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The structure of the Cyberlindnera jadinii genome and its relation to Candida utilis analyzed by the occurrence of single nucleotide polymorphisms. J Biotechnol 2015; 211:20-30. [PMID: 26150016 DOI: 10.1016/j.jbiotec.2015.06.423] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 06/18/2015] [Accepted: 06/29/2015] [Indexed: 11/22/2022]
Abstract
The yeast Cyberlindnera jadinii is a close relative of Candida utilis that is being used in the food and feed industries. Here, we present the 12.7Mb genome sequence of C. jadinii strain CBS 1600 generated by next generation sequencing. The deduced draft genome sequence consists of seven large scaffolds analogous to the seven largest chromosomes of C. utilis. An automated annotation of the C. jadinii genome identified 6147 protein-coding sequences. The level of ploidy for both genomes was analyzed by calling single nucleotide polymorphisms (SNPs) and was verified measuring nuclear DNA contents by florescence activated cell sorting (FACS). Both analyses determined the level of ploidy to diploid for C. jadinii and to triploid for C. utilis. However, SNP calling for C. jadinii also identified scaffold regions that seem to be haploid, triploid or tetraploid.
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52
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Arkowitz RA, Bassilana M. Regulation of hyphal morphogenesis by Ras and Rho small GTPases. FUNGAL BIOL REV 2015. [DOI: 10.1016/j.fbr.2015.02.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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53
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Pérez P, Portales E, Santos B. Rho4 interaction with exocyst and septins regulates cell separation in fission yeast. MICROBIOLOGY-SGM 2015; 161:948-959. [PMID: 25724972 DOI: 10.1099/mic.0.000062] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 02/18/2015] [Indexed: 12/17/2022]
Abstract
Rho GTPases are small proteins present in all eukaryotic cells, from yeast to mammals, with a function in actin organization and morphogenetic processes. Schizosaccharomyces pombe Rho4 is not essential but it displays a role during cell separation at high temperature. In fact, Rho4 is involved in the secretion of the hydrolytic enzymes that are required for cell septum degradation during this process. In rho4Δ cells, vesicles accumulate in the septum area and the glucanases Eng1 and Agn1 are not secreted to the culture medium. The localization of Eng1 and Agn1 depends on the exocyst and the septins. The exocyst is a conserved multiprotein complex important for the targeting and fusion of Golgi-derived vesicles with the plasma membrane. Septins are a family of GTP-binding proteins conserved in eukaryotes that function during cytokinesis. Here we show that Rho4 is required for the proper localization of the exocyst and septins at high temperature. Moreover, pull-down experiments demonstrate that Rho4 can interact with exocyst subunits, such as Sec8 and Exo70, and septin proteins, such as Spn3. We observe that Sec8 preferentially binds to activated GTP-Rho4, suggesting that Sec8 could be an effector of this GTPase. We propose that the interaction of Rho4 with the exocyst and septins confers a precise regulation for the secretion of glucanases at the appropriate place and time during the cell cycle.
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Affiliation(s)
- Pilar Pérez
- Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain
| | - Elvira Portales
- Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain
| | - Beatriz Santos
- Departamento de Microbiología y Genética, Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain.,Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain
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Schmitz HP, Jendretzki A, Wittland J, Wiechert J, Heinisch JJ. Identification of Dck1 and Lmo1 as upstream regulators of the small GTPase Rho5 inSaccharomyces cerevisiae. Mol Microbiol 2015; 96:306-24. [DOI: 10.1111/mmi.12937] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2015] [Indexed: 12/29/2022]
Affiliation(s)
- Hans-Peter Schmitz
- Faculty of Biology/Chemistry, Department of Genetics Barbarastr. 11; University of Osnabrueck; Osnabrueck D-49076 Germany
| | - Arne Jendretzki
- Faculty of Biology/Chemistry, Department of Genetics Barbarastr. 11; University of Osnabrueck; Osnabrueck D-49076 Germany
| | - Janina Wittland
- Faculty of Biology/Chemistry, Department of Genetics Barbarastr. 11; University of Osnabrueck; Osnabrueck D-49076 Germany
| | - Johanna Wiechert
- Faculty of Biology/Chemistry, Department of Genetics Barbarastr. 11; University of Osnabrueck; Osnabrueck D-49076 Germany
| | - Jürgen J. Heinisch
- Faculty of Biology/Chemistry, Department of Genetics Barbarastr. 11; University of Osnabrueck; Osnabrueck D-49076 Germany
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Nishimura S, Tokukura M, Ochi J, Yoshida M, Kakeya H. Balance between exocytosis and endocytosis determines the efficacy of sterol-targeting antibiotics. ACTA ACUST UNITED AC 2014; 21:1690-9. [PMID: 25500221 DOI: 10.1016/j.chembiol.2014.10.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 09/26/2014] [Accepted: 10/30/2014] [Indexed: 02/03/2023]
Abstract
Antifungals targeting membrane ergosterol are longstanding, yet indispensable drugs in clinical use. However, the mechanisms by which the cellular membrane domains recognized by these antibiotics are generated remain largely unknown. Here, we demonstrate that the balance between endocytosis and exocytosis in membrane trafficking is a critical factor in the action of sterol-targeting antibiotics. When fission yeast cells were treated with manumycin A, cellular binding and the action of the antifungals filipin, amphotericin B, and theonellamides, all of which are ergosterol-binders, were abolished. Additionally, manumycin A treatment attenuated Cdc42 activity and inhibited exocytosis, while endocytosis was only moderately suppressed. Similar defects in membrane trafficking could be reproduced by heat shock and genetic perturbation, which also abolished the action of the antibiotics. We propose that exocytosis and endocytosis respectively supply and internalize the specific plasma membrane domains recognized by sterol-targeting antibiotics.
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Affiliation(s)
- Shinichi Nishimura
- Division of Bioinformatics and Chemical Genomics, Department of System Chemotherapy and Molecular Sciences, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
| | - Masato Tokukura
- Division of Bioinformatics and Chemical Genomics, Department of System Chemotherapy and Molecular Sciences, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Junko Ochi
- Division of Bioinformatics and Chemical Genomics, Department of System Chemotherapy and Molecular Sciences, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Minoru Yoshida
- Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198, Japan
| | - Hideaki Kakeya
- Division of Bioinformatics and Chemical Genomics, Department of System Chemotherapy and Molecular Sciences, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
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Oscillatory AAA+ ATPase Knk1 constitutes a novel morphogenetic pathway in fission yeast. Proc Natl Acad Sci U S A 2014; 111:17899-904. [PMID: 25422470 DOI: 10.1073/pnas.1407226111] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cellular morphogenesis relies partly on cell polarization by the cytoskeleton. In the fission yeast Schizosaccharomyces pombe, it is well established that microtubules (MTs) deliver the spatial cue Tea1, a kelch repeat protein, to the tip regions to direct the growth machinery at the cell tips driving the linear extension of the rod-shaped organism to maintain a straight long axis. Here, we report the characterization of Knk1 (kink), a previously unidentified member of the superfamily of ATPases associated with various cellular activities (AAA(+)), whose deletion causes a unique morphological defect characterized by the formation of kinks close to cell tips. Through genetic analysis, we place Knk1 into a novel pathway controlling cell shape independently of MTs and Tea1. Knk1 localizes at cell tips. Its localization is mediated by the Knk1 N terminus and is enhanced upon ATP binding to the C-terminal ATPase domain. Furthermore, Knk1 tip recruitment is regulated by SRC-like adaptor 2 (Sla2) and cell division cycle 42 (Cdc42) independently of Sla2's role in endocytosis. Finally, we discovered that Knk1 shows an anticorrelated oscillatory behavior between the two cell tips at a periodicity that is different from the reported oscillatory Cdc42 dynamics.
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Wang N, Wang M, Zhu YH, Grosel TW, Sun D, Kudryashov DS, Wu JQ. The Rho-GEF Gef3 interacts with the septin complex and activates the GTPase Rho4 during fission yeast cytokinesis. Mol Biol Cell 2014; 26:238-55. [PMID: 25411334 PMCID: PMC4294672 DOI: 10.1091/mbc.e14-07-1196] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Rho GTPases, activated by Rho guanine nucleotide exchange factors (GEFs), are conserved molecular switches for signal transductions that regulate diverse cellular processes, including cell polarization and cytokinesis. The fission yeast Schizosaccharomyces pombe has six Rho GTPases (Cdc42 and Rho1-Rho5) and seven Rho GEFs (Scd1, Rgf1-Rgf3, and Gef1-Gef3). The GEFs for Rho2-Rho5 have not been unequivocally assigned. In particular, Gef3, the smallest Rho GEF, was barely studied. Here we show that Gef3 colocalizes with septins at the cell equator. Gef3 physically interacts with septins and anillin Mid2 and depends on them to localize. Gef3 coprecipitates with GDP-bound Rho4 in vitro and accelerates nucleotide exchange of Rho4, suggesting that Gef3 is a GEF for Rho4. Consistently, Gef3 and Rho4 are in the same genetic pathways to regulate septum formation and/or cell separation. In gef3∆ cells, the localizations of two potential Rho4 effectors--glucanases Eng1 and Agn1--are abnormal, and active Rho4 level is reduced, indicating that Gef3 is involved in Rho4 activation in vivo. Moreover, overexpression of active Rho4 or Eng1 rescues the septation defects of mutants containing gef3∆. Together our data support that Gef3 interacts with the septin complex and activates Rho4 GTPase as a Rho GEF for septation in fission yeast.
