1
|
Ma L, Ma J, Tian Y, Li X, Tai B, Xing F. Fus3 Interacts with Gal83, Revealing the MAPK Crosstalk to Snf1/AMPK to Regulate Secondary Metabolic Substrates in Aspergillus flavus. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:10065-10075. [PMID: 38634532 DOI: 10.1021/acs.jafc.4c01229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/19/2024]
Abstract
Aflatoxins (AFs), highly carcinogenic natural products, are produced by the secondary metabolism of fungi such as Aspergillus flavus. Essential for the fungi to respond to environmental changes and aflatoxin synthesis, the pheromone mitogen-activated protein kinase (MAPK) is a potential regulator of aflatoxin biosynthesis. However, the mechanism by which pheromone MAPK regulates aflatoxin biosynthesis is not clear. Here, we showed Gal83, a new target of Fus3, and identified the pheromone Fus3-MAPK signaling pathway as a regulator of the Snf1/AMPK energy-sensing pathway modulating aflatoxins synthesis substrates. The screening for Fus3 target proteins identified the β subunit of Snf1/AMPK complexes using tandem affinity purification and multiomics. This subunit physically interacted with Fus3 both in vivo and in vitro and received phosphorylation from Fus3. Although the transcript levels of aflatoxin synthesis genes were not noticeably downregulated in both gal83 and fus3 deletion mutant strains, the levels of aflatoxin B1 and its synthesis substrates and gene expression levels of primary metabolizing enzymes were significantly reduced. This suggests that both the Fus3-MAPK and Snf1/AMPK pathways respond to energy signals. In conclusion, all the evidence unlocks a novel pathway of Fus3-MAPK to regulate AFs synthesis substrates by cross-talking with the Snf1/AMPK complexes.
Collapse
Affiliation(s)
- Longxue Ma
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
| | - Junning Ma
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
| | - Yuanyuan Tian
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
| | - Xu Li
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
| | - Bowen Tai
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
| | - Fuguo Xing
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences / Key Laboratory of Agro-products Quality and Safety Control in Storage and Transport Process, Ministry of Agriculture and Rural Affairs, Beijing 100193, P. R. China
| |
Collapse
|
2
|
TORC1 Signaling in Fungi: From Yeasts to Filamentous Fungi. Microorganisms 2023; 11:microorganisms11010218. [PMID: 36677510 PMCID: PMC9864104 DOI: 10.3390/microorganisms11010218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 01/18/2023] Open
Abstract
Target of rapamycin complex 1 (TORC1) is an important regulator of various signaling pathways. It can control cell growth and development by integrating multiple signals from amino acids, glucose, phosphate, growth factors, pressure, oxidation, and so on. In recent years, it has been reported that TORC1 is of great significance in regulating cytotoxicity, morphology, protein synthesis and degradation, nutrient absorption, and metabolism. In this review, we mainly discuss the upstream and downstream signaling pathways of TORC1 to reveal its role in fungi.
Collapse
|
3
|
Cao C, Wang K, Wang Y, Liu TB, Rivera A, Xue C. Ubiquitin proteolysis of a CDK-related kinase regulates titan cell formation and virulence in the fungal pathogen Cryptococcus neoformans. Nat Commun 2022; 13:6397. [PMID: 36302775 PMCID: PMC9613880 DOI: 10.1038/s41467-022-34151-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 10/17/2022] [Indexed: 12/25/2022] Open
Abstract
Fungal pathogens often undergo morphological switches, including cell size changes, to adapt to the host environment and cause disease. The pathogenic yeast Cryptococcus neoformans forms so-called 'titan cells' during infection. Titan cells are large, polyploid, display alterations in cell wall and capsule, and are more resistant to phagocytosis and various types of stress. Titan cell formation is regulated by the cAMP/PKA signal pathway, which is stimulated by the protein Gpa1. Here, we show that Gpa1 is activated through phosphorylation by a CDK-related kinase (Crk1), which is targeted for degradation by an E3 ubiquitin ligase (Fbp1). Strains overexpressing CRK1 or an allele lacking a PEST domain exhibit increased production of titan cells similarly to the fbp1∆ mutant. Conversely, CRK1 deletion results in reduced titan cell production, indicating that Crk1 stimulates titan cell formation. Crk1 phosphorylates Gpa1, which then localizes to the plasma membrane and activates the cAMP/PKA signal pathway to induce cell enlargement. Furthermore, titan cell-overproducing strains trigger increased Th1 and Th17 cytokine production in CD4+ T cells and show attenuated virulence in a mouse model of systemic cryptococcosis. Overall, our study provides insights into the regulation of titan cell formation and fungal virulence.
Collapse
Affiliation(s)
- Chengjun Cao
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, 07103, USA
| | - Keyi Wang
- Center for Immunity and Inflammation, New Jersey Medical School, Rutgers University, Newark, NJ, 07103, USA
| | - Yina Wang
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, 07103, USA
| | - Tong-Bao Liu
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, 07103, USA
- Medical Research Institute, Southwest University, Chongqing, 400715, China
| | - Amariliz Rivera
- Center for Immunity and Inflammation, New Jersey Medical School, Rutgers University, Newark, NJ, 07103, USA
| | - Chaoyang Xue
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, NJ, 07103, USA.
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, New Jersey Medical School, Rutgers University, Newark, NJ, 07103, USA.
