1
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Nagano M, Shimamura H, Toshima JY, Toshima J. Requirement of Rab5 GTPase during heat stress-induced endocytosis in yeast. J Biol Chem 2024:107553. [PMID: 39002672 DOI: 10.1016/j.jbc.2024.107553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 06/03/2024] [Accepted: 06/27/2024] [Indexed: 07/15/2024] Open
Abstract
The plasma membrane (PM) is constantly exposed to various stresses from the extracellular environment, such as heat and oxidative stress. These stresses often cause denaturation of membrane proteins and destabilize PM integrity, which is essential for normal cell viability and function. For maintenance of PM integrity, most eukaryotic cells have the PM quality control (PMQC) system, which removes damaged membrane proteins by endocytosis. Removal of damaged proteins from the PM by ubiquitin-mediated endocytosis is a key mechanism for maintenance of the PM integrity, but the importance of the early endosome in the PMQC system is still not well understood. Here we show that key proteins in early/sorting endosome function, Vps21p (yeast Rab5), Vps15p (phosphatidylinositol-3 kinase subunit), and Vps3p/8p (CORVET complex subunits), are involved in maintaining PM integrity. We found that Vps21p-enriched endosomes change the localization in the vicinity of the PM in response to heat stress and then rapidly fuse and form the enlarged compartments to efficiently transport Can1p to the vacuole. Additionally, we show that the deubiquitinating enzyme Doa4p is also involved in the PM integrity and its deletion causes mislocalization of Vps21p to the vacuolar lumen. Interestingly, in cells lacking Doa4p or Vps21p the amounts of free ubiquitin are decreased, and overexpression of ubiquitin restored defective cargo internalization in vps9Δ cells, suggesting that defective PM integrity in vps9Δ cells is caused by lack of free ubiquitin.
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Affiliation(s)
- Makoto Nagano
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo 125-8585, Japan; Research Center for Drug and Vaccine Development, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan.
| | - Hiroki Shimamura
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Junko Y Toshima
- School of Health Science, Tokyo University of Technology, 5-23-22 Nishikamata, Ota-ku, Tokyo 144-8535, Japan
| | - Jiro Toshima
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo 125-8585, Japan.
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2
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Nishimura A. Regulations and functions of proline utilization in yeast Saccharomyces cerevisiae. Biosci Biotechnol Biochem 2024; 88:131-137. [PMID: 37994668 DOI: 10.1093/bbb/zbad165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 11/18/2023] [Indexed: 11/24/2023]
Abstract
The quality of alcoholic beverages strongly depends on the metabolic characteristics of the yeast cells being used. To control the aroma and the taste of alcoholic beverages, as well as the production of ethanol in them, it is thus crucial to select yeast cells with the proper characteristics. Grape must contain a high concentration of proline, an amino acid that can potentially be a useful nitrogen source. However, Saccharomyces cerevisiae cannot utilize proline during the wine-making process, resulting in the elevated levels of proline in wine and consequent negative effects on wine quality. In this article, I review and discuss recent discoveries about the inhibitory mechanisms and roles of proline utilization in yeast. The information can help in developing novel yeast strains that can improve fermentation and enhance the quality and production efficiency of wine.
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Affiliation(s)
- Akira Nishimura
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Nara, Japan
- Institute for Research Initiatives, Nara Institute of Science and Technology, Ikoma, Nara, Japan
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3
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Stanchev LD, Møller-Hansen I, Lojko P, Rocha C, Borodina I. Screening of Saccharomyces cerevisiae metabolite transporters by 13C isotope substrate labeling. Front Microbiol 2023; 14:1286597. [PMID: 38116525 PMCID: PMC10729909 DOI: 10.3389/fmicb.2023.1286597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 11/10/2023] [Indexed: 12/21/2023] Open
Abstract
The transportome of Saccharomyces cerevisiae comprises approximately 340 membrane-bound proteins, of which very few are well-characterized. Elucidating transporter proteins' function is essential not only for understanding central cellular processes in metabolite exchange with the external milieu but also for optimizing the production of value-added compounds in microbial cell factories. Here, we describe the application of 13C-labeled stable isotopes and detection by targeted LC-MS/MS as a screening tool for identifying Saccharomyces cerevisiae metabolite transporters. We compare the transport assay's sensitivity, reproducibility, and accuracy in yeast transporter mutant cell lines and Xenopus oocytes. As proof of principle, we analyzed the transport profiles of five yeast amino acid transporters. We first cultured yeast transporter deletion or overexpression mutants on uniformly labeled 13C-glucose and then screened their ability to facilitate the uptake or export of an unlabeled pool of amino acids. Individual transporters were further studied by heterologous expression in Xenopus oocytes, followed by an uptake assay with 13C labeled yeast extract. Uptake assays in Xenopus oocytes showed higher reproducibility and accuracy. Although having lower accuracy, the results from S. cerevisiae indicated the system's potential for initial high-throughput screening for native metabolite transporters. We partially confirmed previously reported substrates for all five amino acid transporters. In addition, we propose broader substrate specificity for two of the transporter proteins. The method presented here demonstrates the application of a comprehensive screening platform for the knowledge expansion of the transporter-substrate relationship for native metabolites in S. cerevisiae.
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Affiliation(s)
| | | | | | | | - Irina Borodina
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, Denmark
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4
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Tanahashi R, Nishimura A, Morita F, Nakazawa H, Taniguchi A, Ichikawa K, Nakagami K, Boundy-Mills K, Takagi H. The arginine transporter Can1 acts as a transceptor for regulation of proline utilization in the yeast Saccharomyces cerevisiae. Yeast 2023; 40:333-348. [PMID: 36573467 DOI: 10.1002/yea.3836] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 11/29/2022] [Accepted: 12/23/2022] [Indexed: 12/28/2022] Open
Abstract
Proline is the most abundant amino acid in wine and beer, because the yeast Saccharomyces cerevisiae hardly assimilates proline during fermentation processes. Our previous studies showed that arginine induces endocytosis of the proline transporter Put4, resulting in inhibition of proline utilization. We here report a possible role of arginine sensing in the inhibition of proline utilization. We first found that two basic amino acids, ornithine, and lysine, inhibit proline utilization by inducing Put4 endocytosis in a manner similar to arginine, but citrulline does not. Our genetic screening revealed that the arginine transporter Can1 is involved in the inhibition of proline utilization by arginine. Intriguingly, the arginine uptake activity of Can1 was not required for the arginine-dependent inhibition of proline utilization, suggesting that Can1 has a function beyond its commonly known function of transporting arginine. More importantly, our biochemical analyses revealed that Can1 activates signaling cascades of protein kinase A in response to extracellular arginine. Hence, we proposed that Can1 regulates proline utilization by functioning as a transceptor possessing the activity of both a transporter and receptor of arginine.
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Affiliation(s)
- Ryoya Tanahashi
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
- Division for Research Strategy, Institute for Research Initiatives, Nara Institute of Science and Technology, Ikoma, Japan
- Department of Food Science and Technology, University of California Davis, Davis, California, USA
| | - Akira Nishimura
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Fumika Morita
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Hayate Nakazawa
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Atsuki Taniguchi
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Kazuki Ichikawa
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Kazuki Nakagami
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
| | - Kyria Boundy-Mills
- Department of Food Science and Technology, University of California Davis, Davis, California, USA
| | - Hiroshi Takagi
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Ikoma, Japan
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5
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Hepowit NL, Moon B, Ebert AC, Dickson RC, MacGurn JA. Art2 mediates selective endocytosis of methionine transporters during adaptation to sphingolipid depletion. J Cell Sci 2023; 136:jcs260675. [PMID: 37337792 PMCID: PMC10399987 DOI: 10.1242/jcs.260675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 06/01/2023] [Indexed: 06/21/2023] Open
Abstract
Accumulating evidence in several model organisms indicates that reduced sphingolipid biosynthesis promotes longevity, although underlying mechanisms remain unclear. In yeast, sphingolipid depletion induces a state resembling amino acid restriction, which we hypothesized might be due to altered stability of amino acid transporters at the plasma membrane. To test this, we measured surface abundance for a diverse panel of membrane proteins in the presence of myriocin, a sphingolipid biosynthesis inhibitor, in Saccharomyces cerevisiae. Unexpectedly, we found that surface levels of most proteins examined were either unaffected or increased during myriocin treatment, consistent with an observed decrease in bulk endocytosis. In contrast, sphingolipid depletion triggered selective endocytosis of the methionine transporter Mup1. Unlike methionine-induced Mup1 endocytosis, myriocin triggered Mup1 endocytosis that required the Rsp5 adaptor Art2, C-terminal lysine residues of Mup1 and the formation of K63-linked ubiquitin polymers. These findings reveal cellular adaptation to sphingolipid depletion by ubiquitin-mediated remodeling of nutrient transporter composition at the cell surface.
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Affiliation(s)
- Nathaniel L. Hepowit
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Bradley Moon
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Adam C. Ebert
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Robert C. Dickson
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536, USA
| | - Jason A. MacGurn
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37240, USA
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6
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Wang W, Lu J, Yang WC, Spear ED, Michaelis S, Matunis MJ. Analysis of a degron-containing reporter protein GFP-CL1 reveals a role for SUMO1 in cytosolic protein quality control. J Biol Chem 2023; 299:102851. [PMID: 36587767 PMCID: PMC9898758 DOI: 10.1016/j.jbc.2022.102851] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 12/16/2022] [Accepted: 12/19/2022] [Indexed: 12/30/2022] Open
Abstract
Misfolded proteins are recognized and degraded through protein quality control (PQC) pathways, which are essential for maintaining proteostasis and normal cellular functions. Defects in PQC can result in disease, including cancer, cardiovascular disease, and neurodegeneration. The small ubiquitin-related modifiers (SUMOs) were previously implicated in the degradation of nuclear misfolded proteins, but their functions in cytoplasmic PQC are unclear. Here, in a systematic screen of SUMO protein mutations in the budding yeast Saccharomyces cerevisiae, we identified a mutant allele (Smt3-K38A/K40A) that sensitizes cells to proteotoxic stress induced by amino acid analogs. Smt3-K38A/K40A mutant strains also exhibited a defect in the turnover of a soluble PQC model substrate containing the CL1 degron (NES-GFP-Ura3-CL1) localized in the cytoplasm, but not the nucleus. Using human U2OS SUMO1- and SUMO2-KO cell lines, we observed a similar SUMO-dependent pathway for degradation of the mammalian degron-containing PQC reporter protein, GFP-CL1, also only in the cytoplasm but not the nucleus. Moreover, we found that turnover of GFP-CL1 in the cytoplasm was uniquely dependent on SUMO1 but not the SUMO2 paralogue. Additionally, we showed that turnover of GFP-CL1 in the cytoplasm is dependent on the AAA-ATPase, Cdc48/p97. Cellular fractionation studies and analysis of a SUMO1-GFP-CL1 fusion protein revealed that SUMO1 promotes cytoplasmic misfolded protein degradation by maintaining substrate solubility. Collectively, our findings reveal a conserved and previously unrecognized role for SUMO1 in regulating cytoplasmic PQC and provide valuable insights into the roles of sumoylation in PQC-associated diseases.
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Affiliation(s)
- Wei Wang
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jian Lu
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Wei-Chih Yang
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Eric D Spear
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
| | - Susan Michaelis
- Department of Cell Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
| | - Michael J Matunis
- Department of Biochemistry and Molecular Biology, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, Maryland, USA.
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7
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TORC1 Signaling in Fungi: From Yeasts to Filamentous Fungi. Microorganisms 2023; 11:microorganisms11010218. [PMID: 36677510 PMCID: PMC9864104 DOI: 10.3390/microorganisms11010218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 01/18/2023] Open
Abstract
Target of rapamycin complex 1 (TORC1) is an important regulator of various signaling pathways. It can control cell growth and development by integrating multiple signals from amino acids, glucose, phosphate, growth factors, pressure, oxidation, and so on. In recent years, it has been reported that TORC1 is of great significance in regulating cytotoxicity, morphology, protein synthesis and degradation, nutrient absorption, and metabolism. In this review, we mainly discuss the upstream and downstream signaling pathways of TORC1 to reveal its role in fungi.
