The Experts below are selected from a list of 954 Experts worldwide ranked by ideXlab platform
Yasuyoshi Sakai - One of the best experts on this subject based on the ideXlab platform.
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methanol sensor wsc1 and map kinase suppress degradation of methanol induced peroxisomes in methylotrophic yeast
Journal of Cell Science, 2021Co-Authors: Shin Ohsawa, Hiroya Yurimoto, Masahide Oku, Koichi Inoue, Takahiro Isoda, Yasuyoshi SakaiAbstract:In nature, methanol is produced during the hydrolysis of pectin in plant cell walls. Methanol shows circadian dynamics on plant leaves to which methanol-utilizing phyllosphere microorganisms adapt. In the methylotrophic yeast Komagataella phaffii (Pichia pastoris), the plasma membrane protein KpWsc1 senses environmental methanol concentrations, and transmits the information to induce genes for methanol metabolism together with huge peroxisomes. In this study, we show that KpWsc1 and its downstream MAPK negatively regulate Pexophagy in the presence of >0.15% methanol. Although KpMpk1 was not necessary for expression of methanol-inducible genes and peroxisome biogenesis, KpMpk1, KpRlm1 and a phosphatase were found suppress Pexophagy by controlling phosphorylation level of KpAtg30, the key factor of Pexophagy. We reveal at the molecular level how the single methanol sensor KpWsc1 commits the cell to peroxisome synthesis and degradation according to the methanol concentration, and discuss the physiological significance of regulating Pexophagy for survival in the phyllosphere.
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Experimental Systems to Study Yeast Pexophagy.
Methods in molecular biology (Clifton N.J.), 2017Co-Authors: Shun-ichi Yamashita, Yasuyoshi Sakai, Masahide Oku, Yukio FujikiAbstract:Peroxisome abundance is tightly regulated according to the physiological contexts, through regulations of both proliferation and degradation of the organelles. Here, we describe detailed methods to analyze processes for autophagic degradation of peroxisomes, termed Pexophagy, in yeast organisms. The assay systems include a method for biochemical detection of Pexophagy completion, and one for microscopic visualization of specialized membrane structures acting in Pexophagy. As a model yeast organism utilized in studies of Pexophagy, the methylotrophic yeast Komagataella phaffii (Pichia pastoris) is referred to in this chapter and related information on the studies with baker's yeast (Saccharomyces cerevisiae) is also included. The described techniques facilitate elucidation of molecular machineries for Pexophagy and understanding of peroxisome-selective autophagic pathways.
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Pexophagy in yeasts.
Biochimica et biophysica acta, 2015Co-Authors: Masahide Oku, Yasuyoshi SakaiAbstract:Pexophagy, selective degradation of peroxisomes via autophagy, is the main system for reducing organelle abundance. Elucidation of the molecular machinery of Pexophagy has been pioneered in studies of the budding yeast Saccharomyces cerevisiae and the methylotrophic yeasts Pichia pastoris and Hansenula polymorpha. Recent analyses using these yeasts have elucidated the molecular machineries of Pexophagy, especially in terms of the interactions and modifications of the so-called adaptor proteins required for guiding autophagic membrane biogenesis on the organelle surface. Based on the recent findings, functional relevance of Pexophagy and another autophagic pathway, mitophagy (selective autophagy of mitochondria), is discussed. We also discuss the physiological importance of Pexophagy in these yeast systems.
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atg21 regulates Pexophagy via its pi 3 p binding activity in pichia pastoris
Fems Yeast Research, 2014Co-Authors: Naoki Tamura, Masahide Oku, Yasuyoshi SakaiAbstract:Pexophagy is a selective degradation pathway of peroxisomes. In the present study, we revealed that PpAtg21 was required for Pexophagy in the methylotrophic yeast Pichia pastoris. PpAtg21 was essential for efficient lipidation of Atg8 and for de novo synthesis of pexophagic membranes. In contrast to PpAtg18, PpAtg21 was not necessary for vacuolar fission nor invagination during microPexophagy. PpAtg21 specifically bound to PI(3)P, but not to PI(3,5)P2 in vitro, and the localization analyses matched with this phosphoinositide-binding specificity. The mutant which lost the lipid-binding activity showed defect in Pexophagy, suggesting that PI(3)P-binding activity of PpAtg21 was required for Pexophagy.