- Rutgers Center for Lipid Research, Rutgers University, New Brunswick, NJ, 08901, USA.
| |
Collapse
|
4
|
Bosch DE, Jeck WR, Siderovski DP. Self-activating G protein α subunits engage seven-transmembrane Regulator of G protein Signaling (RGS) proteins and a Rho guanine nucleotide exchange factor effector in the amoeba Naegleria fowleri. J Biol Chem 2022; 298:102167. [PMID: 35738399 PMCID: PMC9283941 DOI: 10.1016/j.jbc.2022.102167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Revised: 06/15/2022] [Accepted: 06/16/2022] [Indexed: 11/17/2022] Open
Abstract
The free-living amoeba Naegleria fowleri is a causative agent of primary amoebic meningoencephalitis and is highly resistant to current therapies, resulting in mortality rates >97%. As many therapeutics target G protein-centered signal transduction pathways, further understanding the functional significance of G protein signaling within N. fowleri should aid future drug discovery against this pathogen. Here, we report that the N. fowleri genome encodes numerous transcribed G protein signaling components, including G protein-coupled receptors (GPCRs), heterotrimeric G protein subunits, Regulator of G protein Signaling (RGS) proteins, and candidate Gα effector proteins. We found N. fowleri Gα subunits have diverse nucleotide cycling kinetics; Nf Gα5 and Gα7 exhibit more rapid nucleotide exchange than GTP hydrolysis (i.e. "self-activating" behavior). A crystal structure of Nf Gα7 highlights the stability of its nucleotide-free state, consistent with its rapid nucleotide exchange. Variations in the phosphate binding loop (P-loop) also contribute to nucleotide cycling differences among Gα subunits. Similar to plant G protein signaling pathways, N. fowleri Gα subunits selectively engage members of a large seven-transmembrane RGS protein family, resulting in acceleration of GTP hydrolysis. We show Nf Gα2 and Gα3 directly interact with a candidate Gα effector protein, RGS-RhoGEF, similar to mammalian Gα12/13 signaling pathways. We demonstrate Nf Gα2 and Gα3 each engage RGS-RhoGEF through a canonical Gα/RGS domain interface, suggesting a shared evolutionary origin with G protein signaling in the enteric pathogen Entamoeba histolytica. These findings further illuminate the evolution of G protein signaling and identify potential targets of pharmacological manipulation in Naegleria fowleri.
Collapse
Affiliation(s)
- Dustin E Bosch
- Department of Pathology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
| | - William R Jeck
- Department of Pathology, Duke University School of Medicine, Durham, North Carolina, USA
| | - David P Siderovski
- Department of Pharmacology & Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, USA
| |
Collapse
|
5
|
Laidlaw KME, Paine KM, Bisinski DD, Calder G, Hogg K, Ahmed S, James S, O’Toole PJ, MacDonald C. Endosomal cargo recycling mediated by Gpa1 and phosphatidylinositol 3-kinase is inhibited by glucose starvation. Mol Biol Cell 2022; 33:ar31. [PMID: 35080991 PMCID: PMC9250360 DOI: 10.1091/mbc.e21-04-0163] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Cell surface protein trafficking is regulated in response to nutrient availability, with multiple pathways directing surface membrane proteins to the lysosome for degradation in response to suboptimal extracellular nutrients. Internalized protein and lipid cargoes recycle back to the surface efficiently in glucose-replete conditions, but this trafficking is attenuated following glucose starvation. We find that cells with either reduced or hyperactive phosphatidylinositol 3-kinase (PI3K) activity are defective for endosome to surface recycling. Furthermore, we find that the yeast Gα subunit Gpa1, an endosomal PI3K effector, is required for surface recycling of cargoes. Following glucose starvation, mRNA and protein levels of a distinct Gα subunit Gpa2 are elevated following nuclear translocation of Mig1, which inhibits recycling of various cargoes. As Gpa1 and Gpa2 interact at the surface where Gpa2 concentrates during glucose starvation, we propose that this disrupts PI3K activity required for recycling, potentially diverting Gpa1 to the surface and interfering with its endosomal role in recycling. In support of this model, glucose starvation and overexpression of Gpa2 alter PI3K endosomal phosphoinositide production. Glucose deprivation therefore triggers a survival mechanism to increase retention of surface cargoes in endosomes and promote their lysosomal degradation.
Collapse
Affiliation(s)
| | | | | | - Grant Calder
- Bioscience Technology Facility, Department of Biology, University of York, YO10 5DD York, UK
| | - Karen Hogg
- Bioscience Technology Facility, Department of Biology, University of York, YO10 5DD York, UK
| | - Sophia Ahmed
- Bioscience Technology Facility, Department of Biology, University of York, YO10 5DD York, UK
| | - Sally James
- Bioscience Technology Facility, Department of Biology, University of York, YO10 5DD York, UK
| | - Peter J. O’Toole
- Bioscience Technology Facility, Department of Biology, University of York, YO10 5DD York, UK
| | - Chris MacDonald
- York Biomedical Research Institute and Department of Biology and,*Address correspondence to: Chris MacDonald ()
| |
Collapse
|
6
|
|
7
|
Proteomic analysis of dietary restriction in yeast reveals a role for Hsp26 in replicative lifespan extension. Biochem J 2021; 478:4153-4167. [PMID: 34661239 PMCID: PMC8786290 DOI: 10.1042/bcj20210432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 10/15/2021] [Accepted: 10/18/2021] [Indexed: 11/17/2022]
Abstract
Dietary restriction (DR) has been shown to increase lifespan in organisms ranging from yeast to mammals. This suggests that the underlying mechanisms may be evolutionarily conserved. Indeed, upstream signalling pathways, such as TOR, are strongly linked to DR-induced longevity in various organisms. However, the downstream effector proteins that ultimately mediate lifespan extension are less clear. To shed light on this, we used a proteomic approach on budding yeast. Our reasoning was that analysis of proteome-wide changes in response to DR might enable the identification of proteins that mediate its physiological effects, including replicative lifespan extension. Of over 2500 proteins we identified by liquid chromatography–mass spectrometry, 183 were significantly altered in expression by at least 3-fold in response to DR. Most of these proteins were mitochondrial and/or had clear links to respiration and metabolism. Indeed, direct analysis of oxygen consumption confirmed that mitochondrial respiration was increased several-fold in response to DR. In addition, several key proteins involved in mating, including Ste2 and Ste6, were down-regulated by DR. Consistent with this, shmoo formation in response to α-factor pheromone was reduced by DR, thus confirming the inhibitory effect of DR on yeast mating. Finally, we found that Hsp26, a member of the conserved small heat shock protein (sHSP) family, was up-regulated by DR and that overexpression of Hsp26 extended yeast replicative lifespan. As overexpression of sHSPs in Caenorhabditis elegans and Drosophila has previously been shown to extend lifespan, our data on yeast Hsp26 suggest that sHSPs may be universally conserved effectors of longevity.