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8
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Sagarika P, Yadav K, Sahi C. Volleying plasma membrane proteins from birth to death: Role of J-domain proteins. Front Mol Biosci 2022; 9:1072242. [PMID: 36589230 PMCID: PMC9798423 DOI: 10.3389/fmolb.2022.1072242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/02/2022] [Indexed: 12/23/2022] Open
Abstract
The function, stability, and turnover of plasma membrane (PM) proteins are crucial for cellular homeostasis. Compared to soluble proteins, quality control of plasma membrane proteins is extremely challenging. Failure to meet the high quality control standards is detrimental to cellular and organismal health. J-domain proteins (JDPs) are among the most diverse group of chaperones that collaborate with other chaperones and protein degradation machinery to oversee cellular protein quality control (PQC). Although fragmented, the available literature from different models, including yeast, mammals, and plants, suggests that JDPs assist PM proteins with their synthesis, folding, and trafficking to their destination as well as their degradation, either through endocytic or proteasomal degradation pathways. Moreover, some JDPs interact directly with the membrane to regulate the stability and/or functionality of proteins at the PM. The deconvoluted picture emerging is that PM proteins are relayed from one JDP to another throughout their life cycle, further underscoring the versatility of the Hsp70:JDP machinery in the cell.
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9
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The Rheb GTPase promotes pheromone blindness via a TORC1-independent pathway in the phytopathogenic fungus Ustilago maydis. PLoS Genet 2022; 18:e1010483. [DOI: 10.1371/journal.pgen.1010483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 11/28/2022] [Accepted: 10/17/2022] [Indexed: 11/15/2022] Open
Abstract
The target of the rapamycin (TOR) signaling pathway plays a negative role in controlling virulence in phytopathogenic fungi. However, the actual targets involved in virulence are currently unknown. Using the corn smut fungus Ustilago maydis, we tried to address the effects of the ectopic activation of TOR on virulence. We obtained gain-of-function mutations in the Rheb GTPase, one of the conserved TOR kinase regulators. We have found that unscheduled activation of Rheb resulted in the alteration of the proper localization of the pheromone receptor, Pra1, and thereby pheromone insensitivity. Since pheromone signaling triggers virulence in Ustilaginales, we believe that the Rheb-induced pheromone blindness was responsible for the associated lack of virulence. Strikingly, although these effects required the concourse of the Rsp5 ubiquitin ligase and the Art3 α-arrestin, the TOR kinase was not involved. Several eukaryotic organisms have shown that Rheb transmits environmental information through TOR-dependent and -independent pathways. Therefore, our results expand the range of signaling manners at which environmental conditions could impinge on the virulence of phytopathogenic fungi.
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10
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Golden CK, Kazmirchuk TDD, McNally EK, El eissawi M, Gokbayrak ZD, Richard JD, Brett CL. A two-tiered system for selective receptor and transporter protein degradation. PLoS Genet 2022; 18:e1010446. [PMID: 36215320 PMCID: PMC9584418 DOI: 10.1371/journal.pgen.1010446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 10/20/2022] [Accepted: 09/26/2022] [Indexed: 11/06/2022] Open
Abstract
Diverse physiology relies on receptor and transporter protein down–regulation and degradation mediated by ESCRTs. Loss–of–function mutations in human ESCRT genes linked to cancers and neurological disorders are thought to block this process. However, when homologous mutations are introduced into model organisms, cells thrive and degradation persists, suggesting other mechanisms compensate. To better understand this secondary process, we studied degradation of transporter (Mup1) or receptor (Ste3) proteins when ESCRT genes (VPS27, VPS36) are deleted in Saccharomyces cerevisiae using live-cell imaging and organelle biochemistry. We find that endocytosis remains intact, but internalized proteins aberrantly accumulate on vacuolar lysosome membranes within cells. Here they are sorted for degradation by the intralumenal fragment (ILF) pathway, constitutively or when triggered by substrates, misfolding or TOR activation in vivo and in vitro. Thus, the ILF pathway functions as fail–safe layer of defense when ESCRTs disregard their clients, representing a two–tiered system that ensures degradation of surface polytopic proteins. Receptor, transporter and channel proteins on the plasma membranes (or surface) of all cells mediate extensive physiology. This requires precise control of their numbers, and damaged copies must be removed to prevent cytotoxicity. Their downregulation and degradation is mediated by lysosomes after endocytosis and entry into the multi–vesicular body (MVB) pathway which depends on ESCRTs (Endosomal Sorting Complexes Required for Transport). Loss–of–function mutations in ESCRT genes are linked to cancers and neurological disease, but cells survive and some proteins continue to be degraded. Herein, we use baker’s yeast (Saccharomyces cerevisiae) as model to better understand how surface proteins are degraded in cells missing ESCRT genes. Using fluorescence microscopy matched with biochemical and genetic approaches, we find that the methionine transporter Mup1 and G-protein coupled receptor Ste3 continue to be degraded when two ESCRT genes are deleted. They are endocytosed but rerouted to membranes of vacuolar lysosomes after stimuli are applied to trigger their downregulation. Here they are sorted into intralumenal fragments and degraded by acid hydrolases within vacuolar lysosomes upon homotypic membrane fusion. We propose that this intralumenal fragment (ILF) pathway functions as a secondary mechanism to degrade surface proteins with the canonical MVB pathway is disrupted.
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Affiliation(s)
| | | | - Erin Kate McNally
- Department of Biology, Concordia University, Montreal, Quebec, Canada
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11
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Nishimura A, Ichikawa K, Nakazawa H, Tanahashi R, Morita F, Sitepu I, Boundy-Mills K, Fox G, Takagi H. The Cdc25/Ras/cAMP-dependent protein kinase A signaling pathway regulates proline utilization in wine yeast Saccharomyces cerevisiae under a wine fermentation model. Biosci Biotechnol Biochem 2022; 86:1318-1326. [PMID: 35749464 DOI: 10.1093/bbb/zbac100] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 06/18/2022] [Indexed: 11/14/2022]
Abstract
Proline is a predominant amino acid in grape must, but it is poorly utilized by the yeast Saccharomyces cerevisiae in wine-making processes. This sometimes leads to a nitrogen deficiency during fermentation and proline accumulation in wine. In this study, we clarified that a glucose response is involved in an inhibitory mechanism of proline utilization in yeast. Our genetic screen showed that strains with a loss-of-function mutation on the CDC25 gene can utilize proline even under fermentation conditions. Cdc25 is a regulator of the glucose response consisting of the Ras/cAMP-dependent protein kinase A (PKA) pathway. Moreover, we found that activation of the Ras/PKA pathway is necessary for the inhibitory mechanism of proline utilization. The present data revealed that crosstalk exists between the carbon and proline metabolisms. Our study could hold promise for the development of wine yeast strains that can efficiently assimilate proline during the fermentation processes.
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Affiliation(s)
- Akira Nishimura
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara, Japan
| | - Kazuki Ichikawa
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara, Japan
| | - Hayate Nakazawa
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara, Japan
| | - Ryoya Tanahashi
- Division for Research Strategy, Institute for Research Initiatives, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara, Japan.,Phaff Yeast Culture Collection, Department of Food Science and Technology, University of California Davis, One Shields Ave, Davis, CA, USA
| | - Fumika Morita
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara, Japan
| | - Irnayuli Sitepu
- Phaff Yeast Culture Collection, Department of Food Science and Technology, University of California Davis, One Shields Ave, Davis, CA, USA
| | - Kyria Boundy-Mills
- Phaff Yeast Culture Collection, Department of Food Science and Technology, University of California Davis, One Shields Ave, Davis, CA, USA
| | - Glen Fox
- Department of Food Science and Technology, University of California Davis, One Shields Ave, Davis, CA, USA
| | - Hiroshi Takagi
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara, Japan
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12
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Barata-Antunes C, Talaia G, Broutzakis G, Ribas D, De Beule P, Casal M, Stefan CJ, Diallinas G, Paiva S. Interactions of cytosolic tails in the Jen1 carboxylate transporter are critical for trafficking and transport activity. J Cell Sci 2022; 135:275079. [PMID: 35437607 DOI: 10.1242/jcs.260059] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 04/05/2022] [Indexed: 12/26/2022] Open
Abstract
Plasma membrane (PM) transporters of the major facilitator superfamily (MFS) are essential for cell metabolism, growth and response to stress or drugs. In Saccharomyces cerevisiae, Jen1 is a monocarboxylate/H+ symporter that provides a model to dissect the molecular details underlying cellular expression, transport mechanism and turnover of MFS transporters. Here, we present evidence revealing novel roles of the cytosolic N- and C-termini of Jen1 in its biogenesis, PM stability and transport activity, using functional analyses of Jen1 truncations and chimeric constructs with UapA, an endocytosis-insensitive transporter of Aspergillus nidulans. Our results show that both N- and C-termini are critical for Jen1 trafficking to the PM, transport activity and endocytosis. Importantly, we provide evidence that Jen1 N- and C-termini undergo transport-dependent dynamic intramolecular interactions, which affect the transport activity and turnover of Jen1. Our results support an emerging concept where the cytoplasmic termini of PM transporters control transporter cell surface stability and function through flexible intramolecular interactions with each other. These findings might be extended to other MFS members to understand conserved and evolving mechanisms underlying transporter structure-function relationships. This article has an associated First Person interview with the first authors of the paper.
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Affiliation(s)
- Cláudia Barata-Antunes
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, 4710-057, Braga, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, 4710-057, Braga, Portugal
| | - Gabriel Talaia
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, 4710-057, Braga, Portugal.,Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - George Broutzakis
- Department of Biology, National and Kapodistrian University of Athens, Panepistimiopolis 15784, Athens, Greece
| | - David Ribas
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, 4710-057, Braga, Portugal
| | - Pieter De Beule
- International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga s/n, Braga, Portugal
| | - Margarida Casal
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, 4710-057, Braga, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, 4710-057, Braga, Portugal
| | - Christopher J Stefan
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimiopolis 15784, Athens, Greece.,Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, 70013, Heraklion, Greece
| | - Sandra Paiva
- Centre of Molecular and Environmental Biology, Department of Biology, University of Minho, 4710-057, Braga, Portugal.,Institute of Science and Innovation for Bio-Sustainability (IB-S), University of Minho, 4710-057, Braga, Portugal
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13
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α-Arrestins and Their Functions: From Yeast to Human Health. Int J Mol Sci 2022; 23:ijms23094988. [PMID: 35563378 PMCID: PMC9105457 DOI: 10.3390/ijms23094988] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 12/10/2022] Open
Abstract
α-Arrestins, also called arrestin-related trafficking adaptors (ARTs), constitute a large family of proteins conserved from yeast to humans. Despite their evolutionary precedence over their extensively studied relatives of the β-arrestin family, α-arrestins have been discovered relatively recently, and thus their properties are mostly unexplored. The predominant function of α-arrestins is the selective identification of membrane proteins for ubiquitination and degradation, which is an important element in maintaining membrane protein homeostasis as well as global cellular metabolisms. Among members of the arrestin clan, only α-arrestins possess PY motifs that allow canonical binding to WW domains of Rsp5/NEDD4 ubiquitin ligases and the subsequent ubiquitination of membrane proteins leading to their vacuolar/lysosomal degradation. The molecular mechanisms of the selective substrate’s targeting, function, and regulation of α-arrestins in response to different stimuli remain incompletely understood. Several functions of α-arrestins in animal models have been recently characterized, including redox homeostasis regulation, innate immune response regulation, and tumor suppression. However, the molecular mechanisms of α-arrestin regulation and substrate interactions are mainly based on observations from the yeast Saccharomyces cerevisiae model. Nonetheless, α-arrestins have been implicated in health disorders such as diabetes, cardiovascular diseases, neurodegenerative disorders, and tumor progression, placing them in the group of potential therapeutic targets.
