1
|
Yang L, Li X, Ma Y, Zhu M, Zhang KQ, Yang J. The Arf-GAPs, AoAge1 and AoAge2, regulate diverse cellular processes, conidiation, trap formation, and secondary metabolism in Arthrobotrys oligospora. Microbiol Res 2024; 285:127779. [PMID: 38810485 DOI: 10.1016/j.micres.2024.127779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 05/09/2024] [Accepted: 05/20/2024] [Indexed: 05/31/2024]
Abstract
Guanine nucleotide-binding proteins of the ADP ribosylation factor (Arf) family and their activating proteins (Arf-GAPs) are essential for diverse biological processes. Here, two homologous Arf-GAPs, Age1 (AoAge1) and Age2 (AoAge2), were identified in the widespread nematode-trapping fungus Arthrobotrys oligospora. Our results demonstrated that AoAge1, especially AoAge2, played crucial roles in mycelial growth, sporulation, trap production, stress response, mitochondrial activity, DNA damage, endocytosis, reactive oxygen species production, and autophagy. Notably, transcriptome data revealed that approximately 62.7% of the genes were directly or indirectly regulated by AoAge2, and dysregulated genes in Aoage2 deletion were enriched in metabolism, ribosome biogenesis, secondary metabolite biosynthesis, and autophagy. Furthermore, Aoage2 inactivation caused a substantial reduction in several compounds compared to the wild-type strain. Based on these results, a regulatory network for AoAge1 and AoAge2 was proposed and verified using a yeast two-hybrid assay. Based on our findings, AoAge1 and AoAge2 are essential for vegetative growth and mycelial development. Specifically, AoAge2 is required for sporulation and trapping morphogenesis. Our results demonstrated the critical functions of AoAge1 and AoAge2 in mycelial growth, diverse cellular processes, and pathogenicity, offering deep insights into the functions and regulatory mechanisms of Arf-GAPs in nematode-trapping fungi.
Collapse
Affiliation(s)
- Le Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources, Key Laboratory for Microbial Resources of the Ministry of Education, School of Life Sciences, Yunnan University, Kunming 650091, PR China; Engineering Research Center of Sustainable Development and Utilization of Biomass Energy, Ministry of Education, School of Life Sciences, Yunnan Normal University, Kunming 650500, PR China
| | - Xuemei Li
- State Key Laboratory for Conservation and Utilization of Bio-Resources, Key Laboratory for Microbial Resources of the Ministry of Education, School of Life Sciences, Yunnan University, Kunming 650091, PR China
| | - Yuxin Ma
- State Key Laboratory for Conservation and Utilization of Bio-Resources, Key Laboratory for Microbial Resources of the Ministry of Education, School of Life Sciences, Yunnan University, Kunming 650091, PR China
| | - Meichen Zhu
- State Key Laboratory for Conservation and Utilization of Bio-Resources, Key Laboratory for Microbial Resources of the Ministry of Education, School of Life Sciences, Yunnan University, Kunming 650091, PR China
| | - Ke-Qin Zhang
- State Key Laboratory for Conservation and Utilization of Bio-Resources, Key Laboratory for Microbial Resources of the Ministry of Education, School of Life Sciences, Yunnan University, Kunming 650091, PR China
| | - Jinkui Yang
- State Key Laboratory for Conservation and Utilization of Bio-Resources, Key Laboratory for Microbial Resources of the Ministry of Education, School of Life Sciences, Yunnan University, Kunming 650091, PR China.
| |
Collapse
|
2
|
Brownfield BA, Richardson BC, Halaby SL, Fromme JC. Sec7 regulatory domains scaffold autoinhibited and active conformations. Proc Natl Acad Sci U S A 2024; 121:e2318615121. [PMID: 38416685 DOI: 10.1073/pnas.2318615121] [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: 11/03/2023] [Accepted: 01/16/2024] [Indexed: 03/01/2024] Open
Abstract
The late stages of Golgi maturation involve a series of sequential trafficking events in which cargo-laden vesicles are produced and targeted to multiple distinct subcellular destinations. Each of these vesicle biogenesis events requires activation of an Arf GTPase by the Sec7/BIG guanine nucleotide exchange factor (GEF). Sec7 localization and activity is regulated by autoinhibition, positive feedback, and interaction with other GTPases. Although these mechanisms have been characterized biochemically, we lack a clear picture of how GEF localization and activity is modulated by these signals. Here, we report the cryogenic electron microscopy structure of full-length Sec7 in its autoinhibited form, revealing the architecture of its multiple regulatory domains. We use functional experiments to determine the basis for autoinhibition and use structural predictions to produce a model for an active conformation of the GEF that is supported empirically. This study therefore elucidates the conformational transition that Sec7 undergoes to become active on the organelle membrane surface.
Collapse
Affiliation(s)
- Bryce A Brownfield
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Brian C Richardson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - Steve L Halaby
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| | - J Christopher Fromme
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
| |
Collapse
|
3
|
Brownfield BA, Richardson BC, Halaby SL, Fromme JC. Sec7 regulatory domains scaffold autoinhibited and active conformations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.22.568272. [PMID: 38045260 PMCID: PMC10690275 DOI: 10.1101/2023.11.22.568272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
The late stages of Golgi maturation involve a series of sequential trafficking events in which cargo-laden vesicles are produced and targeted to multiple distinct subcellular destinations. Each of these vesicle biogenesis events requires activation of an Arf GTPase by the Sec7/BIG guanine nucleotide exchange factor (GEF). Sec7 localization and activity is regulated by autoinhibition, positive feedback, and interaction with other GTPases. Although these mechanisms have been characterized biochemically, we lack a clear picture of how GEF localization and activity is modulated by these signals. Here we report the cryoEM structure of full-length Sec7 in its autoinhibited form, revealing the architecture of its multiple regulatory domains. We use functional experiments to determine the basis for autoinhibition and use structural predictions to produce a model for an active conformation of the GEF that is supported empirically. This study therefore elucidates the conformational transition that Sec7 undergoes to become active on the organelle membrane surface.
Collapse
Affiliation(s)
- Bryce A. Brownfield
- Department of Molecular Biology & Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850 USA
| | - Brian C. Richardson
- Department of Molecular Biology & Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850 USA
- Current address: The Hormel Institute, University of Minnesota, Austin MN 55912
| | - Steve L. Halaby
- Department of Molecular Biology & Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850 USA
- Current address: Abbvie Inc., Irvine, CA 92612
| | - J. Christopher Fromme
- Department of Molecular Biology & Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850 USA
| |
Collapse
|
4
|
Manzer KM, Fromme JC. The Arf-GAP Age2 localizes to the late-Golgi via a conserved amphipathic helix. Mol Biol Cell 2023; 34:ar119. [PMID: 37672345 PMCID: PMC10846627 DOI: 10.1091/mbc.e23-07-0283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/29/2023] [Accepted: 08/29/2023] [Indexed: 09/08/2023] Open
Abstract
Arf GTPases are central regulators of the Golgi complex, which serves as the nexus of membrane-trafficking pathways in eukaryotic cells. Arf proteins recruit dozens of effectors to modify membranes, sort cargos, and create and tether transport vesicles, and are therefore essential for orchestrating Golgi trafficking. The regulation of Arf activity is controlled by the action of Arf-GEFs which activate via nucleotide exchange, and Arf-GAPs which inactivate via nucleotide hydrolysis. The localization dynamics of Arf GTPases and their Arf-GAPs during Golgi maturation have not been reported. Here we use the budding yeast model to examine the temporal localization of the Golgi Arf-GAPs. We also determine the mechanisms used by the Arf-GAP Age2 to localize to the Golgi. We find that the catalytic activity of Age2 and a conserved sequence in the unstructured C-terminal domain of Age2 are both required for Golgi localization. This sequence is predicted to form an amphipathic helix and mediates direct binding of Age2 to membranes in vitro. We also report the development of a probe for sensing active Arf1 in living cells and use this probe to characterize the temporal dynamics of Arf1 during Golgi maturation.
Collapse
Affiliation(s)
- Kaitlyn M. Manzer
- Department of Molecular Biology & Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850
| | - J. Christopher Fromme
- Department of Molecular Biology & Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850
| |
Collapse
|
5
|
Manzer KM, Fromme JC. The Arf-GAP Age2 localizes to the late-Golgi via a conserved amphipathic helix. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.23.550229. [PMID: 37546741 PMCID: PMC10402032 DOI: 10.1101/2023.07.23.550229] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Arf GTPases are central regulators of the Golgi complex, which serves as the nexus of membrane trafficking pathways in eukaryotic cells. Arf proteins recruit dozens of effectors to modify membranes, sort cargos, and create and tether transport vesicles, and are therefore essential for orchestrating Golgi trafficking. The regulation of Arf activity is controlled by the action of Arf-GEFs, which activate via nucleotide exchange, and Arf-GAPs, which inactivate via nucleotide hydrolysis. The localization dynamics of Arf GTPases and their Arf-GAPs during Golgi maturation have not been reported. Here we use the budding yeast model to examine the temporal localization of the Golgi Arf-GAPs. We also determine the mechanisms used by the Arf-GAP Age2 to localize to the Golgi. We find that the catalytic activity of Age2 and a conserved sequence in the unstructured C-terminal domain of Age2 are both required for Golgi localization. This sequence is predicted to form an amphipathic helix and mediates direct binding of Age2 to membranes in vitro . We also report the development of a probe for sensing active Arf1 in living cells and use this probe to characterize the temporal dynamics of Arf1 during Golgi maturation.
Collapse
Affiliation(s)
- Kaitlyn M Manzer
- Department of Molecular Biology & Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850 USA
| | - J Christopher Fromme
- Department of Molecular Biology & Genetics and Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14850 USA
| |
Collapse
|
6
|
The Arf-GAP Proteins AoGcs1 and AoGts1 Regulate Mycelial Development, Endocytosis, and Pathogenicity in Arthrobotrys oligospora. J Fungi (Basel) 2022; 8:jof8050463. [PMID: 35628718 PMCID: PMC9146637 DOI: 10.3390/jof8050463] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 04/28/2022] [Accepted: 04/28/2022] [Indexed: 12/10/2022] Open
Abstract
Small GTPases from the ADP-ribosylation factor (Arf) family and their activating proteins (Arf-GAPs) regulate mycelial development, endocytosis, and virulence in fungi. Here, we identified two orthologous Arf-GAP proteins, AoGcs1 and AoGts1, in a typical nematode-trapping fungus Arthrobotrys oligospora. The transcription of Aogcs1 and Aogts1 was highly expressed in the sporulation stage. The deletion of Aogcs1 and Aogts1 caused defects in DNA damage, endocytosis, scavenging of reactive oxygen species, lipid droplet storage, mitochondrial activity, autophagy, serine protease activity, and the response to endoplasmic reticulum stress. The combined effects resulted in slow growth, decreased sporulation capacity, increased susceptibility to chemical stressors and heat shock, and decreased pathogenicity of the mutants compared with the wild-type (WT) strain. Although deletion of Aogcs1 and Aogts1 produced similar phenotfypic traits, their roles varied in conidiation and proteolytic activity. The ΔAogts1 mutant showed a remarkable reduction in conidial yield compared with the WT strain but not in proteolytic activity; in contrast, the ΔAogcs1 mutant showed an increase in proteolytic activity but not in sporulation. In addition, the growth of ΔAogcs1 and ΔAogts1 mutants was promoted by rapamycin, and the ΔAogts1 mutant was sensitive to H-89. Collectively, the ΔAogts1 mutant showed a more remarkable difference compared with the WT strain than the ΔAogcs1 mutant. Our study further illustrates the importance of Arf-GAPs in the growth, development, and pathogenicity of nematode-trapping fungi.