Collapse
|
8
|
Multi-omics analysis of glucose-mediated signaling by a moonlighting Gβ protein Asc1/RACK1. PLoS Genet 2021; 17:e1009640. [PMID: 34214075 PMCID: PMC8282090 DOI: 10.1371/journal.pgen.1009640] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 07/15/2021] [Accepted: 06/02/2021] [Indexed: 12/31/2022] Open
Abstract
Heterotrimeric G proteins were originally discovered through efforts to understand the effects of hormones, such as glucagon and epinephrine, on glucose metabolism. On the other hand, many cellular metabolites, including glucose, serve as ligands for G protein-coupled receptors. Here we investigate the consequences of glucose-mediated receptor signaling, and in particular the role of a Gα subunit Gpa2 and a non-canonical Gβ subunit, known as Asc1 in yeast and RACK1 in animals. Asc1/RACK1 is of particular interest because it has multiple, seemingly unrelated, functions in the cell. The existence of such “moonlighting” operations has complicated the determination of phenotype from genotype. Through a comparative analysis of individual gene deletion mutants, and by integrating transcriptomics and metabolomics measurements, we have determined the relative contributions of the Gα and Gβ protein subunits to glucose-initiated processes in yeast. We determined that Gpa2 is primarily involved in regulating carbohydrate metabolism while Asc1 is primarily involved in amino acid metabolism. Both proteins are involved in regulating purine metabolism. Of the two subunits, Gpa2 regulates a greater number of gene transcripts and was particularly important in determining the amplitude of response to glucose addition. We conclude that the two G protein subunits regulate distinct but complementary processes downstream of the glucose-sensing receptor, as well as processes that lead ultimately to changes in cell growth and metabolism. Despite the societal importance of glucose fermentation in yeast, the mechanisms by which these cells detect and respond to glucose have remained obscure. Glucose detection requires a cell surface receptor coupled to a G protein that is comprised of two subunits, rather than the more typical heterotrimer: an α subunit Gpa2 and the β subunit Asc1 (or RACK1 in humans). Asc1/RACK1 also serves as a subunit of the ribosome, where it regulates the synthesis of proteins involved in glucose fermentation. This manuscript uses global metabolomics and transcriptomics to demonstrate the distinct roles of each G protein subunit in transmitting the glucose signal. Whereas Gpa2 is primarily involved in the metabolism of carbohydrates, Asc1/RACK1 contributes to production of amino acids necessary for protein synthesis and cell division. These findings reveal the initial steps of glucose signaling and several unique and complementary functions of the G protein subunits. More broadly, the integrated approach used here is likely to guide efforts to determine the topology of complex G protein and metabolic signaling networks in humans.
Collapse
|
9
|
Nassiri Toosi Z, Su X, Austin R, Choudhury S, Li W, Pang YT, Gumbart JC, Torres MP. Combinatorial phosphorylation modulates the structure and function of the G protein γ subunit in yeast. Sci Signal 2021; 14:14/688/eabd2464. [PMID: 34158397 DOI: 10.1126/scisignal.abd2464] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intrinsically disordered regions (IDRs) in proteins are often targets of combinatorial posttranslational modifications, which serve to regulate protein structure and function. Emerging evidence suggests that the N-terminal tails of G protein γ subunits, which are essential components of heterotrimeric G proteins, are intrinsically disordered, phosphorylation-dependent determinants of G protein signaling. Here, we found that the yeast Gγ subunit Ste18 underwent combinatorial, multisite phosphorylation events within its N-terminal IDR. G protein-coupled receptor (GPCR) activation and osmotic stress induced phosphorylation at Ser7, whereas glucose and acid stress induced phosphorylation at Ser3, which was a quantitative indicator of intracellular pH. Each site was phosphorylated by a distinct set of kinases, and phosphorylation of one site affected phosphorylation of the other, as determined through exposure to serial stimuli and through phosphosite mutagenesis. Last, we showed that phosphorylation resulted in changes in IDR structure and that different combinations of phosphorylation events modulated the activation rate and amplitude of the downstream mitogen-activated protein kinase Fus3. These data place Gγ subunits among intrinsically disordered proteins that undergo combinatorial posttranslational modifications that govern signaling pathway output.