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14
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Ishii R, Fukui A, Sakihama Y, Kitsukawa S, Futami A, Mochizuki T, Nagano M, Toshima J, Abe F. Substrate-induced differential degradation and partitioning of the two tryptophan permeases Tat1 and Tat2 into eisosomes in Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183858. [PMID: 35031272 DOI: 10.1016/j.bbamem.2021.183858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 12/22/2021] [Accepted: 12/27/2021] [Indexed: 06/14/2023]
Abstract
Tryptophan is a relatively rare amino acid whose influx is strictly controlled to meet cellular demands. The yeast Saccharomyces cerevisiae has two tryptophan permeases, namely Tat1 (low-affinity type) and Tat2 (high-affinity type). These permeases are differentially regulated through ubiquitination based on inducible conditions and dependence on arrestin-related trafficking adaptors, although the physiological significance of their degradation remain unclear. Here, we demonstrated that Tat2 was rapidly degraded in an Rsp5-Bul1-dependent manner upon the addition of tryptophan, phenylalanine, or tyrosine, whereas Tat1 was unaffected. The expression of the ubiquitination-deficient variant Tat25K>R led to a reduction in cell yield at 4 μg/mL tryptophan, suggesting the occurrence of an uncontrolled, excessive consumption of tryptophan at low tryptophan concentrations. Eisosomes are membrane furrows that are thought to be storage compartments for some nutrient permeases. Tryptophan addition caused rapid Tat2 dissociation from eisosomes, whereas Tat1 distribution was unaffected. The 5 K > R mutation had no marked effect on Tat2 dissociation, suggesting that dissociation is independent of ubiquitination. Interestingly, the D74R mutation, which was created within the N-terminal acidic patch, stabilized Tat2 while reducing the degree of partitioning into eisosomes. Moreover, the hyperactive I285V mutation in Tat2, which increases Vmax/Km for tryptophan import by 2-fold, reduced the degree of segregation into eisosomes. Our findings illustrate the coordinated activity of Tat1 and Tat2 in the regulation of tryptophan transport at various tryptophan concentrations and suggest the positive role of substrates in inducing a conformational transition in Tat2, resulting in its dissociation from eisosomes and subsequent ubiquitination-dependent degradation.
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Affiliation(s)
- Ryoga Ishii
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Ayu Fukui
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Yuri Sakihama
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Shoko Kitsukawa
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Ayami Futami
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan
| | - Takahiro Mochizuki
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan; Division of Medical Biochemistry, Faculty of Medicine, Tohoku Medical and Pharmaceutical University, 1-15-1, Fukumuro, Miyagino-ku, Sendai, Miyagi 983-8536, Japan
| | - Makoto Nagano
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Jiro Toshima
- Department of Biological Science and Technology, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo 125-8585, Japan
| | - Fumiyoshi Abe
- Department of Chemistry and Biological Science, College of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara 252-5258, Japan.
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15
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Zhou L, Li M, Cui P, Tian M, Xu Y, Zheng X, Zhang K, Li G, Wang X. Arrestin-Coding Genes Regulate Endocytosis, Sporulation, Pathogenicity, and Stress Resistance in Arthrobotrys oligospora. Front Cell Infect Microbiol 2022; 12:754333. [PMID: 35252023 PMCID: PMC8890662 DOI: 10.3389/fcimb.2022.754333] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/20/2022] [Indexed: 12/12/2022] Open
Abstract
Arrestins are a family of scaffold proteins that play a crucial role in regulating numerous cellular processes, such as GPCR signaling. The Arthrobotrys oligospora arrestin family contains 12 members, which have highly conserved N-terminal and C-terminal domains. In the presence of ammonia, A. oligospora can change its lifestyle from saprotrophic to carnivorous. During this transition, the expression pattern of arrestin-coding (AoArc) genes was markedly upregulated. Therefore, we disrupted seven AoArc genes from A. oligospora to identify their functions. Although individual arrestin mutant strains display similar pathogenesis, phenotypes, and stress resistance, the fundamental data on the roles of AoArc genes in A. oligospora are obtained in this study. Membrane endocytosis in AoArc mutants was significantly reduced. Meanwhile, the capacity of trap device formation against nematodes and ammonia was impaired due to AoArc deletions. We also found that AoArc genes could regulate conidial phenotypes, cell nuclear distribution, pH response, and stress resistance. Results of qRT-PCR assays revealed that sporulation-regulated genes were affected after the deletion of AoArc genes. In particular, among the 12 arrestins, AoArc2 mediates pH signaling in the fungus A. oligospora. Notably, combined with the classical paradigm of arrestin–GPCR signal transduction, we suggest that arrestin-regulated trap formation in A. oligospora may be directly linked to the receptor endocytosis pathway.
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Affiliation(s)
- Liang Zhou
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, China
- Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
| | - Mengfei Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, China
- Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
| | - Peijie Cui
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, China
- Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
| | - Mengqing Tian
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, China
- Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
| | - Ya Xu
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, China
- Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
| | - Xi Zheng
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, China
- Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
| | - Keqin Zhang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, China
- Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
| | - Guohong Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, China
- Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
- *Correspondence: Xin Wang, ; Guohong Li,
| | - Xin Wang
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, China
- Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan University, Kunming, China
- *Correspondence: Xin Wang, ; Guohong Li,
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16
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Moharir A, Gay L, Markus B. Mitochondrial energy metabolism regulates the nutrient import activity and endocytosis of APC transporters. FEBS Lett 2022; 596:1111-1123. [PMID: 35156710 PMCID: PMC9117475 DOI: 10.1002/1873-3468.14314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 01/30/2022] [Accepted: 02/01/2022] [Indexed: 11/11/2022]
Abstract
Nutrient import by APC-type transporters is predicted to have a high energy demand because it depends on the plasma membrane proton gradient established by the ATP-driven proton pump Pma1. We show that Pma1 is indeed a major energy consumer and its activity is tightly linked to the cellular ATP levels. The low Pma1 activity caused by acute loss of respiration resulted in a dramatic drop in cytoplasmic pH, which triggered the downregulation of the major proton importers, the APC transporters. This regulatory system is likely the reason for the observed rapid endocytosis of APC transporters during many environmental stresses. Furthermore, we show the importance of respiration in providing ATP to maintain a strong proton gradient for efficient nutrient uptake.
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Affiliation(s)
- Akshay Moharir
- Henry Eyring Center for Cell and Genome Science, University of Utah, 1390 President Circle, Salt Lake City, UT, 84112, USA
| | - Lincoln Gay
- Henry Eyring Center for Cell and Genome Science, University of Utah, 1390 President Circle, Salt Lake City, UT, 84112, USA
| | - Babst Markus
- Henry Eyring Center for Cell and Genome Science, University of Utah, 1390 President Circle, Salt Lake City, UT, 84112, USA
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17
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Wang T, Woodman P, Humphrey SJ, Petersen J. Environmental control of Pub1 (NEDD4 family E3 ligase) in Schizosaccharomyces pombe is regulated by TORC2 and Gsk3. Life Sci Alliance 2022; 5:5/5/e202101082. [PMID: 35121625 PMCID: PMC8817228 DOI: 10.26508/lsa.202101082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 01/24/2022] [Accepted: 01/25/2022] [Indexed: 11/24/2022] Open
Abstract
The NEDD4 family E3 ligase Pub1 is regulated by the nutrient environment, TORC2, and Gsk3 signalling pathway to control the level of amino acid transporters on the plasma membrane and thus nutrient uptake. Cells respond to changing nutrient environments by adjusting the abundance of surface nutrient transporters and receptors. This can be achieved by modulating ubiquitin-dependent endocytosis, which in part is regulated by the NEDD4 family of E3 ligases. Here we report novel regulation of Pub1, a fission yeast Schizosaccharomyces pombe member of the NEDD4-family of E3 ligases. We show that nitrogen stress inhibits Pub1 function, thereby increasing the abundance of the amino acid transporter Aat1 at the plasma membrane and enhancing sensitivity to the toxic arginine analogue canavanine. We show that TOR complex 2 (TORC2) signalling negatively regulates Pub1, thus TORC2 mutants under nutrient stress have decreased Aat1 at the plasma membrane and are resistant to canavanine. Inhibition of TORC2 signalling increases Pub1 phosphorylation, and this is dependent on Gsk3 activity. Addition of the Tor inhibitor Torin1 increases phosphorylation of Pub1 at serine 199 (S199) by 2.5-fold, and Pub1 protein levels in S199A phospho-ablated mutants are reduced. S199 is conserved in NEDD4 and is located immediately upstream of a WW domain required for protein interaction. Together, we describe how the major TORC2 nutrient-sensing signalling network regulates environmental control of Pub1 to modulate the abundance of nutrient transporters.
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Affiliation(s)
- Tingting Wang
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, Australia
| | - Philip Woodman
- School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Sean J Humphrey
- Charles Perkins Centre, School of Life and Environmental Sciences, The University of Sydney, Camperdown, Australia
| | - Janni Petersen
- Flinders Health and Medical Research Institute, Flinders Centre for Innovation in Cancer, Flinders University, Adelaide, Australia
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18
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Development and quantitative analysis of a biosensor based on the Arabidopsis SWEET1 sugar transporter. Proc Natl Acad Sci U S A 2022; 119:2119183119. [PMID: 35046045 PMCID: PMC8794804 DOI: 10.1073/pnas.2119183119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/13/2021] [Indexed: 01/01/2023] Open
Abstract
Transporters are the gatekeepers of the cell. Transporters facilitate the exchange of ions and metabolites between cellular and subcellular compartments, thus controlling processes from bacterial chemotaxis to the release of neurotransmitters. In plants, transporters have key roles in the allocation of carbon to nonphotosynthetic organs. Biosensors derived from transporters have been generated to monitor the activity of these proteins within the complex environment of the cell. However, a quantitative framework that reconciles molecular and cellular-level events to help interpret the response of biosensors is still lacking. Here, we created a sugar transporter biosensor and formulated a mathematical model to explain its response. These types of models can help realize multiscale, dynamic simulations of metabolite allocation to guide crop improvement. SWEETs are transporters with homologs in Archeae, plants, some fungi, and animals. As the only transporters known to facilitate the cellular release of sugars in plants, SWEETs play critical roles in the allocation of sugars from photosynthetic leaves to storage tissues in seeds, fruits, and tubers. Here, we report the design and use of genetically encoded biosensors to measure the activity of SWEETs. We created a SweetTrac1 sensor by inserting a circularly permutated green fluorescent protein into the Arabidopsis SWEET1, resulting in a chimera that translates substrate binding during the transport cycle into detectable changes in fluorescence intensity. We demonstrate that a combination of cell sorting and bioinformatics can accelerate the design of biosensors and formulate a mass action kinetics model to correlate the fluorescence response of SweetTrac1 with the transport of glucose. Our analysis suggests that SWEETs are low-affinity, symmetric transporters that can rapidly equilibrate intra- and extracellular concentrations of sugars. This approach can be extended to SWEET homologs and other transporters.
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19
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Kapetanakis GC, Gournas C, Prévost M, Georis I, André B. Overlapping Roles of Yeast Transporters Aqr1, Qdr2, and Qdr3 in Amino Acid Excretion and Cross-Feeding of Lactic Acid Bacteria. Front Microbiol 2021; 12:752742. [PMID: 34887841 PMCID: PMC8649695 DOI: 10.3389/fmicb.2021.752742] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 11/01/2021] [Indexed: 11/16/2022] Open
Abstract
Microbial species occupying the same ecological niche or codeveloping during a fermentation process can exchange metabolites and mutualistically influence each other’s metabolic states. For instance, yeast can excrete amino acids, thereby cross-feeding lactic acid bacteria unable to grow without an external amino acid supply. The yeast membrane transporters involved in amino acid excretion remain poorly known. Using a yeast mutant overproducing and excreting threonine (Thr) and its precursor homoserine (Hom), we show that excretion of both amino acids involves the Aqr1, Qdr2, and Qdr3 proteins of the Drug H+-Antiporter Family (DHA1) family. We further investigated Aqr1 as a representative of these closely related amino acid exporters. In particular, structural modeling and molecular docking coupled to mutagenesis experiments and excretion assays enabled us to identify residues in the Aqr1 substrate-binding pocket that are crucial for Thr and/or Hom export. We then co-cultivated yeast and Lactobacillus fermentum in an amino-acid-free medium and found a yeast mutant lacking Aqr1, Qdr2, and Qdr3 to display a reduced ability to sustain the growth of this lactic acid bacterium, a phenotype not observed with strains lacking only one of these transporters. This study highlights the importance of yeast DHA1 transporters in amino acid excretion and mutualistic interaction with lactic acid bacteria.