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Affiliation(s)
| | - Mo Wang
- Department of Molecular Genetics
| | | | | | | | | | - Jian-Qiu Wu
- Department of Molecular Genetics Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210
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Nagawa S, Xu T, Yang Z. RHO GTPase in plants: Conservation and invention of regulators and effectors. Small GTPases 2014; 1:78-88. [PMID: 21686259 DOI: 10.4161/sgtp.1.2.14544] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Revised: 12/13/2010] [Accepted: 12/20/2010] [Indexed: 12/30/2022] Open
Abstract
Plants possess a single subfamily of Rho GTPases, ROP, which does usual things as do Rho-family GTPases in animal and fungal systems, namely participating in the spatial control of cellular processes by signaling to the cytoskeleton and vesicular trafficking. As one would expect, ROPs are modulated by conserved regulators such as DHR2-type GEFs, RhoGAPs and Rho GDIs. What is surprising is that plants have invented new regulators such as PRONE-type GEFs (known as RopGEFs) and effectors such as RICs and ICRs/RIPs in the regulation of the cytoskeleton and vesicular trafficking. This review will discuss recent work on characterizing ROP regulators and effectors as well as addressing why and how a mixture of conserved and novel Rho signaling mechanisms is utilized to modulate fundamental cellular processes such as cytoskeletal dynamics/reorganization and vesicular trafficking.
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Affiliation(s)
- Shingo Nagawa
- Center for Plant Cell Biology; Department of Botany and Plant Sciences; University of California; Riverside, CA USA
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59
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Engelberg D, Perlman R, Levitzki A. Transmembrane signaling in Saccharomyces cerevisiae as a model for signaling in metazoans: state of the art after 25 years. Cell Signal 2014; 26:2865-78. [PMID: 25218923 DOI: 10.1016/j.cellsig.2014.09.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 09/02/2014] [Indexed: 02/07/2023]
Abstract
In the very first article that appeared in Cellular Signalling, published in its inaugural issue in October 1989, we reviewed signal transduction pathways in Saccharomyces cerevisiae. Although this yeast was already a powerful model organism for the study of cellular processes, it was not yet a valuable instrument for the investigation of signaling cascades. In 1989, therefore, we discussed only two pathways, the Ras/cAMP and the mating (Fus3) signaling cascades. The pivotal findings concerning those pathways undoubtedly contributed to the realization that yeast is a relevant model for understanding signal transduction in higher eukaryotes. Consequently, the last 25 years have witnessed the discovery of many signal transduction pathways in S. cerevisiae, including the high osmotic glycerol (Hog1), Stl2/Mpk1 and Smk1 mitogen-activated protein (MAP) kinase pathways, the TOR, AMPK/Snf1, SPS, PLC1 and Pkr/Gcn2 cascades, and systems that sense and respond to various types of stress. For many cascades, orthologous pathways were identified in mammals following their discovery in yeast. Here we review advances in the understanding of signaling in S. cerevisiae over the last 25 years. When all pathways are analyzed together, some prominent themes emerge. First, wiring of signaling cascades may not be identical in all S. cerevisiae strains, but is probably specific to each genetic background. This situation complicates attempts to decipher and generalize these webs of reactions. Secondly, the Ras/cAMP and the TOR cascades are pivotal pathways that affect all processes of the life of the yeast cell, whereas the yeast MAP kinase pathways are not essential. Yeast cells deficient in all MAP kinases proliferate normally. Another theme is the existence of central molecular hubs, either as single proteins (e.g., Msn2/4, Flo11) or as multisubunit complexes (e.g., TORC1/2), which are controlled by numerous pathways and in turn determine the fate of the cell. It is also apparent that lipid signaling is less developed in yeast than in higher eukaryotes. Finally, feedback regulatory mechanisms seem to be at least as important and powerful as the pathways themselves. In the final chapter of this essay we dare to imagine the essence of our next review on signaling in yeast, to be published on the 50th anniversary of Cellular Signalling in 2039.
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Affiliation(s)
- David Engelberg
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel; CREATE-NUS-HUJ, Cellular & Molecular Mechanisms of Inflammation Programme, National University of Singapore, 1 CREATE Way, Innovation Wing, #03-09, Singapore 138602, Singapore.
| | - Riki Perlman
- Hematology Division, Hadassah Hebrew University Medical Center, POB 12000, 91120 Jerusalem, Israel
| | - Alexander Levitzki
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
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60
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Nordmann D, Lickfeld M, Warnsmann V, Wiechert J, Jendretzki A, Schmitz HP. The small GTP-binding proteins AgRho2 and AgRho5 regulate tip-branching, maintenance of the growth axis and actin-ring-integrity in the filamentous fungus Ashbya gossypii. PLoS One 2014; 9:e106236. [PMID: 25171205 PMCID: PMC4149541 DOI: 10.1371/journal.pone.0106236] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 08/04/2014] [Indexed: 12/02/2022] Open
Abstract
GTPases of the Rho family are important molecular switches that regulate many basic cellular processes. The function of the Rho2 and Rho5 proteins from Saccharomyces cerevisiae and of their homologs in other species is poorly understood. Here, we report on the analysis of the AgRho2 and AgRho5 proteins of the filamentous fungus Ashbya gossypii. In contrast to S. cerevisiae mutants of both encoding genes displayed a strong morphological phenotype. The Agrho2 mutants showed defects in tip-branching, while Agrho5 mutants had a significantly decreased growth rate and failed to maintain their growth axis. In addition, the Agrho5 mutants had highly defective actin rings at septation sites. We also found that a deletion mutant of a putative GDP-GTP-exchange factor (GEF) that was homologous to a Rac-GEF from other species phenocopied the Agrho5 mutant, suggesting that both proteins act in the same pathway, but the AgRho5 protein has acquired functions that are fulfilled by Rac-proteins in other species.
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Affiliation(s)
- Doris Nordmann
- Department of Genetics, University of Osnabrück, Osnabrück, Germany
| | - Manuela Lickfeld
- Department of Genetics, University of Osnabrück, Osnabrück, Germany
| | - Verena Warnsmann
- Department of Genetics, University of Osnabrück, Osnabrück, Germany
| | - Johanna Wiechert
- Department of Genetics, University of Osnabrück, Osnabrück, Germany
| | - Arne Jendretzki
- Department of Genetics, University of Osnabrück, Osnabrück, Germany
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Abstract
The rod is a ubiquitous shape adopted by walled cells from diverse organisms ranging from bacteria to fungi to plants. Although rod-like shapes are found in cells of vastly different sizes and are constructed by diverse mechanisms, the geometric similarities among these shapes across kingdoms suggest that there are common evolutionary advantages, which may result from simple physical principles in combination with chemical and physiological constraints. Here, we review mechanisms of constructing rod-shaped cells and the bases of different biophysical models of morphogenesis, comparing and contrasting model organisms in different kingdoms. We then speculate on possible advantages of the rod shape, and suggest strategies for elucidating the relative importance of each of these advantages.
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Muñoz S, Manjón E, Sánchez Y. The putative exchange factor Gef3p interacts with Rho3p GTPase and the septin ring during cytokinesis in fission yeast. J Biol Chem 2014; 289:21995-2007. [PMID: 24947517 DOI: 10.1074/jbc.m114.548792] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The small GTP-binding proteins of the Rho family and its regulatory proteins play a central role in cytokinetic actomyosin ring assembly and cytokinesis. Here we show that the fission yeast guanine nucleotide exchange factor Gef3p interacts with Rho3p at the division site. Gef3p contains a putative DH homology domain and a BAR/IMD-like domain. The protein localized to the division site late in mitosis, where it formed a ring that did not constrict with actomyosin ring (cytokinetic actomyosin ring) invagination; instead, it split into a double ring that resembled the septin ring. Gef3p co-localized with septins and Mid2p and required septins and Mid2p for its localization. Gef3p interacts physically with the GTP-bound form of Rho3p. Although Gef3p is not essential for cell separation, the simultaneous disruption of gef3(+) and Rho3p-interacting proteins, such as Sec8p, an exocyst component, Apm1p, a subunit of the clathrin adaptor complex or For3p, an actin-polymerizing protein, yielded cells with strong defects in septation and polarity respectively. Our results suggest that interactions between septins and Rho-GEFs provide a new targeting mechanism for GTPases in cytokinesis, in this case probably contributing to Rho3p function in vesicle tethering and vesicle trafficking in the later steps of cell separation.
