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AG1478 Elicits a Novel Anti-Influenza Function via an EGFR-Independent, GBF1-Dependent Pathway. Int J Mol Sci 2022; 23:ijms23105557. [PMID: 35628375 PMCID: PMC9145774 DOI: 10.3390/ijms23105557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Revised: 05/10/2022] [Accepted: 05/12/2022] [Indexed: 12/10/2022] Open
Abstract
Current options for preventing or treating influenza are still limited, and new treatments for influenza viral infection are urgently needed. In the present study, we serendipitously found that a small-molecule inhibitor (AG1478), previously used for epidermal growth factor receptor (EGFR) inhibition, demonstrated a potent activity against influenza both in vitro and in vivo. Surprisingly, the antiviral effect of AG1478 was not mediated by its EGFR inhibitory activity, as influenza virus was insensitive to EGFR blockade by other EGFR inhibitors or by siRNA knockdown of EGFR. Its antiviral activity was also interferon independent as demonstrated by a Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) knockout approach. Instead, AG1478 was found to target the Golgi-specific brefeldin A-resistance guanine nucleotide exchange factor 1 (GBF1)–ADP-ribosylation factor 1 (ARF1) system by reversibly inhibiting GBF1 activity and disrupting its Golgi-cytoplasmic trafficking. Compared to known GBF1 inhibitors, AG1478 demonstrated lower cellular toxicity and better preservation of Golgi structure. Furthermore, GBF1 was found to interact with a specific set of viral proteins including M1, NP, and PA. Additionally, the alternation of GBF1 distribution induced by AG1478 treatment disrupted these interactions. Because targeting host factors, instead of the viral component, imposes a higher barrier for developing resistance, GBF1 modulation may be an effective approach to treat influenza infection.
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Chia J, Wang SC, Wee S, Gill DJ, Tay F, Kannan S, Verma CS, Gunaratne J, Bard FA. Src activates retrograde membrane traffic through phosphorylation of GBF1. eLife 2021; 10:68678. [PMID: 34870592 PMCID: PMC8727025 DOI: 10.7554/elife.68678] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 12/05/2021] [Indexed: 12/14/2022] Open
Abstract
The Src tyrosine kinase controls cancer-critical protein glycosylation through Golgi to ER relocation of GALNTs enzymes. How Src induces this trafficking event is unknown. Golgi to ER transport depends on the GTP exchange factor (GEF) GBF1 and small GTPase Arf1. Here, we show that Src induces the formation of tubular transport carriers containing GALNTs. The kinase phosphorylates GBF1 on 10 tyrosine residues; two of them, Y876 and Y898, are located near the C-terminus of the Sec7 GEF domain. Their phosphorylation promotes GBF1 binding to the GTPase; molecular modeling suggests partial melting of the Sec7 domain and intramolecular rearrangement. GBF1 mutants defective for these rearrangements prevent binding, carrier formation, and GALNTs relocation, while phosphomimetic GBF1 mutants induce tubules. In sum, Src promotes GALNTs relocation by promoting GBF1 binding to Arf1. Based on residue conservation, similar regulation of GEF-Arf complexes by tyrosine phosphorylation could be a conserved and widespread mechanism.
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Affiliation(s)
- Joanne Chia
- Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Shyi-Chyi Wang
- Institute of Molecular and Cell Biology, Singapore, Singapore.,Institute of Bioengineering and Bioimaging, Singapore, Singapore
| | - Sheena Wee
- Institute of Molecular and Cell Biology, Singapore, Singapore
| | | | - Felicia Tay
- Institute of Molecular and Cell Biology, Singapore, Singapore
| | | | - Chandra S Verma
- Bioinformatics Institute, Singapore, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore, Singapore.,School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | | | - Frederic A Bard
- Institute of Molecular and Cell Biology, Singapore, Singapore
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Li J, Lambright DG, Hsu VW. Coordination of Grp1 recruitment mechanisms by its phosphorylation. Mol Biol Cell 2020; 31:2816-2825. [PMID: 33026967 PMCID: PMC7851867 DOI: 10.1091/mbc.e20-03-0173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The action of guanine nucleotide exchange factors (GEFs) on the ADP-ribosylation factor (ARF) family of small GTPases initiates intracellular transport pathways. This role requires ARF GEFs to be recruited from the cytosol to intracellular membrane compartments. An ARF GEF known as General receptor for 3-phosphoinositides 1 (Grp1) is recruited to the plasma membrane through its pleckstrin homology (PH) domain that recognizes phosphatidylinositol 3,4,5-trisphosphate (PIP3). Here, we find that the phosphorylation of Grp1 induces its PH domain to recognize instead phosphatidylinositol 4-phosphate (PI4P). This phosphorylation also releases an autoinhibitory mechanism that results in the coil–coil (CC) domain of Grp1 engaging two peripheral membrane proteins of the recycling endosome. Because the combination of these actions results in Grp1 being recruited preferentially to the recycling endosome rather than to the plasma membrane, our findings reveal the complexity of recruitment mechanisms that need to be coordinated in localizing an ARF GEF to an intracellular compartment to initiate a transport pathway. Our elucidation is also remarkable for having revealed that phosphoinositide recognition by a PH domain can be switched through its phosphorylation.
