitutive, bypassing the requirement for Rtg2p, and is no longer repressible by glutamate. We show further that Mks1p is a phosphoprotein whose phosphorylation pattern parallels that of Rtg3p in response to activation of the RTG pathway, and that Mks1p is in a complex with Rtg2p. MKS1 was previously implicated in the formation of [URE3], an inactive prion form of a negative regulator of the nitrogen catabolite repression pathway, Ure2p.rtgΔ mutations induce [URE3] and can do so independently of MKS1. We find that glutamate suppresses [URE3] formation, suggesting that the Mks1p effect on the formation of [URE3] can occur indirectly via regulation of theRTG pathway.
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Affiliation(s)
- Takayuki Sekito
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148
| | - Zhengchang Liu
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148
| | - Janet Thornton
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148
| | - Ronald A. Butow
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148
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Sekito T, Liu Z, Thornton J, Butow RA. RTG-dependent mitochondria-to-nucleus signaling is regulated by MKS1 and is linked to formation of yeast prion [URE3]. Mol Biol Cell 2002; 13:795-804. [PMID: 11907262 PMCID: PMC99599 DOI: 10.1091/mbc.01-09-0473] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
An important function of the RTG signaling pathway is maintenance of intracellular glutamate supplies in yeast cells with dysfunctional mitochondria. Herein, we report that MKS1 is a negative regulator of the RTG pathway, acting between Rtg2p, a proximal sensor of mitochondrial function, and the bHLH transcription factors Rtg1p and Rtg3p. In mks1 Delta cells, RTG target gene expression is constitutive, bypassing the requirement for Rtg2p, and is no longer repressible by glutamate. We show further that Mks1p is a phosphoprotein whose phosphorylation pattern parallels that of Rtg3p in response to activation of the RTG pathway, and that Mks1p is in a complex with Rtg2p. MKS1 was previously implicated in the formation of [URE3], an inactive prion form of a negative regulator of the nitrogen catabolite repression pathway, Ure2p. rtg Delta mutations induce [URE3] and can do so independently of MKS1. We find that glutamate suppresses [URE3] formation, suggesting that the Mks1p effect on the formation of [URE3] can occur indirectly via regulation of the RTG pathway.
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Affiliation(s)
- Takayuki Sekito
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA
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44
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Abstract
In cells with reduced mitochondrial function, RTG1, 2 and 3 are required for expression of genes involved in glutamate synthesis. Glutamate negatively regulates RTG-dependent gene expression upstream of Rtg2p, which, in turn, acts upstream of the bHLH/Zip transcription factors, Rtg1p and Rtg3p. Here we report that some mutations [lst8-(2-5)] in LST8, an essential gene encoding a seven WD40-repeat protein required for targeting of amino acid permeases (AAPs) to the plasma membrane, bypass the requirement for Rtg2p and abolish glutamate repression of RTG-dependent gene expression. The lst8-1 mutation, however, which reduces plasma membrane expression of AAP, cannot bypass the Rtg2p requirement, but still suppresses glutamate repression of RTG target gene expression. We show that Lst8p negatively regulates RTG gene function, acting at two sites, one upstream of Rtg2p, affecting glutamate repression of RTG-dependent gene expression through Ssy1p, an AAP-like sensor of external amino acids, and the other between Rtg2p and Rtg1p-Rtg3p. These data, together with genome-wide transcription profiling, reveal pathways regulated by glutamate, and provide insight into the regulation of cellular responses to mitochondrial dysfunction.