Collapse
|
7
|
Schoppe J, Mari M, Yavavli E, Auffarth K, Cabrera M, Walter S, Fröhlich F, Ungermann C. AP-3 vesicle uncoating occurs after HOPS-dependent vacuole tethering. EMBO J 2020; 39:e105117. [PMID: 32840906 PMCID: PMC7560216 DOI: 10.15252/embj.2020105117] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 07/16/2020] [Accepted: 07/22/2020] [Indexed: 11/09/2022] Open
Abstract
Heterotetrameric adapter (AP) complexes cooperate with the small GTPase Arf1 or lipids in cargo selection, vesicle formation, and budding at endomembranes in eukaryotic cells. While most AP complexes also require clathrin as the outer vesicle shell, formation of AP-3-coated vesicles involved in Golgi-to-vacuole transport in yeast has been postulated to depend on Vps41, a subunit of the vacuolar HOPS tethering complex. HOPS has also been identified as the tether of AP-3 vesicles on vacuoles. To unravel this conundrum of a dual Vps41 function, we anchored Vps41 stably to the mitochondrial outer membrane. By monitoring AP-3 recruitment, we now show that Vps41 can tether AP-3 vesicles to mitochondria, yet AP-3 vesicles can form in the absence of Vps41 or clathrin. By proximity labeling and mass spectrometry, we identify the Arf1 GTPase-activating protein (GAP) Age2 at the AP-3 coat and show that tethering, but not fusion at the vacuole can occur without complete uncoating. We conclude that AP-3 vesicles retain their coat after budding and that their complete uncoating occurs only after tethering at the vacuole.
Collapse
Affiliation(s)
- Jannis Schoppe
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Muriel Mari
- Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Erdal Yavavli
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Kathrin Auffarth
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany
| | - Margarita Cabrera
- Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Farba, Barcelona, Spain
| | - Stefan Walter
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
| | - Florian Fröhlich
- Center of Cellular Nanoanalytic Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany.,Department of Biology/Chemistry, Molecular Membrane Biology Section, University of Osnabrück, Osnabrück, Germany
| | - Christian Ungermann
- Department of Biology/Chemistry, Biochemistry Section, University of Osnabrück, Osnabrück, Germany.,Center of Cellular Nanoanalytic Osnabrück (CellNanOs), University of Osnabrück, Osnabrück, Germany
| |
Collapse
|
8
|
Zhao YY, Cao CL, Liu YL, Wang J, Li SY, Li J, Deng Y. Genetic analysis of oxidative and endoplasmic reticulum stress responses induced by cobalt toxicity in budding yeast. Biochim Biophys Acta Gen Subj 2020; 1864:129516. [DOI: 10.1016/j.bbagen.2020.129516] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 12/07/2019] [Accepted: 12/31/2019] [Indexed: 12/23/2022]
|
9
|
Arakel EC, Huranova M, Estrada AF, Rau EM, Spang A, Schwappach B. Dissection of GTPase-activating proteins reveals functional asymmetry in the COPI coat of budding yeast. J Cell Sci 2019; 132:jcs.232124. [PMID: 31331965 PMCID: PMC6737914 DOI: 10.1242/jcs.232124] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 07/12/2019] [Indexed: 12/11/2022] Open
Abstract
The Arf GTPase controls formation of the COPI vesicle coat. Recent structural models of COPI revealed the positioning of two Arf1 molecules in contrasting molecular environments. Each of these pockets for Arf1 is expected to also accommodate an Arf GTPase-activating protein (ArfGAP). Structural evidence and protein interactions observed between isolated domains indirectly suggest that each niche preferentially recruits one of the two ArfGAPs known to affect COPI, i.e. Gcs1/ArfGAP1 and Glo3/ArfGAP2/3, although only partial structures are available. The functional role of the unique non-catalytic domain of either ArfGAP has not been integrated into the current COPI structural model. Here, we delineate key differences in the consequences of triggering GTP hydrolysis through the activity of one versus the other ArfGAP. We demonstrate that Glo3/ArfGAP2/3 specifically triggers Arf1 GTP hydrolysis impinging on the stability of the COPI coat. We show that the Snf1 kinase complex, the yeast homologue of AMP-activated protein kinase (AMPK), phosphorylates the region of Glo3 that is crucial for this effect and, thereby, regulates its function in the COPI-vesicle cycle. Our results revise the model of ArfGAP function in the molecular context of COPI. This article has an associated First Person interview with the first author of the paper. Highlighted Article: The regulatory domain of the COPI-associated ArfGAP Glo3 can stabilize the COPI coat. GTP hydrolysis is necessary to resolve the stabilised state. This mechanism is regulated by phosphorylation.
Collapse
Affiliation(s)
- Eric C Arakel
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
| | - Martina Huranova
- Growth and Development, Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland.,Laboratory of Adaptive Immunity, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 142 20 Prague 4, Czech Republic
| | - Alejandro F Estrada
- Growth and Development, Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - E-Ming Rau
- Growth and Development, Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Anne Spang
- Growth and Development, Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Blanche Schwappach
- Department of Molecular Biology, Universitätsmedizin Göttingen, Humboldtallee 23, 37073 Göttingen, Germany .,Max-Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| |
Collapse
|
10
|
Abstract
ADP-ribosylation factors (Arfs) and ADP-ribosylation factor-like proteins (Arls) are highly conserved small GTPases that function as main regulators of vesicular trafficking and cytoskeletal reorganization. Arl1, the first identified member of the large Arl family, is an important regulator of Golgi complex structure and function in organisms ranging from yeast to mammals. Together with its effectors, Arl1 has been shown to be involved in several cellular processes, including endosomal trans-Golgi network and secretory trafficking, lipid droplet and salivary granule formation, innate immunity and neuronal development, stress tolerance, as well as the response of the unfolded protein. In this Commentary, we provide a comprehensive summary of the Arl1-dependent cellular functions and a detailed characterization of several Arl1 effectors. We propose that involvement of Arl1 in these diverse cellular functions reflects the fact that Arl1 is activated at several late-Golgi sites, corresponding to specific molecular complexes that respond to and integrate multiple signals. We also provide insight into how the GTP-GDP cycle of Arl1 is regulated, and highlight a newly discovered mechanism that controls the sophisticated regulation of Arl1 activity at the Golgi complex.
Collapse
Affiliation(s)
- Chia-Jung Yu
- Department of Cell and Molecular Biology, College of Medicine, Chang Gung University, Linkou, Tao-Yuan 33302, Taiwan.,Department of Thoracic Medicine, Chang Gung Memorial Hospital, Linkou, Tao-Yuan 33305, Taiwan
| | - Fang-Jen S Lee
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 10002, Taiwan .,Department of Medical Research, National Taiwan University Hospital, Taipei 10002, Taiwan
| |
Collapse
|
11
|
Fernández-Acero T, Rodríguez-Escudero I, Molina M, Cid VJ. The yeast cell wall integrity pathway signals from recycling endosomes upon elimination of phosphatidylinositol (4,5)-bisphosphate by mammalian phosphatidylinositol 3-kinase. Cell Signal 2015; 27:2272-84. [PMID: 26261079 DOI: 10.1016/j.cellsig.2015.08.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 08/05/2015] [Indexed: 11/29/2022]
Abstract
Phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P(2)] is essential for recognition of the plasma membrane inner leaf by protein complexes. We expressed mammalian class I phosphoinositide 3-kinase (PI3K) in Saccharomyces cerevisiae to eliminate PtdIns(4,5)P(2) by its conversion into PtdIns(3,4,5)P(3), a lipid naturally missing in this yeast. This led to loss of actin function and endocytosis defects, causing a blockage in polarized secretion. Also, the cell wall integrity (CWI) mitogen-activated protein kinase (MAPK) pathway was activated, triggering a typical transcriptional response. In the absence of PtdIns(4,5)P(2) at the plasma membrane, the Pkc1 protein kinase upstream the CWI MAPK module localized to post-Golgi endosomes marked by SNARE Snc1 and Rab GTPases Ypt31 and Ypt32. Other components at the head of the pathway, like the mechanosensor Wsc1, the GTPase Rho1 and its activator the GDP/GTP exchange factor Rom2, co-localized with Pkc1 in these compartments. Chemical inhibition of PI3K proved that both CWI activation and Pkc1 relocation to endosomes are reversible. These results suggest that the CWI pathway is able to respond to loss of plasma membrane identity from recycling endosomes.
Collapse
Affiliation(s)
- Teresa Fernández-Acero
- Dpto. de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain; Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), Madrid, Spain
| | - Isabel Rodríguez-Escudero
- Dpto. de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain; Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), Madrid, Spain
| | - María Molina
- Dpto. de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain; Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), Madrid, Spain.
| | - Víctor J Cid
- Dpto. de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain; Instituto Ramón y Cajal de Investigaciones Sanitarias (IRYCIS), Madrid, Spain
| |
Collapse
|
12
|
Xie S, Naslavsky N, Caplan S. Diacylglycerol kinases in membrane trafficking. CELLULAR LOGISTICS 2015; 5:e1078431. [PMID: 27057419 DOI: 10.1080/21592799.2015.1078431] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 07/22/2015] [Accepted: 07/24/2015] [Indexed: 10/23/2022]
Abstract
Diacylglycerol kinases (DGKs) belong to a family of cytosolic kinases that regulate the phosphorylation of diacylglycerol (DAG), converting it into phosphatidic acid (PA). There are 10 known mammalian DGK isoforms, each with a different tissue distribution and substrate specificity. These differences allow regulation of cellular responses by fine-tuning the delicate balance of cellular DAG and PA. DGK isoforms are best characterized as mediators of signal transduction and immune function. However, since recent studies reveal that DAG and PA are also involved in the regulation of endocytic trafficking, it is therefore anticipated that DGKs also plays an important role in membrane trafficking. In this review, we summarize the literature discussing the role of DGK isoforms at different stages of endocytic trafficking, including endocytosis, exocytosis, endocytic recycling, and transport from/to the Golgi apparatus. Overall, these studies contribute to our understanding of the involvement of PA and DAG in endocytic trafficking, an area of research that is drawing increasing attention in recent years.