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Atg21 regulates Pexophagy via its PI(3)P‐binding activity in Pichia pastoris
FEMS yeast research, 2014Co-Authors: Naoki Tamura, Masahide Oku, Yasuyoshi SakaiAbstract:Pexophagy is a selective degradation pathway of peroxisomes. In the present study, we revealed that PpAtg21 was required for Pexophagy in the methylotrophic yeast Pichia pastoris. PpAtg21 was essential for efficient lipidation of Atg8 and for de novo synthesis of pexophagic membranes. In contrast to PpAtg18, PpAtg21 was not necessary for vacuolar fission nor invagination during microPexophagy. PpAtg21 specifically bound to PI(3)P, but not to PI(3,5)P2 in vitro, and the localization analyses matched with this phosphoinositide-binding specificity. The mutant which lost the lipid-binding activity showed defect in Pexophagy, suggesting that PI(3)P-binding activity of PpAtg21 was required for Pexophagy.
Suresh Subramani - One of the best experts on this subject based on the ideXlab platform.
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autophagic degradation of peroxisomes in mammals
Biochemical Society Transactions, 2016Co-Authors: Katarzyna Zientararytter, Suresh SubramaniAbstract:Peroxisomes are essential organelles required for proper cell function in all eukaryotic organisms. They participate in a wide range of cellular processes including the metabolism of lipids and generation, as well as detoxification, of hydrogen peroxide (H2O2). Therefore, peroxisome homoeostasis, manifested by the precise and efficient control of peroxisome number and functionality, must be tightly regulated in response to environmental changes. Due to the existence of many physiological disorders and diseases associated with peroxisome homoeostasis imbalance, the dynamics of peroxisomes have been widely examined. The increasing volume of reports demonstrating significant involvement of the autophagy machinery in peroxisome removal leads us to summarize current knowledge of peroxisome degradation in mammalian cells. In this review we present current models of peroxisome degradation. We particularly focus on Pexophagy–the selective clearance of peroxisomes through autophagy. We also critically discuss concepts of peroxisome recognition for Pexophagy, including signalling and selectivity factors. Finally, we present examples of the pathological effects of Pexophagy dysfunction and suggest promising future directions. * AMPK, : AMP-activated protein kinase; ATM, : Ataxia-telangiectasia mutated; CMA, : chaperone-mediated autophagy; EGFP, : enhanced green fluorescent protein; HIF-2α, : hypoxia-inducible factor 2α; 15-LOX, : 15-lipoxygenase; mTORC1, : mammalian target of rapamycin complex 1; PAS, : preautophagosomal structure; PIP, : phosphatidylinositol-phosphate; PTS, : peroxisome targeting signal; ROS, : reactive oxygen species; RPC, : receptor protein complex; TSC, : tuberous sclerosis complex; UBA, : ubiquitin-associated; ULK1, : unc51-like protein kinase 1
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Autophagic degradation of peroxisomes in mammals.
Biochemical Society transactions, 2016Co-Authors: Katarzyna Zientara-rytter, Suresh SubramaniAbstract:Peroxisomes are essential organelles required for proper cell function in all eukaryotic organisms. They participate in a wide range of cellular processes including the metabolism of lipids and generation, as well as detoxification, of hydrogen peroxide (H2O2). Therefore, peroxisome homoeostasis, manifested by the precise and efficient control of peroxisome number and functionality, must be tightly regulated in response to environmental changes. Due to the existence of many physiological disorders and diseases associated with peroxisome homoeostasis imbalance, the dynamics of peroxisomes have been widely examined. The increasing volume of reports demonstrating significant involvement of the autophagy machinery in peroxisome removal leads us to summarize current knowledge of peroxisome degradation in mammalian cells. In this review we present current models of peroxisome degradation. We particularly focus on Pexophagy-the selective clearance of peroxisomes through autophagy. We also critically discuss concepts of peroxisome recognition for Pexophagy, including signalling and selectivity factors. Finally, we present examples of the pathological effects of Pexophagy dysfunction and suggest promising future directions.
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A mammalian Pexophagy target
Nature Cell Biology, 2015Co-Authors: Suresh SubramaniAbstract:Protein ubiquitylation in mammals is known to trigger selective autophagy of peroxisomes through a process termed Pexophagy. The physiological peroxisomal target for Pexophagy-related ubiquitylation has been controversial, but two studies have now identified the protein PEX5 as the real candidate.
