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Tong Y, Wu H, Liu Z, Wang Z, Huang B. G-Protein Subunit Gα i in Mitochondria, MrGPA1, Affects Conidiation, Stress Resistance, and Virulence of Entomopathogenic Fungus Metarhizium robertsii. Front Microbiol 2020; 11:1251. [PMID: 32612588 PMCID: PMC7309505 DOI: 10.3389/fmicb.2020.01251] [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: 03/08/2020] [Accepted: 05/15/2020] [Indexed: 12/16/2022] Open
Abstract
G proteins are critical modulators or transducers in various transmembrane signaling systems. They play key roles in numerous biological processes in fungi, including vegetative growth, development of infection-related structures, asexual conidiation, and virulence. However, functions of G proteins in entomopathogenic fungi remain unclear. Here, we characterized the roles of MrGPA1, a G-protein subunit Gαi, in conidiation, stress resistance, and virulence in Metarhizium robertsii. MrGPA1 was localized in the mitochondria. MrGpa1 deletion resulted in a significant reduction (47%) in the conidiation capacity, and reduced expression of several key conidiation-related genes, including fluG, flbD, brlA, wetA, phiA, and stuA. Further, MrGpa1 disruption resulted in decreased fungal sensitivity to UV irradiation and thermal stress, as determined based on conidial germination of ΔMrGpa1 and wild-type (WT) strains. Chemical stress analysis indicated that MrGpa1 contributes to fungal antioxidant capacity and cell wall integrity, but is not involved in tolerance to antifungal drug and osmotic stress. Importantly, insect bioassays involving (topical inoculation and injection) of Galleria mellonella larvae revealed decreased virulence of ΔMrGpa1 strain after cuticle infection. This was accompanied by decreased rates of appressorium formation and reduced expression of several cuticle penetration-related genes. Further assays showed that MrGpa1 regulated intracellular cyclic AMP (cAMP) levels, but feeding with cAMP could not recover the appressorium formation rate of ΔMrGpa1. These observations suggest that MrGpa1 contributes to the regulation of conidiation, UV irradiation, thermal stress response, antioxidant capacity, and cell wall integrity in M. robertsii. This gene is also involved in insect cuticle penetration during infection. These findings raise the possibility of designing powerful strategies for genetic improvement of M. robertsii conidiation capacity and virulence for killing pests.
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Affiliation(s)
- Youmin Tong
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
| | - Hao Wu
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
| | - Zhenbang Liu
- School of Life Sciences, University of Science and Technology of China, Hefei, China
| | - Zhangxun Wang
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
- School of Plant Protection, Anhui Agricultural University, Hefei, China
| | - Bo Huang
- Anhui Provincial Key Laboratory of Microbial Pest Control, Anhui Agricultural University, Hefei, China
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Wu Q, Regan M, Furukawa H, Jackson D. Role of heterotrimeric Gα proteins in maize development and enhancement of agronomic traits. PLoS Genet 2018; 14:e1007374. [PMID: 29708966 PMCID: PMC5945058 DOI: 10.1371/journal.pgen.1007374] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Revised: 05/10/2018] [Accepted: 04/20/2018] [Indexed: 12/03/2022] Open
Abstract
Plant shoot systems derive from the shoot apical meristems (SAMs), pools of stems cells that are regulated by a feedback between the WUSCHEL (WUS) homeobox protein and CLAVATA (CLV) peptides and receptors. The maize heterotrimeric G protein α subunit COMPACT PLANT2 (CT2) functions with CLV receptors to regulate meristem development. In addition to the sole canonical Gα CT2, maize also contains three eXtra Large GTP-binding proteins (XLGs), which have a domain with homology to Gα as well as additional domains. By either forcing CT2 to be constitutively active, or by depleting XLGs using CRISPR-Cas9, here we show that both CT2 and XLGs play important roles in maize meristem regulation, and their manipulation improved agronomic traits. For example, we show that expression of a constitutively active CT2 resulted in higher spikelet density and kernel row number, larger ear inflorescence meristems (IMs) and more upright leaves, all beneficial traits selected during maize improvement. Our findings suggest that both the canonical Gα, CT2 and the non-canonical XLGs play important roles in maize meristem regulation and further demonstrate that weak alleles of plant stem cell regulatory genes have the capacity to improve agronomic traits.
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Affiliation(s)
- Qingyu Wu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Michael Regan
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - Hiro Furukawa
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
| | - David Jackson
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States of America
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Abstract
Regulator of G protein signalling (RGS) proteins are vital in the adaptation of cells to stimulation via G protein-coupled receptors. Yeast have been integral in elucidating the important role that RGS proteins play within cellular processes. In addition to extensive characterisation of the endogenous RGS proteins, these organisms have enabled the identification and analysis of numerous mammalian homologues. The simplicity and plasticity of the yeast pheromone-response pathway has facilitated studies which would have been impossible in mammalian systems and it is certain that yeast will continue to have a great impact on this field of research in the future.