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Affiliation(s)
- Sofía Muñoz
- From the Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas and Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Zacarías González, s/n. 37007 Salamanca, Spain
| | - Elvira Manjón
- From the Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas and Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Zacarías González, s/n. 37007 Salamanca, Spain
| | - Yolanda Sánchez
- From the Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas and Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Zacarías González, s/n. 37007 Salamanca, Spain
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63
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Chang YC, Khanal Lamichhane A, Garraffo HM, Walter PJ, Leerkes M, Kwon-Chung KJ. Molecular mechanisms of hypoxic responses via unique roles of Ras1, Cdc24 and Ptp3 in a human fungal pathogen Cryptococcus neoformans. PLoS Genet 2014; 10:e1004292. [PMID: 24762475 PMCID: PMC3998916 DOI: 10.1371/journal.pgen.1004292] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 02/21/2014] [Indexed: 12/26/2022] Open
Abstract
Cryptococcus neoformans encounters a low oxygen environment when it enters the human host. Here, we show that the conserved Ras1 (a small GTPase) and Cdc24 (the guanine nucleotide exchange factor for Cdc42) play an essential role in cryptococcal growth in hypoxia. Suppressor studies indicate that PTP3 functions epistatically downstream of both RAS1 and CDC24 in regulating hypoxic growth. Ptp3 shares sequence similarity to the family of phosphotyrosine-specific protein phosphatases and the ptp3Δ strain failed to grow in 1% O2. We demonstrate that RAS1, CDC24 and PTP3 function in parallel to regulate thermal tolerance but RAS1 and CDC24 function linearly in regulating hypoxic growth while CDC24 and PTP3 reside in compensatory pathways. The ras1Δ and cdc24Δ strains ceased to grow at 1% O2 and became enlarged but viable single cells. Actin polarization in these cells, however, was normal for up to eight hours after transferring to hypoxic conditions. Double deletions of the genes encoding Rho GTPase Cdc42 and Cdc420, but not of the genes encoding Rac1 and Rac2, caused a slight growth retardation in hypoxia. Furthermore, growth in hypoxia was not affected by the deletion of several central genes functioning in the pathways of cAMP, Hog1, or the two-component like phosphorylation system that are critical in the cryptococcal response to osmotic and genotoxic stresses. Interestingly, although deletion of HOG1 rescued the hypoxic growth defect of ras1Δ, cdc24Δ, and ptp3Δ, Hog1 was not hyperphosphorylated in these three mutants in hypoxic conditions. RNA sequencing analysis indicated that RAS1, CDC24 and PTP3 acted upon the expression of genes involved in ergosterol biosynthesis, chromosome organization, RNA processing and protein translation. Moreover, growth of the wild-type strain under low oxygen conditions was affected by sub-inhibitory concentrations of the compounds that inhibit these biological processes, demonstrating the importance of these biological processes in the cryptococcal hypoxia response. When Cryptococcus neoformans, an environmental fungal pathogen, enters the human host, it encounters a low oxygen condition. The well conserved Ras1 and Cdc24 proteins are known for their key roles in maintenance of the actin cytoskeletal integrity in eukaryotic cells. In this work, we show a unique role of RAS1 and CDC24 in the growth of C. neoformans in a low oxygen environment. Actin polarization, however, appeared normal in the ras1Δ and cdc24Δ strains under hypoxic conditions for up to eight hours. We show that PTP3 is required for hypoxic growth and it can rescue the hypoxic growth defect in ras1Δ and cdc24Δ. Genetic analysis suggested that RAS1 and CDC24 function linearly while CDC24 and PTP3 function parallelly in regulating hypoxic growth. RNA sequencing combined with analysis by small molecular inhibitors revealed that RAS1, CDC24 and PTP3 regulate several biological processes such as ergosterol biosynthesis, chromosome organization, RNA processing and protein translation which are required in the cryptococcal response to hypoxic conditions.
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Affiliation(s)
- Yun C. Chang
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, NIAID, NIH Bethesda, Maryland, United States of America
- * E-mail:
| | - Ami Khanal Lamichhane
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, NIAID, NIH Bethesda, Maryland, United States of America
| | - H. Martin Garraffo
- Clinical Mass Spectrometry Core, NIDDK, NIH, Bethesda, Maryland, United States of America
| | - Peter J. Walter
- Clinical Mass Spectrometry Core, NIDDK, NIH, Bethesda, Maryland, United States of America
| | - Maarten Leerkes
- Bioinformatics and Computational Biosciences Branch, NIAID, NIH, Bethesda, Maryland, United States of America
| | - Kyung J. Kwon-Chung
- Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, NIAID, NIH Bethesda, Maryland, United States of America
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Putative RhoGAP proteins orchestrate vegetative growth, conidiogenesis and pathogenicity of the rice blast fungus Magnaporthe oryzae. Fungal Genet Biol 2014; 67:37-50. [PMID: 24731806 DOI: 10.1016/j.fgb.2014.03.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 03/02/2014] [Accepted: 03/31/2014] [Indexed: 11/21/2022]
Abstract
Rho GTPases, acting as molecular switches, are involved in the regulation of diverse cellular functions. Rho GTPase activating proteins (Rho GAPs) function as negative regulators of Rho GTPases and are required for a variety of signaling processes in cell development. But the mechanisms underlying Rho GAPs in Rho-mediated signaling pathways in fungi are still elusive. There are eight RhoGAP domain-containing genes annotated in the Magnaporthe oryzae genome. To understand the function of these RhoGAP genes, we generated knockout mutants of each of the RhoGAP genes through a homologous recombination-based method. Phenotypic analysis showed that growth rate of aerial hyphae of the Molrg1 deletion mutant decreased dramatically. The ΔMolrg1 mutant showed significantly reduced conidiation and appressorium formation by germ tubes. Moreover, it lost pathogenicity completely. Deletion of another Rho GAP (MoRga1) resulted in high percentage of larger or gherkin-shaped conidia and slight decrease in conidiation. Appressorial formation of the ΔMoRga1 mutant was delayed significantly on hydrophobic surface, while the development of mycelial growth and pathogenicity in plants was not affected. Confocal fluorescence microscopy imaging showed that MoRga1-GFP localizes to septal pore of the conidium, and this localization pattern requires both LIM and RhoGAP domains. Furthermore, either deleting the LIM or RhoGAP domain or introducing an inactivating R1032A mutation in the RhoGAP domain of MoRga1 caused similar defects as the Morga1 deletion mutant in terms of conidial morphology and appressorial formation, suggesting that MoRga1 is a stage-specific regulator of conidial differentiation by regulating some specific Rho GTPases. In this regard, MoRga1 and MoLrg1 physically interacted with both MoRac1-CA and MoCdc42-CA in the yeast two-hybrid and pull-down assays, suggesting that the actions of these two GAPs are involved in MoRac1 and MoCdc42 pathways. On the other hand, six other putative Rho GAPs (MoRga2 to MoRga7) were dispensable for conidiation, vegetative growth, appressorial formation and pathogenicity, suggesting that these Rho GAPs function redundantly during fungal development. Taking together, Rho GAP genes play important roles in M. oryzae development and infectious processes through coordination and modulation of Rho GTPases.
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65
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Muñoz S, Manjón E, García P, Sunnerhagen P, Sánchez Y. The checkpoint-dependent nuclear accumulation of Rho1p exchange factor Rgf1p is important for tolerance to chronic replication stress. Mol Biol Cell 2014; 25:1137-50. [PMID: 24478458 PMCID: PMC3967976 DOI: 10.1091/mbc.e13-11-0689] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Guanine nucleotide exchange factors control many aspects of cell morphogenesis by turning on Rho-GTPases. The fission yeast exchange factor Rgf1p (Rho gef1) specifically regulates Rho1p during polarized growth and localizes to cortical sites. Here we report that Rgf1p is relocalized to the cell nucleus during the stalled replication caused by hydroxyurea (HU). Import to the nucleus is mediated by a nuclear localization sequence at the N-terminus of Rgf1p, whereas release into the cytoplasm requires two leucine-rich nuclear export sequences at the C-terminus. Moreover, Rgf1p nuclear accumulation during replication arrest depends on the 14-3-3 chaperone Rad24p and the DNA replication checkpoint kinase Cds1p. Both proteins control the nuclear accumulation of Rgf1p by inhibition of its nuclear export. A mutant, Rgf1p-9A, that substitutes nine serine potential phosphorylation Cds1p sites for alanine fails to accumulate in the nucleus in response to replication stress, and this correlates with a severe defect in survival in the presence of HU. In conclusion, we propose that the regulation of Rgf1p could be part of the mechanism by which Cds1p and Rad24p promote survival in the presence of chronic replication stress. It will be of general interest to understand whether the same is true for homologues of Rgf1p in budding yeast and higher eukaryotes.
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Affiliation(s)
- Sofía Muñoz
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, CSIC/Universidad de Salamanca, 37008 Salamanca, Spain Department of Chemistry and Molecular Biology, Lundberg Laboratory, University of Gothenburg, S-405 30 Gothenburg, Sweden
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66
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Abstract
Polarized cell growth requires a well-orchestrated number of events, namely selection of growth site, organization of cytoskeleton elements and delivery of new material to the growth region. The small Rho GTPase Cdc42 has emerged as a major organizer of polarized growth through its participation in many of these events. In the present short review, we focus on the regulation of Cdc42 activity and localization as well as how it controls downstream events necessary for polarized cell growth in Schizosaccharomyces pombe. Owing to the high level of similarity of the polarity pathways, analogies between fission yeast and other model systems can be useful to decipher how cells can actively define their shape by polarized growth.