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coordinates their interaction with Atg8 and Atg11
2015Co-Authors: Aaron Burkenroad, Sarah F Burnett, Suresh SubramaniAbstract:The selective autophagy receptors Atg19 and Atg32 interact with two proteins of the core autophagic machinery: the scaffold protein Atg11 and the ubiquitin-like protein Atg8. We found that the Pichia pastoris Pexophagy receptor, Atg30, also interacts with Atg8. Both Atg30 and Atg32 interactions are regulated by phosphorylation close to Atg8-interaction motifs. Extending this finding to Saccharomyces cerevisiae, we confirmed phospho-regulation for the mitophagy and Pexophagy receptors, Atg32 and Atg36. Each Atg30 molecule must interact with both Atg8 and Atg11 for full functionality, and these interactions occur independently and not simultaneously, but rather in random order. We present a common model for the phosphoregulation of selective autophagy receptors
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peroxisomal pex3 activates selective autophagy of peroxisomes via interaction with the Pexophagy receptor atg30
Journal of Biological Chemistry, 2015Co-Authors: Sarah F Burnett, Jeanclaude Farre, Taras Y Nazarko, Suresh SubramaniAbstract:Abstract Pexophagy is a process that selectively degrades peroxisomes by autophagy. The Pichia pastoris Pexophagy receptor Atg30 is recruited to peroxisomes under peroxisome proliferation conditions. During Pexophagy, Atg30 undergoes phosphorylation, a prerequisite for its interactions with the autophagy scaffold protein Atg11 and the ubiquitin-like protein Atg8. Atg30 is subsequently shuttled to the vacuole along with the targeted peroxisome for degradation. Here, we defined the binding site for Atg30 on the peroxisomal membrane protein Pex3 and uncovered a role for Pex3 in the activation of Atg30 via phosphorylation and in the recruitment of Atg11 to the receptor protein complex. Pex3 is classically a docking protein for other proteins that affect peroxisome biogenesis, division, and segregation. We conclude that Pex3 has a role beyond simple docking of Atg30 and that its interaction with Atg30 regulates Pexophagy in the yeast P. pastoris.
Andrei Sibirny - One of the best experts on this subject based on the ideXlab platform.
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differences in glucose sensing and signaling for Pexophagy between the baker s yeast saccharomyces cerevisiae and the methylotrophic yeast pichia pastoris
Autophagy, 2008Co-Authors: Volodymyr Y Nazarko, Johan M. Thevelein, Kateryna O. Futej, Andrei SibirnyAbstract:The mechanism(s) of glucose sensing for inducing the autophagic peroxisome degradation (Pexophagy) is not known. Recently, we have found that defects in the S. cerevisiae PKA-cAMP signaling pathway due to knockouts of GPR1 and/or GPA2 suppressed glucose-induced degradation of peroxisomal thiolase. Here we report that single defects of high (SNF3) and low (RGT2) affinity glucose sensors involved in glucose-dependent induction of hexose transporters have only a slight effect on glucose-induced degradation of peroxisomal thiolase, although simultaneous defects of both sensors, SNF3 and RGT2 (which are known to strongly affect glucose transport) strongly inhibit this process in S. cerevisiae. Most likely, glucose is sensed for Pexophagy using the Gpr1 sensor involved in the PKA-cAMP signaling pathway. In the methylotrophic yeast P. pastoris, however, knock out of S. cerevisiae orthologs of GPR1 and GPA2 did not affect glucose-induced degradation of oleate-induced thiolase or the methanolinduced key peroxisomal protein, alcohol oxidase. This implies that glucose sensing for Pexophagy is different in baker's and methylotrophic yeasts.
