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Ali U, Lu S, Fadlalla T, Iqbal S, Yue H, Yang B, Hong Y, Wang X, Guo L. The functions of phospholipases and their hydrolysis products in plant growth, development and stress responses. Prog Lipid Res 2022; 86:101158. [PMID: 35134459 DOI: 10.1016/j.plipres.2022.101158] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 01/31/2022] [Accepted: 01/31/2022] [Indexed: 12/15/2022]
Abstract
Cell membranes are the initial site of stimulus perception from environment and phospholipids are the basic and important components of cell membranes. Phospholipases hydrolyze membrane lipids to generate various cellular mediators. These phospholipase-derived products, such as diacylglycerol, phosphatidic acid, inositol phosphates, lysophopsholipids, and free fatty acids, act as second messengers, playing vital roles in signal transduction during plant growth, development, and stress responses. This review focuses on the structure, substrate specificities, reaction requirements, and acting mechanism of several phospholipase families. It will discuss their functional significance in plant growth, development, and stress responses. In addition, it will highlight some critical knowledge gaps in the action mechanism, metabolic and signaling roles of these phospholipases and their products in the context of plant growth, development and stress responses.
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Affiliation(s)
- Usman Ali
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China; Hubei Hongshan Laboratory, Wuhan, 430070, China
| | - Shaoping Lu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China; Hubei Hongshan Laboratory, Wuhan, 430070, China
| | - Tarig Fadlalla
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Sidra Iqbal
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China; Department of Agriculture, University of Swabi, Khyber Pakhtunkhwa, Pakistan
| | - Hong Yue
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China; Hubei Hongshan Laboratory, Wuhan, 430070, China
| | - Bao Yang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China; Hubei Hongshan Laboratory, Wuhan, 430070, China
| | - Yueyun Hong
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China; Hubei Hongshan Laboratory, Wuhan, 430070, China
| | - Xuemin Wang
- Department of Biology, University of Missouri-St. Louis, St. Louis, MO 63121, USA; Donald Danforth Plant Science Center, St. Louis, MO 63132, USA
| | - Liang Guo
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China; Hubei Hongshan Laboratory, Wuhan, 430070, China.
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2
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Cannon AE, Chapman KD. Lipid Signaling through G Proteins. TRENDS IN PLANT SCIENCE 2021; 26:720-728. [PMID: 33468433 DOI: 10.1016/j.tplants.2020.12.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/10/2020] [Accepted: 12/19/2020] [Indexed: 06/12/2023]
Abstract
N-Acylethanolamine (NAE) signaling has received considerable attention in vertebrates as part of the endocannabinoid signaling system, where anandamide acts as a ligand for G protein-coupled cannabinoid receptors. Recent studies indicate that G proteins also are required for some types of NAE signaling in plants. The genetic ablation of the Gβγ dimer or loss of the full set of extra-large G proteins strongly attenuated NAE-induced chloroplast responses in seedlings. Intriguing parallels and distinct differences have emerged between plants and animals in NAE signaling, despite the conserved use of these lipid mediators to modulate cellular processes. Here we compare similarities and differences and identify open questions in a fundamental lipid signaling pathway in eukaryotes with components that are both conserved and diverged in plants.
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Affiliation(s)
- Ashley E Cannon
- Wheat Health, Genetics, and Quality Research Unit, Agriculture Research Service, U.S. Department of Agriculture, Pullman, WA 99163, USA; Department of Crop and Soil Science, Washington State University, Pullman, WA 99163, USA.
| | - Kent D Chapman
- BioDiscovery Institute, Department of Biological Sciences, University of North Texas, Denton, TX 76203, USA.