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Muñoz J, Cortés JCG, Sipiczki M, Ramos M, Clemente-Ramos JA, Moreno MB, Martins IM, Pérez P, Ribas JC. Extracellular cell wall β(1,3)glucan is required to couple septation to actomyosin ring contraction. ACTA ACUST UNITED AC 2013; 203:265-82. [PMID: 24165938 PMCID: PMC3812973 DOI: 10.1083/jcb.201304132] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
β(1,3)glucan is critical for contractile ring positioning and for coupling septum synthesis to constriction of the contractile ring and plasma membrane extension during cytokinesis. Cytokinesis has been extensively studied in different models, but the role of the extracellular cell wall is less understood. Here we studied this process in fission yeast. The essential protein Bgs4 synthesizes the main cell wall β(1,3)glucan. We show that Bgs4-derived β(1,3)glucan is required for correct and stable actomyosin ring positioning in the cell middle, before the start of septum formation and anchorage to the cell wall. Consequently, β(1,3)glucan loss generated ring sliding, oblique positioned rings and septa, misdirected septum synthesis indicative of relaxed rings, and uncoupling between a fast ring and membrane ingression and slow septum synthesis, suggesting that cytokinesis can progress with defective septum pushing and/or ring pulling forces. Moreover, Bgs4-derived β(1,3)glucan is essential for secondary septum formation and correct primary septum completion. Therefore, our results show that extracellular β(1,3)glucan is required for cytokinesis to connect the cell wall with the plasma membrane and for contractile ring function, as proposed for the equivalent extracellular matrix in animal cells.
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Affiliation(s)
- Javier Muñoz
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, 37007 Salamanca, Spain
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68
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Smethurst DG, Dawes IW, Gourlay CW. Actin - a biosensor that determines cell fate in yeasts. FEMS Yeast Res 2013; 14:89-95. [DOI: 10.1111/1567-1364.12119] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 10/15/2013] [Accepted: 10/16/2013] [Indexed: 01/22/2023] Open
Affiliation(s)
| | - Ian W. Dawes
- School of Biotechnology and Biomolecular Sciences; University of NSW; Kensington Sydney NSW Australia
| | - Campbell W. Gourlay
- Kent Fungal Group; School of Biosciences; University of Kent; Canterbury Kent UK
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Muzzy R, Hable W. RAC1 regulates actin arrays during polarity establishment in the brown alga, Silvetia compressa. Dev Biol 2013; 383:28-38. [PMID: 24036312 DOI: 10.1016/j.ydbio.2013.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 08/29/2013] [Accepted: 09/03/2013] [Indexed: 10/26/2022]
Abstract
Multicellular development has evolved independently on numerous occasions and there is great interest in the developmental mechanisms utilized by each of the divergent lineages. Fucoid algae, in the stramenopile lineage (distinct from metazoans, fungi and green plants) have long been used as a model for early development based on unique life cycle characteristics. The initially symmetric fucoid zygote generates a developmental axis that determines not only the site of growth, but also the orientation of the first cell division, whose products have distinct developmental fates. Establishment and maintenance of this growth axis is dependent on formation of a filamentous actin array that directs vesicular movement, depositing new membrane and wall material for development of the rhizoid. What is not well known, is how formation and placement of the actin array is regulated in fucoid algae. A candidate for this function is Rac1, a small GTPase of the highly conserved Rho family, which has been implicated in controlling the formation of actin arrays in diverse eukaryotes. We demonstrate that Rac1 is not only present during formation of the filamentous actin array, but that its localization overlaps with the array in polarizing zygotes. Pharmacologically inhibiting Rac1 activity was shown to impede formation and maintenance of the actin array, and ultimately polar growth. Evidence is provided that a requirement of Rac1 function is its ability to associate with membranes via a post-translationally added lipid tail. Taken together, the data indicate that Rac1 is a necessary participant in establishment of the growth pole, presumably by regulating the placement and formation of the actin array. A role for Rac1 and related proteins in regulating actin is shared by animals, plants, fungi and with this work, brown algae, thus a conserved mechanism for generating polarity is in operation in unique eukaryotic lineages.
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Affiliation(s)
- Rachel Muzzy
- University of Massachusetts Dartmouth, Department of Biology, 285 Old Westport Rd, Dartmouth, MA 02747, USA
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70
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Vjestica A, Zhang D, Liu J, Oliferenko S. Hsp70-Hsp40 chaperone complex functions in controlling polarized growth by repressing Hsf1-driven heat stress-associated transcription. PLoS Genet 2013; 9:e1003886. [PMID: 24146635 PMCID: PMC3798271 DOI: 10.1371/journal.pgen.1003886] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Accepted: 09/03/2013] [Indexed: 01/09/2023] Open
Abstract
How the molecular mechanisms of stress response are integrated at the cellular level remains obscure. Here we show that the cellular polarity machinery in the fission yeast Schizosaccharomyces pombe undergoes dynamic adaptation to thermal stress resulting in a period of decreased Cdc42 activity and altered, monopolar growth. Cells where the heat stress-associated transcription was genetically upregulated exhibit similar growth patterning in the absence of temperature insults. We identify the Ssa2-Mas5/Hsp70-Hsp40 chaperone complex as repressor of the heat shock transcription factor Hsf1. Cells lacking this chaperone activity constitutively activate the heat-stress-associated transcriptional program. Interestingly, they also exhibit intermittent monopolar growth within a physiological temperature range and are unable to adapt to heat stress. We propose that by negatively regulating the heat stress-associated transcription, the Ssa2-Mas5 chaperone system could optimize cellular growth under different temperature regiments. Heat stress, caused by fluctuations in ambient temperature, occurs frequently in nature. How organisms adapt and maintain regular patterns of growth over a range of environmental conditions remain poorly understood. Our work in the simple unicellular yeast Schizosaccharomyces pombe suggests that the heat stress-associated transcription must be repressed by the evolutionary conserved Hsp70-Hsp40 chaperone complex to allow cells to adapt the polarized growth machinery to elevated temperature.
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Affiliation(s)
- Aleksandar Vjestica
- Temasek Life Sciences Laboratory, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Dan Zhang
- Temasek Life Sciences Laboratory, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
| | | | - Snezhana Oliferenko
- Temasek Life Sciences Laboratory, Singapore
- Department of Biological Sciences, National University of Singapore, Singapore
- * E-mail: ,
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71
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Zhu YH, Ye Y, Wu Z, Wu JQ. Cooperation between Rho-GEF Gef2 and its binding partner Nod1 in the regulation of fission yeast cytokinesis. Mol Biol Cell 2013; 24:3187-204. [PMID: 23966468 PMCID: PMC3806657 DOI: 10.1091/mbc.e13-06-0301] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Previous results showed that putative Rho-GEF Gef2 regulates division-site positioning during early cytokinesis in fission yeast. Here Nod1 is identified as a binding partner of Gef2. The two proteins form a complex to regulate division-site positioning and contractile-ring maintenance. In addition, Gef2 binds to GTPases Rho1, Rho4, and Rho5 in vitro. Cytokinesis is the last step of the cell-division cycle, which requires precise spatial and temporal regulation to ensure genetic stability. Rho guanine nucleotide exchange factors (Rho GEFs) and Rho GTPases are among the key regulators of cytokinesis. We previously found that putative Rho-GEF Gef2 coordinates with Polo kinase Plo1 to control the medial cortical localization of anillin-like protein Mid1 in fission yeast. Here we show that an adaptor protein, Nod1, colocalizes with Gef2 in the contractile ring and its precursor cortical nodes. Like gef2∆, nod1∆ has strong genetic interactions with various cytokinesis mutants involved in division-site positioning, suggesting a role of Nod1 in early cytokinesis. We find that Nod1 and Gef2 interact through the C-termini, which is important for their localization. The contractile-ring localization of Nod1 and Gef2 also depends on the interaction between Nod1 and the F-BAR protein Cdc15, where the Nod1/Gef2 complex plays a role in contractile-ring maintenance and affects the septation initiation network. Moreover, Gef2 binds to purified GTPases Rho1, Rho4, and Rho5 in vitro. Taken together, our data indicate that Nod1 and Gef2 function cooperatively in a protein complex to regulate fission yeast cytokinesis.
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Affiliation(s)
- Yi-Hua Zhu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210 Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210 Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
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72
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Cruz S, Muñoz S, Manjón E, García P, Sanchez Y. The fission yeast cell wall stress sensor-like proteins Mtl2 and Wsc1 act by turning on the GTPase Rho1p but act independently of the cell wall integrity pathway. Microbiologyopen 2013; 2:778-94. [PMID: 23907979 PMCID: PMC3831639 DOI: 10.1002/mbo3.113] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 06/07/2013] [Accepted: 06/11/2013] [Indexed: 12/27/2022] Open
Abstract
Sensing stressful conditions that affect the cell wall reorganization is important for yeast survival. Here, we studied two proteins SpWsc1p and SpMtl2p with structural features indicative of plasma membrane-associated cell wall sensors. We found that Mtl2p and Wsc1p act by turning on the Rho1p GTPase. Each gene could be deleted individually without affecting viability, but the deletion of both was lethal and this phenotype was rescued by overexpression of the genes encoding either Rho1p or its GDP/GTP exchange factors (GEFs). In addition, wsc1Δ and mtl2Δ cells showed a low level of Rho1p-GTP under cell wall stress. Mtl2p-GFP (green fluorescent protein) localized to the cell periphery and was necessary for survival under different types of cell wall stress. Wsc1p-GFP was concentrated in patches at the cell tips, it interacted with the Rho-GEF Rgf2p, and its overexpression activated cell wall biosynthesis. Our results are consistent with the notion that cell wall assembly is regulated by two different networks involving Rho1p. One includes signaling from Mtl2p through Rho1p to Pck1p, while the second one implicates signaling from Wsc1p and Rgf2p through Rho1p to activate glucan synthase (GS). Finally, signaling through the mitogen-activated protein kinase (MAPK) Pmk1p remained active in mtl2Δ and wsc1Δ disruptants exposed to cell wall stress, suggesting that the cell wall stress-sensing spectrum of Schizosaccharomyces pombe sensor-like proteins differs from that of Saccharomyces cerevisiae.