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Affiliation(s)
- Jian Li
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital and Department of Medicine, Harvard Medical School, Boston, MA 02115
| | - David G Lambright
- Program in Molecular Medicine, Department of Biochemistry and Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Victor W Hsu
- Division of Rheumatology, Inflammation and Immunity, Brigham and Women's Hospital and Department of Medicine, Harvard Medical School, Boston, MA 02115
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4
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Zeledon C, Sun X, Plutoni C, Emery G. The ArfGAP Drongo Promotes Actomyosin Contractility during Collective Cell Migration by Releasing Myosin Phosphatase from the Trailing Edge. Cell Rep 2020; 28:3238-3248.e3. [PMID: 31533044 DOI: 10.1016/j.celrep.2019.08.044] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 07/26/2019] [Accepted: 08/13/2019] [Indexed: 02/07/2023] Open
Abstract
Collective cell migration is involved in various developmental and pathological processes, including the dissemination of various cancer cells. During Drosophila melanogaster oogenesis, a group of cells called border cells migrate collectively toward the oocyte. Herein, we show that members of the Arf family of small GTPases and some of their regulators are required for normal border cell migration. Notably, we found that the ArfGAP Drongo and its GTPase-activating function are essential for the initial detachment of the border cell cluster from the basal lamina. We demonstrate through protein localization and genetic interactions that Drongo controls the localization of the myosin phosphatase in order to regulate myosin II activity at the back of the cluster. Moreover, we show that toward the class III Arf, Drongo acts antagonistically to the guanine exchange factor Steppke. Overall, our work describes a mechanistic pathway that promotes the local actomyosin contractility necessary for border cell detachment.
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Affiliation(s)
- Carlos Zeledon
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, QC, Canada
| | - Xiaojuan Sun
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, QC, Canada
| | - Cédric Plutoni
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, QC, Canada
| | - Gregory Emery
- Institute for Research in Immunology and Cancer (IRIC), Université de Montréal, Montréal, QC, Canada; Department of Pathology and Cell Biology, Faculty of Medicine, Université de Montréal, Montréal, QC, Canada.
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5
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Chan CJ, Le R, Burns K, Ahmed K, Coyaud E, Laurent EMN, Raught B, Melançon P. BioID Performed on Golgi Enriched Fractions Identify C10orf76 as a GBF1 Binding Protein Essential for Golgi Maintenance and Secretion. Mol Cell Proteomics 2019; 18:2285-2297. [PMID: 31519766 PMCID: PMC6823846 DOI: 10.1074/mcp.ra119.001645] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 09/04/2019] [Indexed: 12/29/2022] Open
Abstract
The Golgi-specific Brefeldin-A resistance factor 1 (GBF1) is the only large GEF that regulates Arf activation at the cis-Golgi and is actively recruited to membranes on an increase in Arf-GDP. Recent studies have revealed that GBF1 recruitment requires one or more heat-labile and protease-sensitive protein factor(s) (Quilty et al., 2018, J. Cell Science, 132). Proximity-dependent biotinylation (BioID) and mass spectrometry from enriched Golgi fractions identified GBF1 proximal proteins that may regulate its recruitment. Knockdown studies revealed C10orf76 to be involved in Golgi maintenance. We find that C10orf76 interacts with GBF1 and rapidly cycles on and off GBF1-positive Golgi structures. More importantly, its depletion causes Golgi fragmentation, alters GBF1 recruitment, and impairs secretion. Homologs were identified in most species, suggesting its presence in the last eukaryotic common ancestor.