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Affiliation(s)
- George C Kapetanakis
- Molecular Physiology of the Cell, Université Libre de Bruxelles, Biopark, Gosselies, Belgium
| | - Christos Gournas
- Microbial Molecular Genetics Laboratory, Institute of Biosciences and Applications, National Centre for Scientific Research "Demokritos", Agia Paraskevi, Greece
| | - Martine Prévost
- Structure et Fonction des Membranes Biologiques, Université Libre de Bruxelles, Brussels, Belgium
| | - Isabelle Georis
- Transport of Amino Acids, Sensing and Signaling in Eukaryotes, Labiris, Brussels, Belgium
| | - Bruno André
- Molecular Physiology of the Cell, Université Libre de Bruxelles, Biopark, Gosselies, Belgium
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20
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Robinson BP, Hawbaker S, Chiang A, Jordahl EM, Anaokar S, Nikiforov A, Bowman RW, Ziegler P, McAtee CK, Patton-Vogt J, O'Donnell AF. Alpha-arrestins Aly1/Art6 and Aly2/Art3 regulate trafficking of the glycerophosphoinositol transporter Git1 and impact phospholipid homeostasis. Biol Cell 2021; 114:3-31. [PMID: 34562280 DOI: 10.1111/boc.202100007] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 06/23/2021] [Accepted: 07/15/2021] [Indexed: 12/20/2022]
Abstract
BACKGROUND INFORMATION Phosphatidylinositol (PI) is an essential phospholipid, critical to membrane bilayers. The complete deacylation of PI by B-type phospholipases produces intracellular and extracellular glycerophosphoinositol (GPI). Extracellular GPI is transported into the cell via Git1, a member of the Major Facilitator Superfamily of transporters at the yeast plasma membrane. Internalized GPI is degraded to produce inositol, phosphate and glycerol, thereby contributing to these pools. GIT1 gene expression is controlled by nutrient balance, with phosphate or inositol starvation increasing GIT1 expression to stimulate GPI uptake. However, less is known about control of Git1 protein levels or localization. RESULTS We find that the α-arrestins, an important class of protein trafficking adaptor, regulate Git1 localization and this is dependent upon their interaction with the ubiquitin ligase Rsp5. Specifically, α-arrestin Aly2 stimulates Git1 trafficking to the vacuole under basal conditions, but in response to GPI-treatment, either Aly1 or Aly2 promote Git1 vacuole trafficking. Cell surface retention of Git1, as occurs in aly1∆ aly2∆ cells, is linked to impaired growth in the presence of exogenous GPI and results in increased uptake of radiolabeled GPI, suggesting that accumulation of GPI somehow causes cellular toxicity. Regulation of α-arrestin Aly1 by the protein phosphatase calcineurin improves steady-state and substrate-induced trafficking of Git1, however, calcineurin plays a larger role in Git1 trafficking beyond regulation of α-arrestins. Interestingly, loss of Aly1 and Aly2 increased phosphatidylinositol-3-phosphate on the limiting membrane of the vacuole, and this was further exacerbated by GPI addition, suggesting that the effect is partially linked to Git1. Loss of Aly1 and Aly2 leads to increased incorporation of inositol label from [3 H]-inositol-labelled GPI into PI, confirming that internalized GPI influences PI balance and indicating a role for the a-arrestins in this regulation. CONCLUSIONS The α-arrestins Aly1 and Aly2 are novel regulators of Git1 trafficking with previously unanticipated roles in controlling phospholipid distribution and balance. SIGNIFICANCE To our knowledge, this is the first example of α-arrestin regulation of phosphatidyliniositol-3-phosphate levels. In future studies it will be exciting to determine if other α-arrestins similarly alter PI and PIPs to change the cellular landscape.
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Affiliation(s)
- Benjamin P Robinson
- Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania, USA
| | - Sarah Hawbaker
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Annette Chiang
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Eric M Jordahl
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Sanket Anaokar
- Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania, USA
| | - Alexiy Nikiforov
- Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania, USA
| | - Ray W Bowman
- Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania, USA.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Philip Ziegler
- Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania, USA
| | - Ceara K McAtee
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Jana Patton-Vogt
- Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania, USA
| | - Allyson F O'Donnell
- Department of Biological Sciences, Duquesne University, Pittsburgh, Pennsylvania, USA.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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21
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The Bul1/2 Alpha-Arrestins Promote Ubiquitylation and Endocytosis of the Can1 Permease upon Cycloheximide-Induced TORC1-Hyperactivation. Int J Mol Sci 2021; 22:ijms221910208. [PMID: 34638549 PMCID: PMC8508209 DOI: 10.3390/ijms221910208] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 09/15/2021] [Accepted: 09/16/2021] [Indexed: 12/12/2022] Open
Abstract
Selective endocytosis followed by degradation is a major mechanism for downregulating plasma membrane transporters in response to specific environmental cues. In Saccharomyces cerevisiae, this endocytosis is promoted by ubiquitylation catalyzed by the Rsp5 ubiquitin-ligase, targeted to transporters via adaptors of the alpha-arrestin family. However, the molecular mechanisms of this targeting and their control according to conditions remain incompletely understood. In this work, we dissect the molecular mechanisms eliciting the endocytosis of Can1, the arginine permease, in response to cycloheximide-induced TORC1 hyperactivation. We show that cycloheximide promotes Rsp5-dependent Can1 ubiquitylation and endocytosis in a manner dependent on the Bul1/2 alpha-arrestins. Also crucial for this downregulation is a short acidic patch sequence in the N-terminus of Can1 likely acting as a binding site for Bul1/2. The previously reported inhibition by cycloheximide of transporter recycling, from the trans-Golgi network to the plasma membrane, seems to additionally contribute to efficient Can1 downregulation. Our results also indicate that, contrary to the previously described substrate-transport elicited Can1 endocytosis mediated by the Art1 alpha-arrestin, Bul1/2-mediated Can1 ubiquitylation occurs independently of the conformation of the transporter. This study provides further insights into how distinct alpha-arrestins control the ubiquitin-dependent downregulation of a specific amino acid transporter under different conditions.
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22
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Zhang C, Sui D, Zhang T, Hu J. Molecular Basis of Zinc-Dependent Endocytosis of Human ZIP4 Transceptor. Cell Rep 2021; 31:107582. [PMID: 32348750 PMCID: PMC7661102 DOI: 10.1016/j.celrep.2020.107582] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 02/03/2020] [Accepted: 04/07/2020] [Indexed: 12/05/2022] Open
Abstract
Nutrient transporters can be rapidly removed from the cell surface via substrate-stimulated endocytosis as a way to control nutrient influx, but the molecular underpinnings are not well understood. In this work, we focus on zinc-dependent endocytosis of human ZIP4 (hZIP4), a zinc transporter that is essential for dietary zinc uptake. Structure-guided mutagenesis and internalization assay reveal that hZIP4 per se acts as the exclusive zinc sensor, with the transport site’s being responsible for zinc sensing. In an effort of seeking sorting signal, a scan of the longest cytosolic loop (L2) leads to identification of a conserved Leu-Gln-Leu motif that is essential for endocytosis. Partial proteolysis of purified hZIP4 demonstrates a structural coupling between the transport site and the L2 upon zinc binding, which supports a working model of how zinc ions at physiological concentration trigger a conformation-dependent endocytosis of the zinc transporter. This work provides a paradigm on post-translational regulation of nutrient transporters. Cell surface expression of ZIP4, a transporter for intestinal zinc uptake, is regulated by zinc availability. Zhang et al. report that human ZIP4 acts as the exclusive zinc sensor in initiating the zinc-dependent endocytosis, and a cytosolic motif is essential for sorting signal formation, indicating that ZIP4 is a transceptor.
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Affiliation(s)
- Chi Zhang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Dexin Sui
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Tuo Zhang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Jian Hu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
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23
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Tanahashi R, Matsushita T, Nishimura A, Takagi H. Downregulation of the broad-specificity amino acid permease Agp1 mediated by the ubiquitin ligase Rsp5 and the arrestin-like protein Bul1 in yeast. Biosci Biotechnol Biochem 2021; 85:1266-1274. [PMID: 33620458 DOI: 10.1093/bbb/zbab028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 02/16/2021] [Indexed: 11/13/2022]
Abstract
Most of plasma membrane transporters are downregulated by ubiquitination-dependent endocytosis to avoid the excess uptake of their substrates. In Saccharomyces cerevisiae, ubiquitination of transporters is mediated by the HECT-type ubiquitin ligase Rsp5. We report here a mechanism underlying the substrate-induced endocytosis of the broad-specificity amino acid permease Agp1. First, we found that Agp1 underwent ubiquitination and endocytosis in response to the addition of excess asparagine, which is a substrate of Agp1. Moreover, the substrate-induced internalization of Agp1 was dependent on the ubiquitination activity of Rsp5. Since Rsp5 requires α-arrestin family proteins as adaptors to bind with substrates, we next developed a method of genetic screening to identify adaptor proteins for Agp1 endocytosis. This screening and biochemical analysis revealed that Bul1, but not its paralogue Bul2, was essential for the substrate-induced endocytosis of Agp1. Our results support that the substrate-induced endocytosis of Agp1 requires Rsp5 and Bul1.
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Affiliation(s)
- Ryoya Tanahashi
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Nara, Japan
| | - Tomonori Matsushita
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Nara, Japan
| | - Akira Nishimura
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Nara, Japan
| | - Hiroshi Takagi
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Nara, Japan
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24
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Yoshinari A, Hosokawa T, Beier MP, Oshima K, Ogino Y, Hori C, Takasuka TE, Fukao Y, Fujiwara T, Takano J. Transport-coupled ubiquitination of the borate transporter BOR1 for its boron-dependent degradation. THE PLANT CELL 2021; 33:420-438. [PMID: 33866370 PMCID: PMC8136889 DOI: 10.1093/plcell/koaa020] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Accepted: 11/20/2020] [Indexed: 05/17/2023]
Abstract
Plants take up and translocate nutrients through transporters. In Arabidopsis thaliana, the borate exporter BOR1 acts as a key transporter under boron (B) limitation in the soil. Upon sufficient-B supply, BOR1 undergoes ubiquitination and is transported to the vacuole for degradation, to avoid overaccumulation of B. However, the mechanisms underlying B-sensing and ubiquitination of BOR1 are unknown. In this study, we confirmed the lysine-590 residue in the C-terminal cytosolic region of BOR1 as the direct ubiquitination site and showed that BOR1 undergoes K63-linked polyubiquitination. A forward genetic screen identified that amino acid residues located in vicinity of the substrate-binding pocket of BOR1 are essential for the vacuolar sorting. BOR1 variants that lack B-transport activity showed a significant reduction of polyubiquitination and subsequent vacuolar sorting. Coexpression of wild-type (WT) and a transport-defective variant of BOR1 in the same cells showed degradation of the WT but not the variant upon sufficient-B supply. These findings suggest that polyubiquitination of BOR1 relies on its conformational transition during the transport cycle. We propose a model in which BOR1, as a B transceptor, directly senses the B concentration and promotes its own polyubiquitination and vacuolar sorting for quick and precise maintenance of B homeostasis.
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Affiliation(s)
- Akira Yoshinari
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, 599-8531, Japan
- Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589 Hokkaido, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, 464-8601 Japan
| | - Takuya Hosokawa
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, 599-8531, Japan
| | - Marcel Pascal Beier
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, 599-8531, Japan
- Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo 113-8657, Japan
| | - Keishi Oshima
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, 599-8531, Japan
| | - Yuka Ogino
- Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589 Hokkaido, Japan
| | - Chiaki Hori
- Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589 Hokkaido, Japan
| | - Taichi E Takasuka
- Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589 Hokkaido, Japan
| | - Yoichiro Fukao
- Plant Global Education Project, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, 630-0101, Japan
- Department of Bioinformatics, Ritsumeikan University, 1-1-1, Nodihigashi, Kusatsu, 525-8577, Japan
| | - Toru Fujiwara
- Graduate School of Agricultural and Life Sciences, the University of Tokyo, Tokyo 113-8657, Japan
| | - Junpei Takano
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, 599-8531, Japan
- Graduate School of Agriculture, Hokkaido University, Sapporo, 060-8589 Hokkaido, Japan
- Author for communication:
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Endocytosis of nutrient transporters in fungi: The ART of connecting signaling and trafficking. Comput Struct Biotechnol J 2021; 19:1713-1737. [PMID: 33897977 PMCID: PMC8050425 DOI: 10.1016/j.csbj.2021.03.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 03/14/2021] [Accepted: 03/14/2021] [Indexed: 12/11/2022] Open
Abstract
Plasma membrane transporters play pivotal roles in the import of nutrients, including sugars, amino acids, nucleobases, carboxylic acids, and metal ions, that surround fungal cells. The selective removal of these transporters by endocytosis is one of the most important regulatory mechanisms that ensures a rapid adaptation of cells to the changing environment (e.g., nutrient fluctuations or different stresses). At the heart of this mechanism lies a network of proteins that includes the arrestin‐related trafficking adaptors (ARTs) which link the ubiquitin ligase Rsp5 to nutrient transporters and endocytic factors. Transporter conformational changes, as well as dynamic interactions between its cytosolic termini/loops and with lipids of the plasma membrane, are also critical during the endocytic process. Here, we review the current knowledge and recent findings on the molecular mechanisms involved in nutrient transporter endocytosis, both in the budding yeast Saccharomyces cerevisiae and in some species of the filamentous fungus Aspergillus. We elaborate on the physiological importance of tightly regulated endocytosis for cellular fitness under dynamic conditions found in nature and highlight how further understanding and engineering of this process is essential to maximize titer, rate and yield (TRY)-values of engineered cell factories in industrial biotechnological processes.