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3
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Bhardwaj D, Sahoo RK, Naqvi AR, Lakhanpaul S, Tuteja N. Pea Gβ subunit of G proteins has a role in nitric oxide-induced stomatal closure in response to heat and drought stress. PROTOPLASMA 2020; 257:1639-1654. [PMID: 32737572 DOI: 10.1007/s00709-020-01529-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 06/18/2020] [Indexed: 06/11/2023]
Abstract
Heterotrimeric G proteins consisting of Gα, Gβ and Gγ subunits act as downstream effectors to regulate multiple functions including abiotic stress tolerance. However, the mechanism of Gβ-mediated heat and drought tolerance is yet to be established. To explore the role of Pisum sativum Gβ subunit (PsGβ) in heat and drought stress, transgenic tobacco plants overexpressing (OEs) PsGβ were raised. Transgenic plants showing ectopic expression of PsGβ performed better under heat and drought stress in comparison with vector control plants. The seed germination, relative water content (RWC) and nitric oxide (NO) induction in the guard cells of transgenic plants were significantly higher in contrast to control plants. PsGβ promoter was isolated and several stress-responsive elements were identified. The change in Gβ expression in response to heat, methyl jasmonate (MeJA), abscisic acid (ABA), drought and salt confirms the presence of heat, low temperature and drought-responsive elements in the PsGβ promoter. Also, heat and drought stress caused the release of NO-induced stomatal closure in the leaves of transgenic tobacco plants OEs PsGβ. The better performance of transgenic plant OEs PsGβ is also attributed to the improved photosynthetic parameters as compared with control plants. These findings suggest a role of PsGβ in the signalling pathway leading to NO-induced stomatal closure during heat and drought stress.
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Affiliation(s)
- Deepak Bhardwaj
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
- Department of Botany, Central University of Jammu, Jammu and Kashmir, 181143, India
- Department of Botany, University of Delhi, Delhi, India
| | - Ranjan Kumar Sahoo
- Department of Biotechnology, Centurion University of Technology and Management, Bhubaneswar, Odisha, 752050, India
| | - Afsar Raza Naqvi
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India
| | | | - Narendra Tuteja
- Plant Molecular Biology Group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, 110067, India.
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Pandey S. Heterotrimeric G-Protein Signaling in Plants: Conserved and Novel Mechanisms. ANNUAL REVIEW OF PLANT BIOLOGY 2019; 70:213-238. [PMID: 31035831 DOI: 10.1146/annurev-arplant-050718-100231] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Heterotrimeric GTP-binding proteins are key regulators of a multitude of signaling pathways in all eukaryotes. Although the core G-protein components and their basic biochemistries are broadly conserved throughout evolution, the regulatory mechanisms of G proteins seem to have been rewired in plants to meet specific needs. These proteins are currently the focus of intense research in plants due to their involvement in many agronomically important traits, such as seed yield, organ size regulation, biotic and abiotic stress responses, symbiosis, and nitrogen use efficiency. The availability of massive sequence information from a variety of plant species, extensive biochemical data generated over decades, and impressive genetic resources for plant G proteins have made it possible to examine their role, unique properties, and novel regulation. This review focuses on some recent advances in our understanding of the mechanistic details of this critical signaling pathway to enable the precise manipulation and generation of plants to meet future needs.
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Affiliation(s)
- Sona Pandey
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA;
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5
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Roy Choudhury S, Marlin MA, Pandey S. The Role of Gβ Protein in Controlling Cell Expansion via Potential Interaction with Lipid Metabolic Pathways. PLANT PHYSIOLOGY 2019; 179:1159-1175. [PMID: 30622152 PMCID: PMC6393804 DOI: 10.1104/pp.18.01312] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 12/10/2018] [Indexed: 05/23/2023]
Abstract
Heterotrimeric G-proteins influence almost all aspects of plant growth, development, and responses to biotic and abiotic stresses in plants, likely via their interaction with specific effectors. However, the identity of such effectors and their mechanism of action are mostly unknown. While investigating the roles of different G-protein subunits in modulating the oil content in Camelina (Camelina sativa), an oil seed crop, we uncovered a role of Gβ proteins in controlling anisotropic cell expansion. Knockdown of Gβ genes causes reduced longitudinal and enhanced transverse expansion, resulting in altered cell, tissue, and organ shapes in transgenic plants during vegetative and reproductive development. These plants also exhibited substantial changes in their fatty acid and phospholipid profiles, which possibly leads to the increased oil content of the transgenic seeds. This increase is potentially caused by the direct interaction of Gβ proteins with a specific patatin-like phospholipase, pPLAIIIδ. Camelina plants with suppressed Gβ expression exhibit higher lipase activity, and show phenotypes similar to plants overexpressing pPLAIIIδ, suggesting that the Gβ proteins are negative regulators of pPLAIIIδ. These results reveal interactions between the G-protein-mediated and lipid signaling/metabolic pathways, where specific phospholipases may act as effectors that control key developmental and environmental responses of plants.