Collapse
Affiliation(s)
- Zahra Nassiri Toosi
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Xinya Su
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Ruth Austin
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Shilpa Choudhury
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Wei Li
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA.,Southeast Center for Mathematics and Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Yui Tik Pang
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - James C Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Matthew P Torres
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA. .,Southeast Center for Mathematics and Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA
| |
Collapse
|
10
|
Blockade of AMPK-Mediated cAMP-PKA-CREB/ATF1 Signaling Synergizes with Aspirin to Inhibit Hepatocellular Carcinoma. Cancers (Basel) 2021; 13:cancers13071738. [PMID: 33917483 PMCID: PMC8038809 DOI: 10.3390/cancers13071738] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/25/2021] [Accepted: 04/02/2021] [Indexed: 02/05/2023] Open
Abstract
Simple Summary Epidemiological and experimental studies have demonstrated that aspirin (acetylsalicylic acid) may prevent the incidence of some types of human cancer, including colorectal cancer and hepatocellular carcinoma (HCC). In addition, preclinical studies indicate that aspirin in combination with other treatments may achieve a more significant anti-cancer effect for established tumors. This study aims to improve the anti-cancer effect of aspirin by targeting signaling pathways related to aspirin and its targets. We find that aspirin may induce cAMP–PKA–CREB/ATF1 signaling in HCC via AMPK and its downstream target carbamoyl-phosphate synthase 1 (CPS1). Blockade of PKA–CREB/ATF1 signaling by the natural agent berbamine could sensitize HCC to aspirin. This research indicates that the combination of two inexpensive drugs, aspirin and berbamine, holds promise in preventing and treating HCC. Abstract Aspirin can prevent or inhibit inflammation-related cancers, such as colorectal cancer and hepatocellular carcinoma (HCC). However, the effectiveness of chemotherapy may be compromised by activating oncogenic pathways in cancer cells. Elucidation of such chemoresistance mechanisms is crucial to developing novel strategies to maximize the anti-cancer effects of aspirin. Here, we report that aspirin markedly induces CREB/ATF1 phosphorylation in HCC cells, which compromises aspirin’s anti-HCC effect. Inhibition of AMP-activated protein kinase (AMPK) abrogates the induction of CREB/ATF1 phosphorylation by aspirin. Mechanistically, activation of AMPK by aspirin results in decreased expression of the urea cycle enzyme carbamoyl-phosphate synthase 1 (CPS1) in HCC cells and xenografts. Treatment with aspirin or CPS1 knockdown stimulates soluble adenylyl cyclase expression, thereby increasing cyclic AMP (cAMP) synthesis and stimulating PKA–CREB/ATF1 signaling. Importantly, abrogation of aspirin-induced CREB/ATF1 phosphorylation could sensitize HCC to aspirin. The bis-benzylisoquinoline alkaloid berbamine suppresses the expression of cancerous inhibitor of protein phosphatase 2A (CIP2A), leading to protein phosphatase 2A-mediated downregulation of CREB/ATF1 phosphorylation. The combination of berbamine and aspirin significantly inhibits HCC in vitro and in vivo. These data demonstrate that the regulation of cAMP-PKA-CREB/ATF1 signaling represents a noncanonical function of CPS1. Targeting the PKA–CREB/ATF1 axis may be a strategy to improve the therapeutic effects of aspirin on HCC.
Collapse
|
11
|
Qiu M, Li Y, Zhang X, Xuan M, Zhang B, Ye W, Zheng X, Govers F, Wang Y. G protein α subunit suppresses sporangium formation through a serine/threonine protein kinase in Phytophthora sojae. PLoS Pathog 2020; 16:e1008138. [PMID: 31961913 PMCID: PMC7010300 DOI: 10.1371/journal.ppat.1008138] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 02/10/2020] [Accepted: 10/09/2019] [Indexed: 02/06/2023] Open
Abstract
Eukaryotic heterotrimeric guanine nucleotide-binding proteins consist of α, β, and γ subunits, which act as molecular switches to regulate a number of fundamental cellular processes. In the oomycete pathogen Phytophthora sojae, the sole G protein α subunit (Gα; encoded by PsGPA1) has been found to be involved in zoospore mobility and virulence, but how it functions remains unclear. In this study, we show that the Gα subunit PsGPA1 directly interacts with PsYPK1, a serine/threonine protein kinase that consists of an N-terminal region with unknown function and a C-terminal region with a conserved catalytic kinase domain. We generated knockout and knockout-complemented strains of PsYPK1 and found that deletion of PsYPK1 resulted in a pronounced reduction in the production of sporangia and oospores, in mycelial growth on nutrient poor medium, and in virulence. PsYPK1 exhibits a cytoplasmic-nuclear localization pattern that is essential for sporangium formation and virulence of P. sojae. Interestingly, PsGPA1 overexpression was found to prevent nuclear localization of PsYPK1 by exclusively binding to the N-terminal region of PsYPK1, therefore accounting for its negative role in sporangium formation. Our data demonstrate that PsGPA1 negatively regulates sporangium formation by repressing the nuclear localization of its downstream kinase PsYPK1.
Collapse
Affiliation(s)
- Min Qiu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, Jiangsu, China
| | - Yaning Li
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, Jiangsu, China
| | - Xin Zhang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, Jiangsu, China
| | - Mingrun Xuan
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, Jiangsu, China
| | - Baiyu Zhang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, Jiangsu, China
| | - Wenwu Ye
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, Jiangsu, China
| | - Xiaobo Zheng
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, Jiangsu, China
| | - Francine Govers
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- The Key Laboratory of Integrated Management of Crop Diseases and Pests (Ministry of Education), Nanjing, Jiangsu, China
| |
Collapse
|
12
|
Abstract
Many sensory and chemical signal inputs are transmitted by intracellular GTP-binding (G) proteins. G proteins make up two major subfamilies: "large" G proteins comprising three subunits and "small" G proteins, such as the proto-oncogene product RAS, which contains a single subunit. Members of both subfamilies are regulated by post-translational modifications, including lipidation, proteolysis, and carboxyl methylation. Emerging studies have shown that these proteins are also modified by ubiquitination. Much of our current understanding of this post-translational modification comes from investigations of the large G-protein α subunit from yeast (Gpa1) and the three RAS isotypes in humans, NRAS, KRAS, and HRAS. Gα undergoes both mono- and polyubiquitination, and these modifications have distinct consequences for determining the sites and mechanisms of its degradation. Genetic and biochemical reconstitution studies have revealed the enzymes and binding partners required for addition and removal of ubiquitin, as well as the delivery and destruction of both the mono- and polyubiquitinated forms of the G protein. Complementary studies of RAS have identified multiple ubiquitination sites, each having distinct consequences for binding to regulatory proteins, shuttling to and from the plasma membrane, and degradation. Here, we review what is currently known about these two well-studied examples, Gpa1 and the human RAS proteins, that have revealed additional mechanisms of signal regulation and dysregulation relevant to human physiology. We also compare and contrast the effects of G-protein ubiquitination with other post-translational modifications of these proteins.