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Key Words
- AAs, amino acids
- ACT, amino Acid/Choline Transporter
- AP, adaptor protein
- APC, amino acid-polyamine-organocation
- Arg, arginine
- Arrestins
- Arts, arrestin‐related trafficking adaptors
- Asp, aspartic acid
- Aspergilli
- Biotechnology
- C, carbon
- C-terminus, carboxyl-terminus
- Cell factories
- Conformational changes
- Cu, copper
- DUBs, deubiquitinating enzymes
- EMCs, eisosome membrane compartments
- ER, endoplasmic reticulum
- ESCRT, endosomal sorting complex required for transport
- Endocytic signals
- Endocytosis
- Fe, iron
- Fungi
- GAAC, general amino acid control
- Glu, glutamic acid
- H+, proton
- IF, inward-facing
- LAT, L-type Amino acid Transporter
- LID, loop Interaction Domain
- Lys, lysine
- MCCs, membrane compartments containing the arginine permease Can1
- MCCs/eisosomes
- MCPs, membrane compartments of Pma1
- MFS, major facilitator superfamily
- MVB, multi vesicular bodies
- Met, methionine
- Metabolism
- Mn, manganese
- N, nitrogen
- N-terminus, amino-terminus
- NAT, nucleobase Ascorbate Transporter
- NCS1, nucleobase/Cation Symporter 1
- NCS2, nucleobase cation symporter family 2
- NH4+, ammonium
- Nutrient transporters
- OF, outward-facing
- PEST, proline (P), glutamic acid (E), serine (S), and threonine (T)
- PM, plasma membrane
- PVE, prevacuolar endosome
- Saccharomyces cerevisiae
- Signaling pathways
- Structure-function
- TGN, trans-Golgi network
- TMSs, transmembrane segments
- TORC1, target of rapamycin complex 1
- TRY, titer, rate and yield
- Trp, tryptophan
- Tyr, tyrosine
- Ub, ubiquitin
- Ubiquitylation
- VPS, vacuolar protein sorting
- W/V, weight per volume
- YAT, yeast Amino acid Transporter
- Zn, Zinc
- fAATs, fungal AA transporters
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26
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Fletcher E, Mercurio K, Walden EA, Baetz K. A yeast chemogenomic screen identifies pathways that modulate adipic acid toxicity. iScience 2021; 24:102327. [PMID: 33889823 PMCID: PMC8050732 DOI: 10.1016/j.isci.2021.102327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 02/19/2021] [Accepted: 03/15/2021] [Indexed: 11/18/2022] Open
Abstract
Adipic acid production by yeast fermentation is gaining attention as a renewable source of platform chemicals for making nylon products. However, adipic acid toxicity inhibits yeast growth and fermentation. Here, we performed a chemogenomic screen in Saccharomyces cerevisiae to understand the cellular basis of adipic acid toxicity. Our screen revealed that KGD1 (a key gene in the tricarboxylic acid cycle) deletion improved tolerance to adipic acid and its toxic precursor, catechol. Conversely, disrupting ergosterol biosynthesis as well as protein trafficking and vacuolar transport resulted in adipic acid hypersensitivity. Notably, we show that adipic acid disrupts the Membrane Compartment of Can1 (MCC) on the plasma membrane and impacts endocytosis. This was evidenced by the rapid internalization of Can1 for vacuolar degradation. As ergosterol is an essential component of the MCC and protein trafficking mechanisms are required for endocytosis, we highlight the importance of these cellular processes in modulating adipic acid toxicity. Deletion of the TCA cycle gene KGD1 improves tolerance to adipic acid and catechol Ergosterol and Pdr12 play non-overlapping roles protecting cell from adipic acid Adipic acid-induced plasma membrane localization of Pdr12 is independent of ergosterol Adipic acid disrupts the Membrane Compartment of Can1 (MCC) and induces endocytosis
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Affiliation(s)
- Eugene Fletcher
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Kevin Mercurio
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Elizabeth A. Walden
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Kristin Baetz
- Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
- Corresponding author
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27
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Kahlhofer J, Leon S, Teis D, Schmidt O. The α-arrestin family of ubiquitin ligase adaptors links metabolism with selective endocytosis. Biol Cell 2021; 113:183-219. [PMID: 33314196 DOI: 10.1111/boc.202000137] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 12/03/2020] [Indexed: 12/14/2022]
Abstract
The regulation of nutrient uptake into cells is important, as it allows to either increase biomass for cell growth or to preserve homoeostasis. A key strategy to adjust cellular nutrient uptake is the reconfiguration of the nutrient transporter repertoire at the plasma membrane by the addition of nutrient transporters through the secretory pathway and by their endocytic removal. In this review, we focus on the mechanisms that regulate selective nutrient transporter endocytosis, which is mediated by the α-arrestin protein family. In the budding yeast Saccharomyces cerevisiae, 14 different α-arrestins (also named arrestin-related trafficking adaptors, ARTs) function as adaptors for the ubiquitin ligase Rsp5. They instruct Rsp5 to ubiquitinate subsets of nutrient transporters to orchestrate their endocytosis. The ART proteins are under multilevel control of the major nutrient sensing systems, including amino acid sensing by the general amino acid control and target of rapamycin pathways, and energy sensing by 5'-adenosine-monophosphate-dependent kinase. The function of the six human α-arrestins is comparably under-characterised. Here, we summarise the current knowledge about the function, regulation and substrates of yeast ARTs and human α-arrestins, and highlight emerging communalities and general principles.
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Affiliation(s)
- Jennifer Kahlhofer
- Institute for Cell Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Sebastien Leon
- Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - David Teis
- Institute for Cell Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
| | - Oliver Schmidt
- Institute for Cell Biology, Biocenter, Medical University Innsbruck, Innsbruck, Austria
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28
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Sardana R, Emr SD. Membrane Protein Quality Control Mechanisms in the Endo-Lysosome System. Trends Cell Biol 2021; 31:269-283. [PMID: 33414051 DOI: 10.1016/j.tcb.2020.11.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/26/2020] [Accepted: 11/30/2020] [Indexed: 01/12/2023]
Abstract
Protein quality control (PQC) machineries play a critical role in selective identification and removal of mistargeted, misfolded, and aberrant proteins. This task is extremely complicated due to the enormous diversity of the proteome. It also requires nuanced and careful differentiation between 'normal' and 'folding intermediates' from 'abnormal' and 'misfolded' protein states. Multiple genetic and proteomic approaches have started to delineate the molecular underpinnings of how these machineries recognize their target and how their activity is regulated. In this review, we summarize our understanding of the various E3 ubiquitin ligases and associated machinery that mediate PQC in the endo-lysosome system in yeast and humans, how they are regulated, and mechanisms of target selection, with the intent of guiding future research in this area.
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Affiliation(s)
- Richa Sardana
- Weill Institute of Cell and Molecular Biology, Cornell University, Ithaca, NY, USA; Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Scott D Emr
- Weill Institute of Cell and Molecular Biology, Cornell University, Ithaca, NY, USA; Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA.
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29
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Haindrich AC, Ernst V, Naguleswaran A, Oliveres QF, Roditi I, Rentsch D. Nutrient availability regulates proline/alanine transporters in Trypanosoma brucei. J Biol Chem 2021; 296:100566. [PMID: 33745971 PMCID: PMC8094907 DOI: 10.1016/j.jbc.2021.100566] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 03/09/2021] [Accepted: 03/17/2021] [Indexed: 11/23/2022] Open
Abstract
Trypanosoma brucei is a species of unicellular parasite that can cause severe diseases in livestock and humans, including African trypanosomiasis and Chagas disease. Adaptation to diverse environments and changes in nutritional conditions is essential for T. brucei to establish an infection when changing hosts or during invasion of different host tissues. One such adaptation is the ability of T. brucei to rapidly switch its energy metabolism from glucose metabolism in the mammalian blood to proline catabolism in the insect stages and vice versa. However, the mechanisms that support the parasite's response to nutrient availability remain unclear. Using RNAseq and qRT-PCR, we investigated the response of T. brucei to amino acid or glucose starvation and found increased mRNA levels of several amino acid transporters, including all genes of the amino acid transporter AAT7-B subgroup. Functional characterization revealed that AAT7-B members are plasma membrane-localized in T. brucei and when expressed in Saccharomyces cerevisiae supported the uptake of proline, alanine, and cysteine, while other amino acids were poorly recognized. All AAT7-B members showed a preference for proline, which is transported with high or low affinity. RNAi-mediated AAT7-B downregulation resulted in a reduction of intracellular proline concentrations and growth arrest under low proline availability in cultured procyclic form parasites. Taken together, these results suggest a role of AAT7-B transporters in the response of T. brucei to proline starvation and proline catabolism.
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Affiliation(s)
| | - Viona Ernst
- Institute of Plant Sciences, University of Bern, Bern, Switzerland
| | | | | | - Isabel Roditi
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Doris Rentsch
- Institute of Plant Sciences, University of Bern, Bern, Switzerland.
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30
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Growth Inhibition by Amino Acids in Saccharomyces cerevisiae. Microorganisms 2020; 9:microorganisms9010007. [PMID: 33375077 PMCID: PMC7822121 DOI: 10.3390/microorganisms9010007] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 12/17/2020] [Accepted: 12/18/2020] [Indexed: 12/17/2022] Open
Abstract
Amino acids are essential metabolites but can also be toxic when present at high levels intracellularly. Substrate-induced downregulation of amino acid transporters in Saccharomyces cerevisiae is thought to be a mechanism to avoid this toxicity. It has been shown that unregulated uptake by the general amino acid permease Gap1 causes cells to become sensitive to amino acids. Here, we show that overexpression of eight other amino acid transporters (Agp1, Bap2, Can1, Dip5, Gnp1, Lyp1, Put4, or Tat2) also induces a growth defect when specific single amino acids are present at concentrations of 0.5-5 mM. We can now state that all proteinogenic amino acids, as well as the important metabolite ornithine, are growth inhibitory to S. cerevisiae when transported into the cell at high enough levels. Measurements of initial transport rates and cytosolic pH show that toxicity is due to amino acid accumulation and not to the influx of co-transported protons. The amino acid sensitivity phenotype is a useful tool that reports on the in vivo activity of transporters and has allowed us to identify new transporter-specific substrates.