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Affiliation(s)
| | - Maria A Marlin
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
| | - Sona Pandey
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132
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Miller JC, Chezem WR, Clay NK. Ternary WD40 Repeat-Containing Protein Complexes: Evolution, Composition and Roles in Plant Immunity. FRONTIERS IN PLANT SCIENCE 2016; 6:1108. [PMID: 26779203 PMCID: PMC4703829 DOI: 10.3389/fpls.2015.01108] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Accepted: 11/23/2015] [Indexed: 05/18/2023]
Abstract
Plants, like mammals, rely on their innate immune system to perceive and discriminate among the majority of their microbial pathogens. Unlike mammals, plants respond to this molecular dialog by unleashing a complex chemical arsenal of defense metabolites to resist or evade pathogen infection. In basal or non-host resistance, plants utilize signal transduction pathways to detect "non-self," "damaged-self," and "altered-self"- associated molecular patterns and translate these "danger" signals into largely inducible chemical defenses. The WD40 repeat (WDR)-containing proteins Gβ and TTG1 are constituents of two independent ternary protein complexes functioning at opposite ends of a plant immune signaling pathway. They are also encoded by single-copy genes that are ubiquitous in higher plants, implying the limited diversity and functional conservation of their respective complexes. In this review, we summarize what is currently known about the evolutionary history of these WDR-containing ternary complexes, their repertoire and combinatorial interactions, and their downstream effectors and pathways in plant defense.
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Affiliation(s)
- Jimi C. Miller
- Department of Molecular Biophysics and Biochemistry, Yale UniversityNew Haven, CT, USA
| | - William R. Chezem
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew Haven, CT, USA
| | - Nicole K. Clay
- Department of Molecular, Cellular and Developmental Biology, Yale UniversityNew Haven, CT, USA
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7
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Tu H, Qin Y. Cloning and expression analysis of G-protein Gαq subunit and Gβ1 subunit from Bemisia tabaci Gennadius (Homoptera: Aleyrodidae). ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2014; 87:53-71. [PMID: 25042293 DOI: 10.1002/arch.21180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The heterotrimeric G proteins play an essential role in a wide variety of signal transduction pathways, mediating the process of chemical signals from the environment in all higher eukaryotic organisms. In this article, two G-protein subunit genes encoding Gαq and Gβ1 were cloned from Bemisia tabaci Gennadius. The full-length cDNA sequence of BtGαq consisted of 2,336 bp with an ORF of 1,062 bp encoding 353 amino acids and BtGβ1 had a full length of 1,942 bp with an ORF of 1,023 nucleotides encoding 340 amino acids. The amino acid sequences of BtGαq and BtGβ1 from B. tabaci B biotype were identical to those from the Q biotype. Phylogenetic analysis identified G protein α and β subunit families from insects based on their amino acid sequences. The expression patterns of BtGαq and BtGβ1 at different development stages and in different body regions were analyzed by real-time quantitative PCR and Western blot. The results show that BtGαq and BtGβ1 are neither developmental stage-specific nor tissue-specific. The transcript levels of BtGαq in the B biotype are similar to that in the Q biotype, the transcript levels of BtGβ1 at egg, first instar and pupae in B biotype were significantly higher than that in Q biotype. The transcript levels of BtGαq and BtGβ1 in the head were significantly higher than those in thorax and abdomen indicating that they are involved in nervous system and sensory functions.