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Affiliation(s)
- Calvin J Chan
- Department of Cell Biology, University of Alberta, Edmonton, AB, T6G 2H7
| | - Roberta Le
- Department of Cell Biology, University of Alberta, Edmonton, AB, T6G 2H7
| | - Kaylan Burns
- Department of Cell Biology, University of Alberta, Edmonton, AB, T6G 2H7
| | - Khadra Ahmed
- Department of Cell Biology, University of Alberta, Edmonton, AB, T6G 2H7
| | - Etienne Coyaud
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Estelle M N Laurent
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Brian Raught
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada
| | - Paul Melançon
- Department of Cell Biology, University of Alberta, Edmonton, AB, T6G 2H7.
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Quilty D, Chan CJ, Yurkiw K, Bain A, Babolmorad G, Melançon P. The Arf-GDP-regulated recruitment of GBF1 to Golgi membranes requires domains HDS1 and HDS2 and a Golgi-localized protein receptor. J Cell Sci 2018; 132:jcs.208199. [PMID: 29507113 PMCID: PMC6398479 DOI: 10.1242/jcs.208199] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 02/14/2018] [Indexed: 01/02/2023] Open
Abstract
We previously proposed a novel mechanism by which the enzyme Golgi-specific Brefeldin A resistance factor 1 (GBF1) is recruited to the membranes of the cis-Golgi, based on in vivo experiments. Here, we extended our in vivo analysis on the production of regulatory Arf-GDP and observed that ArfGAP2 and ArfGAP3 do not play a role in GBF1 recruitment. We confirm that Arf-GDP localization is critical, as a TGN-localized Arf-GDP mutant protein fails to promote GBF1 recruitment. We also reported the establishment of an in vitro GBF1 recruitment assay that supports the regulation of GBF1 recruitment by Arf-GDP. This in vitro assay yielded further evidence for the requirement of a Golgi-localized protein because heat denaturation or protease treatment of Golgi membranes abrogated GBF1 recruitment. Finally, combined in vivo and in vitro measurements indicated that the recruitment to Golgi membranes via a putative receptor requires only the HDS1 and HDS2 domains in the C-terminal half of GBF1. Summary:In vivo and in vitro experiments demonstrate Arf-GDP regulation of GBF1 recruitment to a heat-labile and protease-sensitive site on Golgi membranes. This recruitment requires the HDS1 and HDS2 domains.
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Affiliation(s)
- Douglas Quilty
- Department of Cell Biology, University of Alberta, Edmonton, AB, Canada T6G 2H7
| | - Calvin J Chan
- Department of Cell Biology, University of Alberta, Edmonton, AB, Canada T6G 2H7
| | - Katherine Yurkiw
- Department of Cell Biology, University of Alberta, Edmonton, AB, Canada T6G 2H7
| | - Alexandra Bain
- Department of Cell Biology, University of Alberta, Edmonton, AB, Canada T6G 2H7
| | - Ghazal Babolmorad
- Department of Cell Biology, University of Alberta, Edmonton, AB, Canada T6G 2H7
| | - Paul Melançon
- Department of Cell Biology, University of Alberta, Edmonton, AB, Canada T6G 2H7
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Kaczmarek B, Verbavatz JM, Jackson CL. GBF1 and Arf1 function in vesicular trafficking, lipid homoeostasis and organelle dynamics. Biol Cell 2017; 109:391-399. [PMID: 28985001 DOI: 10.1111/boc.201700042] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/22/2017] [Accepted: 09/25/2017] [Indexed: 01/07/2023]
Abstract
The ADP-ribosylation factor (Arf) small G proteins act as molecular switches to coordinate multiple downstream pathways that regulate membrane dynamics. Their activation is spatially and temporally controlled by the guanine nucleotide exchange factors (GEFs). Members of the evolutionarily conserved GBF/Gea family of Arf GEFs are well known for their roles in formation of coat protein complex I (COPI) vesicles, essential for maintaining the structure and function of the Golgi apparatus. However, studies over the past 10 years have found new functions for these GEFs, along with their substrate Arf1, in lipid droplet metabolism, clathrin-independent endocytosis, signalling at the plasma membrane, mitochondrial dynamics and transport along microtubules. Here, we describe these different functions, focussing in particular on the emerging theme of GFB1 and Arf1 regulation of organelle movement on microtubules.