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Differences in glucose sensing and signaling for Pexophagy between the baker’s yeast Saccharomyces cerevisiae and the methylotrophic yeast Pichia pastoris
Autophagy, 2008Co-Authors: Volodymyr Y Nazarko, Johan M. Thevelein, Kateryna O. Futej, Andrei SibirnyAbstract:The mechanism(s) of glucose sensing for inducing the autophagic peroxisome degradation (Pexophagy) is not known. Recently, we have found that defects in the S. cerevisiae PKA-cAMP signaling pathway due to knockouts of GPR1 and/or GPA2 suppressed glucose-induced degradation of peroxisomal thiolase. Here we report that single defects of high (SNF3) and low (RGT2) affinity glucose sensors involved in glucose-dependent induction of hexose transporters have only a slight effect on glucose-induced degradation of peroxisomal thiolase, although simultaneous defects of both sensors, SNF3 and RGT2 (which are known to strongly affect glucose transport) strongly inhibit this process in S. cerevisiae. Most likely, glucose is sensed for Pexophagy using the Gpr1 sensor involved in the PKA-cAMP signaling pathway. In the methylotrophic yeast P. pastoris, however, knock out of S. cerevisiae orthologs of GPR1 and GPA2 did not affect glucose-induced degradation of oleate-induced thiolase or the methanolinduced key peroxisomal protein, alcohol oxidase. This implies that glucose sensing for Pexophagy is different in baker's and methylotrophic yeasts.
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Trs85 is Required for Macroautophagy, Pexophagy and Cytoplasm to Vacuole Targeting in Yarrowia lipolytica and Saccharomyces cerevisiae.
Autophagy, 2005Co-Authors: Taras Nazarko, Ju Huang, Jean-marc Nicaud, Daniel Klionsky, Andrei SibirnyAbstract:Yarrowia lipolytica was recently introduced as a new model organism to study peroxisome degradation in yeasts. Transfer of Y. lipolytica cells from oleate/ethylamine to glucose/ammonium chloride medium leads to selective macroautophagy of peroxisomes. To decipher the molecular mechanisms of macroPexophagy we isolated mutants of Y. lipolytica defective in the inactivation of peroxisomal enzymes under Pexophagy conditions. Through this analysis we identified the gene YlTRS85, the ortholog of Saccharomyces cerevisiae TRS85 that encodes the 85 kDa subunit of transport protein particle (TRAPP). A parallel genetic screen in S. cerevisiae also identified the trs85 mutant. Here, we report that Trs85 is required for nonspecific autophagy, Pexophagy and the cytoplasm to vacuole targeting pathway in both yeasts.
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sterol glucosyltransferases have different functional roles inpichia pastoris and yarrowia lipolytica
Cell Biology International, 2003Co-Authors: Taras Y Nazarko, James M Cregg, Oleh V. Stasyk, Dirk Warnecke, Jean-marc Nicaud, Andrei Sibirny, Olena S KrasovskaAbstract:Mutants of the methanol-utilizing yeast Pichia pastoris and the alkane-utilizing yeast Yarrowia lipolytica defective in the orthologue of UGT51 (encoding sterol glucosyltransferase) were isolated and compared. These mutants do not contain the specific ergosterol derivate, ergosterol glucoside. We observed that the P. pastoris UGT51 gene is required for Pexophagy, the process by which peroxisomes containing methanol-metabolizing enzymes are selectively shipped to and degraded in the vacuole upon shifting methanol-grown cells of this yeast to glucose or ethanol. PpUGT51 is also required for other vacuole related processes. In contrast, the Y. lipolytica UGT51 gene is required for utilization of decane, but not for Pexophagy. Thus, sterol glucosyltransferases play different functional roles in P. pastoris and Y. lipolytica.
Andriy A Sibirny - One of the best experts on this subject based on the ideXlab platform.
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Pexophagy Sensing and Signaling in the Methylotrophic Yeasts
Molecular Machines Involved in Peroxisome Biogenesis and Maintenance, 2014Co-Authors: Andriy A SibirnyAbstract:Methylotrophic yeasts are unique eukaryotic organisms capable of utilizing the one-carbon toxic substrate, methanol. During methylotrophic growth, peroxisomes occupy 30–80 % of the cellular volume. A shift of methanol-grown cells to media with the alternative carbon sources, glucose or ethanol, induces massive peroxisome degradation. In Pichia pastoris, two morphologically distinct events have been observed namely, macro- and microautophagy. In other species, macroautophagy was mostly noted under massive peroxisome degradation. It was found that genes involved in non-specific autophagy (most of them known as ATG genes) also participate in carbon source-induced Pexophagy. Many ATG genes have been discovered using methylotrophic yeasts models, mainly in P. pastoris, due to convenient and easy methods to monitor Pexophagy. However, the mechanisms of glucose and ethanol sensing and signaling, which initiate the subsequent events of micro- and macroautophagy are poorly understood. Similarly, the nature of the low-molecular-weight effectors, derivatives of glucose and ethanol, which induce Pexophagy, has not been identified.