Collapse
Affiliation(s)
- Shuwei Xie
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
| | - Naava Naslavsky
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
| | - Steve Caplan
- Department of Biochemistry and Molecular Biology and the Fred and Pamela Buffett Cancer Center; University of Nebraska Medical Center ; Omaha, NE USA
| |
Collapse
|
13
|
Seneviratne CJ, Zeng G, Truong T, Sze S, Wong W, Samaranayake L, Chan FY, Wang YM, Wang H, Gao J, Wang Y. New "haploid biofilm model" unravels IRA2 as a novel regulator of Candida albicans biofilm formation. Sci Rep 2015. [PMID: 26202015 PMCID: PMC5378891 DOI: 10.1038/srep12433] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Clinical isolates of the fungal human pathogen Candida albicans are invariably diploid and heterozygous, impeding genetic study. Recent isolation of C. albicans haploids opens opportunities to apply technologies unfeasible in diploids. However, doubts remain on whether the haploids, derived from chromosome loss, can represent the diploids. Here, we use C. albicans haploids to investigate biofilm, a key virulence attribute. We conducted the first comprehensive characterization of biofilm formation of the haploids in comparison with the diploids. We demonstrate that the haploids form biofilms with essentially the same characteristics as the diploids. Screening a haploid mutant library has uncovered novel GTPase-related genes as biofilm regulators, including IRA2 that encodes an activator of the Ras GTPase. IRA2-deletion mutants develop poorly constructed biofilm in both haploid and diploid C. albicans. Our results demonstrate that the haploids are a valid model for C. albicans biofilm research and a powerful tool for uncovering novel regulators.
Collapse
Affiliation(s)
| | - Guisheng Zeng
- Institute of Molecular &Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore
| | - Thuyen Truong
- Oral Sciences, Faculty of Dentistry, National University of Singapore
| | - Sarah Sze
- Oral Sciences, Faculty of Dentistry, National University of Singapore
| | - Wah Wong
- Faculty of Dentistry, The University of Hong Kong, Hong Kong
| | - Lakshman Samaranayake
- 1] Faculty of Dentistry, The University of Hong Kong, Hong Kong [2] School of Dentistry, Queensland University, Australia
| | - Fong Yee Chan
- Institute of Molecular &Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore
| | - Yan-Ming Wang
- Institute of Molecular &Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore
| | - Haitao Wang
- Institute of Molecular &Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore
| | - Jiaxin Gao
- Institute of Molecular &Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore
| | - Yue Wang
- 1] Institute of Molecular &Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore [2] Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| |
Collapse
|
14
|
Estrada AF, Muruganandam G, Prescianotto-Baschong C, Spang A. The ArfGAP2/3 Glo3 and ergosterol collaborate in transport of a subset of cargoes. Biol Open 2015; 4:792-802. [PMID: 25964658 PMCID: PMC4571087 DOI: 10.1242/bio.011528] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Proteins reach the plasma membrane through the secretory pathway in which the trans Golgi network (TGN) acts as a sorting station. Transport from the TGN to the plasma membrane is maintained by a number of different pathways that act either directly or via the endosomal system. Here we show that a subset of cargoes depends on the ArfGAP2/3 Glo3 and ergosterol to maintain their proper localization at the plasma membrane. While interfering with neither ArfGAP2/3 activity nor ergosterol biosynthesis individually significantly altered plasma membrane localization of the tryptophan transporter Tat2, the general amino acid permease Gap1 and the v-SNARE Snc1, in a Δglo3 Δerg3 strain those proteins accumulated in internal endosomal structures. Export from the TGN to the plasma membrane and recycling from early endosomes appeared unaffected as the chitin synthase Chs3 that travels along these routes was localized normally. Our data indicate that a subset of proteins can reach the plasma membrane efficiently but after endocytosis becomes trapped in endosomal structures. Our study supports a role for ArfGAP2/3 in recycling from endosomes and in transport to the vacuole/lysosome.
Collapse
Affiliation(s)
- Alejandro F Estrada
- Growth & Development, Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland
| | - Gopinath Muruganandam
- Growth & Development, Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland
| | | | - Anne Spang
- Growth & Development, Biozentrum, University of Basel, Klingelbergstrasse 70, 4056 Basel, Switzerland
| |
Collapse
|
15
|
Johansen J, Ramanathan V, Beh CT. Vesicle trafficking from a lipid perspective: Lipid regulation of exocytosis in Saccharomyces cerevisiae. CELLULAR LOGISTICS 2014. [PMID: 23181198 PMCID: PMC3498074 DOI: 10.4161/cl.20490] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The protein cargo transported by specific types of vesicles largely defines the different secretory trafficking pathways operating within cells. However, mole per mole the most abundant cargo contained within transport vesicles is not protein, but lipid. Taking a "lipid-centric" point-of-view, we examine the importance of lipid signaling, membrane lipid organization and lipid metabolism for vesicle transport during exocytosis in budding yeast. In fact, the essential requirement for some exocytosis regulatory proteins can be bypassed by making simple manipulations of the lipids involved. During polarized exocytosis the sequential steps required to generate post-Golgi vesicles and target them to the plasma membrane (PM) involves the interplay of several types of lipids that are coordinately linked through PI4P metabolism and signaling. In turn, PI4P levels are regulated by PI4P kinases, the Sac1p PI4P phosphatase and the yeast Osh proteins, which are homologs of mammalian oxysterol-binding protein (OSBP). Together these regulators integrate the transitional steps required for vesicle maturation directly through changes in lipid composition and organization.
Collapse
Affiliation(s)
- Jesper Johansen
- Department of Molecular Biology and Biochemistry; Simon Fraser University; Burnaby, BC Canada
| | | | | |
Collapse
|
16
|
Kawada D, Kobayashi H, Tomita T, Nakata E, Nagano M, Siekhaus DE, Toshima JY, Toshima J. The yeast Arf-GAP Glo3p is required for the endocytic recycling of cell surface proteins. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:144-56. [PMID: 25409928 DOI: 10.1016/j.bbamcr.2014.10.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 10/09/2014] [Accepted: 10/10/2014] [Indexed: 11/26/2022]
Abstract
Small GTP-binding proteins of the Ras superfamily play diverse roles in intracellular trafficking. Among them, the Rab, Arf, and Rho families function in successive steps of vesicle transport, in forming vesicles from donor membranes, directing vesicle trafficking toward target membranes and docking vesicles onto target membranes. These proteins act as molecular switches that are controlled by a cycle of GTP binding and hydrolysis regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). In this study we explored the role of GAPs in the regulation of the endocytic pathway using fluorescently labeled yeast mating pheromone α-factor. Among 25 non-essential GAP mutants, we found that deletion of the GLO3 gene, encoding Arf-GAP protein, caused defective internalization of fluorescently labeled α-factor. Quantitative analysis revealed that glo3Δ cells show defective α-factor binding to the cell surface. Interestingly, Ste2p, the α-factor receptor, was mis-localized from the plasma membrane to the vacuole in glo3Δ cells. Domain deletion mutants of Glo3p revealed that a GAP-independent function, as well as the GAP activity, of Glo3p is important for both α-factor binding and Ste2p localization at the cell surface. Additionally, we found that deletion of the GLO3 gene affects the size and number of Arf1p-residing Golgi compartments and causes a defect in transport from the TGN to the plasma membrane. Furthermore, we demonstrated that glo3Δ cells were defective in the late endosome-to-TGN transport pathway, but not in the early endosome-to-TGN transport pathway. These findings suggest novel roles for Arf-GAP Glo3p in endocytic recycling of cell surface proteins.
Collapse
Affiliation(s)
- Daiki Kawada
- Department of Biological Science and Technology, Tokyo University of Science, Niijuku 6-3-1, Katsushika-ku, Tokyo 125-8585, Japan
| | - Hiromu Kobayashi
- Department of Biological Science and Technology, Tokyo University of Science, Niijuku 6-3-1, Katsushika-ku, Tokyo 125-8585, Japan
| | - Tsuyoshi Tomita
- Department of Biological Science and Technology, Tokyo University of Science, Niijuku 6-3-1, Katsushika-ku, Tokyo 125-8585, Japan
| | - Eisuke Nakata
- Department of Biological Science and Technology, Tokyo University of Science, Niijuku 6-3-1, Katsushika-ku, Tokyo 125-8585, Japan
| | - Makoto Nagano
- Department of Biological Science and Technology, Tokyo University of Science, Niijuku 6-3-1, Katsushika-ku, Tokyo 125-8585, Japan; Research Center for RNA Science, RIST, Tokyo University of Science, Niijuku 6-3-1, Katsushika-ku, Tokyo 125-8585, Japan
| | | | - Junko Y Toshima
- Research Center for RNA Science, RIST, Tokyo University of Science, Niijuku 6-3-1, Katsushika-ku, Tokyo 125-8585, Japan; Faculty of Science and Engineering, Waseda University, Wakamatsu-cho 2-2, Shinjuku-ku, Tokyo 162-8480, Japan.
| | - Jiro Toshima
- Department of Biological Science and Technology, Tokyo University of Science, Niijuku 6-3-1, Katsushika-ku, Tokyo 125-8585, Japan; Research Center for RNA Science, RIST, Tokyo University of Science, Niijuku 6-3-1, Katsushika-ku, Tokyo 125-8585, Japan.