Collapse
Affiliation(s)
- Henrik G Dohlman
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599.
| | - Sharon L Campbell
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599.
| |
Collapse
|
13
|
Negative Feedback Phosphorylation of Gγ Subunit Ste18 and the Ste5 Scaffold Synergistically Regulates MAPK Activation in Yeast. Cell Rep 2019; 23:1504-1515. [PMID: 29719261 PMCID: PMC5987779 DOI: 10.1016/j.celrep.2018.03.135] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 12/15/2017] [Accepted: 03/29/2018] [Indexed: 01/08/2023] Open
Abstract
Heterotrimeric G proteins (Gαβγ) are essential transducers in G protein signaling systems in all eukaryotes. In yeast, G protein signaling differentially activates mitogen-activated protein kinases (MAPKs)—Fus3 and Kss1—a phenomenon controlled by plasma membrane (PM) association of the scaffold protein Ste5. Here, we show that phosphorylation of the yeast Gγ subunit (Ste18), together with Fus3 docking on Ste5, controls the rate and stability of Ste5/PM association. Disruption of either element alone by point mutation has mild but reciprocal effects on MAPK activation. Disabling both elements results in ultra-fast and stable bulk Ste5/PM localization and Fus3 activation that is 6 times faster and 4 times more amplified compared to wild-type cells. These results further resolve the mechanism by which MAPK negative feedback phosphorylation controls pathway activation and provides compelling evidence that Gγ subunits can serve as intrinsic regulators of G protein signaling.
Collapse
|
14
|
G protein subunit phosphorylation as a regulatory mechanism in heterotrimeric G protein signaling in mammals, yeast, and plants. Biochem J 2018; 475:3331-3357. [PMID: 30413679 DOI: 10.1042/bcj20160819] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 09/28/2018] [Accepted: 10/02/2018] [Indexed: 12/15/2022]
Abstract
Heterotrimeric G proteins composed of Gα, Gβ, and Gγ subunits are vital eukaryotic signaling elements that convey information from ligand-regulated G protein-coupled receptors (GPCRs) to cellular effectors. Heterotrimeric G protein-based signaling pathways are fundamental to human health [Biochimica et Biophysica Acta (2007) 1768, 994-1005] and are the target of >30% of pharmaceuticals in clinical use [Biotechnology Advances (2013) 31, 1676-1694; Nature Reviews Drug Discovery (2017) 16, 829-842]. This review focuses on phosphorylation of G protein subunits as a regulatory mechanism in mammals, budding yeast, and plants. This is a re-emerging field, as evidence for phosphoregulation of mammalian G protein subunits from biochemical studies in the early 1990s can now be complemented with contemporary phosphoproteomics and genetic approaches applied to a diversity of model systems. In addition, new evidence implicates a family of plant kinases, the receptor-like kinases, which are monophyletic with the interleukin-1 receptor-associated kinase/Pelle kinases of metazoans, as possible GPCRs that signal via subunit phosphorylation. We describe early and modern observations on G protein subunit phosphorylation and its functional consequences in these three classes of organisms, and suggest future research directions.
Collapse
|
15
|
Aymoz D, Solé C, Pierre JJ, Schmitt M, de Nadal E, Posas F, Pelet S. Timing of gene expression in a cell-fate decision system. Mol Syst Biol 2018; 14:e8024. [PMID: 29695607 PMCID: PMC5916086 DOI: 10.15252/msb.20178024] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
During development, morphogens provide extracellular cues allowing cells to select a specific fate by inducing complex transcriptional programs. The mating pathway in budding yeast offers simplified settings to understand this process. Pheromone secreted by the mating partner triggers the activity of a MAPK pathway, which results in the expression of hundreds of genes. Using a dynamic expression reporter, we quantified the kinetics of gene expression in single cells upon exogenous pheromone stimulation and in the physiological context of mating. In both conditions, we observed striking differences in the timing of induction of mating‐responsive promoters. Biochemical analyses and generation of synthetic promoter variants demonstrated how the interplay between transcription factor binding and nucleosomes contributes to determine the kinetics of transcription in a simplified cell‐fate decision system.
Collapse
Affiliation(s)
- Delphine Aymoz
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Carme Solé
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Spain
| | - Jean-Jerrold Pierre
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Marta Schmitt
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Eulàlia de Nadal
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Spain
| | - Francesc Posas
- Cell Signaling Research Group, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Spain
| | - Serge Pelet
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| |
Collapse
|
16
|
Isom DG, Page SC, Collins LB, Kapolka NJ, Taghon GJ, Dohlman HG. Coordinated regulation of intracellular pH by two glucose-sensing pathways in yeast. J Biol Chem 2017; 293:2318-2329. [PMID: 29284676 DOI: 10.1074/jbc.ra117.000422] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 12/22/2017] [Indexed: 12/19/2022] Open
Abstract
The yeast Saccharomyces cerevisiae employs multiple pathways to coordinate sugar availability and metabolism. Glucose and other sugars are detected by a G protein-coupled receptor, Gpr1, as well as a pair of transporter-like proteins, Rgt2 and Snf3. When glucose is limiting, however, an ATP-driven proton pump (Pma1) is inactivated, leading to a marked decrease in cytoplasmic pH. Here we determine the relative contribution of the two sugar-sensing pathways to pH regulation. Whereas cytoplasmic pH is strongly dependent on glucose abundance and is regulated by both glucose-sensing pathways, ATP is largely unaffected and therefore cannot account for the changes in Pma1 activity. These data suggest that the pH is a second messenger of the glucose-sensing pathways. We show further that different sugars differ in their ability to control cellular acidification, in the manner of inverse agonists. We conclude that the sugar-sensing pathways act via Pma1 to invoke coordinated changes in cellular pH and metabolism. More broadly, our findings support the emerging view that cellular systems have evolved the use of pH signals as a means of adapting to environmental stresses such as those caused by hypoxia, ischemia, and diabetes.