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Cytoplasmic extension peptide of Pichia pastoris glucose sensor Gss1 is not compulsory for glucose signalling.
Cell biology international, 2013Co-Authors: Andriy S Polupanov, Andriy A SibirnyAbstract:In the methylotrophic yeast, Pichia pastoris, Gss1 protein is a glucose sensor involved in Pexophagy, glucose utilization and glucose catabolite repression. This study identifies that deletion of 150 residues of Gss1 affects slightly glucose catabolite repression and Pexophagy, while maintaining signalling function of Gss1. Substitution of one conserved amino acid R180K of Gss1 protein has no visible phenotype, in contrast to corresponding changes in glucose sensors from other yeast species. We suggest that C-terminal cytoplasmic extension of PpGss1plays different role to that of its homologs in Saccharomyces cerevisiae and Hansenula polymorpha.
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gss1 protein of the methylotrophic yeast pichia pastoris is involved in glucose sensing Pexophagy and catabolite repression
The International Journal of Biochemistry & Cell Biology, 2012Co-Authors: Andriy S Polupanov, Volodymyr Y Nazarko, Andriy A SibirnyAbstract:In the yeast Saccharomyces cerevisiae, the one-at-a-time deletions of either the high-affinity glucose sensor gene SNF3 or the low-affinity glucose sensor gene RGT2 only slightly reduced Pexophagy; however, deleting both genes greatly reduced Pexophagy, evincing interaction beyond the sum of the additive effects, as recently shown. The present study identifies the only ScSNF3/RGT2 ortholog in the methylotrophic yeast Pichia pastoris (designated as PpGSS1, from GlucoSe Sensor) and describes its roles in autophagic pathways (non-selective and selective). GSS1 knock-out strain has been constructed. The experiments support the hypothesis that Gss1 plays an important role in autophagic degradation of peroxisomes and glucose catabolite repression in P. pastoris.
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G-protein-coupled receptor Gpr1 and G-protein Gpa2 of cAMP-dependent signaling pathway are involved in glucose-induced Pexophagy in the yeast Saccharomyces cerevisiae
Cell biology international, 2007Co-Authors: Volodymyr Y Nazarko, Johan M. Thevelein, Andriy A SibirnyAbstract:In yeast cell, glucose induces various changes of cellular metabolism on genetic and metabolic levels. One of such changes is autophagic degradation of dispensable peroxisomes (Pexophagy) which occurs in vacuoles. We have found that in Saccharomyces cerevisiae, defect of G-protein-coupled receptor Gpr1 and G-protein Gpa2, both the components of cAMP-signaling pathway, strongly suppressed glucose-induced degradation of matrix peroxisomal protein thiolase. We conclude that proteins Gpr1 and Gpa2 are involved in glucose sensing and signal transduction during Pexophagy process in yeast.
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The requirement of sterol glucoside for Pexophagy in yeast is dependent on the species and nature of peroxisome inducers.
Molecular biology of the cell, 2006Co-Authors: Taras Y Nazarko, Ravi Manjithaya, Suresh Subramani, Andriy S Polupanov, Andriy A SibirnyAbstract:Sterol glucosyltransferase, Ugt51/Atg26, is essential for both microPexophagy and macroPexophagy of methanol-induced peroxisomes in Pichia pastoris. However, the role of this protein in Pexophagy in other yeast remained unclear. We show that oleate- and amine-induced peroxisomes in Yarrowia lipolytica are degraded by Atg26-independent macroPexophagy. Surprisingly, Atg26 was also not essential for macroPexophagy of oleate- and amine-induced peroxisomes in P. pastoris, suggesting that the function of sterol glucoside (SG) in Pexophagy is both species and peroxisome inducer specific. However, the rates of degradation of oleate- and amine-induced peroxisomes in P. pastoris were reduced in the absence of SG, indicating that P. pastoris specifically uses sterol conversion by Atg26 to enhance selective degradation of peroxisomes. However, methanol-induced peroxisomes apparently have lost the redundant ability to be degraded without SG. We also show that the P. pastoris Vac8 armadillo repeat protein is not essential for macroPexophagy of methanol-, oleate-, or amine-induced peroxisomes, which makes PpVac8 the first known protein required for the microPexophagy, but not for the macroPexophagy, machinery. The uniqueness of Atg26 and Vac8 functions under different Pexophagy conditions demonstrates that not only Pexophagy inducers, such as glucose or ethanol, but also the inducers of peroxisomes, such as methanol, oleate, or primary amines, determine the requirements for subsequent Pexophagy in yeast.