| |
Collapse
|
17
|
Payet LA, Pineau L, Snyder ECR, Colas J, Moussa A, Vannier B, Bigay J, Clarhaut J, Becq F, Berjeaud JM, Vandebrouck C, Ferreira T. Saturated Fatty Acids Alter the Late Secretory Pathway by Modulating Membrane Properties. Traffic 2013; 14:1228-41. [DOI: 10.1111/tra.12117] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 08/30/2013] [Accepted: 09/06/2013] [Indexed: 01/26/2023]
Affiliation(s)
- Laurie-Anne Payet
- Université de Poitiers; Institut de Physiologie et de Biologie Cellulaires; FRE CNRS 3511, Pôle Biologie-Santé, 1, Rue Georges BONNET, BP 633 86022 Poitiers Cedex France
| | | | - Ellen C. R. Snyder
- Université de Poitiers; Institut de Physiologie et de Biologie Cellulaires; FRE CNRS 3511, Pôle Biologie-Santé, 1, Rue Georges BONNET, BP 633 86022 Poitiers Cedex France
| | - Jenny Colas
- Université de Poitiers; Institut de Physiologie et de Biologie Cellulaires; FRE CNRS 3511, Pôle Biologie-Santé, 1, Rue Georges BONNET, BP 633 86022 Poitiers Cedex France
| | - Ahmed Moussa
- Ecole Nationale des Sciences Appliquées de Tanger; BP 1818 90000 Tanger Morocco
| | - Brigitte Vannier
- Université de Poitiers; Institut de Physiologie et de Biologie Cellulaires; FRE CNRS 3511, Pôle Biologie-Santé, 1, Rue Georges BONNET, BP 633 86022 Poitiers Cedex France
| | - Joelle Bigay
- Institut de Pharmacologie Moléculaire et Cellulaire; UMR CNRS 7275, Université de Nice-Sophia Antipolis; 660 Route des Lucioles, Sophia Antipolis 06560 Valbonne France
| | - Jonathan Clarhaut
- INSERM CIC 0802; CHU de Poitiers; 2 rue de la Milétrie 86021 Poitiers France
| | - Frédéric Becq
- Université de Poitiers; Institut de Physiologie et de Biologie Cellulaires; FRE CNRS 3511, Pôle Biologie-Santé, 1, Rue Georges BONNET, BP 633 86022 Poitiers Cedex France
| | - Jean-Marc Berjeaud
- Université de Poitiers; Ecologie et Biologie des Interactions; UMR CNRS 7267, 40 avenue du Recteur Pineau 86022 Poitiers Cedex France
| | - Clarisse Vandebrouck
- Université de Poitiers; Institut de Physiologie et de Biologie Cellulaires; FRE CNRS 3511, Pôle Biologie-Santé, 1, Rue Georges BONNET, BP 633 86022 Poitiers Cedex France
| | - Thierry Ferreira
- Université de Poitiers; Institut de Physiologie et de Biologie Cellulaires; FRE CNRS 3511, Pôle Biologie-Santé, 1, Rue Georges BONNET, BP 633 86022 Poitiers Cedex France
| |
Collapse
|
18
|
Xu P, Baldridge RD, Chi RJ, Burd CG, Graham TR. Phosphatidylserine flipping enhances membrane curvature and negative charge required for vesicular transport. ACTA ACUST UNITED AC 2013; 202:875-86. [PMID: 24019533 PMCID: PMC3776346 DOI: 10.1083/jcb.201305094] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Drs2 flippase increases membrane curvature and anionic phospholipid composition of the membrane by flipping phosphatidylserine, which is critical for vesicular transport between the trans-Golgi network and early endosomes. Vesicle-mediated protein transport between organelles of the secretory and endocytic pathways is strongly influenced by the composition and organization of membrane lipids. In budding yeast, protein transport between the trans-Golgi network (TGN) and early endosome (EE) requires Drs2, a phospholipid translocase in the type IV P-type ATPase family. However, downstream effectors of Drs2 and specific phospholipid substrate requirements for protein transport in this pathway are unknown. Here, we show that the Arf GTPase-activating protein (ArfGAP) Gcs1 is a Drs2 effector that requires a variant of the ArfGAP lipid packing sensor (+ALPS) motif for localization to TGN/EE membranes. Drs2 increases membrane curvature and anionic phospholipid composition of the cytosolic leaflet, both of which are sensed by the +ALPS motif. Using mutant forms of Drs2 and the related protein Dnf1, which alter their ability to recognize phosphatidylserine, we show that translocation of this substrate to the cytosolic leaflet is essential for +ALPS binding and vesicular transport between the EE and the TGN.
Collapse
Affiliation(s)
- Peng Xu
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235
| | | | | | | | | |
Collapse
|
19
|
Zendeh-boodi Z, Yamamoto T, Sakane H, Tanaka K. Identification of a second amphipathic lipid-packing sensor-like motif that contributes to Gcs1p function in the early endosome-to-TGN pathway. J Biochem 2013; 153:573-87. [PMID: 23564908 DOI: 10.1093/jb/mvt025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
ArfGAPs, GTPase-activating proteins for Arf small GTPases, are involved in multiple steps of vesicle formation of various transport pathways. Amphipathic lipid-packing sensor (ALPS) motif was first identified in the C-terminal regions of ArfGAP1 and its yeast homologue Gcs1p as a region that adsorbs preferentially onto highly curved membranes by folding into an amphipathic α-helix (AH). We previously showed that Gcs1p functionally interacted with the phospholipid flippase Cdc50p-Drs2p in the early endosome-to-TGN retrieval pathway. In this study, we performed functional analyses of the C-terminal region of Gcs1p containing ALPS. Hydrophobic cluster analysis suggested that there is another potential AH-forming region downstream of ALPS in Gcs1p. Mutational analysis suggested that the ALPS motif is important for the Gcs1p function in the Golgi-to-ER retrograde pathway, whereas ALPS and the predicted AH region redundantly function in the post-Golgi pathways including the early endosome-to-TGN pathway. Liposome flotation assay indicated that this downstream region preferentially interacted with liposomes of smaller size. The region containing the ALPS motif was also required for the interaction with SNARE proteins including Snc1p and Tlg1p. These results suggest that ALPS and the predicted AH region are involved in the regulation and function of Gcs1p by interacting with membrane phospholipids and vesicle proteins.
Collapse
Affiliation(s)
- Zahra Zendeh-boodi
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Life Science, N15 W7, Kita-ku, Sapporo 060-0815, Japan
| | | | | | | |
Collapse
|
20
|
Shiba Y, Randazzo PA. ArfGAP1 function in COPI mediated membrane traffic: currently debated models and comparison to other coat-binding ArfGAPs. Histol Histopathol 2012; 27:1143-53. [PMID: 22806901 DOI: 10.14670/hh-27.1143] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The ArfGAPs are a family of proteins containing an ArfGAP catalytic domain that induces the hydrolysis of GTP bound to the small guanine nucleotide binding-protein ADP-ribosylation factor (Arf). Functional models for Arfs, which are regulators of membrane traffic, are based on the idea that guanine nucleotide-binding proteins function as switches: Arf with GTP bound is active and binds to effector proteins; the conversion of GTP to GDP inactivates Arf. The cellular activities of ArfGAPs have been examined primarily as regulatory proteins that inactivate Arf; however, Arf function in membrane traffic does not strictly adhere to the concept of a simple switch, adding complexity to models explaining the role of ArfGAPs. Here, we review the literature addressing the function Arf and ArfGAP1 in COPI mediated transport, focusing on two critical and integrated functions of membrane traffic, cargo sorting and vesicle coat polymerization. We briefly discuss other ArfGAPs that may have similar function in Arf-dependent membrane traffic outside the ER-Golgi.
Collapse
Affiliation(s)
- Yoko Shiba
- National Cancer Institute, Laboratory of Cellular and Molecular Biology, Bethesda, MD 20892, USA
| | | |
Collapse
|
21
|
Paczkowski JE, Richardson BC, Strassner AM, Fromme JC. The exomer cargo adaptor structure reveals a novel GTPase-binding domain. EMBO J 2012; 31:4191-203. [PMID: 23000721 DOI: 10.1038/emboj.2012.268] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 08/30/2012] [Indexed: 11/09/2022] Open
Abstract
Cargo adaptors control intracellular trafficking of transmembrane proteins by sorting them into membrane transport carriers. The COPI, COPII, and clathrin cargo adaptors are structurally well characterized, but other cargo adaptors remain poorly understood. Exomer is a specialized cargo adaptor that sorts specific proteins into trans-Golgi network (TGN)-derived vesicles in response to cellular signals. Exomer is recruited to the TGN by the Arf1 GTPase, a universally conserved trafficking regulator. Here, we report the crystal structure of a tetrameric exomer complex composed of two copies each of the Chs5 and Chs6 subunits. The structure reveals the FN3 and BRCT domains of Chs5, which together we refer to as the FBE domain (FN3-BRCT of exomer), project from the exomer core complex. The overall architecture of the FBE domain is reminiscent of the appendage domains of other cargo adaptors, although it exhibits a distinct topology. In contrast to appendage domains, which bind accessory factors, we show that the primary role of the FBE domain is to bind Arf1 for recruitment of exomer to membranes.
Collapse
Affiliation(s)
- Jon E Paczkowski
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA
| | | | | | | |
Collapse
|
22
|
|
23
|
Benjamin JJR, Poon PP, Drysdale JD, Wang X, Singer RA, Johnston GC. Dysregulated Arl1, a regulator of post-Golgi vesicle tethering, can inhibit endosomal transport and cell proliferation in yeast. Mol Biol Cell 2011; 22:2337-47. [PMID: 21562219 PMCID: PMC3128535 DOI: 10.1091/mbc.e10-09-0765] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Small monomeric G proteins regulated in part by GTPase-activating proteins (GAPs) are molecular switches for several aspects of vesicular transport. The yeast Gcs1 protein is a dual-specificity GAP for ADP-ribosylation factor (Arf) and Arf-like (Arl)1 G proteins, and also has GAP-independent activities. The absence of Gcs1 imposes cold sensitivity for growth and endosomal transport; here we present evidence that dysregulated Arl1 may cause these impairments. We show that gene deletions affecting the Arl1 or Ypt6 vesicle-tethering pathways prevent Arl1 activation and membrane localization, and restore growth and trafficking in the absence of Gcs1. A mutant version of Gcs1 deficient for both ArfGAP and Arl1GAP activity in vitro still allows growth and endosomal transport, suggesting that the function of Gcs1 that is required for these processes is independent of GAP activity. We propose that, in the absence of this GAP-independent regulation by Gcs1, the resulting dysregulated Arl1 prevents growth and impairs endosomal transport at low temperatures. In cells with dysregulated Arl1, an increased abundance of the Arl1 effector Imh1 restores growth and trafficking, and does so through Arl1 binding. Protein sequestration at the trans-Golgi membrane by dysregulated, active Arl1 may therefore be the mechanism of inhibition.
Collapse
Affiliation(s)
- Jeremy J R Benjamin
- Department of Microbiology & Immunology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 1X5
| | | | | | | | | | | |
Collapse
|
24
|
Hong H, Nadesan P, Poon R, Alman BA. Testosterone regulates cell proliferation in aggressive fibromatosis (desmoid tumour). Br J Cancer 2011; 104:1452-8. [PMID: 21468052 PMCID: PMC3101926 DOI: 10.1038/bjc.2011.107] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Background: Aggressive fibromatosis (desmoid tumour) is a locally invasive tumour caused by mutations resulting in β-catenin protein stabilisation. Apc1638N mice are predisposed to developing aggressive fibromatosis tumours, and male mice develop greater numbers of tumours than female mice, suggesting a role for androgens in this tumour type. Methods: Human aggressive fibromatosis tumours were examined for the expression of the androgen receptor, and primary human tumour cell cultures were treated with testosterone. Orchidectomised Apc1638N mice were investigated for the development of tumours, and were treated with testosterone to study the effect of tumour formation and the level of β-catenin. Results: Androgen receptors are universally expressed in human aggressive fibromatosis tumours. Testosterone increased the proliferation rate and β-catenin protein level in a dose-dependent manner in human aggressive fibromatosis tumours. Orchiectomy reduced the number and size of tumours that formed in male Apc1638N mice to a similar level as observed in female mice. Testosterone treatment increased the number of tumours that formed in orchidectomised male mice, and resulted in a marked increase in β-catenin protein levels. Conclusion: Testosterone regulates β-catenin protein level and proliferation rate in this mesenchymal tumour. This work identifies the therapeutic use of testosterone blockade in aggressive fibromatosis as an area for further investigation.