Collapse
Affiliation(s)
- Daniel G Isom
- From the Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599-7365, .,the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, and
| | - Stephani C Page
- From the Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599-7365
| | - Leonard B Collins
- the Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina 27599-7432
| | - Nicholas J Kapolka
- the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, and
| | - Geoffrey J Taghon
- the Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, and
| | - Henrik G Dohlman
- From the Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599-7365,
| |
Collapse
|
17
|
Shellhammer JP, Morin-Kensicki E, Matson JP, Yin G, Isom DG, Campbell SL, Mohney RP, Dohlman HG. Amino acid metabolites that regulate G protein signaling during osmotic stress. PLoS Genet 2017; 13:e1006829. [PMID: 28558063 PMCID: PMC5469498 DOI: 10.1371/journal.pgen.1006829] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 06/13/2017] [Accepted: 05/17/2017] [Indexed: 12/29/2022] Open
Abstract
All cells respond to osmotic stress by implementing molecular signaling events to protect the organism. Failure to properly adapt can lead to pathologies such as hypertension and ischemia-reperfusion injury. Mitogen-activated protein kinases (MAPKs) are activated in response to osmotic stress, as well as by signals acting through G protein-coupled receptors (GPCRs). For proper adaptation, the action of these kinases must be coordinated. To identify second messengers of stress adaptation, we conducted a mass spectrometry-based global metabolomics profiling analysis, quantifying nearly 300 metabolites in the yeast S. cerevisiae. We show that three branched-chain amino acid (BCAA) metabolites increase in response to osmotic stress and require the MAPK Hog1. Ectopic addition of these BCAA derivatives promotes phosphorylation of the G protein α subunit and dampens G protein-dependent transcription, similar to that seen in response to osmotic stress. Conversely, genetic ablation of Hog1 activity or the BCAA-regulatory enzymes leads to diminished phosphorylation of Gα and increased transcription. Taken together, our results define a new class of candidate second messengers that mediate cross talk between osmotic stress and GPCR signaling pathways.
Collapse
Affiliation(s)
- James P. Shellhammer
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | | | - Jacob P. Matson
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Guowei Yin
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Daniel G. Isom
- The University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Sharon L. Campbell
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Robert P. Mohney
- Metabolon, Inc., Research Triangle Park, North Carolina, United States of America
| | - Henrik G. Dohlman
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
| |
Collapse
|
18
|
Ly N, Cyert MS. Calcineurin, the Ca 2+-dependent phosphatase, regulates Rga2, a Cdc42 GTPase-activating protein, to modulate pheromone signaling. Mol Biol Cell 2017; 28:576-586. [PMID: 28077617 PMCID: PMC5328617 DOI: 10.1091/mbc.e16-06-0432] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Revised: 01/04/2017] [Accepted: 01/04/2017] [Indexed: 11/11/2022] Open
Abstract
Calcineurin, the conserved Ca2+/calmodulin-activated phosphatase, is required for viability during prolonged exposure to pheromone and acts through multiple substrates to down-regulate yeast pheromone signaling. Calcineurin regulates Dig2 and Rod1/Art4 to inhibit mating-induced gene expression and activate receptor internalization, respectively. Recent systematic approaches identified Rga2, a GTPase-activating protein (GAP) for the Cdc42 Rho-type GTPase, as a calcineurin substrate. Here we establish a physiological context for this regulation and show that calcineurin dephosphorylates and positively regulates Rga2 during pheromone signaling. Mating factor activates the Fus3/MAPK kinase, whose substrates induce gene expression, cell cycle arrest, and formation of the mating projection. Our studies demonstrate that Fus3 also phosphorylates Rga2 at inhibitory S/TP sites, which are targeted by Cdks during the cell cycle, and that calcineurin opposes Fus3 to activate Rga2 and decrease Cdc42 signaling. Yeast expressing an Rga2 mutant that is defective for regulation by calcineurin display increased gene expression in response to pheromone. This work is the first to identify cross-talk between Ca2+/calcineurin and Cdc42 signaling and to demonstrate modulation of Cdc42 activity through a GAP during mating.
Collapse
Affiliation(s)
- Nina Ly
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Martha S Cyert
- Department of Biology, Stanford University, Stanford, CA 94305
| |
Collapse
|
19
|
Tunc-Ozdemir M, Urano D, Jaiswal DK, Clouse SD, Jones AM. Direct Modulation of Heterotrimeric G Protein-coupled Signaling by a Receptor Kinase Complex. J Biol Chem 2016; 291:13918-13925. [PMID: 27235398 DOI: 10.1074/jbc.c116.736702] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Indexed: 01/17/2023] Open
Abstract
Plants and some protists have heterotrimeric G protein complexes that activate spontaneously without canonical G protein-coupled receptors (GPCRs). In Arabidopsis, the sole 7-transmembrane regulator of G protein signaling 1 (AtRGS1) modulates the G protein complex by keeping it in the resting state (GDP-bound). However, it remains unknown how a myriad of biological responses is achieved with a single G protein modulator. We propose that in complete contrast to G protein activation in animals, plant leucine-rich repeat receptor-like kinases (LRR RLKs), not GPCRs, provide this discrimination through phosphorylation of AtRGS1 in a ligand-dependent manner. G protein signaling is directly activated by the pathogen-associated molecular pattern flagellin peptide 22 through its LRR RLK, FLS2, and co-receptor BAK1.