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Affiliation(s)
- Hongtao Tu
- Department of Entomology, China Agricultural University, Beijing, China; Zhengzhou Fruit Research Institute, Chinese Academy of Agricultural Sciences, Zhengzhou, China
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8
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Montgomery ER, Temple BRS, Peters KA, Tolbert CE, Booker BK, Martin JW, Hamilton TP, Tagliatela AC, Smolski WC, Rogers SL, Jones AM, Meigs TE. Gα12 structural determinants of Hsp90 interaction are necessary for serum response element-mediated transcriptional activation. Mol Pharmacol 2014; 85:586-97. [PMID: 24435554 PMCID: PMC3965892 DOI: 10.1124/mol.113.088443] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 01/16/2014] [Indexed: 12/31/2022] Open
Abstract
The G12/13 class of heterotrimeric G proteins, comprising the α-subunits Gα12 and Gα13, regulates multiple aspects of cellular behavior, including proliferation and cytoskeletal rearrangements. Although guanine nucleotide exchange factors for the monomeric G protein Rho (RhoGEFs) are well characterized as effectors of this G protein class, a variety of other downstream targets has been reported. To identify Gα12 determinants that mediate specific protein interactions, we used a structural and evolutionary comparison between the G12/13, Gs, Gi, and Gq classes to identify "class-distinctive" residues in Gα12 and Gα13. Mutation of these residues in Gα12 to their deduced ancestral forms revealed a subset necessary for activation of serum response element (SRE)-mediated transcription, a G12/13-stimulated pathway implicated in cell proliferative signaling. Unexpectedly, this subset of Gα12 mutants showed impaired binding to heat-shock protein 90 (Hsp90) while retaining binding to RhoGEFs. Corresponding mutants of Gα13 exhibited robust SRE activation, suggesting a Gα12-specific mechanism, and inhibition of Hsp90 by geldanamycin or small interfering RNA-mediated lowering of Hsp90 levels resulted in greater downregulation of Gα12 than Gα13 signaling in SRE activation experiments. Furthermore, the Drosophila G12/13 homolog Concertina was unable to signal to SRE in mammalian cells, and Gα12:Concertina chimeras revealed Gα12-specific determinants of SRE activation within the switch regions and a C-terminal region. These findings identify Gα12 determinants of SRE activation, implicate Gα12:Hsp90 interaction in this signaling mechanism, and illuminate structural features that arose during evolution of Gα12 and Gα13 to allow bifurcated mechanisms of signaling to a common cell proliferative pathway.
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Affiliation(s)
- Ellyn R Montgomery
- Department of Biology, University of North Carolina at Asheville, Asheville, North Carolina (E.R.M., B.K.B., J.W.M., T.P.H., A.C.T., W.C.S., T.E.M.); Departments of Biology (K.A.P., S.L.R., A.M.J.), Biochemistry and Biophysics (B.R.S.T.), Cell Biology and Physiology (C.E.T.), and Pharmacology (A.M.J.), R. L. Juliano Structural Bioinformatics Core Facility (B.R.S.T.), and Carolina Center for Genome Sciences (S.L.R.), University of North Carolina, and the Lineberger Comprehensive Cancer Center, (S.L.R., T.E.M.), Chapel Hill, North Carolina
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9
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Reinhardt JA, Jones CD. Two rapidly evolving genes contribute to male fitness in Drosophila. J Mol Evol 2013; 77:246-59. [PMID: 24221639 DOI: 10.1007/s00239-013-9594-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 11/01/2013] [Indexed: 12/21/2022]
Abstract
Purifying selection often results in conservation of gene sequence and function. The most functionally conserved genes are also thought to be among the most biologically essential. These observations have led to the use of sequence conservation as a proxy for functional conservation. Here we describe two genes that are exceptions to this pattern. We show that lack of sequence conservation among orthologs of CG15460 and CG15323-herein named jean-baptiste (jb) and karr, respectively-does not necessarily predict lack of functional conservation. These two Drosophila melanogaster genes are among the most rapidly evolving protein-coding genes in this species, being nearly as diverged from their D. yakuba orthologs as random sequences are. jb and karr are both expressed at an elevated level in larval males and adult testes, but they are not accessory gland proteins and their loss does not affect male fertility. Instead, knockdown of these genes in D. melanogaster via RNA interference caused male-biased viability defects. These viability effects occur prior to the third instar for jb and during late pupation for karr. We show that putative orthologs to jb and karr are also expressed strongly in the testes of other Drosophila species and have similar gene structure across species despite low levels of sequence conservation. While standard molecular evolution tests could not reject neutrality, other data hint at a role for natural selection. Together these data provide a clear case where a lack of sequence conservation does not imply a lack of conservation of expression or function.