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31
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Tanahashi R, Afiah TSN, Nishimura A, Watanabe D, Takagi H. The C2 domain of the ubiquitin ligase Rsp5 is required for ubiquitination of the endocytic protein Rvs167 upon change of nitrogen source. FEMS Yeast Res 2020; 20:5986617. [PMID: 33201982 DOI: 10.1093/femsyr/foaa058] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 10/16/2020] [Indexed: 12/26/2022] Open
Abstract
Ubiquitination is a key signal for endocytosis of proteins on the plasma membrane. The ubiquitin ligase Rsp5 of Saccharomyces cerevisiae, which contains an amino-terminal membrane-binding C2 domain, three substrate-recognizing tryptophan-tryptophan (WW) domains and a carboxyl-terminal catalytic homologous to the E6-AP carboxyl terminus (HECT) domain, can ubiquitinate plasma membrane proteins directing them for endocytosis. Here, we examined the roles of the C2 domain in endocytosis for the downregulation of the general amino acid permease Gap1, which is one of nitrogen-regulated permeases in S. cerevisiae. First, we constructed several rsp5 mutants producing Rsp5 variants without the C2 domain or with amino acid changes of membrane-binding lysine residues. These mutants showed defects in endocytosis of Gap1 in response to a preferred nitrogen source. Intriguingly, we found that ubiquitination of Gap1 in these mutant cells was highly similar to that in wild-type cells during endocytosis. These results indicate that the C2 domain is essential for endocytosis but not for ubiquitination of substrates such as Gap1. Moreover, genetic and biochemical analyses showed that the endocytic protein Rvs167 was ubiquitinated via Rsp5 and the C2 domain was required for efficient ubiquitination in response to a preferred nitrogen source. Here, we propose a mechanism for the C2 domain-mediated endocytosis of plasma membrane permeases.
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Affiliation(s)
- Ryoya Tanahashi
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
| | - Tira Siti Nur Afiah
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
| | - Akira Nishimura
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
| | - Daisuke Watanabe
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
| | - Hiroshi Takagi
- Division of Biological Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, 8916-5 Takayama-cho, Ikoma, Nara 630-0192, Japan
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32
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van‘t Klooster JS, Bianchi F, Doorn RB, Lorenzon M, Lusseveld JH, Punter CM, Poolman B. Extracellular loops matter - subcellular location and function of the lysine transporter Lyp1 from Saccharomyces cerevisiae. FEBS J 2020; 287:4401-4414. [PMID: 32096906 PMCID: PMC7687128 DOI: 10.1111/febs.15262] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 02/05/2020] [Accepted: 02/24/2020] [Indexed: 12/01/2022]
Abstract
Yeast amino acid transporters of the APC superfamily are responsible for the proton motive force-driven uptake of amino acids into the cell, which for most secondary transporters is a reversible process. The l-lysine proton symporter Lyp1 of Saccharomyces cerevisiae is special in that the Michaelis constant from out-to-in transport ( K m out → in ) is much lower than K m in → out , which allows accumulation of l-lysine to submolar concentration. It has been proposed that high intracellular lysine is part of the antioxidant mechanism of the cell. The molecular basis for the unique kinetic properties of Lyp1 is unknown. We compared the sequence of Lyp1 with APC para- and orthologues and find structural features that set Lyp1 apart, including differences in extracellular loop regions. We screened the extracellular loops by alanine mutagenesis and determined Lyp1 localization and activity and find positions that affect either the localization or activity of Lyp1. Half of the affected mutants are located in the extension of extracellular loop 3 or in a predicted α-helix in extracellular loop 4. Our data indicate that extracellular loops not only connect the transmembrane helices but also serve functionally important roles.
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Affiliation(s)
- Joury S. van‘t Klooster
- Department of BiochemistryGroningen Biomolecular Sciences and Biotechnology InstituteUniversity of GroningenThe Netherlands
| | - Frans Bianchi
- Department of BiochemistryGroningen Biomolecular Sciences and Biotechnology InstituteUniversity of GroningenThe Netherlands
| | - Ruben B. Doorn
- Department of BiochemistryGroningen Biomolecular Sciences and Biotechnology InstituteUniversity of GroningenThe Netherlands
| | - Mirco Lorenzon
- Department of BiochemistryGroningen Biomolecular Sciences and Biotechnology InstituteUniversity of GroningenThe Netherlands
| | - Jarnick H. Lusseveld
- Department of BiochemistryGroningen Biomolecular Sciences and Biotechnology InstituteUniversity of GroningenThe Netherlands
| | - Christiaan M. Punter
- Department of BiochemistryGroningen Biomolecular Sciences and Biotechnology InstituteUniversity of GroningenThe Netherlands
| | - Bert Poolman
- Department of BiochemistryGroningen Biomolecular Sciences and Biotechnology InstituteUniversity of GroningenThe Netherlands
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33
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Buelto D, Hung CW, Aoh QL, Lahiri S, Duncan MC. Plasma membrane to vacuole traffic induced by glucose starvation requires Gga2-dependent sorting at the trans-Golgi network. Biol Cell 2020; 112:349-367. [PMID: 32761633 DOI: 10.1111/boc.202000058] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 07/27/2020] [Indexed: 12/17/2022]
Abstract
BACKGROUND INFORMATION In the yeast Saccharomyces cerevisiae, acute glucose starvation induces rapid endocytosis followed by vacuolar degradation of many plasma membrane proteins. This process is essential for cell viability, but the regulatory mechanisms that control it remain poorly understood. Under normal growth conditions, a major regulatory decision for endocytic cargo occurs at the trans-Golgi network (TGN) where proteins can recycle back to the plasma membrane or can be recognized by TGN-localised clathrin adaptors that direct them towards the vacuole. However, glucose starvation reduces recycling and alters the localization and post-translational modification of TGN-localised clathrin adaptors. This raises the possibility that during glucose starvation endocytosed proteins are routed to the vacuole by a novel mechanism that bypasses the TGN or does not require TGN-localised clathrin adaptors. RESULTS Here, we investigate the role of TGN-localised clathrin adaptors in the traffic of several amino acid permeases, including Can1, during glucose starvation. We find that Can1 transits through the TGN after endocytosis in both starved and normal conditions. Can1 and other amino acid permeases require TGN-localised clathrin adaptors for maximal delivery to the vacuole. Furthermore, these permeases are actively sorted to the vacuole, because ectopically forced de-ubiquitination at the TGN results in the recycling of the Tat1 permase in starved cells. Finally, we report that the Mup1 permease requires the clathrin adaptor Gga2 for vacuolar delivery. In contrast, the clathrin adaptor protein complex AP-1 plays a minor role, potentially in retaining permeases in the TGN, but it is otherwise dispensable for vacuolar delivery. CONCLUSIONS AND SIGNIFICANCE This work elucidates one membrane trafficking pathway needed for yeast to respond to acute glucose starvation. It also reveals the functions of TGNlocalised clathrin adaptors in this process. Our results indicate that the same machinery is needed for vacuolar protein sorting at the GN in glucose starved cells as is needed in the presence of glucose. In addition, our findings provide further support for the model that the TGN is a transit point for many endocytosed proteins, and that Gga2 and AP-1 function in distinct pathways at the TGN.
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Affiliation(s)
- Destiney Buelto
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Chao-Wei Hung
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.,Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Quyen L Aoh
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sagar Lahiri
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Mara C Duncan
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
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34
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Alghamdi AH, Munday JC, Campagnaro GD, Gurvic D, Svensson F, Okpara CE, Kumar A, Quintana J, Martin Abril ME, Milić P, Watson L, Paape D, Settimo L, Dimitriou A, Wielinska J, Smart G, Anderson LF, Woodley CM, Kelly SPY, Ibrahim HM, Hulpia F, Al-Salabi MI, Eze AA, Sprenger T, Teka IA, Gudin S, Weyand S, Field M, Dardonville C, Tidwell RR, Carrington M, O'Neill P, Boykin DW, Zachariae U, De Koning HP. Positively selected modifications in the pore of TbAQP2 allow pentamidine to enter Trypanosoma brucei. eLife 2020; 9:56416. [PMID: 32762841 PMCID: PMC7473772 DOI: 10.7554/elife.56416] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 08/06/2020] [Indexed: 11/25/2022] Open
Abstract
Mutations in the Trypanosoma brucei aquaporin AQP2 are associated with resistance to pentamidine and melarsoprol. We show that TbAQP2 but not TbAQP3 was positively selected for increased pore size from a common ancestor aquaporin. We demonstrate that TbAQP2’s unique architecture permits pentamidine permeation through its central pore and show how specific mutations in highly conserved motifs affect drug permeation. Introduction of key TbAQP2 amino acids into TbAQP3 renders the latter permeable to pentamidine. Molecular dynamics demonstrates that permeation by dicationic pentamidine is energetically favourable in TbAQP2, driven by the membrane potential, although aquaporins are normally strictly impermeable for ionic species. We also identify the structural determinants that make pentamidine a permeant although most other diamidine drugs are excluded. Our results have wide-ranging implications for optimising antitrypanosomal drugs and averting cross-resistance. Moreover, these new insights in aquaporin permeation may allow the pharmacological exploitation of other members of this ubiquitous gene family. African sleeping sickness is a potentially deadly illness caused by the parasite Trypanosoma brucei. The disease is treatable, but many of the current treatments are old and are becoming increasingly ineffective. For instance, resistance is growing against pentamidine, a drug used in the early stages in the disease, as well as against melarsoprol, which is deployed when the infection has progressed to the brain. Usually, cases resistant to pentamidine are also resistant to melarsoprol, but it is still unclear why, as the drugs are chemically unrelated. Studies have shown that changes in a water channel called aquaglyceroporin 2 (TbAQP2) contribute to drug resistance in African sleeping sickness; this suggests that it plays a role in allowing drugs to kill the parasite. This molecular ‘drain pipe’ extends through the surface of T. brucei, and should allow only water and a molecule called glycerol in and out of the cell. In particular, the channel should be too narrow to allow pentamidine or melarsoprol to pass through. One possibility is that, in T. brucei, the TbAQP2 channel is abnormally wide compared to other members of its family. Alternatively, pentamidine and melarsoprol may only bind to TbAQP2, and then ‘hitch a ride’ when the protein is taken into the parasite as part of the natural cycle of surface protein replacement. Alghamdi et al. aimed to tease out these hypotheses. Computer models of the structure of the protein were paired with engineered changes in the key areas of the channel to show that, in T. brucei, TbAQP2 provides a much broader gateway into the cell than observed for similar proteins. In addition, genetic analysis showed that this version of TbAQP2 has been actively selected for during the evolution process of T. brucei. This suggests that the parasite somehow benefits from this wider aquaglyceroporin variant. This is a new resistance mechanism, and it is possible that aquaglyceroporins are also larger than expected in other infectious microbes. The work by Alghamdi et al. therefore provides insight into how other germs may become resistant to drugs.
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Affiliation(s)
- Ali H Alghamdi
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Jane C Munday
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | | | - Dominik Gurvic
- Computational Biology Centre for Translational and Interdisciplinary Research, University of Dundee, Dundee, United Kingdom
| | - Fredrik Svensson
- IOTA Pharmaceuticals Ltd, St Johns Innovation Centre, Cambridge, United Kingdom
| | - Chinyere E Okpara
- Department of Chemistry, University of Liverpool, Liverpool, United Kingdom
| | - Arvind Kumar
- Chemistry Department, Georgia State University, Atlanta, United States
| | - Juan Quintana
- School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | | | - Patrik Milić
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Laura Watson
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Daniel Paape
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Luca Settimo
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Anna Dimitriou
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Joanna Wielinska
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Graeme Smart
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Laura F Anderson
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | | | - Siu Pui Ying Kelly
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Hasan Ms Ibrahim
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Fabian Hulpia
- Laboratory for Medicinal Chemistry, University of Ghent, Ghent, Belgium
| | - Mohammed I Al-Salabi
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Anthonius A Eze
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Teresa Sprenger
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Ibrahim A Teka
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Simon Gudin
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Simone Weyand
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Mark Field
- School of Life Sciences, University of Dundee, Dundee, United Kingdom.,Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Ceske Budejovice, Czech Republic
| | | | - Richard R Tidwell
- Department of Pathology and Lab Medicine, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Mark Carrington
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Paul O'Neill
- Department of Chemistry, University of Liverpool, Liverpool, United Kingdom
| | - David W Boykin
- Chemistry Department, Georgia State University, Atlanta, United States
| | - Ulrich Zachariae
- Computational Biology Centre for Translational and Interdisciplinary Research, University of Dundee, Dundee, United Kingdom
| | - Harry P De Koning
- Institute of Infection, Immunity and Inflammation, University of Glasgow, Glasgow, United Kingdom
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35
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Nitrogen coordinated import and export of arginine across the yeast vacuolar membrane. PLoS Genet 2020; 16:e1008966. [PMID: 32776922 PMCID: PMC7440668 DOI: 10.1371/journal.pgen.1008966] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 08/20/2020] [Accepted: 06/30/2020] [Indexed: 11/19/2022] Open
Abstract
The vacuole of the yeast Saccharomyces cerevisiae plays an important role in nutrient storage. Arginine, in particular, accumulates in the vacuole of nitrogen-replete cells and is mobilized to the cytosol under nitrogen starvation. The arginine import and export systems involved remain poorly characterized, however. Furthermore, how their activity is coordinated by nitrogen remains unknown. Here we characterize Vsb1 as a novel vacuolar membrane protein of the APC (amino acid-polyamine-organocation) transporter superfamily which, in nitrogen-replete cells, is essential to active uptake and storage of arginine into the vacuole. A shift to nitrogen starvation causes apparent inhibition of Vsb1-dependent activity and mobilization of stored vacuolar arginine to the cytosol. We further show that this arginine export involves Ypq2, a vacuolar protein homologous to the human lysosomal cationic amino acid exporter PQLC2 and whose activity is detected only in nitrogen-starved cells. Our study unravels the main arginine import and export systems of the yeast vacuole and suggests that they are inversely regulated by nitrogen. The lysosome-like vacuole of the yeast Saccharomyces cerevisiae is an important storage compartment for diverse nutrients, including the cationic amino acid arginine, which accumulates at high concentrations in this organelle in nitrogen-replete cells. When these cells are transferred to a nitrogen-free medium, vacuolar arginine is mobilized to the cytosol, where it is used as an alternative nitrogen source to sustain growth. Although this phenomenon has been observed since the 1980s, the identity of the vacuolar transporters involved in the accumulation and the mobilization of arginine is not well established, and whether these processes are regulated according to nutritional cues remains unknown. In this study, we exploited in vitro and in vivo uptake assays in vacuoles to identify and characterize Vsb1 and Ypq2 as vacuolar membrane proteins mediating import and export of arginine, respectively. We further provide evidence that Vsb1 and Ypq2 are inversely regulated according to the nitrogen status of the cell. Our study sheds new light on the poorly studied topic of the diversity and metabolic control of vacuolar transporters. It also raises novel questions about the molecular mechanisms underlying their coordinated regulation and, by extension, the regulation of lysosomal transporters in human cells.