Collapse
Affiliation(s)
- Meral Tunc-Ozdemir
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Daisuke Urano
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Dinesh Kumar Jaiswal
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599
| | - Steven D Clouse
- Department of Horticultural Science, North Carolina State University, Raleigh, North Carolina 27695-7609
| | - Alan M Jones
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599; Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina 27599.
| |
Collapse
|
20
|
Torres M. Chapter Two - Heterotrimeric G Protein Ubiquitination as a Regulator of G Protein Signaling. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016; 141:57-83. [PMID: 27378755 DOI: 10.1016/bs.pmbts.2016.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Ubiquitin-mediated regulation of G proteins has been known for over 20 years as a result of discoveries made independently in yeast and vertebrate model systems for pheromone and photoreception, respectively. Since that time, several details underlying the cause and effect of G protein ubiquitination have been determined-including the initiating signals, responsible enzymes, trafficking pathways, and their effects on protein structure, function, interactions, and cell signaling. The collective body of evidence suggests that Gα subunits are the primary targets of ubiquitination. However, longstanding and recent results suggest that Gβ and Gγ subunits are also ubiquitinated, in some cases impacting cell polarization-a process essential for chemotaxis and polarized cell growth. More recently, evidence from mass spectrometry (MS)-based proteomics coupled with advances in PTM bioinformatics have revealed that protein families representing G protein subunits contain several structural hotspots for ubiquitination-most of which have not been investigated for a functional role in signal transduction. Taken together, our knowledge and understanding of heterotrimeric G protein ubiquitination as a regulator of G protein signaling-despite 20 years of research-is still emerging.
Collapse
Affiliation(s)
- M Torres
- Georgia Institute of Technology, School of Biology, Atlanta, GA, United States.
| |
Collapse
|
21
|
Dewhurst HM, Choudhury S, Torres MP. Structural Analysis of PTM Hotspots (SAPH-ire)--A Quantitative Informatics Method Enabling the Discovery of Novel Regulatory Elements in Protein Families. Mol Cell Proteomics 2015; 14:2285-97. [PMID: 26070665 PMCID: PMC4528253 DOI: 10.1074/mcp.m115.051177] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Indexed: 11/08/2022] Open
Abstract
Predicting the biological function potential of post-translational modifications (PTMs) is becoming increasingly important in light of the exponential increase in available PTM data from high-throughput proteomics. We developed structural analysis of PTM hotspots (SAPH-ire)—a quantitative PTM ranking method that integrates experimental PTM observations, sequence conservation, protein structure, and interaction data to allow rank order comparisons within or between protein families. Here, we applied SAPH-ire to the study of PTMs in diverse G protein families, a conserved and ubiquitous class of proteins essential for maintenance of intracellular structure (tubulins) and signal transduction (large and small Ras-like G proteins). A total of 1728 experimentally verified PTMs from eight unique G protein families were clustered into 451 unique hotspots, 51 of which have a known and cited biological function or response. Using customized software, the hotspots were analyzed in the context of 598 unique protein structures. By comparing distributions of hotspots with known versus unknown function, we show that SAPH-ire analysis is predictive for PTM biological function. Notably, SAPH-ire revealed high-ranking hotspots for which a functional impact has not yet been determined, including phosphorylation hotspots in the N-terminal tails of G protein gamma subunits—conserved protein structures never before reported as regulators of G protein coupled receptor signaling. To validate this prediction we used the yeast model system for G protein coupled receptor signaling, revealing that gamma subunit–N-terminal tail phosphorylation is activated in response to G protein coupled receptor stimulation and regulates protein stability in vivo. These results demonstrate the utility of integrating protein structural and sequence features into PTM prioritization schemes that can improve the analysis and functional power of modification-specific proteomics data.
Collapse
Affiliation(s)
- Henry M Dewhurst
- From the ‡Georgia Institute of Technology; School of Biology; 310 Ferst Drive; Atlanta, Georgia 30332
| | - Shilpa Choudhury
- From the ‡Georgia Institute of Technology; School of Biology; 310 Ferst Drive; Atlanta, Georgia 30332
| | - Matthew P Torres
- From the ‡Georgia Institute of Technology; School of Biology; 310 Ferst Drive; Atlanta, Georgia 30332
| |
Collapse
|
22
|
Zeng XQ, Chen GQ, Liu XH, Dong B, Shi HB, Lu JP, Lin F. Crosstalk between SNF1 pathway and the peroxisome-mediated lipid metabolism in Magnaporthe oryzae. PLoS One 2014; 9:e103124. [PMID: 25090011 PMCID: PMC4121083 DOI: 10.1371/journal.pone.0103124] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 06/25/2014] [Indexed: 01/28/2023] Open
Abstract
The SNF1/AMPK pathway has a central role in response to nutrient stress in yeast and mammals. Previous studies on SNF1 function in phytopathogenic fungi mostly focused on the catalytic subunit Snf1 and its contribution to the derepression of cell wall degrading enzymes (CWDEs). However, the MoSnf1 in Magnaporthe oryzae was reported not to be involved in CWDEs regulation. The mechanism how MoSnf1 functions as a virulence determinant remains unclear. In this report, we demonstrate that MoSnf1 retains the ability to respond to nutrient-free environment via its participation in peroxisomal maintenance and lipid metabolism. Observation of GFP-tagged peroxisomal targeting signal-1 (PTS1) revealed that the peroxisomes of ΔMosnf1 were enlarged in mycelia and tended to be degraded before conidial germination, leading to the sharp decline of peroxisomal amount during appressorial development, which might impart the mutant great retard in lipid droplets mobilization and degradation. Consequently, ΔMosnf1 exhibited inability to maintain normal appressorial cell wall porosity and turgor pressure, which are key players in epidermal infection process. Exogenous glucose could partially restore the appressorial function and virulence of ΔMosnf1. Toward a further understanding of SNF1 pathway, the β-subunit MoSip2, γ-subunit MoSnf4, and two putative Snf1-activating kinases, MoSak1 and MoTos3, were additionally identified and characterized. Here we show the null mutants ΔMosip2 and ΔMosnf4 performed multiple disorders as ΔMosnf1 did, suggesting the complex integrity is essential for M. oryzae SNF1 kinase function. And the upstream kinases, MoSak1 and MoTos3, play unequal roles in SNF1 activation with a clear preference to MoSak1 over MoTos3. Meanwhile, the mutant lacking both of them exhibited a severe phenotype comparable to ΔMosnf1, uncovering a cooperative relationship between MoSak1 and MoTos3. Taken together, our data indicate that the SNF1 pathway is required for fungal development and facilitates pathogenicity by its contribution to peroxisomal maintenance and lipid metabolism in M. oryzae.