Collapse
Affiliation(s)
- H Hong
- Program in Developmental and Stem Cell Biology, Hospital for Sick Children, Toronto Medical Discovery Tower, 101 College Street, Toronto, ON, Canada M5G 1L7
| | | | | | | |
Collapse
|
25
|
The non-catalytic carboxyl-terminal domain of ARFGAP1 regulates actin cytoskeleton reorganization by antagonizing the activation of Rac1. PLoS One 2011; 6:e18458. [PMID: 21483700 PMCID: PMC3070737 DOI: 10.1371/journal.pone.0018458] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2010] [Accepted: 03/08/2011] [Indexed: 11/26/2022] Open
Abstract
Background The regulation of the actin cytoskeleton and membrane trafficking is coordinated in mammalian cells. One of the regulators of membrane traffic, the small GTP-binding protein ARF1, also activates phosphatidylinositol kinases that in turn affect actin polymerization. ARFGAP1 is a GTPase activating protein (GAP) for ARF1 that is found on Golgi membranes. We present evidence that ARFGAP1 not only serves as a GAP for ARF1, but also can affect the actin cytoskeleton. Principal Findings As cells attach to a culture dish foci of actin appear prior to the cells flattening and spreading. We have observed that overexpression of a truncated ARFGAP1 that lacks catalytic activity for ARF, called GAP273, caused these foci to persist for much longer periods than non-transfected cells. This phenomenon was dependent on the level of GAP273 expression. Furthermore, cell spreading after re-plating or cell migration into a previously scraped area was inhibited in cells transfected with GAP273. Live cell imaging of such cells revealed that actin-rich membrane blebs formed that seldom made protrusions of actin spikes or membrane ruffles, suggesting that GAP273 interfered with the regulation of actin dynamics during cell spreading. The over-expression of constitutively active alleles of ARF6 and Rac1 suppressed the effect of GAP273 on actin. In addition, the activation of Rac1 by serum, but not that of RhoA or ARF6, was inhibited in cells over-expressing GAP273, suggesting that Rac1 is a likely downstream effector of ARFGAP1. The carboxyl terminal 65 residues of ARFGAP1 were sufficient to produce the effects on actin and cell spreading in transfected cells and co-localized with cortical actin foci. Conclusions ARFGAP1 functions as an inhibitor upstream of Rac1 in regulating actin cytoskeleton. In addition to its GAP catalytic domain and Golgi binding domain, it also has an actin regulation domain in the carboxyl-terminal portion of the protein.
Collapse
|
26
|
Funaki T, Kon S, Ronn RE, Henmi Y, Kobayashi Y, Watanabe T, Nakayama K, Tanabe K, Satake M. Localization of SMAP2 to the TGN and its Function in the Regulation of TGN Protein Transport. Cell Struct Funct 2011; 36:83-95. [DOI: 10.1247/csf.10022] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Affiliation(s)
- Tomo Funaki
- Institute of Development, Aging and Cancer, Graduate School of Life Sciences, Tohoku University
| | - Shunsuke Kon
- Institute of Development, Aging and Cancer, Graduate School of Life Sciences, Tohoku University
| | - Roger E. Ronn
- Institute of Development, Aging and Cancer, Graduate School of Life Sciences, Tohoku University
| | - Yuji Henmi
- Graduate School of Medicine and Dentistry, Okayama University
| | - Yuka Kobayashi
- Graduate School of Medicine and Dentistry, Okayama University
| | - Toshio Watanabe
- Institute of Development, Aging and Cancer, Graduate School of Life Sciences, Tohoku University
| | | | - Kenji Tanabe
- Graduate School of Medicine and Dentistry, Okayama University
| | - Masanobu Satake
- Institute of Development, Aging and Cancer, Graduate School of Life Sciences, Tohoku University
| |
Collapse
|
27
|
Benjamin JJR, Poon PP, Lewis SM, Auger A, Wong TA, Singer RA, Johnston GC. The yeast Arf GTPase-activating protein Age1 is regulated by phospholipase D for post-Golgi vesicular transport. J Biol Chem 2010; 286:5187-96. [PMID: 21135091 DOI: 10.1074/jbc.m110.185108] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Vesicular transport shuttles cargo among intracellular compartments. Several stages of vesicular transport are mediated by the small GTPase Arf, which is controlled in a cycle of GTP binding and hydrolysis by Arf guanine-nucleotide exchange factors and Arf GTPase-activating proteins (ArfGAPs), respectively. In budding yeast the Age2 + Gcs1 ArfGAP pair facilitates post-Golgi transport. We have found the AGE1 gene, encoding another ArfGAP, can in high gene-copy number alleviate the temperature sensitivity of cells carrying mutations affecting the Age2 + Gcs1 ArfGAP pair. Moreover, increased AGE1 gene dosage compensates for the complete absence of the otherwise essential Age2 + Gcs1 ArfGAP pair. Increased dosage of SFH2, encoding a phosphatidylinositol transfer protein, also allows cell growth in the absence of the Age2 + Gcs1 pair, but good growth in this situation requires Age1. The ability of Age1 to overcome the need for Age2 + Gcs1 depends on phospholipase D activity that regulates lipid composition. We show by direct assessment of Age1 ArfGAP activity that Age1 is regulated by lipid composition and can provide ArfGAP function for post-Golgi transport.
Collapse
Affiliation(s)
- Jeremy J R Benjamin
- Department of Microbiology and Immunology, DalhousieUniversity, Halifax, Nova Scotia B3H 1X5, Canada
| | | | | | | | | | | | | |
Collapse
|
28
|
Stefano G, Renna L, Rossi M, Azzarello E, Pollastri S, Brandizzi F, Baluska F, Mancuso S. AGD5 is a GTPase-activating protein at the trans-Golgi network. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:790-799. [PMID: 21105926 DOI: 10.1111/j.1365-313x.2010.04369.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
ARF-GTPases are important proteins that control membrane trafficking events. Their activity is largely influenced by the interplay between guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), which facilitate the activation or inactivation of ARF-GTPases, respectively. There are 15 predicted proteins that contain an ARF-GAP domain within the Arabidopsis thaliana genome, and these are classified as ARF-GAP domain (AGD) proteins. The function and subcellular distribution of AGDs, including the ability to activate ARF-GTPases in vivo, that remain largely uncharacterized to date. Here we show that AGD5 is localised to the trans-Golgi network (TGN), where it co-localises with ARF1, a crucial GTPase that is involved in membrane trafficking and which was previously shown to be distributed on Golgi and post-Golgi structures of unknown nature. Taking advantage of the in vivo AGD5-ARF1 interaction at the TGN, we show that mutation of an arginine residue that is critical for ARF-GAP activity of AGD5 leads to longer residence of ARF1 on the membranes, as expected if GTP hydrolysis on ARF1 was impaired due to a defective GAP. Our results establish the nature of the post-Golgi compartments in which ARF1 localises, as well as identifying the role of AGD5 in vivo as a TGN-localised GAP. Furthermore, in vitro experiments established the promiscuous interaction between AGD5 and the plasma membrane-localised ADP ribosylation factor B (ARFB), confirming that ARF-GAP specificity for ARF-GTPases within the cell environment may be spatially regulated.
Collapse
Affiliation(s)
- Giovanni Stefano
- Department of Plant, Soil and Environmental Science, viale delle Idee, University of Florence, Sesto Fiorentino, FI 50019, Italy.
| | | | | | | | | | | | | | | |
Collapse
|
29
|
The antibiotic gentamicin inhibits specific protein trafficking functions of the Arf1/2 family of GTPases. Antimicrob Agents Chemother 2010; 55:246-54. [PMID: 20956596 DOI: 10.1128/aac.00450-10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gentamicin is a highly efficacious antibiotic against Gram-negative bacteria. However, its usefulness in treating infections is compromised by its poorly understood renal toxicity. Toxic effects are also seen in a variety of other organisms. While the yeast Saccharomyces cerevisiae is relatively insensitive to gentamicin, mutations in any one of ∼20 genes cause a dramatic decrease in resistance. Many of these genes encode proteins important for translation termination or specific protein-trafficking complexes. Subsequent inspection of the physical and genetic interactions of the remaining gentamicin-sensitive mutants revealed a network centered on chitin synthase and the Arf GTPases. Further analysis has demonstrated that some conditional arf1 and gea1 alleles make cells hypersensitive to gentamicin under permissive conditions. These results suggest that one consequence of gentamicin exposure is disruption of Arf-dependent protein trafficking.
Collapse
|
30
|
Tani M, Kuge O. Requirement of a specific group of sphingolipid-metabolizing enzyme for growth of yeast Saccharomyces cerevisiae under impaired metabolism of glycerophospholipids. Mol Microbiol 2010; 78:395-413. [DOI: 10.1111/j.1365-2958.2010.07340.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
|
31
|
Lettner T, Zeidler U, Gimona M, Hauser M, Breitenbach M, Bito A. Candida albicans AGE3, the ortholog of the S. cerevisiae ARF-GAP-encoding gene GCS1, is required for hyphal growth and drug resistance. PLoS One 2010; 5:e11993. [PMID: 20700541 PMCID: PMC2916835 DOI: 10.1371/journal.pone.0011993] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 07/12/2010] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Hyphal growth and multidrug resistance of C. albicans are important features for virulence and antifungal therapy of this pathogenic fungus. METHODOLOGY/PRINCIPAL FINDINGS Here we show by phenotypic complementation analysis that the C. albicans gene AGE3 is the functional ortholog of the yeast ARF-GAP-encoding gene GCS1. The finding that the gene is required for efficient endocytosis points to an important functional role of Age3p in endosomal compartments. Most C. albicans age3Delta mutant cells which grew as cell clusters under yeast growth conditions showed defects in filamentation under different hyphal growth conditions and were almost completely disabled for invasive filamentous growth. Under hyphal growth conditions only a fraction of age3Delta cells shows a wild-type-like polarization pattern of the actin cytoskeleton and lipid rafts. Moreover, age3Delta cells were highly susceptible to several unrelated toxic compounds including antifungal azole drugs. Irrespective of the AGE3 genotype, C-terminal fusions of GFP to the drug efflux pumps Cdr1p and Mdr1p were predominantly localized in the plasma membrane. Moreover, the plasma membranes of wild-type and age3Delta mutant cells contained similar amounts of Cdr1p, Cdr2p and Mdr1p. CONCLUSIONS/SIGNIFICANCE The results indicate that the defect in sustaining filament elongation is probably caused by the failure of age3Delta cells to polarize the actin cytoskeleton and possibly of inefficient endocytosis. The high susceptibility of age3Delta cells to azoles is not caused by inefficient transport of efflux pumps to the cell membrane. A possible role of a vacuolar defect of age3Delta cells in drug susceptibility is proposed and discussed. In conclusion, our study shows that the ARF-GAP Age3p is required for hyphal growth which is an important virulence factor of C. albicans and essential for detoxification of azole drugs which are routinely used for antifungal therapy. Thus, it represents a promising antifungal drug target.