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Affiliation(s)
- Sandra Cruz
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca and Departamento de Microbiología y Genética, Universidad de Salamanca, C/Zacarías González s/n., Salamanca, Spain
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73
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Corvest V, Bogliolo S, Follette P, Arkowitz RA, Bassilana M. Spatiotemporal regulation of Rho1 and Cdc42 activity duringCandida albicansfilamentous growth. Mol Microbiol 2013; 89:626-48. [DOI: 10.1111/mmi.12302] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2013] [Indexed: 01/02/2023]
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74
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Abstract
Chemical gradients are used by cells to provide positional information. Two new studies reveal that polarity proteins are highly dynamic in yeast cells responding to a pheromone gradient and suggest that this behavior is important for robust directional growth.
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Affiliation(s)
- Robert A Arkowitz
- Université Nice - Sophia Antipolis, institute of Biology Valrose, Parc Valrose, 06108 Nice, France.
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75
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Yu Y, Li C, Kita A, Katayama Y, Kubouchi K, Udo M, Imanaka Y, Ueda S, Masuko T, Sugiura R. Sip1, an AP-1 accessory protein in fission yeast, is required for localization of Rho3 GTPase. PLoS One 2013; 8:e68488. [PMID: 23840894 PMCID: PMC3698097 DOI: 10.1371/journal.pone.0068488] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 05/29/2013] [Indexed: 11/18/2022] Open
Abstract
Rho family GTPases act as molecular switches to regulate a range of physiological functions, including the regulation of the actin-based cytoskeleton, membrane trafficking, cell morphology, nuclear gene expression, and cell growth. Rho function is regulated by its ability to bind GTP and by its localization. We previously demonstrated functional and physical interactions between Rho3 and the clathrin-associated adaptor protein-1 (AP-1) complex, which revealed a role of Rho3 in regulating Golgi/endosomal trafficking in fission yeast. Sip1, a conserved AP-1 accessory protein, recruits the AP-1 complex to the Golgi/endosomes through physical interaction. In this study, we showed that Sip1 is required for Rho3 localization. First, overexpression of rho3⁺ suppressed defective membrane trafficking associated with sip1-i4 mutant cells, including defects in vacuolar fusion, Golgi/endosomal trafficking and secretion. Notably, Sip1 interacted with Rho3, and GFP-Rho3, similar to Apm1-GFP, did not properly localize to the Golgi/endosomes in sip1-i4 mutant cells at 27°C. Interestingly, the C-terminal region of Sip1 is required for its localization to the Golgi/endosomes, because Sip1-i4-GFP protein failed to properly localize to Golgi/endosomes, whereas the fluorescence of Sip1ΔN mutant protein co-localized with that of FM4-64. Consistently, in the sip1-i4 mutant cells, which lack the C-terminal region of Sip1, binding between Apm1 and Rho3 was greatly impaired, presumably due to mislocalization of these proteins in the sip1-i4 mutant cells. Furthermore, the interaction between Apm1 and Rho3 as well as Rho3 localization to the Golgi/endosomes were significantly rescued in sip1-i4 mutant cells by the expression of Sip1ΔN. Taken together, these results suggest that Sip1 recruits Rho3 to the Golgi/endosomes through physical interaction and enhances the formation of the Golgi/endosome AP-1/Rho3 complex, thereby promoting crosstalk between AP-1 and Rho3 in the regulation of Golgi/endosomal trafficking in fission yeast.
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Affiliation(s)
- Yang Yu
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Cuifang Li
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
- Japan Society for the Promotion of Science, Tokyo, Japan
| | - Ayako Kita
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Yuta Katayama
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Koji Kubouchi
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Masako Udo
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Yukako Imanaka
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Shiho Ueda
- Laboratory of Molecular Cell Biology, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Takashi Masuko
- Laboratory of Molecular Cell Biology, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
| | - Reiko Sugiura
- Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae, Higashi-Osaka, Japan
- * E-mail:
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Hsu JW, Lee FJS. Arf3p GTPase is a key regulator of Bud2p activation for invasive growth in Saccharomyces cerevisiae. Mol Biol Cell 2013; 24:2328-39. [PMID: 23783029 PMCID: PMC3727926 DOI: 10.1091/mbc.e13-03-0136] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The regulation and signaling pathways involved in the invasive growth of yeast have been studied extensively because of their general applicability to fungal pathogenesis. Bud2p, which functions as a GTPase-activating protein (GAP) for Bud1p/Rsr1p, is required for appropriate budding patterns and filamentous growth. The regulatory mechanisms leading to Bud2p activation, however, are poorly understood. In this study, we report that ADP-ribosylation factor 3p (Arf3p) acts as a regulator of Bud2p activation during invasive growth. Arf3p binds directly to the N-terminal region of Bud2p and promotes its GAP activity both in vitro and in vivo. Genetic analysis shows that deletion of BUD1 suppresses the defect of invasive growth in arf3Δ or bud2Δ cells. Lack of Arf3p, like that of Bud2p, causes the intracellular accumulation of Bud1p-GTP. The Arf3p-Bud2p interaction is important for invasive growth and facilitates the Bud2p-Bud1p association in vivo. Finally, we show that under glucose depletion-induced invasion conditions in yeast, more Arf3p is activated to the GTP-bound state, and the activation is independent of Arf3p guanine nucleotide-exchange factor Yel1p. Thus we demonstrate that a novel spatial activation of Arf3p plays a role in regulating Bud2p activation during glucose depletion-induced invasive growth.
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Affiliation(s)
- Jia-Wei Hsu
- Institute of Molecular Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
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77
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78
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The Saccharomyces cerevisiae RhoGAP Rgd1 is phosphorylated by the Aurora B like kinase Ipl1. Biochem Biophys Res Commun 2013; 433:1-5. [PMID: 23454383 DOI: 10.1016/j.bbrc.2013.02.081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 02/20/2013] [Indexed: 11/21/2022]
Abstract
Polarized growth of the yeast Saccharomyces cerevisiae depends on different biological processes and requires several signaling pathways. Signaling is mediated through a set of proteins, which include Rho3p and Rho4p GTPases. Although these two proteins are involved in the control of distinct aspects of polarized growth in yeast, they have a common regulator: the Rgd1 RhoGAP protein. Here we demonstrate that Rgd1p is phosphorylated by the Aurora B like kinase Ipl1 and we observe that loss of Ipl1 function leads to a new Rgd1p distribution in a small part of the cell population.
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79
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Chan E, Nance J. Mechanisms of CDC-42 activation during contact-induced cell polarization. J Cell Sci 2013; 126:1692-702. [PMID: 23424200 DOI: 10.1242/jcs.124594] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Polarization of early embryos provides a foundation to execute essential patterning and morphogenetic events. In Caenorhabditis elegans, cell contacts polarize early embryos along their radial axis by excluding the cortical polarity protein PAR-6 from sites of cell contact, thereby restricting PAR-6 to contact-free cell surfaces. Radial polarization requires the cortically enriched Rho GTPase CDC-42, which in its active form recruits PAR-6 through direct binding. The Rho GTPase activating protein (RhoGAP) PAC-1, which localizes specifically to cell contacts, triggers radial polarization by inactivating CDC-42 at these sites. The mechanisms responsible for activating CDC-42 at contact-free surfaces are unknown. Here, in an overexpression screen of Rho guanine nucleotide exchange factors (RhoGEFs), which can activate Rho GTPases, we identify CGEF-1 and ECT-2 as RhoGEFs that act through CDC-42 to recruit PAR-6 to the cortex. We show that ECT-2 and CGEF-1 localize to the cell surface and that removing their activity causes a reduction in levels of cortical PAR-6. Through a structure-function analysis, we show that the tandem DH-PH domains of CGEF-1 and ECT-2 are sufficient for GEF activity, but that regions outside of these domains target each protein to the cell surface. Finally, we provide evidence suggesting that the N-terminal region of ECT-2 may direct its in vivo preference for CDC-42 over another known target, the Rho GTPase RHO-1. We propose that radial polarization results from a competition between RhoGEFs, which activate CDC-42 throughout the cortex, and the RhoGAP PAC-1, which inactivates CDC-42 at cell contacts.