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Affiliation(s)
| | - Takayuki Sekito
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9148, USA
Present address: Department of Cell Biology, National Institute for Basic Biology, Nishigonaka 38, Myodaiji 444-585, Aichi, Japan Present address: Aventis Pharmaceuticals, Inc., 26 Landsdowne Street, Cambridge, MA 02139, USA Corresponding author e-mail:
| | - Charles B. Epstein
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9148, USA
Present address: Department of Cell Biology, National Institute for Basic Biology, Nishigonaka 38, Myodaiji 444-585, Aichi, Japan Present address: Aventis Pharmaceuticals, Inc., 26 Landsdowne Street, Cambridge, MA 02139, USA Corresponding author e-mail:
| | - Ronald A. Butow
- Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9148, USA
Present address: Department of Cell Biology, National Institute for Basic Biology, Nishigonaka 38, Myodaiji 444-585, Aichi, Japan Present address: Aventis Pharmaceuticals, Inc., 26 Landsdowne Street, Cambridge, MA 02139, USA Corresponding author e-mail:
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Sekito T, Thornton J, Butow RA. Mitochondria-to-nuclear signaling is regulated by the subcellular localization of the transcription factors Rtg1p and Rtg3p. Mol Biol Cell 2000; 11:2103-15. [PMID: 10848632 PMCID: PMC14906 DOI: 10.1091/mbc.11.6.2103] [Citation(s) in RCA: 199] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cells modulate the expression of nuclear genes in response to changes in the functional state of mitochondria, an interorganelle communication pathway called retrograde regulation. In yeast, expression of the CIT2 gene shows a typical retrograde response in that its expression is dramatically increased in cells with dysfunctional mitochondria, such as in rho(o) petites. Three genes control this signaling pathway: RTG1 and RTG3, which encode basic helix-loop-helix leucine zipper transcription factors that bind as heterodimer to the CIT2 upstream activation site, and RTG2, which encodes a protein of unknown function. We show that in respiratory-competent (rho(+)) cells in which CIT2 expression is low, Rtg1p and Rtg3p exist as a complex largely in the cytoplasm, and in rho(o) petites in which CIT2 expression is high, they exist as a complex predominantly localized in the nucleus. Cytoplasmic Rtg3p is multiply phosphorylated and becomes partially dephosphorylated when localized in the nucleus. Rtg2p, which is cytoplasmic in both rho(+) and rho(o) cells, is required for the dephosphorylation and nuclear localization of Rtg3p. Interaction of Rtg3p with Rtg1p is required to retain Rtg3p in the cytoplasm of rho(+) cells; in the absence of such interaction, nuclear localization and dephosphorylation of Rtg3p is independent of Rtg2p. Our data show that Rtg1p acts as both a positive and negative regulator of the retrograde response and that Rtg2p acts to transduce mitochondrial signals affecting the phosphorylation state and subcellular localization of Rtg3p.
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Affiliation(s)
- T Sekito
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9148, USA
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Okamoto K, Sekito T, Yoshida K. The secondary structure and phylogenetic relationship deduced from complete nucleotide sequence of mitochondrial small subunit rRNA in yeast Hansenula wingei. Genes Genet Syst 1996; 71:69-74. [PMID: 8752867 DOI: 10.1266/ggs.71.69] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
We have accomplished the nucleotide sequence of the 1537 bp mitochondrial gene coding for small subunit (SSU) rRNA of yeast Hansenula wingei, and also determined the 5'- and 3'-termini by S1 nuclease mapping. Eight universally conserved (U) elements of the SSU rRNA were identified. Comparison of U regions among five fungal mitochondrial SSU rRNA shows the striking similarity between H. wingei and Saccharomyces cerevisiae. The construction of the secondary structure revealed a core structure similar to the counterpart of Escherichia coli 16S rRNA. The secondary structure also enabled us the specify seven variable (V) regions differing from those of other mitochondrial SSU rRNAs in size, sequence and possible secondary structure. Molecular phylogenetic evaluation based on U regions of five fungi indicates that mitochondria of H. wingei and S. cerevisiae diverged from the same lineage. This suggests that the evolution of mitochondria-encoded genes does not directly correlate with the alteration of mitochondrial genetic system: genome size, gene organization and codon usage.
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Affiliation(s)
- K Okamoto
- Department of Biological Science, Faculty of Science, Hiroshima University, Japan
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Abstract
For sequencing, mitochondrial DNA from Hansenula wingei yeast was digested with various restriction enzymes and the resultant DNA fragments were cloned into a pEMBL phasmid vector. Our clone bank consists of 39 overlapping clones which cover the entire 27,694 bp region of the H. wingei mitochondrial genome.