Collapse
Affiliation(s)
- Thomas Lettner
- Department of Cell Biology, University of Salzburg, Salzburg, Austria
| | - Ute Zeidler
- Institut Pasteur, Unité Biologie et Pathogénicité Fongiques, Paris, France
| | - Mario Gimona
- Department of Cell Biology, University of Salzburg, Salzburg, Austria
| | - Michael Hauser
- Department of Molecular Biology, University of Salzburg, Salzburg, Austria
| | | | - Arnold Bito
- Department of Cell Biology, University of Salzburg, Salzburg, Austria
| |
Collapse
|
32
|
Spang A, Shiba Y, Randazzo PA. Arf GAPs: gatekeepers of vesicle generation. FEBS Lett 2010; 584:2646-51. [PMID: 20394747 DOI: 10.1016/j.febslet.2010.04.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2010] [Revised: 03/26/2010] [Accepted: 04/03/2010] [Indexed: 11/17/2022]
Abstract
Arf GAP proteins are a versatile and diverse group of proteins. They control the activity of the GTP-binding proteins of the ARF family by inducing the hydrolysis of GTP that is bound to Arf proteins. The best-studied role of Arf GAPs is in intracellular traffic. In this review, we will focus mainly on the Arf GAPs that play a role in vesicle formation, Arf GAP1, Arf GAP2 and Arf GAP3 and their yeast homologues, Gcs1p and Glo3p. We discuss the roles of Arf GAPs as regulators and effectors for Arf GTP-binding proteins.
Collapse
Affiliation(s)
- Anne Spang
- University of Basel, Growth and Development, Biozentrum, Switzerland.
| | | | | |
Collapse
|
33
|
Epp E, Vanier G, Harcus D, Lee AY, Jansen G, Hallett M, Sheppard DC, Thomas DY, Munro CA, Mullick A, Whiteway M. Reverse genetics in Candida albicans predicts ARF cycling is essential for drug resistance and virulence. PLoS Pathog 2010; 6:e1000753. [PMID: 20140196 PMCID: PMC2816695 DOI: 10.1371/journal.ppat.1000753] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Accepted: 01/06/2010] [Indexed: 12/03/2022] Open
Abstract
Candida albicans, the major fungal pathogen of humans, causes life-threatening infections in immunocompromised individuals. Due to limited available therapy options, this can frequently lead to therapy failure and emergence of drug resistance. To improve current treatment strategies, we have combined comprehensive chemical-genomic screening in Saccharomyces cerevisiae and validation in C. albicans with the goal of identifying compounds that can couple with the fungistatic drug fluconazole to make it fungicidal. Among the genes identified in the yeast screen, we found that only AGE3, which codes for an ADP-ribosylation factor GTPase activating effector protein, abrogates fluconazole tolerance in C. albicans. The age3 mutant was more sensitive to other sterols and cell wall inhibitors, including caspofungin. The deletion of AGE3 in drug resistant clinical isolates and in constitutively active calcineurin signaling mutants restored fluconazole sensitivity. We confirmed chemically the AGE3-dependent drug sensitivity by showing a potent fungicidal synergy between fluconazole and brefeldin A (an inhibitor of the guanine nucleotide exchange factor for ADP ribosylation factors) in wild type C. albicans as well as in drug resistant clinical isolates. Addition of calcineurin inhibitors to the fluconazole/brefeldin A combination only initially improved pathogen killing. Brefeldin A synergized with different drugs in non-albicans Candida species as well as Aspergillus fumigatus. Microarray studies showed that core transcriptional responses to two different drug classes are not significantly altered in age3 mutants. The therapeutic potential of inhibiting ARF activities was demonstrated by in vivo studies that showed age3 mutants are avirulent in wild type mice, attenuated in virulence in immunocompromised mice and that fluconazole treatment was significantly more efficacious when ARF signaling was genetically compromised. This work describes a new, widely conserved, broad-spectrum mechanism involved in fungal drug resistance and virulence and offers a potential route for single or improved combination therapies. Candida albicans is a fungus that normally resides as part of the microflora in the human gut. Candida species can cause superficial infections like thrush in the healthy human population and life-threatening invasive infections in immunocompromised patients. Fungal infections are often treated with azole drugs, but due to the fungistatic nature of these agents, C. albicans can develop drug resistance, leading to therapy failure. To improve the action of azoles and convert them into fungicidal drugs, we first systematically analyzed the genetic requirements for tolerance to one such azole drug, fluconazole. We show, both genetically and pharmacologically, that components of the ARF cycling machinery are critical in mediating both azole and echinocandin tolerance in C. albicans as well as several other pathogenic Candida species and in the pathogenic mold Aspergillus fumigatus. We highlight the importance of ARF cycling in drug resistance by showing that genetic compromise of ARF functions overrides common drug resistance mechanisms in clinical samples and other key regulators of azole/echinocandin tolerance. We validated the therapeutic potential of ARF cycling in two mouse models and provide evidence that drug treatment is more efficacious when ARF activities are genetically compromised. Our study demonstrates a new mechanism involved in two important aspects of the biology of human fungal pathogens and provides a potential route for improved antifungal therapies.
Collapse
Affiliation(s)
- Elias Epp
- Biotechnology Research Institute, National Research Council of Canada, Montréal, Québec, Canada
- Department of Biology, McGill University, Montréal, Québec, Canada
| | - Ghyslaine Vanier
- Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada
| | - Doreen Harcus
- Biotechnology Research Institute, National Research Council of Canada, Montréal, Québec, Canada
| | - Anna Y. Lee
- McGill Centre for Bioinformatics, McGill University, Montréal, Québec, Canada
| | - Gregor Jansen
- Department of Biochemistry, McGill University, Montréal, Québec, Canada
| | - Michael Hallett
- McGill Centre for Bioinformatics, McGill University, Montréal, Québec, Canada
| | - Don C. Sheppard
- Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada
| | - David Y. Thomas
- Department of Biochemistry, McGill University, Montréal, Québec, Canada
| | - Carol A. Munro
- School of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Alaka Mullick
- Biotechnology Research Institute, National Research Council of Canada, Montréal, Québec, Canada
- Département de Microbiologie et Immunologie, l'Université de Montréal, Montréal, Québec, Canada
| | - Malcolm Whiteway
- Biotechnology Research Institute, National Research Council of Canada, Montréal, Québec, Canada
- Department of Biology, McGill University, Montréal, Québec, Canada
- * E-mail:
| |
Collapse
|
34
|
Liljegren SJ, Leslie ME, Darnielle L, Lewis MW, Taylor SM, Luo R, Geldner N, Chory J, Randazzo PA, Yanofsky MF, Ecker JR. Regulation of membrane trafficking and organ separation by the NEVERSHED ARF-GAP protein. Development 2009; 136:1909-18. [PMID: 19429787 DOI: 10.1242/dev.033605] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cell separation, or abscission, is a highly specialized process in plants that facilitates remodeling of their architecture and reproductive success. Because few genes are known to be essential for organ abscission, we conducted a screen for mutations that alter floral organ shedding in Arabidopsis. Nine recessive mutations that block shedding were found to disrupt the function of an ADP-ribosylation factor-GTPase-activating protein (ARF-GAP) we have named NEVERSHED (NEV). As predicted by its homology to the yeast Age2 ARF-GAP and transcriptional profile, NEV influences other aspects of plant development, including fruit growth. Co-localization experiments carried out with NEV-specific antiserum and a set of plant endomembrane markers revealed that NEV localizes to the trans-Golgi network and endosomes in Arabidopsis root epidermal cells. Interestingly, transmission electron micrographs of abscission zone regions from wild-type and nev flowers reveal defects in the structure of the Golgi apparatus and extensive accumulation of vesicles adjacent to the cell walls. Our results suggest that NEV ARF-GAP activity at the trans-Golgi network and distinct endosomal compartments is required for the proper trafficking of cargo molecules required for cell separation.
Collapse
Affiliation(s)
- Sarah J Liljegren
- Department of Biology and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Schindler C, Rodriguez F, Poon PP, Singer RA, Johnston GC, Spang A. The GAP domain and the SNARE, coatomer and cargo interaction region of the ArfGAP2/3 Glo3 are sufficient for Glo3 function. Traffic 2009; 10:1362-75. [PMID: 19602196 DOI: 10.1111/j.1600-0854.2009.00952.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ArfGAP Glo3 is required for coat protein I vesicle generation in the Golgi-endoplasmic reticulum (ER) shuttle. The best-understood role of Glo3 is the stimulation of the GTPase activity of Arf1. In this study, we characterized functional domains of the ArfGAP Glo3 and identified an interaction interface for coatomer, SNAREs and cargo in the central region of Glo3 (BoCCS region). The GAP domain together with the BoCCS region is necessary and sufficient for all vital Glo3 functions. Expression of a truncated Glo3 lacking the GAP domain results in a dominant negative growth phenotype in glo3Delta cells at 37 degrees C. This phenotype was alleviated by mutating either the BoCCS region or the Glo3 regulatory motif (GRM), or by overexpression of ER-Golgi SNAREs or the ArfGAP Gcs1. The GRM is not essential for Glo3 function; it may act as an intrinsic sensor coupling GAP activity to SNARE binding to avoid dead-end complex formation at the Golgi membrane. Our data suggest that membrane-interaction modules and cargo-sensing regions have evolved independently in ArfGAP1s versus ArfGAP2/3s.
Collapse
Affiliation(s)
- Christina Schindler
- Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
| | | | | | | | | | | |
Collapse
|
36
|
Toret CP, Lee L, Sekiya-Kawasaki M, Drubin DG. Multiple pathways regulate endocytic coat disassembly in Saccharomyces cerevisiae for optimal downstream trafficking. Traffic 2008; 9:848-59. [PMID: 18298676 DOI: 10.1111/j.1600-0854.2008.00726.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Recently, a pathway involving the highly choreographed recruitment of endocytic proteins to sites of clathrin/actin-mediated endocytosis has been revealed in budding yeast. Here, we investigated possible roles for candidate disassembly factors in regulation of the dynamics of the endocytic coat proteins Sla2p, Ent1p, Ent2p, Sla1p, Pan1p and End3p, each of which has mammalian homologues. Live cell imaging analysis revealed that in addition to the synaptojanin, Sjl2p, the Ark1p and Prk1p protein kinases, the putative Arf GTPase-activating protein, Gts1p and the Arf GTPase-interacting protein, Lsb5p, also arrive at endocytic sites late in the internalization pathway, consistent with roles in coat disassembly. Analysis of coat dynamics in various mutant backgrounds revealed that multiple pathways, including the ones mediated by an Arf guanosine triphosphatase and a synaptojanin, facilitate efficient disassembly of different endocytic coat proteins. In total, at least four separate processes are important for disassembly of endocytic complexes and efficient downstream trafficking of endocytic cargo.
Collapse
Affiliation(s)
- Christopher P Toret
- Department of Molecular and Cell Biology, University of California, 16 Barker Hall, Berkeley, CA 94720-3202, USA
| | | | | | | |
Collapse
|
37
|
DeRegis CJ, Rahl PB, Hoffman GR, Cerione RA, Collins RN. Mutational analysis of betaCOP (Sec26p) identifies an appendage domain critical for function. BMC Cell Biol 2008; 9:3. [PMID: 18211691 PMCID: PMC2262067 DOI: 10.1186/1471-2121-9-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2007] [Accepted: 01/22/2008] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The appendage domain of the gammaCOP subunit of the COPI vesicle coat bears a striking structural resemblance to adaptin-family appendages despite limited primary sequence homology. Both the gammaCOP appendage domain and an equivalent region on betaCOP contain the FxxxW motif; the conservation of this motif suggested the existence of a functional appendage domain in betaCOP. RESULTS Sequence comparisons in combination with structural prediction tools show that the fold of the COOH-terminus of Sec26p is strongly predicted to closely mimic that of adaptin-family appendages. Deletion of the appendage domain of Sec26p results in inviability in yeast, over-expression of the deletion construct is dominant negative and mutagenesis of this region identifies residues critical for function. The ArfGAP Glo3p was identified via suppression screening as a potential downstream modulator of Sec26p in a manner that is independent of the GAP activity of Glo3p but requires the presence of the COOH-terminal ISS motifs. CONCLUSION Together, these results indicate an essential function for the predicted betaCOP appendage and suggest that both COPI appendages perform a biologically active regulatory role with a structure related to adaptin-family appendage domains.