Collapse
Affiliation(s)
- Xiao-Qing Zeng
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Hangzhou, China
| | - Guo-Qing Chen
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Hangzhou, China
| | - Xiao-Hong Liu
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Hangzhou, China
| | - Bo Dong
- Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Science, Hangzhou, China
| | - Huan-Bin Shi
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Hangzhou, China
| | - Jian-Ping Lu
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Fucheng Lin
- State Key Laboratory for Rice Biology, Biotechnology Institute, Zhejiang University, Hangzhou, China
- China Tobacco Gene Research Center, Zhengzhou Tobacco Institute of CNTC, Zhengzhou, China
- * E-mail:
| |
Collapse
|
23
|
Dixit G, Baker R, Sacks CM, Torres MP, Dohlman HG. Guanine nucleotide-binding protein (Gα) endocytosis by a cascade of ubiquitin binding domain proteins is required for sustained morphogenesis and proper mating in yeast. J Biol Chem 2014; 289:15052-63. [PMID: 24722989 PMCID: PMC4031556 DOI: 10.1074/jbc.m114.566117] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Revised: 04/07/2014] [Indexed: 01/10/2023] Open
Abstract
Heterotrimeric G proteins are well known to transmit signals from cell surface receptors to intracellular effector proteins. There is growing appreciation that G proteins are also present at endomembrane compartments, where they can potentially interact with a distinct set of signaling proteins. Here, we examine the cellular trafficking function of the G protein α subunit in yeast, Gpa1. Gpa1 contains a unique 109-amino acid insert within the α-helical domain that undergoes a variety of posttranslational modifications. Among these is monoubiquitination, catalyzed by the NEDD4 family ubiquitin ligase Rsp5. Using a newly optimized method for G protein purification together with biophysical measures of structure and function, we show that the ubiquitination domain does not influence enzyme activity. By screening a panel of 39 gene deletion mutants, each lacking a different ubiquitin binding domain protein, we identify seven that are necessary to deliver Gpa1 to the vacuole compartment including four proteins (Ede1, Bul1, Ddi1, and Rup1) previously not known to be involved in this process. Finally, we show that proper endocytosis of the G protein is needed for sustained cellular morphogenesis and mating in response to pheromone stimulation. We conclude that a cascade of ubiquitin-binding proteins serves to deliver the G protein to its final destination within the cell. In this instance and in contrast to the previously characterized visual system, endocytosis from the plasma membrane is needed for proper signal transduction rather than for signal desensitization.
Collapse
Affiliation(s)
- Gauri Dixit
- From the Department of Biochemistry and Biophysics
| | | | | | - Matthew P Torres
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Henrik G Dohlman
- From the Department of Biochemistry and Biophysics, Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 and
| |
Collapse
|
24
|
Conrad M, Schothorst J, Kankipati HN, Van Zeebroeck G, Rubio-Texeira M, Thevelein JM. Nutrient sensing and signaling in the yeast Saccharomyces cerevisiae. FEMS Microbiol Rev 2014; 38:254-99. [PMID: 24483210 PMCID: PMC4238866 DOI: 10.1111/1574-6976.12065] [Citation(s) in RCA: 419] [Impact Index Per Article: 41.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 12/23/2013] [Accepted: 01/22/2014] [Indexed: 02/04/2023] Open
Abstract
The yeast Saccharomyces cerevisiae has been a favorite organism for pioneering studies on nutrient-sensing and signaling mechanisms. Many specific nutrient responses have been elucidated in great detail. This has led to important new concepts and insight into nutrient-controlled cellular regulation. Major highlights include the central role of the Snf1 protein kinase in the glucose repression pathway, galactose induction, the discovery of a G-protein-coupled receptor system, and role of Ras in glucose-induced cAMP signaling, the role of the protein synthesis initiation machinery in general control of nitrogen metabolism, the cyclin-controlled protein kinase Pho85 in phosphate regulation, nitrogen catabolite repression and the nitrogen-sensing target of rapamycin pathway, and the discovery of transporter-like proteins acting as nutrient sensors. In addition, a number of cellular targets, like carbohydrate stores, stress tolerance, and ribosomal gene expression, are controlled by the presence of multiple nutrients. The protein kinase A signaling pathway plays a major role in this general nutrient response. It has led to the discovery of nutrient transceptors (transporter receptors) as nutrient sensors. Major shortcomings in our knowledge are the relationship between rapid and steady-state nutrient signaling, the role of metabolic intermediates in intracellular nutrient sensing, and the identity of the nutrient sensors controlling cellular growth.
Collapse
Affiliation(s)
- Michaela Conrad
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
| | - Joep Schothorst
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
| | - Harish Nag Kankipati
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
| | - Griet Van Zeebroeck
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
| | - Marta Rubio-Texeira
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
| | - Johan M Thevelein
- Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU LeuvenLeuven-Heverlee, Flanders, Belgium
- Department of Molecular Microbiology, VIBLeuven-Heverlee, Flanders, Belgium
| |
Collapse
|
25
|
Abstract
In yeast, the mating response pathway is activated when a peptide pheromone binds to a heterotrimeric guanine nucleotide-binding protein (G protein)-coupled receptor, which leads to the activation of a mitogen-activated protein kinase signaling cascade and the stimulation of mating behavior. However, when nutrients in the environment are limiting, stimulation of the mating response would be maladaptive. A study indicates that the signaling pathways that respond to nutrient availability dampen the mating response by directly phosphorylating Gpa1, the G protein α subunit that initiates the mating response pathway. Snf1, the yeast homolog of adenosine monophosphate-activated protein kinase, is a highly conserved kinase that maintains energy homeostasis in response to nutrient limitation. The study found that the upstream kinases and phosphatase that control the activity of Snf1 also act on Gpa1 and provide a direct means to coordinate cell behavior and integrate the mating response with nutrient sensing.
Collapse
Affiliation(s)
- Martin C Schmidt
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA.
| |
Collapse
|