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Affiliation(s)
- Emily Chan
- Helen L. and Martin S. Kimmel Center for Biology and Medicine at the Skirball Institute of Biomolecular Medicine, NYU School of Medicine, New York, NY 10016, USA
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Madrid M, Fernández-Zapata J, Sánchez-Mir L, Soto T, Franco A, Vicente-Soler J, Gacto M, Cansado J. Role of the fission yeast cell integrity MAPK pathway in response to glucose limitation. BMC Microbiol 2013; 13:34. [PMID: 23398982 PMCID: PMC3572419 DOI: 10.1186/1471-2180-13-34] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Accepted: 02/05/2013] [Indexed: 11/19/2022] Open
Abstract
Background Glucose is a signaling molecule which regulates multiple events in eukaryotic organisms and the most preferred carbon source in the fission yeast Schizosaccharomyces pombe. The ability of this yeast to grow in the absence of glucose becomes strongly limited due to lack of enzymes of the glyoxylate cycle that support diauxic growth. The stress-activated protein kinase (SAPK) pathway and its effectors, Sty1 MAPK and transcription factor Atf1, play a critical role in the adaptation of fission yeast to grow on alternative non-fermentable carbon sources by inducing the expression of fbp1+ gene, coding for the gluconeogenic enzyme fructose-1,6-bisphosphatase. The cell integrity Pmk1 pathway is another MAPK cascade that regulates various processes in fission yeast, including cell wall construction, cytokinesis, and ionic homeostasis. Pmk1 pathway also becomes strongly activated in response to glucose deprivation but its role during glucose exhaustion and ensuing adaptation to respiratory metabolism is currently unknown. Results We found that Pmk1 activation in the absence of glucose takes place only after complete depletion of this carbon source and that such activation is not related to an endogenous oxidative stress. Notably, Pmk1 MAPK activation relies on de novo protein synthesis, is independent on known upstream activators of the pathway like Rho2 GTPase, and involves PKC ortholog Pck2. Also, the Glucose/cAMP pathway is required operative for full activation of the Pmk1 signaling cascade. Mutants lacking Pmk1 displayed a partial growth defect in respiratory media which was not observed in the presence of glucose. This phenotype was accompanied by a decreased and delayed expression of transcription factor Atf1 and target genes fbp1+ and pyp2+. Intriguingly, the kinetics of Sty1 activation in Pmk1-less cells was clearly altered during growth adaptation to non-fermentable carbon sources. Conclusions Unknown upstream elements mediate Pck2-dependent signal transduction of glucose withdrawal to the cell integrity MAPK pathway. This signaling cascade reinforces the adaptive response of fission yeast to such nutritional stress by enhancing the activity of the SAPK pathway.
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Affiliation(s)
- Marisa Madrid
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071 Murcia, Spain.
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81
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Abstract
Brown algae are an extremely interesting, but surprisingly poorly explored, group of organisms. They are one of only five eukaryotic lineages to have independently evolved complex multicellularity, which they express through a wide variety of morphologies ranging from uniseriate branched filaments to complex parenchymatous thalli with multiple cell types. Despite their very distinct evolutionary history, brown algae and land plants share a striking amount of developmental features. This has led to an interest in several aspects of brown algal development, including embryogenesis, polarity, cell cycle, asymmetric cell division and a putative role for plant hormone signalling. This review describes how investigations using brown algal models have helped to increase our understanding of the processes controlling early embryo development, in particular polarization, axis formation and asymmetric cell division. Additionally, the diversity of life cycles in the brown lineage and the emergence of Ectocarpus as a powerful model organism, are affording interesting insights on the molecular mechanisms underlying haploid-diploid life cycles. The use of these and other emerging brown algal models will undoubtedly add to our knowledge on the mechanisms that regulate development in multicellular photosynthetic organisms.
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Affiliation(s)
- Kenny A Bogaert
- Phycology Research Group, Department of Biology, Center for Molecular Phylogenetics and Evolution, Ghent University, Ghent, Belgium
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83
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Role of the guanine nucleotide exchange factor Rom2 in cell wall integrity maintenance of Aspergillus fumigatus. EUKARYOTIC CELL 2012; 12:288-98. [PMID: 23264643 DOI: 10.1128/ec.00246-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Aspergillus fumigatus is a mold and the causal agent of invasive aspergillosis, a systemic disease with high lethality. Recently, we identified and functionally characterized three stress sensors implicated in the cell wall integrity (CWI) signaling of this pathogen, namely, Wsc1, Wsc3, and MidA. Here, we functionally characterize Rom2, a guanine nucleotide exchange factor with essential function for the cell wall integrity of A. fumigatus. A conditional rom2 mutant has severe growth defects under repressive conditions and incorporates all phenotypes of the three cell wall integrity sensor mutants, e.g., the echinocandin sensitivity of the Δwsc1 mutant and the Congo red, calcofluor white, and heat sensitivity of the ΔmidA mutant. Rom2 interacts with Rho1 and shows a similar intracellular distribution focused at the hyphal tips. Our results place Rom2 between the cell surface stress sensors Wsc1, Wsc3, MidA, and Rho1 and their downstream effector mitogen-activated protein (MAP) kinase module Bck1-Mkk2-MpkA.
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84
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Cerone L, Novák B, Neufeld Z. Mathematical model for growth regulation of fission yeast Schizosaccharomyces pombe. PLoS One 2012; 7:e49675. [PMID: 23209589 PMCID: PMC3507836 DOI: 10.1371/journal.pone.0049675] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 10/16/2012] [Indexed: 11/18/2022] Open
Abstract
Regulation of polarised cell growth is essential for many cellular processes including spatial coordination of cell morphology changes during the division cycle. We present a mathematical model of the core mechanism responsible for the regulation of polarised growth dynamics during the fission yeast cell cycle. The model is based on the competition of growth zones localised at the cell tips for a common substrate distributed uniformly in the cytosol. We analyse the bifurcations in this model as the cell length increases, and show that the growth activation dynamics provides an explanation for the new-end take-off (NETO) as a saddle-node bifurcation at which the cell sharply switches from monopolar to bipolar growth. We study the parameter sensitivity of the bifurcation diagram and relate qualitative changes of the growth pattern, e.g. delayed or absent NETO, to previously observed mutant phenotypes. We investigate the effects of imperfect asymmetric cell division, and show that this leads to distinct growth patterns that provide experimentally testable predictions for validating the presented competitive growth zone activation model. Finally we discuss extension of the model for describing mutant cells with more than two growth zones.
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Affiliation(s)
- Luca Cerone
- School of Mathematical Sciences and Complex and Adaptive Systems Laboratory, University College Dublin, Dublin, Ireland
| | - Béla Novák
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | - Zoltán Neufeld
- School of Mathematics and Physics, University of Queensland, Brisbane, Australia
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85
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Signaling regulated endocytosis and exocytosis lead to mating pheromone concentration dependent morphologies in yeast. FEBS Lett 2012; 586:4208-4214. [PMID: 23108052 DOI: 10.1016/j.febslet.2012.10.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 10/01/2012] [Accepted: 10/14/2012] [Indexed: 11/22/2022]
Abstract
Polarized cell morphogenesis requires actin cytoskeleton rearrangement for polarized transport of proteins, organelles and secretory vesicles, which fundamentally underlies cell differentiation and behavior. During yeast mating, Saccharomyces cerevisiae responds to extracellular pheromone gradients by extending polarized projections, which are likely maintained through vesicle transport to (exocytosis) and from (endocytosis) the membrane. We experimentally demonstrate that the projection morphology is pheromone concentration-dependent, and propose the underlying mechanism through mathematical modeling. The inclusion of membrane flux and dynamically evolving cell boundary into our yeast mating signaling model shows good agreement with experimental measurements, and provides a plausible explanation for pheromone-induced cell morphology.
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86
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Fernandez-Piñar P, Alemán A, Sondek J, Dohlman HG, Molina M, Martín H. The Salmonella Typhimurium effector SteC inhibits Cdc42-mediated signaling through binding to the exchange factor Cdc24 in Saccharomyces cerevisiae. Mol Biol Cell 2012; 23:4430-43. [PMID: 23015760 PMCID: PMC3496616 DOI: 10.1091/mbc.e12-03-0243] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Expression of the Salmonella effector SteC in yeast leads to down-regulation of the mating and HOG pathways by Cdc42 inhibition. This is mediated by the SteC N-terminal domain through binding to the GEF Cdc24. SteC alters Cdc24 localization and also interacts with human GEF Vav1, suggesting that SteC could target Cdc42 function in host cells. Intracellular survival of Salmonella relies on the activity of proteins translocated into the host cell by type III secretion systems (T3SS). The protein kinase activity of the T3SS effector SteC is required for F-actin remodeling in host cells, although no SteC target has been identified so far. Here we show that expression of the N-terminal non-kinase domain of SteC down-regulates the mating and HOG pathways in Saccharomyces cerevisiae. Epistasis analyses using constitutively active components of these pathways indicate that SteC inhibits signaling at the level of the GTPase Cdc42. We demonstrate that SteC interacts through its N-terminal domain with the catalytic domain of Cdc24, the sole S. cerevisiae Cdc42 guanine nucleotide exchange factor (GEF). SteC also binds to the human Cdc24-like GEF protein Vav1. Moreover, expression of human Cdc42 suppresses growth inhibition caused by SteC. Of interest, the N-terminal SteC domain alters Cdc24 cellular localization, preventing its nuclear accumulation. These data reveal a novel functional domain within SteC, raising the possibility that this effector could also target GTPase function in mammalian cells. Our results also highlight the key role of the Cdc42 switch in yeast mating and HOG pathways and provide a new tool to study the functional consequences of Cdc24 localization.