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Affiliation(s)
- Josephine A Reinhardt
- Department of Biology, The University of North Carolina at Chapel Hill, CB# 3280, Coker Hall, Chapel Hill, NC, 27599-3280, USA,
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10
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Abstract
Phospholipase C (PLC) enzymes convert phosphatidylinositol-4,5-bisphosphate into the second messengers diacylglycerol and inositol-1,4,5-triphosphate. The production of these molecules promotes the release of intracellular calcium and activation of protein kinase C, which results in profound cellular changes. The PLCβ subfamily is of particular interest given its prominent role in cardiovascular and neuronal signaling and its regulation by G protein-coupled receptors, as PLCβ is the canonical downstream target of the heterotrimeric G protein Gαq. However, this is not the only mechanism regulating PLCβ activity. Extensive structural and biochemical evidence has revealed regulatory roles for autoinhibitory elements within PLCβ, Gβγ, small molecular weight G proteins, and the lipid membrane itself. Such complex regulation highlights the central role that this enzyme plays in cell signaling. A better understanding of the molecular mechanisms underlying the control of its activity will greatly facilitate the search for selective small molecule modulators of PLCβ.
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Affiliation(s)
- Angeline M Lyon
- Life Sciences Institute and the Departments of Pharmacology and Biological Chemistry, University of Michigan, Ann Arbor, Michigan
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11
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Jiang K, Frick-Cheng A, Trusov Y, Delgado-Cerezo M, Rosenthal DM, Lorek J, Panstruga R, Booker FL, Botella JR, Molina A, Ort DR, Jones AM. Dissecting Arabidopsis Gβ signal transduction on the protein surface. PLANT PHYSIOLOGY 2012; 159:975-83. [PMID: 22570469 PMCID: PMC3387721 DOI: 10.1104/pp.112.196337] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The heterotrimeric G-protein complex provides signal amplification and target specificity. The Arabidopsis (Arabidopsis thaliana) Gβ-subunit of this complex (AGB1) interacts with and modulates the activity of target cytoplasmic proteins. This specificity resides in the structure of the interface between AGB1 and its targets. Important surface residues of AGB1, which were deduced from a comparative evolutionary approach, were mutated to dissect AGB1-dependent physiological functions. Analysis of the capacity of these mutants to complement well-established phenotypes of Gβ-null mutants revealed AGB1 residues critical for specific AGB1-mediated biological processes, including growth architecture, pathogen resistance, stomata-mediated leaf-air gas exchange, and possibly photosynthesis. These findings provide promising new avenues to direct the finely tuned engineering of crop yield and traits.