Daniel J. Klionsky - One of the best experts on this subject based on the ideXlab platform.
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endoplasmic reticulum mitochondria contacts are required for Pexophagy in saccharomyces cerevisiae
Contact (Thousand Oaks (Ventura County Calif.)), 2019Co-Authors: Xu Liu, Xin Wen, Daniel J. KlionskyAbstract:Peroxisomes play important roles in lipid metabolism. Surplus or damaged peroxisomes can be selectively targeted for autophagic degradation, a process termed Pexophagy. Maintaining a proper level o...
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Endoplasmic Reticulum–Mitochondria Contacts Are Required for Pexophagy in Saccharomyces cerevisiae
Contact (Thousand Oaks (Ventura County Calif.)), 2019Co-Authors: Xu Liu, Xin Wen, Daniel J. KlionskyAbstract:Peroxisomes play important roles in lipid metabolism. Surplus or damaged peroxisomes can be selectively targeted for autophagic degradation, a process termed Pexophagy. Maintaining a proper level o...
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Supplemental material for Endoplasmic Reticulum–Mitochondria Contacts Are Required for Pexophagy in Saccharomyces cerevisiae
2019Co-Authors: Xu Liu, Xin Wen, Daniel J. KlionskyAbstract:Supplemental Material for Endoplasmic Reticulum–Mitochondria Contacts Are Required for Pexophagy in Saccharomyces cerevisiae by Xu Liu, Xin Wen and Daniel J. Klionsky in Contact
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The progression of peroxisomal degradation through autophagy requires peroxisomal division
Autophagy, 2014Co-Authors: Kai Mao, Xu Liu, Yuchen Feng, Daniel J. KlionskyAbstract:Peroxisomes are highly dynamic organelles that have multiple functions in cellular metabolism. To adapt the intracellular conditions to the changing extracellular environment, peroxisomes undergo constitutive segregation and degradation. The segregation of peroxisomes is mediated by 2 dynamin-related GTPases, Dnm1 and Vps1, whereas, the degradation of peroxisomes is accomplished through Pexophagy, a selective type of autophagy. During Pexophagy, the size of the organelle is always a challenging factor for the efficiency of engulfment by the sequestering compartment, the phagophore, which implies a potential role for peroxisomal fission in the degradation process, similar to the situation with selective mitochondria degradation. In this study, we report that peroxisomal fission is indeed critical for the efficient elimination of the organelle. When Pexophagy is induced, both Dnm1 and Vps1 are recruited to the degrading peroxisomes through interactions with Atg11 and Atg36. In addition, we found that specific peroxisomal fission, which is only needed for Pexophagy, occurs at mitochondria-peroxisome contact sites.
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cvt18 gsa12 is required for cytoplasm to vacuole transport Pexophagy and autophagy in saccharomyces cerevisiae and pichia pastoris
Molecular Biology of the Cell, 2001Co-Authors: Ju Guan, William A. Dunn, Per E Stromhaug, Michael D George, Pouran Habibzadegahtari, Andrew Bevan, Daniel J. KlionskyAbstract:: Eukaryotic cells have the ability to degrade proteins and organelles by selective and nonselective modes of micro- and macroautophagy. In addition, there exist both constitutive and regulated forms of autophagy. For example, Pexophagy is a selective process for the regulated degradation of peroxisomes by autophagy. Our studies have shown that the differing pathways of autophagy have many molecular events in common. In this article, we have identified a new member in the family of autophagy genes. GSA12 in Pichia pastoris and its Saccharomyces cerevisiae counterpart, CVT18, encode a soluble protein with two WD40 domains. We have shown that these proteins are required for Pexophagy and autophagy in P. pastoris and the Cvt pathway, autophagy, and Pexophagy in S. cerevisiae. In P. pastoris, Gsa12 appears to be required for an early event in Pexophagy. That is, the involution of the vacuole or extension of vacuole arms to engulf the peroxisomes does not occur in the gsa12 mutant. Consistent with its role in vacuole engulfment, we have found that this cytosolic protein is also localized to the vacuole surface. Similarly, Cvt18 displays a subcellular localization that distinguishes it from the characterized proteins required for cytoplasm-to-vacuole delivery pathways.