Collapse
Affiliation(s)
- Carol J DeRegis
- Graduate Program in Comparative Biomedical Sciences, Cornell University, Ithaca NY 14853, USA
| | - Peter B Rahl
- Graduate Program in Pharmacology, Cornell University, Ithaca, NY 14853, USA
| | - Gregory R Hoffman
- Graduate Program in Biophysics, Cornell University, Ithaca, NY 14853, USA
| | - Richard A Cerione
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
| | - Ruth N Collins
- Department of Molecular Medicine, Cornell University, Ithaca, NY 14853, USA
- Department of Molecular Medicine, Cornell University, C4-109 Veterinary Medical Center, Ithaca, NY 14853, USA
| |
Collapse
|
38
|
Abstract
Small G proteins play a central role in the organization of the secretory and endocytic pathways. The majority of such small G proteins are members of the Rab family, which are anchored to the bilayer by C-terminal prenyl groups. However, the recruitment of some effectors, including vesicle coat proteins, is mediated by a second class of small G proteins that is unique in having an N-terminal amphipathic helix that becomes available for membrane insertion upon GTP binding. Sar1, Arf1, and Arf6 are the best-characterized members of this ADP-ribosylation factor (Arf) family. In addition, all eukaryotes contain additional distantly related G proteins, often called Arf like, or Arls. The complete Arf family in humans has 29 members. The roles of these related G proteins are poorly understood, but recent work has shown that some are involved in membrane traffic or organizing the cytoskeleton. Here we review what is known about all the members of the Arf family, along with the known regulatory molecules that convert them between GDP- and GTP-bound states.
Collapse
|
39
|
Abstract
ADP-ribosylation factors (ARFs) are critical regulators of vesicular trafficking pathways and act at multiple intracellular sites. ADP-ribosylation factor-GTPase-activating proteins (ARFGAPs) are proposed to contribute to site-specific regulation. In yeast, two distinct proteins, Glo3p and Gcs1p, together provide overlapping, essential ARFGAP function required for coat protein (COP)-I-dependent trafficking. In mammalian cells, only the Gcs1p orthologue, named ARFGAP1, has been characterized in detail. However, Glo3p is known to make the stronger contribution to COP I traffic in yeast. Here, based on a conserved signature motif close to the carboxy terminus, we identify ARFGAP2 and ARFGAP3 as the human orthologues of yeast Glo3p. By immunofluorescence (IF), ARFGAP2 and ARFGAP3 are closely colocalized with coatomer subunits in NRK cells in the Golgi complex and peripheral punctate structures. In contrast to ARFGAP1, both ARFGAP2 and ARFGAP3 are associated with COP-I-coated vesicles generated from Golgi membranes in the presence of GTP-γ-S in vitro. ARFGAP2 lacking its zinc finger domain directly binds to coatomer. Expression of this truncated mutant (ΔN-ARFGAP2) inhibits COP-I-dependent Golgi-to-endoplasmic reticulum transport of cholera toxin (CTX-K63) in vivo. Silencing of ARFGAP1 or a combination of ARFGAP2 and ARFGAP3 in HeLa cells does not decrease cell viability. However, silencing all three ARFGAPs causes cell death. Our data provide strong evidence that ARFGAP2 and ARFGAP3 function in COP I traffic.
Collapse
Affiliation(s)
- Gabriella Frigerio
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of CambridgeHills Road, Cambridge CB2 2XY, United Kingdom
- European Bioinformatics Institute, Wellcome Trust Genome CampusHinxton, Cambridge CB10 1SD, United Kingdom
| | - Neil Grimsey
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of CambridgeHills Road, Cambridge CB2 2XY, United Kingdom
| | - Martin Dale
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of CambridgeHills Road, Cambridge CB2 2XY, United Kingdom
| | - Irina Majoul
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of CambridgeHills Road, Cambridge CB2 2XY, United Kingdom
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of LondonEgham TW20 0EX, United Kingdom
| | - Rainer Duden
- Department of Clinical Biochemistry, Cambridge Institute for Medical Research, University of CambridgeHills Road, Cambridge CB2 2XY, United Kingdom
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of LondonEgham TW20 0EX, United Kingdom
- Rainer Duden,
| |
Collapse
|
40
|
Griac P. Sec14 related proteins in yeast. Biochim Biophys Acta Mol Cell Biol Lipids 2007; 1771:737-45. [PMID: 17395532 DOI: 10.1016/j.bbalip.2007.02.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2006] [Revised: 02/20/2007] [Accepted: 02/21/2007] [Indexed: 11/18/2022]
Abstract
Lipid transport between membranes of eukaryotic organisms represents an essential aspect of organelle biogenesis. This transport must be strictly selective and directional to assure specific lipid composition of individual membranes. Despite the intensive research effort in the last few years, our understanding of how lipids are sorted and moved within cells is still rather limited. Evidence indicates that at least some of the mechanisms generating and maintaining non-random distribution of lipids in cells are linked to the action of phosphatidylinositol transfer proteins (PITPs). The major PITP in yeast Saccharomyces cerevisiae, Sec14p, is essential in promoting Golgi secretory function by modulating of its membrane lipid composition. This review focuses on a group of five yeast proteins that share significant sequence homology with Sec14p. Based on this sequence identity, they were termed Sfh (Sec fourteen homologue) proteins. It is a diverse group of proteins with distinct subcellular localizations and varied physiological functions related to lipid metabolism, phosphoinositide mediated signaling and membrane trafficking.
Collapse
Affiliation(s)
- Peter Griac
- Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Moyzesova 61, 900 28 Ivanka pri Dunaji, Slovakia.
| |
Collapse
|
41
|
Schindler C, Spang A. Interaction of SNAREs with ArfGAPs precedes recruitment of Sec18p/NSF. Mol Biol Cell 2007; 18:2852-63. [PMID: 17522384 PMCID: PMC1949378 DOI: 10.1091/mbc.e06-08-0756] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins are key components of the fusion machinery in vesicular transport and in homotypic membrane fusion. We previously found that ADP-ribosylation factor GTPase activating proteins (ArfGAPs) promoted a conformational change on SNAREs that allowed recruitment of the small GTPase Arf1p in stoichiometric amounts. Here, we show that the ArfGAP Gcs1p accelerates vesicle (v)-target membrane (t)-SNARE complex formation in vitro, indicating that ArfGAPs may act as folding chaperones. These SNARE complexes were resolved in the presence of ATP by the yeast homologues of alpha-soluble N-ethylmaleimide-sensitive factor attachment protein and N-ethylmaleimide-sensitive factor, Sec17p and Sec18p, respectively. In addition, Sec18p and Sec17p also recognized the "activated" SNAREs even when they were not engaged in v-t-SNARE complexes. Here again, the induction of a conformational change by ArfGAPs was essential. Surprisingly, recruitment of Sec18p to SNAREs did not require Sec17p or ATP hydrolysis. Moreover, Sec18p displaced prebound Arf1p from SNAREs, indicating that Sec18p may have more than one function: first, to ensure that all vesicle coat proteins are removed from the SNAREs before the engagement in a trans-SNARE complex; and second, to resolve cis-SNARE complexes after fusion has occurred.
Collapse
Affiliation(s)
| | - Anne Spang
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| |
Collapse
|
42
|
Strahl T, Thorner J. Synthesis and function of membrane phosphoinositides in budding yeast, Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1771:353-404. [PMID: 17382260 PMCID: PMC1868553 DOI: 10.1016/j.bbalip.2007.01.015] [Citation(s) in RCA: 231] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 01/29/2007] [Accepted: 01/30/2007] [Indexed: 02/02/2023]
Abstract
It is now well appreciated that derivatives of phosphatidylinositol (PtdIns) are key regulators of many cellular processes in eukaryotes. Of particular interest are phosphoinositides (mono- and polyphosphorylated adducts to the inositol ring in PtdIns), which are located at the cytoplasmic face of cellular membranes. Phosphoinositides serve both a structural and a signaling role via their recruitment of proteins that contain phosphoinositide-binding domains. Phosphoinositides also have a role as precursors of several types of second messengers for certain intracellular signaling pathways. Realization of the importance of phosphoinositides has brought increased attention to characterization of the enzymes that regulate their synthesis, interconversion, and turnover. Here we review the current state of our knowledge about the properties and regulation of the ATP-dependent lipid kinases responsible for synthesis of phosphoinositides and also the additional temporal and spatial controls exerted by the phosphatases and a phospholipase that act on phosphoinositides in yeast.
Collapse
Affiliation(s)
- Thomas Strahl
- Divisions of Biochemistry & Molecular Biology and of Cell & Developmental Biology.Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720 USA
| | - Jeremy Thorner
- Divisions of Biochemistry & Molecular Biology and of Cell & Developmental Biology.Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720 USA
| |
Collapse
|
43
|
Tanabe K, Kon S, Natsume W, Torii T, Watanabe T, Satake M. Involvement of a novel ADP-ribosylation factor GTPase-activating protein, SMAP, in membrane trafficking: implications in cancer cell biology. Cancer Sci 2006; 97:801-6. [PMID: 16805823 PMCID: PMC11158781 DOI: 10.1111/j.1349-7006.2006.00251.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The endocytosis of cell membrane proteins is initiated by the binding of activated Arf6, a member of Ras-related GTPases, to the PM. A GAP specific for Arf6 triggers the budding of endocytotic vesicles from the PM by inactivating GTP-bound Arf6. We recently identified the SMAP gene that encodes an ArfGAP and is involved in the endocytosis of TfnR and possibly E-cadherin. In this review, we summarize the process of intracellular membrane trafficking, highlighting the roles played by the SMAP gene. Progression of cancer to malignancy occurs in parallel with the disappearance of E-cadherin, a central component of the adherens junction in epithelial cells. Therefore, elucidation of the molecular mechanism of E-cadherin endocytosis should be one of the key elements in tumor cell biology.