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36
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Ivashov V, Zimmer J, Schwabl S, Kahlhofer J, Weys S, Gstir R, Jakschitz T, Kremser L, Bonn GK, Lindner H, Huber LA, Leon S, Schmidt O, Teis D. Complementary α-arrestin-ubiquitin ligase complexes control nutrient transporter endocytosis in response to amino acids. eLife 2020; 9:e58246. [PMID: 32744498 PMCID: PMC7449699 DOI: 10.7554/elife.58246] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 08/01/2020] [Indexed: 12/12/2022] Open
Abstract
How cells adjust nutrient transport across their membranes is incompletely understood. Previously, we have shown that S. cerevisiae broadly re-configures the nutrient transporters at the plasma membrane in response to amino acid availability, through endocytosis of sugar- and amino acid transporters (AATs) (Müller et al., 2015). A genome-wide screen now revealed that the selective endocytosis of four AATs during starvation required the α-arrestin family protein Art2/Ecm21, an adaptor for the ubiquitin ligase Rsp5, and its induction through the general amino acid control pathway. Art2 uses a basic patch to recognize C-terminal acidic sorting motifs in AATs and thereby instructs Rsp5 to ubiquitinate proximal lysine residues. When amino acids are in excess, Rsp5 instead uses TORC1-activated Art1 to detect N-terminal acidic sorting motifs within the same AATs, which initiates exclusive substrate-induced endocytosis. Thus, amino acid excess or starvation activate complementary α-arrestin-Rsp5-complexes to control selective endocytosis and adapt nutrient acquisition.
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Affiliation(s)
- Vasyl Ivashov
- Institute for Cell Biology, Medical University of InnsbruckInnsbruckAustria
| | - Johannes Zimmer
- Institute for Cell Biology, Medical University of InnsbruckInnsbruckAustria
| | - Sinead Schwabl
- Institute for Cell Biology, Medical University of InnsbruckInnsbruckAustria
| | - Jennifer Kahlhofer
- Institute for Cell Biology, Medical University of InnsbruckInnsbruckAustria
| | - Sabine Weys
- Institute for Cell Biology, Medical University of InnsbruckInnsbruckAustria
| | - Ronald Gstir
- ADSI – Austrian Drug Screening Institute GmbHInnsbruckAustria
| | | | - Leopold Kremser
- Division of Clinical Biochemistry, ProteinMicroAnalysis Facility, Medical University of InnsbruckInnsbruckAustria
| | - Günther K Bonn
- ADSI – Austrian Drug Screening Institute GmbHInnsbruckAustria
| | - Herbert Lindner
- Division of Clinical Biochemistry, ProteinMicroAnalysis Facility, Medical University of InnsbruckInnsbruckAustria
| | - Lukas A Huber
- Institute for Cell Biology, Medical University of InnsbruckInnsbruckAustria
- ADSI – Austrian Drug Screening Institute GmbHInnsbruckAustria
| | - Sebastien Leon
- Université de Paris, CNRS, Institut Jacques MonodParisFrance
| | - Oliver Schmidt
- Institute for Cell Biology, Medical University of InnsbruckInnsbruckAustria
| | - David Teis
- Institute for Cell Biology, Medical University of InnsbruckInnsbruckAustria
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37
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Athanasopoulos A, André B, Sophianopoulou V, Gournas C. Fungal plasma membrane domains. FEMS Microbiol Rev 2020; 43:642-673. [PMID: 31504467 DOI: 10.1093/femsre/fuz022] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/25/2019] [Indexed: 12/11/2022] Open
Abstract
The plasma membrane (PM) performs a plethora of physiological processes, the coordination of which requires spatial and temporal organization into specialized domains of different sizes, stability, protein/lipid composition and overall architecture. Compartmentalization of the PM has been particularly well studied in the yeast Saccharomyces cerevisiae, where five non-overlapping domains have been described: The Membrane Compartments containing the arginine permease Can1 (MCC), the H+-ATPase Pma1 (MCP), the TORC2 kinase (MCT), the sterol transporters Ltc3/4 (MCL), and the cell wall stress mechanosensor Wsc1 (MCW). Additional cortical foci at the fungal PM are the sites where clathrin-dependent endocytosis occurs, the sites where the external pH sensing complex PAL/Rim localizes, and sterol-rich domains found in apically grown regions of fungal membranes. In this review, we summarize knowledge from several fungal species regarding the organization of the lateral PM segregation. We discuss the mechanisms of formation of these domains, and the mechanisms of partitioning of proteins there. Finally, we discuss the physiological roles of the best-known membrane compartments, including the regulation of membrane and cell wall homeostasis, apical growth of fungal cells and the newly emerging role of MCCs as starvation-protective membrane domains.
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Affiliation(s)
- Alexandros Athanasopoulos
- Microbial Molecular Genetics Laboratory, Institute of Biosciences and Applications, National Centre for Scientific Research 'Demokritos,' Patr. Grigoriou E & 27 Neapoleos St. 15341, Agia Paraskevi, Greece
| | - Bruno André
- Molecular Physiology of the Cell laboratory, Université Libre de Bruxelles (ULB), Institut de Biologie et de Médecine Moléculaires, rue des Pr Jeener et Brachet 12, 6041, Gosselies, Belgium
| | - Vicky Sophianopoulou
- Microbial Molecular Genetics Laboratory, Institute of Biosciences and Applications, National Centre for Scientific Research 'Demokritos,' Patr. Grigoriou E & 27 Neapoleos St. 15341, Agia Paraskevi, Greece
| | - Christos Gournas
- Microbial Molecular Genetics Laboratory, Institute of Biosciences and Applications, National Centre for Scientific Research 'Demokritos,' Patr. Grigoriou E & 27 Neapoleos St. 15341, Agia Paraskevi, Greece
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38
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Nishimura A, Tanikawa T, Takagi H. Inhibitory effect of arginine on proline utilization in
Saccharomyces cerevisiae. Yeast 2020; 37:531-540. [DOI: 10.1002/yea.3504] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 05/15/2020] [Accepted: 06/11/2020] [Indexed: 11/10/2022] Open
Affiliation(s)
- Akira Nishimura
- Division of Biological Science, Graduate School of Science and Technology Nara Institute of Science and Technology Nara 630‐0192 Japan
| | - Tsubasa Tanikawa
- Division of Biological Science, Graduate School of Science and Technology Nara Institute of Science and Technology Nara 630‐0192 Japan
| | - Hiroshi Takagi
- Division of Biological Science, Graduate School of Science and Technology Nara Institute of Science and Technology Nara 630‐0192 Japan
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39
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van 't Klooster JS, Cheng TY, Sikkema HR, Jeucken A, Moody B, Poolman B. Periprotein lipidomes of Saccharomyces cerevisiae provide a flexible environment for conformational changes of membrane proteins. eLife 2020; 9:57003. [PMID: 32301705 PMCID: PMC7182430 DOI: 10.7554/elife.57003] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 04/09/2020] [Indexed: 12/20/2022] Open
Abstract
Yeast tolerates a low pH and high solvent concentrations. The permeability of the plasma membrane (PM) for small molecules is low and lateral diffusion of proteins is slow. These findings suggest a high degree of lipid order, which raises the question of how membrane proteins function in such an environment. The yeast PM is segregated into the Micro-Compartment-of-Can1 (MCC) and Pma1 (MCP), which have different lipid compositions. We extracted proteins from these microdomains via stoichiometric capture of lipids and proteins in styrene-maleic-acid-lipid-particles (SMALPs). We purified SMALP-lipid-protein complexes by chromatography and quantitatively analyzed periprotein lipids located within the diameter defined by one SMALP. Phospholipid and sterol concentrations are similar for MCC and MCP, but sphingolipids are enriched in MCP. Ergosterol is depleted from this periprotein lipidome, whereas phosphatidylserine is enriched relative to the bulk of the plasma membrane. Direct detection of PM lipids in the 'periprotein space' supports the conclusion that proteins function in the presence of a locally disordered lipid state.
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Affiliation(s)
- Joury S van 't Klooster
- Department of Biochemistry, University of Groningen Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, Netherlands
| | - Tan-Yun Cheng
- Division of Rheumatology, Inflammation and Immunity Brigham and Women's Hospital, Harvard Medical School, Boston, United States
| | - Hendrik R Sikkema
- Department of Biochemistry, University of Groningen Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, Netherlands
| | - Aike Jeucken
- Department of Biochemistry, University of Groningen Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, Netherlands
| | - Branch Moody
- Division of Rheumatology, Inflammation and Immunity Brigham and Women's Hospital, Harvard Medical School, Boston, United States.,Department of Medicine, Harvard Medical School, Boston, United States
| | - Bert Poolman
- Department of Biochemistry, University of Groningen Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, Netherlands
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40
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Tumolo JM, Hepowit NL, Joshi SS, MacGurn JA. A Snf1-related nutrient-responsive kinase antagonizes endocytosis in yeast. PLoS Genet 2020; 16:e1008677. [PMID: 32191698 PMCID: PMC7176151 DOI: 10.1371/journal.pgen.1008677] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 04/22/2020] [Accepted: 02/17/2020] [Indexed: 12/18/2022] Open
Abstract
Endocytosis is regulated in response to changing environmental conditions to adjust plasma membrane (PM) protein composition for optimal cell growth. Protein networks involved in cargo capture and sorting, membrane sculpting and deformation, and vesicle scission have been well-characterized, but less is known about the networks that sense extracellular cues and relay signals to trigger endocytosis of specific cargo. Hal4 and Hal5 are yeast Snf1-related kinases that were previously reported to regulate nutrient transporter stability by an unknown mechanism. Here we demonstrate that loss of Hal4 and Hal5 activates endocytosis of many different kinds of PM proteins, including Art1-mediated and Art1-independent endocytic events. Acute inhibition of Hal5 in the absence of Hal4 triggers rapid endocytosis, suggesting that Hal kinases function in a nutrient-sensing relay upstream of the endocytic response. Interestingly, Hal5 localizes to the PM, but shifts away from the cell surface in response to stimulation with specific nutrients. We propose that Hal5 functions as a nutrient-responsive regulator of PM protein stability, antagonizing endocytosis and promoting stability of endocytic cargos at the PM in nutrient-limiting conditions. Cellular homeostasis, a fundamental requirement for all living organisms, is maintained in part through evolutionarily conserved mechanisms that regulate the abundance and activity of ion and nutrient transporters at the cell surface. These mechanisms often incorporate signaling networks that sense changes in the environment and relay signals to alter protein composition at the plasma membrane, often by inducing endocytosis of specific transporters in order to adjust and optimize transport activities at the cell surface. Here, we investigate two kinases in yeast–Hal4 and Hal5 –that are related to the yeast and human AMP sensing kinases. Loss of both Hal4 and Hal5 was previously reported to result in destabilization of ion and nutrient transporters by an unknown mechanism. Our data indicates that Hal kinases function broadly in the regulation of many different classes of endocytic cargo. Hal5 localizes to the plasma membrane in a manner that is responsive to nutrient availability and acute loss of Hal5 activity triggers rapid internalization of endocytic cargo. By uncovering a role for Hal5 as a nutrient-responsive regulator of endocytosis, this research sheds light on how signaling molecules regulate membrane trafficking events to coordinate adaptive growth responses.