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Affiliation(s)
- Beata Kaczmarek
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
| | - Jean-Marc Verbavatz
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
| | - Catherine L Jackson
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Paris, F-75013, France
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Chen J, Wu X, Yao L, Yan L, Zhang L, Qiu J, Liu X, Jia S, Meng A. Impairment of Cargo Transportation Caused by gbf1 Mutation Disrupts Vascular Integrity and Causes Hemorrhage in Zebrafish Embryos. J Biol Chem 2016; 292:2315-2327. [PMID: 28003365 DOI: 10.1074/jbc.m116.767608] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 12/19/2016] [Indexed: 12/11/2022] Open
Abstract
ADP-ribosylation factor GTPases are activated by guanine nucleotide exchange factors including Gbf1 (Golgi brefeldin A-resistant factor 1) and play important roles in regulating organelle structure and cargo-selective vesicle trafficking. However, the developmental role of Gbf1 in vertebrates remains elusive. In this study, we report the zebrafish mutant line tsu3994 that arises from N-ethyl-N-nitrosourea (ENU)-mediated mutagenesis and is characterized by prominent intracerebral and trunk hemorrhage. The mutant embryos develop hemorrhage accompanied by fewer pigments and shorter caudal fin at day 2 of development. The hemorrhage phenotype is caused by vascular breakage in a cell autonomous fashion. Positional cloning identifies a T → G nucleotide substitution in the 23rd exon of the gbf1 locus, resulting in a leucine → arginine substitution (L1246R) in the HDS2 domain. The mutant phenotype is mimicked by gbf1 knockouts and morphants, suggesting a nature of loss of function. Experimental results in mammalian cells show that the mutant form Gbf1(L1246R) is unable to be recruited to the Golgi apparatus and fails to activate Arf1 for recruiting COPI complex. The hemorrhage in tsu3994 mutants can be prevented partially and temporally by treating with the endoplasmic reticulum stress/apoptosis inhibitor tauroursodeoxycholic acid or by knocking down the proapoptotic gene baxb Therefore, endothelial endoplasmic reticulum stress and subsequent apoptosis induced by gbf1 deficiency may account for the vascular collapse and hemorrhage.
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Affiliation(s)
- Jing Chen
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaotong Wu
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Likun Yao
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Lu Yan
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Lin Zhang
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Juhui Qiu
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xingfeng Liu
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shunji Jia
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Anming Meng
- From the Laboratory of Molecular Developmental Biology, State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
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9
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Thinon E, Morales-Sanfrutos J, Mann DJ, Tate EW. N-Myristoyltransferase Inhibition Induces ER-Stress, Cell Cycle Arrest, and Apoptosis in Cancer Cells. ACS Chem Biol 2016; 11:2165-76. [PMID: 27267252 PMCID: PMC5077176 DOI: 10.1021/acschembio.6b00371] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 05/24/2016] [Indexed: 12/16/2022]
Abstract
N-Myristoyltransferase (NMT) covalently attaches a C14 fatty acid to the N-terminal glycine of proteins and has been proposed as a therapeutic target in cancer. We have recently shown that selective NMT inhibition leads to dose-responsive loss of N-myristoylation on more than 100 protein targets in cells, and cytotoxicity in cancer cells. N-myristoylation lies upstream of multiple pro-proliferative and oncogenic pathways, but to date the complex substrate specificity of NMT has limited determination of which diseases are most likely to respond to a selective NMT inhibitor. We describe here the phenotype of NMT inhibition in HeLa cells and show that cells die through apoptosis following or concurrent with accumulation in the G1 phase. We used quantitative proteomics to map protein expression changes for more than 2700 proteins in response to treatment with an NMT inhibitor in HeLa cells and observed down-regulation of proteins involved in cell cycle regulation and up-regulation of proteins involved in the endoplasmic reticulum stress and unfolded protein response, with similar results in breast (MCF-7, MDA-MB-231) and colon (HCT116) cancer cell lines. This study describes the cellular response to NMT inhibition at the proteome level and provides a starting point for selective targeting of specific diseases with NMT inhibitors, potentially in combination with other targeted agents.