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Affiliation(s)
- Claire Hill
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
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Wang P, Cutler J, King J, Palmer D. Mutation of the regulator of G protein signaling Crg1 increases virulence in Cryptococcus neoformans. EUKARYOTIC CELL 2004; 3:1028-35. [PMID: 15302835 PMCID: PMC500888 DOI: 10.1128/ec.3.4.1028-1035.2004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2004] [Accepted: 06/08/2004] [Indexed: 12/14/2022]
Abstract
The regulator of G protein signaling homolog Crg1 was found to be a key regulator of pheromone-responsive mating in the opportunistic human fungal pathogen Cryptococcus neoformans. A mutation in the CRG1 gene has greatly increased virulence in the prevalently distributed MATalpha strains of the fungus. Mouse survival time was shortened by 40%, and the lethal dosage was 100-fold less than that of wild-type strains. In addition, the increased virulence of crg1 mutant strains was dependent on the transcription factor homolog Ste12alpha but not on the mitogen-activated protein kinase homolog Cpk1. The enhanced mating due to CRG1 mutation, however, was still dependent on Cpk1. Interestingly, crg1 mutants of MATalpha cells produced dark melanin pigment under normally inhibitory conditions, which may relate to the mechanism for increased virulence.
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Affiliation(s)
- Ping Wang
- Department of Pediatrics, Research Institute for Children, Children's Hospital, 200 Henry Clay Ave., New Orleans, LA 70118, USA.
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Hao N, Yildirim N, Wang Y, Elston TC, Dohlman HG. Regulators of G protein signaling and transient activation of signaling: experimental and computational analysis reveals negative and positive feedback controls on G protein activity. J Biol Chem 2003; 278:46506-15. [PMID: 12968019 DOI: 10.1074/jbc.m308432200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cellular responses to hormones and neurotransmitters are necessarily transient. The mating pheromone signal in yeast is typical. Signal initiation requires cell surface receptors, a G protein heterotrimer, and down-stream effectors. Signal inactivation requires Sst2, a regulator of G protein signaling (RGS) protein that accelerates GTPase activity. We conducted a quantitative analysis of RGS and G protein expression and devised computational models that describe their activity in vivo. These results indicated that pheromone-dependent transcriptional induction of the RGS protein constitutes a negative feedback loop that leads to desensitization. Modeling also suggested the presence of a positive feedback loop leading to resensitization of the pathway. In confirmation of the model, we found that the RGS protein is ubiquitinated and degraded in response to pheromone stimulation. We identified and quantitated these positive and negative feedback loops, which account for the transient response to external signals observed in vivo.
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Affiliation(s)
- Nan Hao
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-0812, USA
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Guo M, Aston C, Burchett SA, Dyke C, Fields S, Rajarao SJR, Uetz P, Wang Y, Young K, Dohlman HG. The Yeast G Protein α Subunit Gpa1 Transmits a Signal through an RNA Binding Effector Protein Scp160. Mol Cell 2003; 12:517-24. [PMID: 14536090 DOI: 10.1016/s1097-2765(03)00307-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In yeast Saccharomyces cerevisiae the G protein betagamma subunits (Ste4/Ste18) have long been known to transmit the signal required for mating. Here we demonstrate that GTPase-deficient mutants of Galpha (Gpa1) directly activate the mating response pathway. We also show that signaling by activated Gpa1 requires direct coupling to an RNA binding protein Scp160. These findings suggest an additional role for Gpa1 and reveal Scp160 as a component of the mating response pathway in yeast.
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Affiliation(s)
- Ming Guo
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Garrison TR, Apanovitch DM, Dohlman HG. Purification of RGS protein, Sst2, from Saccharomyces cerevisiae and Escherichia coli. Methods Enzymol 2002; 344:632-47. [PMID: 11771416 DOI: 10.1016/s0076-6879(02)44745-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Affiliation(s)
- Tiffany Runyan Garrison
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06536, USA
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Abstract
All cells have the capacity to respond to chemical and sensory stimuli. Central to many such signaling pathways is the heterotrimeric G protein, which transmits a signal from cell surface receptors to intracellular effectors. Recent studies using the yeast Saccharomyces cerevisiae have produced important advances in our understanding of G protein activation and inactivation. This review focuses on the mechanisms by which G proteins transmit a signal from peptide pheromone receptors to the mating response in yeast and how mechanisms elucidated in yeast can provide insights to signaling events in more complex organisms.
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Affiliation(s)
- Henrik G Dohlman
- Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA.