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Affiliation(s)
- Jessica M. Tumolo
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Nathaniel L. Hepowit
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Samika S. Joshi
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Jason A. MacGurn
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
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41
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Yeast α-arrestin Art2 is the key regulator of ubiquitylation-dependent endocytosis of plasma membrane vitamin B1 transporters. PLoS Biol 2019; 17:e3000512. [PMID: 31658248 PMCID: PMC6837554 DOI: 10.1371/journal.pbio.3000512] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 11/07/2019] [Accepted: 10/09/2019] [Indexed: 11/19/2022] Open
Abstract
Endocytosis of membrane proteins in yeast requires α-arrestin-mediated ubiquitylation by the ubiquitin ligase Rsp5. Yet, the diversity of α-arrestin targets studied is restricted to a small subset of plasma membrane (PM) proteins. Here, we performed quantitative proteomics to identify new targets of 12 α-arrestins and gained insight into the diversity of pathways affected by α-arrestins, including the cell wall integrity pathway and PM–endoplasmic reticulum contact sites. We found that Art2 is the main regulator of substrate- and stress-induced ubiquitylation and endocytosis of the thiamine (vitamin B1) transporters: Thi7, nicotinamide riboside transporter 1 (Nrt1), and Thi72. Genetic screening allowed for the isolation of transport-defective Thi7 mutants, which impaired thiamine-induced endocytosis. Coexpression of inactive mutants with wild-type Thi7 revealed that both transporter conformation and transport activity are important to induce endocytosis. Finally, we provide evidence that Art2 mediated Thi7 endocytosis is regulated by the target of rapamycin complex 1 (TORC1) and requires the Sit4 phosphatase but is not inhibited by the Npr1 kinase. A combination of proteomics, protein modeling, and molecular biology sheds light on how endocytosis of the plasma membrane vitamin B1 transporter Thi7 in yeast is regulated by the α-arrestin Art2.
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42
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Baile MG, Guiney EL, Sanford EJ, MacGurn JA, Smolka MB, Emr SD. Activity of a ubiquitin ligase adaptor is regulated by disordered insertions in its arrestin domain. Mol Biol Cell 2019; 30:3057-3072. [PMID: 31618110 PMCID: PMC6880881 DOI: 10.1091/mbc.e19-08-0451] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The protein composition of the plasma membrane is rapidly remodeled in response to changes in nutrient availability or cellular stress. This occurs, in part, through the selective ubiquitylation and endocytosis of plasma membrane proteins, which in the yeast Saccharomyces cerevisiae is mediated by the HECT E3 ubiquitin ligase Rsp5 and arrestin-related trafficking (ART) adaptors. Here, we provide evidence that the ART protein family members are composed of an arrestin fold with interspersed disordered loops. Using Art1 as a model, we show that these loop and tail regions, while not strictly required for function, regulate its activity through two separate mechanisms. Disruption of one loop mediates Art1 substrate specificity. Other loops are subjected to phosphorylation in a manner dependent on the Pho85 cyclins Clg1 and Pho80. Phosphorylation of the loops controls Art1’s localization to the plasma membrane, which promotes cargo ubiquitylation and endocytosis, demonstrating a mechanism through which Art1 activity is regulated.
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Affiliation(s)
- Matthew G Baile
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Evan L Guiney
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Ethan J Sanford
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Jason A MacGurn
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN 37212
| | - Marcus B Smolka
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Scott D Emr
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
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43
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Abstract
We review the mechanisms responsible for amino acid homeostasis in Saccharomyces cerevisiae and other fungi. Amino acid homeostasis is essential for cell growth and survival. Hence, the de novo synthesis reactions, metabolic conversions, and transport of amino acids are tightly regulated. Regulation varies from nitrogen pool sensing to control by individual amino acids and takes place at the gene (transcription), protein (posttranslational modification and allostery), and vesicle (trafficking and endocytosis) levels. The pools of amino acids are controlled via import, export, and compartmentalization. In yeast, the majority of the amino acid transporters belong to the APC (amino acid-polyamine-organocation) superfamily, and the proteins couple the uphill transport of amino acids to the electrochemical proton gradient. Although high-resolution structures of yeast amino acid transporters are not available, homology models have been successfully exploited to determine and engineer the catalytic and regulatory functions of the proteins. This has led to a further understanding of the underlying mechanisms of amino acid sensing and subsequent downregulation of transport. Advances in optical microscopy have revealed a new level of regulation of yeast amino acid transporters, which involves membrane domain partitioning. The significance and the interrelationships of the latest discoveries on amino acid homeostasis are put in context.
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44
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Cytosolic N- and C-Termini of the Aspergillus nidulans FurE Transporter Contain Distinct Elements that Regulate by Long-Range Effects Function and Specificity. J Mol Biol 2019; 431:3827-3844. [DOI: 10.1016/j.jmb.2019.07.013] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 07/04/2019] [Accepted: 07/04/2019] [Indexed: 01/05/2023]
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45
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Abstract
Cell nutrition, detoxification, signalling, homeostasis and response to drugs, processes related to cell growth, differentiation and survival are all mediated by plasma membrane (PM) proteins called transporters. Despite their distinct fine structures, mechanism of function, energetic requirements, kinetics and substrate specificities, all transporters are characterized by a main hydrophobic body embedded in the PM as a series of tightly packed, often intertwined, α-helices that traverse the lipid bilayer in a zigzag mode, connected with intracellular or extracellular loops and hydrophilic N- and C-termini. Whereas longstanding genetic, biochemical and biophysical evidence suggests that specific transmembrane segments, and also their connecting loops, are responsible for substrate recognition and transport dynamics, emerging evidence also reveals the functional importance of transporter N- and C-termini, in respect to transport catalysis, substrate specificity, subcellular expression, stability and signalling. This review highlights selected prototypic examples of transporters in which their termini play important roles in their functioning.
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Affiliation(s)
- Emmanuel Mikros
- Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis, 15771 Athens, Greece
| | - George Diallinas
- Department of Biology, National and Kapodistrian University of Athens, Panepistimioupolis, 15781 Athens, Greece
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46
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Krammer EM, Prévost M. Function and Regulation of Acid Resistance Antiporters. J Membr Biol 2019; 252:465-481. [DOI: 10.1007/s00232-019-00073-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 06/08/2019] [Indexed: 01/07/2023]
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47
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Hatakeyama R, De Virgilio C. TORC1 specifically inhibits microautophagy through ESCRT-0. Curr Genet 2019; 65:1243-1249. [PMID: 31041524 PMCID: PMC6744375 DOI: 10.1007/s00294-019-00982-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 04/18/2019] [Accepted: 04/24/2019] [Indexed: 12/19/2022]
Abstract
Nutrient starvation induces the degradation of specific plasma membrane proteins through the multivesicular body (MVB) sorting pathway and of vacuolar membrane proteins through microautophagy. Both of these processes require the gateway protein Vps27, which recognizes ubiquitinated cargo proteins at phosphatidylinositol 3-phosphate-rich membranes as part of a heterodimeric complex coined endosomal sorting complex required for transport 0. The target of rapamycin complex 1 (TORC1), a nutrient-activated central regulator of cell growth, directly phosphorylates Vps27 to antagonize its function in microautophagy, but whether this also serves to restrain MVB sorting at endosomes is still an open question. Here, we show that TORC1 inhibits both the MVB pathway-driven turnover of the plasma membrane-resident high-affinity methionine permease Mup1 and the inositol transporter Itr1 and the microautophagy-dependent degradation of the vacuolar membrane-associated v-ATPase subunit Vph1. Using a Vps277D variant that mimics the TORC1-phosphorylated state of Vps27, we further show that cargo sorting of Vph1 at the vacuolar membrane, but not of Mup1 and Itr1 at endosomes, is sensitive to the TORC1-controlled modifications of Vps27. Thus, TORC1 specifically modulates microautophagy through phosphorylation of Vps27, but controls MVB sorting through alternative mechanisms.
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Affiliation(s)
- Riko Hatakeyama
- Department of Biology, University of Fribourg, 1700, Fribourg, Switzerland
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48
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Wawrzycka D, Sadlak J, Maciaszczyk-Dziubinska E, Wysocki R. Rsp5-dependent endocytosis and degradation of the arsenite transporter Acr3 requires its N-terminal acidic tail as an endocytic sorting signal and arrestin-related ubiquitin-ligase adaptors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:916-925. [PMID: 30776335 DOI: 10.1016/j.bbamem.2019.02.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 02/06/2019] [Accepted: 02/11/2019] [Indexed: 01/15/2023]
Abstract
The yeast plasma membrane transporter Acr3 mediates efflux of toxic arsenite and antimonite. Here, we investigated the mechanisms of Acr3 turnover. We found that after arrival and residence at the plasma membrane, Acr3 is subjected to internalization followed by proteolysis in the vacuole. Endocytic degradation of Acr3 is promoted by the ubiquitin ligase Rsp5 and requires polyubiquitination of Acr3 at multiple lysine residues via lysine 63-linked ubiquitin chains. The turnover of Acr3 also depends on two arrestin-related proteins, Art3/Aly2 and Art4/Rod1, that enable recruitment of Rsp5 to its targets. Finally, we found that a short acidic patch located in the N-terminal tail of Acr3 is needed for its ubiquitination and internalization. We propose that this motif serves as an endocytic signal that facilitates binding of the arrestin-Rsp5 complexes to the Acr3 cargo.
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Affiliation(s)
- Donata Wawrzycka
- Institute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland
| | - Joanna Sadlak
- Institute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland
| | | | - Robert Wysocki
- Institute of Experimental Biology, University of Wroclaw, 50-328 Wroclaw, Poland.
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49
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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: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [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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The intralumenal fragment pathway mediates ESCRT-independent surface transporter down-regulation. Nat Commun 2018; 9:5358. [PMID: 30560896 PMCID: PMC6299085 DOI: 10.1038/s41467-018-07734-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 11/15/2018] [Indexed: 11/10/2022] Open
Abstract
Surface receptor and transporter protein down-regulation is assumed to be exclusively mediated by the canonical multivesicular body (MVB) pathway and ESCRTs (Endosomal Sorting Complexes Required for Transport). However, few surface proteins are known to require ESCRTs for down-regulation, and reports of ESCRT-independent degradation are emerging, suggesting that alternative pathways exist. Here, using Saccharomyces cerevisiae as a model, we show that the hexose transporter Hxt3 does not require ESCRTs for down-regulation conferring resistance to 2-deoxyglucose. This is consistent with GFP-tagged Hxt3 bypassing ESCRT-mediated entry into intralumenal vesicles at endosomes. Instead, Hxt3-GFP accumulates on vacuolar lysosome membranes and is sorted into an area that, upon fusion, is internalized as an intralumenal fragment (ILF) and degraded. Moreover, heat stress or cycloheximide trigger degradation of Hxt3-GFP and other surface transporter proteins (Itr1, Aqr1) by this ESCRT-independent process. How this ILF pathway compares to the MVB pathway and potentially contributes to physiology is discussed. Cell surface receptors are thought to be internalized via the multivesicular bodies (MVBs) in an ESCRT-dependent pathway. Here, the authors report that in yeast, a hexose transporter is internalized via an ESCRT-independent pathway into intralumenal fragments (ILF).
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