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Affiliation(s)
- Emmanuelle Thinon
- Department
of Chemistry, Imperial College London, Exhibition Road, London SW72AZ, United Kingdom
- Department
of Life Sciences, Imperial College London, Exhibition Road, London SW72AZ, United Kingdom
| | - Julia Morales-Sanfrutos
- Department
of Chemistry, Imperial College London, Exhibition Road, London SW72AZ, United Kingdom
| | - David J. Mann
- Department
of Life Sciences, Imperial College London, Exhibition Road, London SW72AZ, United Kingdom
- Institute
of Chemical Biology, Department of Chemistry, Imperial College London, Exhibition Road, London SW72AZ, United Kingdom
| | - Edward W. Tate
- Department
of Chemistry, Imperial College London, Exhibition Road, London SW72AZ, United Kingdom
- Institute
of Chemical Biology, Department of Chemistry, Imperial College London, Exhibition Road, London SW72AZ, United Kingdom
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10
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Smulan LJ, Ding W, Freinkman E, Gujja S, Edwards YJK, Walker AK. Cholesterol-Independent SREBP-1 Maturation Is Linked to ARF1 Inactivation. Cell Rep 2016; 16:9-18. [PMID: 27320911 DOI: 10.1016/j.celrep.2016.05.086] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 04/29/2016] [Accepted: 05/22/2016] [Indexed: 11/19/2022] Open
Abstract
Lipogenesis requires coordinated expression of genes for fatty acid, phospholipid, and triglyceride synthesis. Transcription factors, such as SREBP-1 (Sterol regulatory element binding protein), may be activated in response to feedback mechanisms linking gene activation to levels of metabolites in the pathways. SREBPs can be regulated in response to membrane cholesterol and we also found that low levels of phosphatidylcholine (a methylated phospholipid) led to SBP-1/SREBP-1 maturation in C. elegans or mammalian models. To identify additional regulatory components, we performed a targeted RNAi screen in C. elegans, finding that both lpin-1/Lipin 1 (which converts phosphatidic acid to diacylglycerol) and arf-1.2/ARF1 (a GTPase regulating Golgi function) were important for low-PC activation of SBP-1/SREBP-1. Mechanistically linking the major hits of our screen, we find that limiting PC synthesis or LPIN1 knockdown in mammalian cells reduces the levels of active GTP-bound ARF1. Thus, changes in distinct lipid ratios may converge on ARF1 to increase SBP-1/SREBP-1 activity.
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Affiliation(s)
- Lorissa J Smulan
- Program in Molecular Medicine, UMASS Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Wei Ding
- Program in Molecular Medicine, UMASS Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Elizaveta Freinkman
- Metabolite Profiling Facility, Whitehead Institute for Biomedical Research, 9 Cambridge Center, Cambridge, MA 02142, USA
| | - Sharvari Gujja
- Program in Molecular Medicine, UMASS Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Yvonne J K Edwards
- Program in Molecular Medicine, UMASS Medical School, 373 Plantation Street, Worcester, MA 01605, USA
| | - Amy K Walker
- Program in Molecular Medicine, UMASS Medical School, 373 Plantation Street, Worcester, MA 01605, USA.
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11
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Arst HN, Hernandez-Gonzalez M, Peñalva MA, Pantazopoulou A. GBF/Gea mutant with a single substitution sustains fungal growth in the absence of BIG/Sec7. FEBS Lett 2014; 588:4799-806. [PMID: 25451223 PMCID: PMC4266534 DOI: 10.1016/j.febslet.2014.11.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 11/07/2014] [Accepted: 11/10/2014] [Indexed: 12/11/2022]
Abstract
A. nidulans has a GBF/Gea and a BIG/Sec7 subfamily Golgi Arf1-GEFs, both essential. The late Golgi Arf1-GEF mutant hypB5 conditionally blocks secretion. Residue substitution in the early Golgi Arf1-GEF GeaA suppresses hypB5 and hypBΔ. The mutation alters a GBF/Gea amino acid motif and shifts GeaA localization. GeaA1 alone satisfies the eukaryotic requirement for two Golgi Arf1 GEFs.
Golgi Arf1-guanine nucleotide exchange factors (GEFs) belong to two subfamilies: GBF/Gea and BIG/Sec7. Both are conserved across eukaryotes, but the physiological role of each is not well understood. Aspergillus nidulans has a single member of the early Golgi GBF/Gea-subfamily, geaA, and the late Golgi BIG/Sec7-subfamily, hypB. Both geaA and hypB are essential. hypB5 conditionally blocks secretion. We sought extragenic hypB5 suppressors and obtained geaA1. geaA1 results in Tyr1022Cys within a conserved GBF/Gea-specific S(Y/W/F)(L/I) motif in GeaA. This mutation alters GeaA localization. Remarkably, geaA1 suppresses hypBΔ, indicating that a single mutant Golgi Arf1-GEF suffices for growth.
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Affiliation(s)
- Herbert N Arst
- Section of Microbiology, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain
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