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Xu BE, Skowronek KR, Kurjan J. The N terminus of Saccharomyces cerevisiae Sst2p plays an RGS-domain-independent, Mpt5p-dependent role in recovery from pheromone arrest. Genetics 2001; 159:1559-71. [PMID: 11779797 PMCID: PMC1461895 DOI: 10.1093/genetics/159.4.1559] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Saccharomyces cerevisiae RGS protein Sst2p is involved in desensitization to pheromone and acts as a GTPase-activating protein for the Galpha subunit Gpa1p. Other results indicate that Sst2p acts through Mpt5p and that this action occurs downstream of Fus3p and through Cln3p/Cdc28p. Our results indicate that the interaction of Sst2p with Mpt5p requires the N-terminal MPI (Mpt5p-interacting) domain of Sst2p and is independent of the C-terminal RGS domain. Overexpression of the MPI domain results in an Mpt5p-dependent increase in recovery from pheromone arrest. Overexpression of either intact Sst2p or the MPI domain leads to partial suppression of a gpa1 growth defect, and this suppression is dependent on Mpt5p, indicating that MPI function occurs downstream of Gpa1p and through Mpt5p. Combination of an mpt5 mutation with the GPA1(G302S) mutation, which uncouples Gpa1p from Sst2p, results in pheromone supersensitivity similar to the sst2 mutant, and promotion of recovery by overexpression of Sst2p is dependent on both Mpt5p and the Gpa1p interaction. These results indicate that Sst2p is a bifunctional protein and that the MPI domain acts through Mpt5p independently of the RGS domain. RGS family members from other fungi contain N-terminal domains with sequence similarity to the Sst2p MPI domain, suggesting that MPI function may be conserved.
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Affiliation(s)
- B E Xu
- Department of Microbiology and Molecular Genetics and the Vermont Cancer Center, University of Vermont, College of Medicine, Burlington, Vermont 05405-0068, USA
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Pereira PS, Jones NC. The RGS domain-containing fission yeast protein, Rgs1p, regulates pheromone signalling and is required for mating. Genes Cells 2001; 6:789-802. [PMID: 11554925 DOI: 10.1046/j.1365-2443.2001.00465.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND When nutritionally starved, the fission yeast Schizosaccharomyces pombe enters a cell differentiation process which leads to mating and meiosis. The Ste11 protein is a key regulator of this differentiation pathway, activating the transcription of mating and meiotic genes upon starvation. RESULTS Here, we describe rgs1, a member of the Regulator of G-protein Signalling (RGS) family, as a novel Ste11 target gene. rgs1 expression requires both an Ste11-mediated nitrogen starvation signal and the pheromone-induced activation of the Byr2/Byr1/Spk1 MAPK pathway. We show that rgs1 deletion results in a sensitivity to pheromone and in a mating defect. Deltargs1 cells initiate the mating pathway normally, undergoing sexual agglutination and G1 arrest, while inducing pheromone-dependent transcription, but then fail to fuse with a mating partner while elongating abnormal conjugation tubes. Endogenous Rgs1 tagged with GFP localizes to the nucleus and cytoplasm, and this localization pattern is not altered during pheromone treatment. Importantly, Rgs1 function requires its C-terminal RGS domain, as well as a central DEP domain and a novel homology domain present in its N-terminal region (Fungal-DR domain). CONCLUSIONS These results demonstrate that rgs1 expression requires nutritional starvation and pheromone signalling. Rgs1 negatively regulates pheromone signalling during mating, acting in a negative feedback loop that is essential for the mating process.
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Affiliation(s)
- P S Pereira
- Imperial Cancer Research Fund, Gene Regulation Laboratory, 44 Lincoln's Inn Fields, London WC2A 3PX, UK
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Cismowski MJ, Metodiev M, Draper E, Stone DE. Biochemical analysis of yeast G(alpha) mutants that enhance adaptation to pheromone. Biochem Biophys Res Commun 2001; 284:247-54. [PMID: 11394869 DOI: 10.1006/bbrc.2001.4959] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mating-specific heterotrimeric G(alpha) protein of Saccharomyces cerevisiae, Gpa1, negatively regulates activation of the pheromone response pathway both by sequestering G(beta)gamma and by triggering an adaptive response through an as yet unknown mechanism. Previous genetic studies identified mutant alleles of GPA1 that downregulate the pheromone response independently of the pheromone receptor (GPA1E364K), or through a receptor-dependent mechanism (GPA1N388D). To further our understanding of the mechanism of action of these mutant alleles, their corresponding proteins were purified and subjected to biochemical analysis. The receptor-dependent activity of Gpa1N388D was further analyzed using yeast strains expressing constitutively active receptor (Ste2) mutants, and C-terminal truncation mutant forms of Gpa1. A combination of G(alpha) affinity chromatography, GTP binding/hydrolysis studies, and genetic analysis allowed us to assign a distinct mechanism of action to each of these mutant proteins.
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Affiliation(s)
- M J Cismowski
- Laboratory for Molecular Biology, University of Illinois at Chicago, Chicago, Illinois 60607, USA
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