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Affiliation(s)
- Pablo Fernandez-Piñar
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, and Instituto Ramón y Cajal de Investigaciones Sanitarias, 28040 Madrid, Spain
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87
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Oda Y, Fukuda H. Initiation of cell wall pattern by a Rho- and microtubule-driven symmetry breaking. Science 2012; 337:1333-6. [PMID: 22984069 DOI: 10.1126/science.1222597] [Citation(s) in RCA: 187] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A specifically patterned cell wall is a determinant of plant cell shape. Yet, the precise mechanisms that underlie initiation of cell wall patterning remain elusive. By using a reconstitution assay, we revealed that ROPGEF4 (Rho of plant guanine nucleotide exchange factor 4) and ROPGAP3 [ROP guanosine triphosphatase (GTPase)-activating protein 3] mediate local activation of the plant Rho GTPase ROP11 to initiate distinct pattern of secondary cell walls in xylem cells. The activated ROP11 recruits MIDD1 to induce local disassembly of cortical microtubules. Conversely, cortical microtubules eliminate active ROP11 from the plasma membrane through MIDD1. Such a mutual inhibitory interaction between active ROP domains and cortical microtubules establishes the distinct pattern of secondary cell walls. This Rho-based regulatory mechanism shows how plant cells initiate and control cell wall patterns to form various cell shapes.
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Affiliation(s)
- Yoshihisa Oda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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88
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Jourdain I, Dooley HC, Toda T. Fission yeast sec3 bridges the exocyst complex to the actin cytoskeleton. Traffic 2012; 13:1481-95. [PMID: 22891673 PMCID: PMC3531892 DOI: 10.1111/j.1600-0854.2012.01408.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 08/10/2012] [Accepted: 08/14/2012] [Indexed: 12/29/2022]
Abstract
The exocyst complex tethers post-Golgi secretory vesicles to the plasma membrane prior to docking and fusion. In this study, we identify Sec3, the missing component of the Schizosaccharomyces pombe exocyst complex (SpSec3). SpSec3 shares many properties with its orthologs, and its mutants are rescued by human Sec3/EXOC1. Although involved in exocytosis, SpSec3 does not appear to mark the site of exocyst complex assembly at the plasma membrane. It does, however, mark the sites of actin cytoskeleton recruitment and controls the organization of all three yeast actin structures: the actin cables, endocytic actin patches and actomyosin ring. Specifically, SpSec3 physically interacts with For3 and sec3 mutants have no actin cables as a result of a failure to polarize this nucleating formin. SpSec3 also interacts with actin patch components and sec3 mutants have depolarized actin patches of reduced endocytic capacity. Finally, the constriction and disassembly of the cytokinetic actomyosin ring is compromised in these sec3 mutant cells. We propose that a role of SpSec3 is to spatially couple actin machineries and their independently polarized regulators. As a consequence of its dual role in secretion and actin organization, Sec3 appears as a major co-ordinator of cell morphology in fission yeast.
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Affiliation(s)
- Isabelle Jourdain
- Cell Regulation Laboratory, London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London, WC2A 3LY, UK.
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89
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Richthammer C, Enseleit M, Sanchez-Leon E, März S, Heilig Y, Riquelme M, Seiler S. RHO1 and RHO2 share partially overlapping functions in the regulation of cell wall integrity and hyphal polarity in Neurospora crassa. Mol Microbiol 2012; 85:716-33. [DOI: 10.1111/j.1365-2958.2012.08133.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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90
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Raudaskoski M, Kothe E, Fowler TJ, Jung EM, Horton JS. Ras and Rho small G proteins: insights from the Schizophyllum commune genome sequence and comparisons to other fungi. Biotechnol Genet Eng Rev 2012; 28:61-100. [PMID: 22616482 DOI: 10.5661/bger-28-61] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Unlike in animal cells and yeasts, the Ras and Rho small G proteins and their regulators have not received extensive research attention in the case of the filamentous fungi. In an effort to begin to rectify this deficiency, the genome sequence of the basidiomycete mushroom Schizophyllum commune was searched for all known components of the Ras and Rho signalling pathways. The results of this study should provide an impetus for further detailed investigations into their role in polarized hyphal growth, sexual reproduction and fruiting body development. These processes have long been the targets for genetic and cell biological research in this fungus.
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Affiliation(s)
- Marjatta Raudaskoski
- Department of Biology, University of Turku, Biocity A, Tykistökatu 6A, FI-20520 Turku, Finland
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91
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Bi E, Park HO. Cell polarization and cytokinesis in budding yeast. Genetics 2012; 191:347-87. [PMID: 22701052 PMCID: PMC3374305 DOI: 10.1534/genetics.111.132886] [Citation(s) in RCA: 217] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Accepted: 11/04/2011] [Indexed: 12/26/2022] Open
Abstract
Asymmetric cell division, which includes cell polarization and cytokinesis, is essential for generating cell diversity during development. The budding yeast Saccharomyces cerevisiae reproduces by asymmetric cell division, and has thus served as an attractive model for unraveling the general principles of eukaryotic cell polarization and cytokinesis. Polarity development requires G-protein signaling, cytoskeletal polarization, and exocytosis, whereas cytokinesis requires concerted actions of a contractile actomyosin ring and targeted membrane deposition. In this chapter, we discuss the mechanics and spatial control of polarity development and cytokinesis, emphasizing the key concepts, mechanisms, and emerging questions in the field.
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Affiliation(s)
- Erfei Bi
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6058, USA.
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92
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Das M, Drake T, Wiley DJ, Buchwald P, Vavylonis D, Verde F. Oscillatory dynamics of Cdc42 GTPase in the control of polarized growth. Science 2012; 337:239-43. [PMID: 22604726 DOI: 10.1126/science.1218377] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Cells promote polarized growth by activation of Rho-family protein Cdc42 at the cell membrane. We combined experiments and modeling to study bipolar growth initiation in fission yeast. Concentrations of a fluorescent marker for active Cdc42, Cdc42 protein, Cdc42-activator Scd1, and scaffold protein Scd2 exhibited anticorrelated fluctuations and oscillations with a 5-minute average period at polarized cell tips. These dynamics indicate competition for active Cdc42 or its regulators and the presence of positive and delayed negative feedbacks. Cdc42 oscillations and spatial distribution were sensitive to the amounts of Cdc42-activator Gef1 and to the activity of Cdc42-dependent kinase Pak1, a negative regulator. Feedbacks regulating Cdc42 oscillations and spatial self-organization appear to provide a flexible mechanism for fission yeast cells to explore polarization states and to control their morphology.
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Affiliation(s)
- Maitreyi Das
- Department of Molecular and Cellular Pharmacology (R-189), University of Miami Miller School of Medicine, Post Office Box 016189, Miami, FL 33101, USA
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93
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Expression of budding yeast IPT1 produces mannosyldiinositol phosphorylceramide in fission yeast and inhibits cell growth. Microbiology (Reading) 2012; 158:1219-1228. [DOI: 10.1099/mic.0.056184-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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94
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Regulation of cell wall biogenesis in Saccharomyces cerevisiae: the cell wall integrity signaling pathway. Genetics 2012; 189:1145-75. [PMID: 22174182 DOI: 10.1534/genetics.111.128264] [Citation(s) in RCA: 617] [Impact Index Per Article: 51.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The yeast cell wall is a strong, but elastic, structure that is essential not only for the maintenance of cell shape and integrity, but also for progression through the cell cycle. During growth and morphogenesis, and in response to environmental challenges, the cell wall is remodeled in a highly regulated and polarized manner, a process that is principally under the control of the cell wall integrity (CWI) signaling pathway. This pathway transmits wall stress signals from the cell surface to the Rho1 GTPase, which mobilizes a physiologic response through a variety of effectors. Activation of CWI signaling regulates the production of various carbohydrate polymers of the cell wall, as well as their polarized delivery to the site of cell wall remodeling. This review article centers on CWI signaling in Saccharomyces cerevisiae through the cell cycle and in response to cell wall stress. The interface of this signaling pathway with other pathways that contribute to the maintenance of cell wall integrity is also discussed.
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95
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Pancaldi V, Saraç ÖS, Rallis C, McLean JR, Převorovský M, Gould K, Beyer A, Bähler J. Predicting the fission yeast protein interaction network. G3 (BETHESDA, MD.) 2012; 2:453-67. [PMID: 22540037 PMCID: PMC3337474 DOI: 10.1534/g3.111.001560] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 01/31/2012] [Indexed: 12/03/2022]
Abstract
A systems-level understanding of biological processes and information flow requires the mapping of cellular component interactions, among which protein-protein interactions are particularly important. Fission yeast (Schizosaccharomyces pombe) is a valuable model organism for which no systematic protein-interaction data are available. We exploited gene and protein properties, global genome regulation datasets, and conservation of interactions between budding and fission yeast to predict fission yeast protein interactions in silico. We have extensively tested our method in three ways: first, by predicting with 70-80% accuracy a selected high-confidence test set; second, by recapitulating interactions between members of the well-characterized SAGA co-activator complex; and third, by verifying predicted interactions of the Cbf11 transcription factor using mass spectrometry of TAP-purified protein complexes. Given the importance of the pathway in cell physiology and human disease, we explore the predicted sub-networks centered on the Tor1/2 kinases. Moreover, we predict the histidine kinases Mak1/2/3 to be vital hubs in the fission yeast stress response network, and we suggest interactors of argonaute 1, the principal component of the siRNA-mediated gene silencing pathway, lost in budding yeast but preserved in S. pombe. Of the new high-quality interactions that were discovered after we started this work, 73% were found in our predictions. Even though any predicted interactome is imperfect, the protein network presented here can provide a valuable basis to explore biological processes and to guide wet-lab experiments in fission yeast and beyond. Our predicted protein interactions are freely available through PInt, an online resource on our website (www.bahlerlab.info/PInt).