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Affiliation(s)
- T Sekito
- Department of Biological Science, Faculty of Science, Hiroshima University, Japan
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Sekito T, Okamoto K, Kitano H, Yoshida K. The complete mitochondrial DNA sequence of Hansenula wingei reveals new characteristics of yeast mitochondria. Curr Genet 1995; 28:39-53. [PMID: 8536312 DOI: 10.1007/bf00311880] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The complete 27,694-bp mitochondrial (mt) DNA sequence of Hansenula wingei, which is a typical budding yeast and contains circular mitochondrial DNA, has been determined. The mt sequence contains genes encoding large and small ribosomal RNAs, 25 tRNAs, three subunits of cytochrome c oxidase (subunits 1, 2 and 3), three subunits of ATPase (subunits 6, 8 and 9), apocytochrome b, seven subunits of NADH dehydrogenase (subunits 1, 2, 3, 4, 4L, 5 and 6), and a ribosomal protein, VAR1. The VAR1 gene is considered to be a typical yeast type. This is consistent with data on DNA and the deduced amino-acid sequence homology comparisons of genes ubiquitous in yeast and fungi. However, we have identified seven genes encoding NADH dehydrogenase subunits, which are not found in other yeast mitochondrial genomes, thus placing the H. wingei mitochondrial genome in a unique position. In addition the H. wingei mitochondrial genome also encodes one tRNA pseudogene and one short unidentified ORF. The genome is compact with only two introns both of which contain an ORF. One intron lies in the large rRNA gene while the other is situated in the cytochrome c oxidase subunit-1 gene. The conserved nonanucleotide motif (A/T)TATAAG (T/A)(A/T), which is a transcription start signal in Saccharomyces cerevisiae mitochondria, has also been found in the H. wingei mitochondrial genome. The codon assignments for ATA and CTN in H. wingei mitochondria are different from those in S. cerevisiae mitochondria. These results indicate a unique and novel structure for the H. wingei mitochondrial genome in terms of characteristics which are typical for both yeast and for filamentous fungi. This is the first complete mt DNA sequence report in yeast.
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Affiliation(s)
- T Sekito
- Department of Biological Science, Faculty of Science, Hiroshima University, Japan
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Okamoto K, Sekito T, Kitano H, Yoshida K. [Structure and diversity of yeast mitochondrial genomes]. Tanpakushitsu Kakusan Koso 1994; 39:1638-50. [PMID: 8090935] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- K Okamoto
- Department of Biological Science, Faculty of Science, Hiroshima University, Japan
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Okamoto K, Sekito T, Yoshida K. The mitochondrial genome of yeast Hansenula wingei encodes NADH dehydrogenase subunit genes ND4L and ND5. Mol Gen Genet 1994; 243:473-6. [PMID: 8202091 DOI: 10.1007/bf00280478] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Genes homologous to those encoding mitochondrial NADH dehydrogenase subunits ND4L and ND5 in filamentous fungi were identified in the mitochondrial genome of a budding yeast, Hansenula wingei. The structure and expression of these genes were investigated. The H. wingei ND4L gene is 282 bp long, and potentially codes for a polypeptide of 94 amino acids. The putative ND4L protein sequence shares about 46% homology with the analogous mitochondrial proteins of filamentous fungi. The H. wingei ND5 gene is 1935 bp long, and encodes a 645-residue polypeptide. The derived ND5 protein shares about 38% sequence homology with the analogue in filamentous fungi. The ND4L and ND5 genes have no intervening sequence, and form a gene cluster in the order of 5'-ND4L-ND5-3'. A presumptive mature dicistronic or polycistronic transcript of these genes was detected by Northern blot hybridization. These results strongly indicate that these ND4L and ND5 genes are active. As far as we are aware, this is the first report on the identification of mitochondrially encoded ND genes in yeast.
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Affiliation(s)
- K Okamoto
- Department of Biological Science, Faculty of Science, Hiroshima University, Higashi-Hiroshima, Japan
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