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12
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Chakravorty D, Trusov Y, Botella JR. Site-directed mutagenesis of the Arabidopsis heterotrimeric G protein β subunit suggests divergent mechanisms of effector activation between plant and animal G proteins. PLANTA 2012; 235:615-27. [PMID: 22002625 DOI: 10.1007/s00425-011-1526-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 09/22/2011] [Indexed: 05/23/2023]
Abstract
Heterotrimeric G proteins are integral components of signal transduction in humans and other mammals and have been therefore extensively studied. However, while they are known to mediate many processes, much less is currently known about the effector pathways and molecular mechanisms used by these proteins to regulate effectors in plants. We designed a complementation strategy to study G protein signaling in Arabidopsis thaliana, particularly the mechanism of action of AGB1, the sole identified β subunit. We used biochemical and effector regulation data from human G protein studies to identify four potentially important residues for site-directed mutagenesis (T65, M111, D250 and W361 of AGB1). Each residue was individually mutated and the resulting mutated protein introduced in the agb1-2 mutant background under the control of the native AGB1 promoter. Interestingly, even though these mutations have been shown to have profound effects on effector signaling in humans, all the mutated subunits were able to restore thirteen of the fifteen Gβ-deficient phenotypes characterized in this study. Only one mutated protein, T65A was unable to complement the hypersensitivity to mannitol during germination observed in agb1 mutants; while only D250A failed to restore lateral root numbers in the agb1 mutant to wild-type levels. Our results suggest that the mechanisms used in mammalian G protein signaling are not well conserved in plant G protein signaling, and that either the effectors used by plant G proteins, or the mechanisms used to activate them, are at least partially divergent from the well-studied mammalian G proteins.
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Affiliation(s)
- David Chakravorty
- Plant Genetic Engineering Laboratory, School of Agriculture and Food Sciences, University of Queensland, Brisbane, QLD 4072, Australia
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13
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Tzima AK, Paplomatas EJ, Tsitsigiannis DI, Kang S. The G protein β subunit controls virulence and multiple growth- and development-related traits in Verticillium dahliae. Fungal Genet Biol 2012; 49:271-83. [PMID: 22387367 DOI: 10.1016/j.fgb.2012.02.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 02/10/2012] [Accepted: 02/13/2012] [Indexed: 11/26/2022]
Abstract
To gain insight into the role of G protein-mediated signaling in virulence and development of the soilborne, wilt causing fungus Verticillium dahliae, the G protein β subunit gene (named as VGB) was disrupted in tomato race 1 strain of V. dahliae. A resulting mutant strain, 70ΔGb15, displayed drastic reduction in virulence, increased microsclerotia formation and conidiation, and decreased ethylene production compared to the corresponding wild type (wt) strain 70wt-r1. Moreover, 70ΔGb15 exhibited an elongated rather than radial growth pattern on agar media. A transformant of 70ΔGb15 (named as 70ΔGbPKAC1) that carries an extra copy of VdPKAC1, a V. dahliae gene encoding the catalytic subunit of the cAMP-dependent protein kinase A, exhibited wt growth pattern and conidiation, was unable to form microsclerotia, produced high amounts of ethylene, and exhibited virulence between that of 70ΔGb15 and 70wt-r1 on tomato plants. Phenotypical changes observed in 70ΔGb15 and 70ΔGbPKAC1 correlated with transcriptional changes in several genes involved in signaling (MAP kinase VMK1) and development (hydrophobin VDH1 and ACC synthase ACS1) of V. dahliae. Results from the present work suggest a linkage between VGB and VdPKAC1 signaling pathways in regulating virulence, hormone production and development in V. dahliae.
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Affiliation(s)
- Aliki K Tzima
- Laboratory of Plant Pathology, Agricultural University of Athens, 75 Iera Odos, 11855 Athens, Greece.