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Affiliation(s)
- Vera Pancaldi
- Department of Genetics, Evolution, and Environment and
- UCL Cancer Institute, University College London, London WC1E 6BT, United Kingdom
| | - Ömer S. Saraç
- Cellular Networks and Systems Biology, Biotechnology Center, Dresden University of Technology (TU Dresden), Dresden 01307, Germany, and
| | - Charalampos Rallis
- Department of Genetics, Evolution, and Environment and
- UCL Cancer Institute, University College London, London WC1E 6BT, United Kingdom
| | - Janel R. McLean
- Howard Hughes Medical Institute
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Martin Převorovský
- Department of Genetics, Evolution, and Environment and
- UCL Cancer Institute, University College London, London WC1E 6BT, United Kingdom
| | - Kathleen Gould
- Howard Hughes Medical Institute
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
| | - Andreas Beyer
- Cellular Networks and Systems Biology, Biotechnology Center, Dresden University of Technology (TU Dresden), Dresden 01307, Germany, and
| | - Jürg Bähler
- Department of Genetics, Evolution, and Environment and
- UCL Cancer Institute, University College London, London WC1E 6BT, United Kingdom
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96
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Abstract
Members of the Rab or ARF/Sar branches of the Ras GTPase superfamily regulate almost every step of intracellular membrane traffic. A rapidly growing body of evidence indicates that these GTPases do not act as lone agents but are networked to one another through a variety of mechanisms to coordinate the individual events of one stage of transport and to link together the different stages of an entire transport pathway. These mechanisms include guanine nucleotide exchange factor (GEF) cascades, GTPase-activating protein (GAP) cascades, effectors that bind to multiple GTPases, and positive-feedback loops generated by exchange factor-effector interactions. Together these mechanisms can lead to an ordered series of transitions from one GTPase to the next. As each GTPase recruits a unique set of effectors, these transitions help to define changes in the functionality of the membrane compartments with which they are associated.
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Affiliation(s)
- Emi Mizuno-Yamasaki
- Institute for Molecular and Cellular Regulation, Gunma University, Maebashi 371-8512, Japan.
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97
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Hernández-Cuevas NA, Hernandez-Rivas R, Sosa-Peinado A, Rojo-Domínguez A, Vargas M. Identification and evaluation of inhibitors of the EhGEF1 protein from Entamoeba histolytica. J Mol Recognit 2012; 24:935-44. [PMID: 22038800 DOI: 10.1002/jmr.1137] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The Dbl family of guanine nucleotide exchange factors (GEFs) is made up of a vast array of members that participate in the activation of the Rho family of small GTPases. Dbl-family proteins promote the exchange of guanosine diphosphate/guanosine triphosphate (GDP/GTP) in their target molecules, resulting in the activation of a variety of signaling pathways involved in diverse cellular events, such as actin-cytoskeleton remodeling, cellular invasion, cell movement, and other functions. It has been reported that members of the Dbl family have important roles in several cellular events in Entamoeba histolytica. These include activation of the actin cytoskeleton, cytokinesis, capping, uroid formation, cellular proliferation, erythrophagocytosis, cell migration, and chemotaxis. Here, we report the identification and testing of inhibitors of the E. histolytica guanine nucleotide exchange factor 1 (EhGEF1) protein (the research compounds 2BYRF, 2BY05, 2BYT6, 2BYLX, and 2BYPD), which decreased the in vitro ability of the protein to exchange GDP/GTP at its target GTPases, EhRacG and EhRho1, by 14.9-85.2%. Interestingly, the drug 1,1'-(1,2-phenylene)-bis-(1H-pyrrole-2,5-dione), which completely inhibits the GEF activity of the Trio protein in human cells, decreases the GEF activity of the EhGEF1 protein on the EhRacG and EhRho1 GTPases by 55.7% and 3.2%, respectively. The identification and evaluation of such inhibitors opens up the possibility of obtaining a new pharmacological tool to study the function of amoeba GEF proteins, their roles in various Rho GTPase-mediated signaling pathways, and the repercussions of modulating their activities with respect to several mechanisms related to E. histolytica pathogenesis.
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Affiliation(s)
- N A Hernández-Cuevas
- Departamento de Biomedicina Molecular, Centro de Investigación y de Estudios Avanzados del IPN, México DF, México
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98
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Lichius A, Yáñez-Gutiérrez ME, Read ND, Castro-Longoria E. Comparative live-cell imaging analyses of SPA-2, BUD-6 and BNI-1 in Neurospora crassa reveal novel features of the filamentous fungal polarisome. PLoS One 2012; 7:e30372. [PMID: 22291944 PMCID: PMC3265482 DOI: 10.1371/journal.pone.0030372] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 12/14/2011] [Indexed: 12/15/2022] Open
Abstract
A key multiprotein complex involved in regulating the actin cytoskeleton and secretory machinery required for polarized growth in fungi, is the polarisome. Recognized core constituents in budding yeast are the proteins Spa2, Pea2, Aip3/Bud6, and the key effector Bni1. Multicellular fungi display a more complex polarized morphogenesis than yeasts, suggesting that the filamentous fungal polarisome might fulfill additional functions. In this study, we compared the subcellular organization and dynamics of the putative polarisome components BUD-6 and BNI-1 with those of the bona fide polarisome marker SPA-2 at various developmental stages of Neurospora crassa. All three proteins exhibited a yeast-like polarisome configuration during polarized germ tube growth, cell fusion, septal pore plugging and tip repolarization. However, the localization patterns of all three proteins showed spatiotemporally distinct characteristics during the establishment of new polar axes, septum formation and cytokinesis, and maintained hyphal tip growth. Most notably, in vegetative hyphal tips BUD-6 accumulated as a subapical cloud excluded from the Spitzenkörper (Spk), whereas BNI-1 and SPA-2 partially colocalized with the Spk and the tip apex. Novel roles during septal plugging and cytokinesis, connected to the reinitiation of tip growth upon physical injury and conidial maturation, were identified for BUD-6 and BNI-1, respectively. Phenotypic analyses of gene deletion mutants revealed additional functions for BUD-6 and BNI-1 in cell fusion regulation, and the maintenance of Spk integrity. Considered together, our findings reveal novel polarisome-independent functions of BUD-6 and BNI-1 in Neurospora, but also suggest that all three proteins cooperate at plugged septal pores, and their complex arrangement within the apical dome of mature hypha might represent a novel aspect of filamentous fungal polarisome architecture.
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Affiliation(s)
- Alexander Lichius
- Department of Microbiology, Center for Scientific Research and Higher Education of Ensenada (CICESE), Ensenada, Baja California, Mexico
- Fungal Cell Biology Group, Institute of Cell Biology, Rutherford Building, The University of Edinburgh, Edinburgh, United Kingdom
| | - Mario E. Yáñez-Gutiérrez
- Department of Microbiology, Center for Scientific Research and Higher Education of Ensenada (CICESE), Ensenada, Baja California, Mexico
| | - Nick D. Read
- Fungal Cell Biology Group, Institute of Cell Biology, Rutherford Building, The University of Edinburgh, Edinburgh, United Kingdom
| | - Ernestina Castro-Longoria
- Department of Microbiology, Center for Scientific Research and Higher Education of Ensenada (CICESE), Ensenada, Baja California, Mexico
- * E-mail:
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99
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Dichtl K, Helmschrott C, Dirr F, Wagener J. Deciphering cell wall integrity signalling in Aspergillus fumigatus: identification and functional characterization of cell wall stress sensors and relevant Rho GTPases. Mol Microbiol 2012; 83:506-19. [DOI: 10.1111/j.1365-2958.2011.07946.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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100
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Eliáš M, Klimeš V. Rho GTPases: deciphering the evolutionary history of a complex protein family. Methods Mol Biol 2012; 827:13-34. [PMID: 22144265 DOI: 10.1007/978-1-61779-442-1_2] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Rho GTPases constitute a significant subgroup of the eukaryotic Ras superfamily of small GTPases implicated in the regulation of diverse cellular processes, such as the dynamics of the actin cytoskeleton, establishment, and maintenance of cell polarity and membrane trafficking. Whereas a few eukaryotes lack Rho genes, a majority of species typically bear multiple Rho paralogs, raising a question about the origin of the family and the paths of its diversification in individual eukaryotic lineages. In this chapter, we ruminate on several aspects of the evolutionary history of the Rho family and methodological challenges of its reconstruction. First, we provide an updated survey of Rho GTPases in diverse eukaryotic branches, demonstrating almost ubiquitous occurrence of Rho genes across the eukaryotic phylogeny most consistent with the presence of at least one Rho gene already in the last eukaryotic common ancestor. Second, we discuss the obstacles in reconstructing the history of gene duplications giving rise to the extant diversity of Rho paralogs in different species, and point to numerous limitations posed by the current phylogenetic methodology. Third, as a case study demonstrating various issues of data collection, phylogenetic analyses and interpretations of trees, we present an analysis of the Rho family in the fungal kingdom, revealing the existence of at least four separate paralogs (Cdc42, Rac, Rho1, and Rho4) in early fungi and subsequent potentially independent expansions of the family in different fungal subgroups. We conclude with the warning that the currently dominating perception of the Rho phylogeny is biased by the metazoan (and especially vertebrate) perspective, and a new, more global view is to be worked out when a better genome sampling and more adequate methods of phylogenetic inference are employed.
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Affiliation(s)
- Marek Eliáš
- Faculty of Science, University of Ostrava, Ostrava, Czech Republic.
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