Collapse
Affiliation(s)
- Kenji Tanabe
- Department of Molecular Immunology, Institute of Development, Aging and Cancer, Tohoku University, Seiryo-machi 4-1, Aoba-ku, Sendai 980-8575, Japan
| | | | | | | | | | | |
Collapse
|
44
|
Sanchatjate S, Schekman R. Chs5/6 complex: a multiprotein complex that interacts with and conveys chitin synthase III from the trans-Golgi network to the cell surface. Mol Biol Cell 2006; 17:4157-66. [PMID: 16855022 PMCID: PMC1635352 DOI: 10.1091/mbc.e06-03-0210] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
In Saccharomyces cerevisiae, the polysaccharide chitin is deposited at the mother bud junction by an integral membrane enzyme, chitin synthase 3 (Chs3p). The traffic of Chs3p to the cell surface from the trans-Golgi network (TGN) depends on two proteins, Chs5p and Chs6p, which sort selected cargo proteins into secretory vesicles. We have found that Chs5p forms a large higher-order complex of around 1 MDa with Chs6p and three Chs6 paralogs: Bch1p, Bud7p, and Bch2p. The Chs5/6 complex transiently interacts with its cargo, Chs3p, and the presence of Chs3p in the complex is dependent on every subunit. Chs5p and Chs6p have unique and crucial roles in Chs3p transport because either a chs5delta or chs6delta mutant drastically reduces the level of Chs3p bound to the remaining subunits of the complex. Bch1p and Bud7p appear to have a redundant function in Chs3p transport because deletion of both is necessary to displace Chs3p from the complex. The role of Bch2p in Chs3p binding is the least important. Chs5p is essential for structural integrity of the Chs5/6 complex and may act as a scaffold through which the other subunits assemble. Our results suggest a model of protein sorting at the TGN that involves a peripheral, possibly coat, complex that includes multiple related copies of a specificity determining subunit.
Collapse
Affiliation(s)
- Siraprapha Sanchatjate
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, Barker Hall, University of California, Berkeley, Berkeley, CA 94720
| | - Randy Schekman
- Department of Molecular and Cell Biology, Howard Hughes Medical Institute, Barker Hall, University of California, Berkeley, Berkeley, CA 94720
| |
Collapse
|
45
|
Yahara N, Sato K, Nakano A. The Arf1p GTPase-activating protein Glo3p executes its regulatory function through a conserved repeat motif at its C-terminus. J Cell Sci 2006; 119:2604-12. [PMID: 16735437 DOI: 10.1242/jcs.02997] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ADP-ribosylation factors (Arfs), key regulators of intracellular membrane traffic, are known to exert multiple roles in vesicular transport. We previously isolated eight temperature-sensitive (ts) mutants of the yeast ARF1 gene, which showed allele-specific defects in protein transport, and classified them into three groups of intragenic complementation. In this study, we show that the overexpression of Glo3p, one of the GTPase-activating proteins of Arf1p (ArfGAP), suppresses the ts growth of a particular group of the arf1 mutants (arf1-16 and arf1-17). Other ArfGAPs do not show such a suppression activity. All these ArfGAPs show sequence similarity in the ArfGAP catalytic domain, but are divergent in the rest of molecules. By domain swapping analysis of Glo3p and another ArfGAP, Gcs1p, we have shown that the non-catalytic C-terminal region of Glo3p is required for the suppression of the growth defect in the arf1 ts mutants. Interestingly, Glo3p and its homologues from other eukaryotes harbor a well-conserved repeated ISSxxxFG sequence near the C-terminus, which is not found in Gcs1p and its homologues. We name this region the Glo3 motif and present evidence that the motif is required for the function of Glo3p in vivo.
Collapse
Affiliation(s)
- Natsuko Yahara
- Molecular Membrane Biology Laboratory, RIKEN Discovery Research Institute, Hirosawa, Wako, Saitama 351-0198, Japan
| | | | | |
Collapse
|
46
|
Griac P, Holic R, Tahotna D. Phosphatidylinositol-transfer protein and its homologues in yeast. Biochem Soc Trans 2006; 34:377-80. [PMID: 16709166 DOI: 10.1042/bst0340377] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Yeast Sec14p acts as a phosphatidylinositol/phosphatidylcholine-transfer protein in vitro. In vivo, it is essential in promoting Golgi secretory function. Products of five genes named SFH1–SFH5 (Sec Fourteen Homologues 1–5) exhibit significant sequence homology to Sec14p and together they form the Sec14p family of lipid-transfer proteins. It is a diverse group of proteins with distinct subcellular localizations and varied physiological functions related to lipid metabolism and membrane trafficking.
Collapse
Affiliation(s)
- P Griac
- Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Ivanka pri Dunaji, Slovakia.
| | | | | |
Collapse
|
47
|
Connolly JE, Engebrecht J. The Arf-GTPase-activating protein Gcs1p is essential for sporulation and regulates the phospholipase D Spo14p. EUKARYOTIC CELL 2006; 5:112-24. [PMID: 16400173 PMCID: PMC1360266 DOI: 10.1128/ec.5.1.112-124.2006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
SPO14, encoding the major Saccharomyces cerevisiae phospholipase D (PLD), is essential for sporulation and mediates synthesis of the new membrane that encompasses the haploid nuclei that arise through meiotic divisions. PLD catalyzes the hydrolysis of phosphatidylcholine to phosphatidic acid (PA) and choline. PA stimulates Arf-GTPase-activating proteins (Arf-GAPs), which are involved in membrane trafficking events and actin cytoskeletal function. To determine if Spo14p-generated PA mediates its biological response through Arf-GAPs, we analyzed the sporulation efficiencies of cells deleted for each of the five known and potential yeast Arf-GAPs. Only gcs1delta mutants display a sporulation defect similar to that of spo14 mutants: cells deleted for GCS1 initiate the sporulation program but are defective in synthesis of the prospore membrane. Endosome-to-vacuole transport is also impaired in gcs1delta cells during sporulation. Furthermore, Arf-GAP catalytic activity, but not the pleckstrin homology domain, is required for both prospore membrane formation and endosome-to-vacuole trafficking. An examination of Gcs1p-green fluorescent protein revealed that it is a soluble protein. Interestingly, cells deleted for GCS1 have reduced levels of Spo14p-generated PA. Taken together, these results indicate that GCS1 is essential for sporulation and suggest that GCS1 positively regulates SPO14.
Collapse
Affiliation(s)
- Jaime E Connolly
- Molecular and Cellular Pharmacology, Graduate Program, State University of New York at Stony Brook, 11794-8651, USA
| | | |
Collapse
|
48
|
Robinson M, Poon PP, Schindler C, Murray LE, Kama R, Gabriely G, Singer RA, Spang A, Johnston GC, Gerst JE. The Gcs1 Arf-GAP mediates Snc1,2 v-SNARE retrieval to the Golgi in yeast. Mol Biol Cell 2006; 17:1845-58. [PMID: 16452633 PMCID: PMC1415299 DOI: 10.1091/mbc.e05-09-0832] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Gcs1 is an Arf GTPase-activating protein (Arf-GAP) that mediates Golgi-ER and post-Golgi vesicle transport in yeast. Here we show that the Snc1,2 v-SNAREs, which mediate endocytosis and exocytosis, interact physically and genetically with Gcs1. Moreover, Gcs1 and the Snc v-SNAREs colocalize to subcellular structures that correspond to the trans-Golgi and endosomal compartments. Studies performed in vitro demonstrate that the Snc-Gcs1 interaction results in the efficient binding of recombinant Arf1Delta17N-Q71L to the v-SNARE and the recruitment of purified coatomer. In contrast, the presence of Snc had no effect on Gcs1 Arf-GAP activity in vitro, suggesting that v-SNARE binding does not attenuate Arf1 function. Disruption of both the SNC and GCS1 genes results in synthetic lethality, whereas overexpression of either SNC gene inhibits the growth of a distinct subset of COPI mutants. We show that GFP-Snc1 recycling to the trans-Golgi is impaired in gcs1Delta cells and these COPI mutants. Together, these results suggest that Gcs1 facilitates the incorporation of the Snc v-SNAREs into COPI recycling vesicles and subsequent endosome-Golgi sorting in yeast.
Collapse
Affiliation(s)
- Micah Robinson
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Sakane H, Yamamoto T, Tanaka K. The Functional Relationship between the Cdc50p-Drs2p Putative Aminophospholipid Translocase and the Arf GAP Gcs1p in Vesicle Formation in the Retrieval Pathway from Yeast Early Endosomes to the TGN. Cell Struct Funct 2006; 31:87-108. [PMID: 17062999 DOI: 10.1247/csf.06021] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Drs2p, the catalytic subunit of the Cdc50p-Drs2p putative aminophospholipid translocase, has been implicated in conjunction with the Arf1 signaling pathway in the formation of clathrin-coated vesicles (CCVs) from the TGN. Herein, we searched for Arf regulator genes whose mutations were synthetically lethal with cdc50Delta, and identified the Arf GAP gene GCS1. Most of the examined transport pathways in the Cdc50p-depleted gcs1Delta mutant were nearly normal, including endocytic transport to vacuoles, carboxypeptidase Y sorting, and the processing and secretion of invertase. In contrast, this mutant exhibited severe defects in the early endosome-to-TGN transport pathway; proteins that are transported via this pathway, such as the v-SNARE Snc1p, the t-SNARE Tlg1p, and the chitin synthase III subunit Chs3p, accumulated in TGN-independent aberrant membrane structures. We extended our analyses to clathrin adaptors, and found that Gga1p/Gga2p and AP-1 were also involved in this pathway. The Cdc50p-depleted gga1Delta gga2Delta mutant and the gcs1Delta apl2Delta (the beta1 subunit of AP-1) mutant exhibited growth defects and intracellular Snc1p-containing membranes accumulated in these cells. These results suggest that Cdc50p-Drs2p plays an important role in the Arf1p-mediated formation of CCVs for the retrieval pathway from early endosomes to the TGN.
Collapse
Affiliation(s)
- Hiroshi Sakane
- Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo 060-0815, Japan
| | | | | |
Collapse
|
50
|
Inadome H, Noda Y, Adachi H, Yoda K. Immunoisolaton of the yeast Golgi subcompartments and characterization of a novel membrane protein, Svp26, discovered in the Sed5-containing compartments. Mol Cell Biol 2005; 25:7696-710. [PMID: 16107716 PMCID: PMC1190314 DOI: 10.1128/mcb.25.17.7696-7710.2005] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Golgi apparatus consists of a set of vesicular compartments which are distinguished by their marker proteins. These compartments are physically separated in the Saccharomyces cerevisiae cell. To characterize them extensively, we immunoisolated vesicles carrying either of the SNAREs Sed5 or Tlg2, the markers of the early and late Golgi compartments, respectively, and analyzed the membrane proteins. The composition of proteins was mostly consistent with the position of each compartment in the traffic. We found six uncharacterized but evolutionarily conserved proteins and named them Svp26 (Sed5 compartment vesicle protein of 26 kDa), Tvp38, Tvp23, Tvp18, Tvp15 (Tlg2 compartment vesicle proteins of 38, 23, 18, and 15 kDa), and Gvp36 (Golgi vesicle protein of 36 kDa). The localization of Svp26 in the early Golgi compartment was confirmed by microscopic and biochemical means. Immunoprecipitation indicated that Svp26 binds to itself and a Golgi mannosyltransferase, Ktr3. In the absence of Svp26, a considerable portion of Ktr3 was mislocalized in the endoplasmic reticulum. Our data suggest that Svp26 has a novel role in retention of a subset of membrane proteins in the early Golgi compartments.
Collapse
|