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14
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Friedman EJ, Wang HX, Jiang K, Perovic I, Deshpande A, Pochapsky TC, Temple BRS, Hicks SN, Harden TK, Jones AM. Acireductone dioxygenase 1 (ARD1) is an effector of the heterotrimeric G protein beta subunit in Arabidopsis. J Biol Chem 2011; 286:30107-18. [PMID: 21712381 PMCID: PMC3191050 DOI: 10.1074/jbc.m111.227256] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Revised: 06/27/2011] [Indexed: 01/30/2023] Open
Abstract
Heterotrimeric G protein complexes are conserved from plants to mammals, but the complexity of each system varies. Arabidopsis thaliana contains one Gα, one Gβ (AGB1), and at least three Gγ subunits, allowing it to form three versions of the heterotrimer. This plant model is ideal for genetic studies because mammalian systems contain hundreds of unique heterotrimers. The activation of these complexes promotes interactions between both the Gα subunit and the Gβγ dimer with enzymes and scaffolds to propagate signaling to the cytoplasm. However, although effectors of Gα and Gβ are known in mammals, no Gβ effectors were previously known in plants. Toward identifying AGB1 effectors, we genetically screened for dominant mutations that suppress Gβ-null mutant (agb1-2) phenotypes. We found that overexpression of acireductone dioxygenase 1 (ARD1) suppresses the 2-day-old etiolated phenotype of agb1-2. ARD1 is homologous to prokaryotic and eukaryotic ARD proteins; one function of ARDs is to operate in the methionine salvage pathway. We show here that ARD1 is an active metalloenzyme, and AGB1 and ARD1 both control embryonic hypocotyl length by modulating cell division; they also may contribute to the production of ethylene, a product of the methionine salvage pathway. ARD1 physically interacts with AGB1, and ARD enzymatic activity is stimulated by AGB1 in vitro. The binding interface on AGB1 was deduced using a comparative evolutionary approach and tested using recombinant AGB1 mutants. A possible mechanism for AGB1 activation of ARD1 activity was tested using directed mutations in a loop near the substrate-binding site.
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Affiliation(s)
| | - Helen X. Wang
- From the Department of Biology
- SmileNature Corporation, San Diego, California 92129
| | | | | | - Aditi Deshpande
- Biochemistry, Brandeis University, Waltham, Massachusetts 02454, and
| | | | - Brenda R. S. Temple
- R. L. Juliano Structural Bioinformatics Core Facility
- Departments of Biochemistry and Biophysics and
| | | | - T. Kendall Harden
- Pharmacology, and
- Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599
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15
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Sun J, Liu X, Pan Y. The physical interaction between LdPLCs and Arabidopsis G beta in a yeast two-hybrid system. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/s11703-011-1063-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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16
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Temple BRS, Jones CD, Jones AM. Evolution of a signaling nexus constrained by protein interfaces and conformational States. PLoS Comput Biol 2010; 6:e1000962. [PMID: 20976244 PMCID: PMC2954821 DOI: 10.1371/journal.pcbi.1000962] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Accepted: 09/17/2010] [Indexed: 01/03/2023] Open
Abstract
Heterotrimeric G proteins act as the physical nexus between numerous receptors that respond to extracellular signals and proteins that drive the cytoplasmic response. The Gα subunit of the G protein, in particular, is highly constrained due to its many interactions with proteins that control or react to its conformational state. Various organisms contain differing sets of Gα-interacting proteins, clearly indicating that shifts in sequence and associated Gα functionality were acquired over time. These numerous interactions constrained much of Gα evolution; yet Gα has diversified, through poorly understood processes, into several functionally specialized classes, each with a unique set of interacting proteins. Applying a synthetic sequence-based approach to mammalian Gα subunits, we established a set of seventy-five evolutionarily important class-distinctive residues, sites where a single Gα class is differentiated from the three other classes. We tested the hypothesis that shifts at these sites are important for class-specific functionality. Importantly, we mapped known and well-studied class-specific functionalities from all four mammalian classes to sixteen of our class-distinctive sites, validating the hypothesis. Our results show how unique functionality can evolve through the recruitment of residues that were ancestrally functional. We also studied acquisition of functionalities by following these evolutionarily important sites in non-mammalian organisms. Our results suggest that many class-distinctive sites were established early on in eukaryotic diversification and were critical for the establishment of new Gα classes, whereas others arose in punctuated bursts throughout metazoan evolution. These Gα class-distinctive residues are rational targets for future structural and functional studies.
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Affiliation(s)
- Brenda R S Temple
- R. L. Juliano Structural Bioinformatics Core Facility, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
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Co-expression of nAChRs and molecules of the bitter taste transduction pathway by epithelial cells of intrapulmonary airways. Life Sci 2010; 86:281-8. [DOI: 10.1016/j.lfs.2009.12.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 12/16/2009] [Accepted: 12/28/2009] [Indexed: 11/23/2022]
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