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Musielak M, Sterk CC, Schubert F, Meyer C, Paululat A, Heinisch JJ. The small GTPase KlRho5 responds to oxidative stress and affects cytokinesis. J Cell Sci 2021; 134:271953. [PMID: 34435638 DOI: 10.1242/jcs.258301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 08/19/2021] [Indexed: 01/11/2023] Open
Abstract
Rho5 is the yeast homolog of the human small GTPase Rac1. We characterized the genes encoding Rho5 and the subunits of its dimeric activating guanine-nucleotide-exchange factor (GEF), Dck1 and Lmo1, in the yeast Kluyveromyces lactis. Rapid translocation of the three GFP-tagged components to mitochondria upon oxidative stress and carbon starvation indicate a similar function of KlRho5 in energy metabolism and mitochondrial dynamics as described for its Saccharomyces cerevisiae homolog. Accordingly, Klrho5 deletion mutants are hyper-resistant towards hydrogen peroxide. Moreover, synthetic lethalities of rho5 deletions with key components in nutrient sensing, such as sch9 and gpr1, are not conserved in K. lactis. Instead, Klrho5 deletion mutants display morphological defects with strengthened lateral cell walls and protruding bud scars. The latter result from aberrant cytokinesis, as observed by following the budding process in vivo and by transmission electron microscopy of the bud neck region. This phenotype can be suppressed by KlCDC42G12V, which encodes a hyper-active variant. Data from live-cell fluorescence microscopy support the notion that KlRho5 interferes with the actin moiety of the contractile actomyosin ring, with consequences different from those previously reported for mutants lacking myosin.
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Affiliation(s)
- Marius Musielak
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, Barbarastr. 11, D-49076 Osnabrück, Germany
| | - Carolin C Sterk
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, Barbarastr. 11, D-49076 Osnabrück, Germany
| | - Felix Schubert
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, Barbarastr. 11, D-49076 Osnabrück, Germany
| | - Christian Meyer
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Zoologie, Barbarastr. 11, D-49076 Osnabrück, Germany
| | - Achim Paululat
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Zoologie, Barbarastr. 11, D-49076 Osnabrück, Germany
| | - Jürgen J Heinisch
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, Barbarastr. 11, D-49076 Osnabrück, Germany
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Milk and sugar: Regulation of cell wall synthesis in the milk yeast Kluyveromyces lactis. Eur J Cell Biol 2011; 90:745-50. [DOI: 10.1016/j.ejcb.2011.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Rodicio R, Buchwald U, Schmitz HP, Heinisch JJ. Dissecting sensor functions in cell wall integrity signaling in Kluyveromyces lactis. Fungal Genet Biol 2007; 45:422-35. [PMID: 17827039 DOI: 10.1016/j.fgb.2007.07.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Revised: 07/24/2007] [Accepted: 07/25/2007] [Indexed: 10/23/2022]
Abstract
KlWSC1, KlWSC2/3 and KlMID2, which encode putative plasma membrane sensors for cell wall integrity signaling in Kluyveromyces lactis, were cloned and characterized. Double and triple deletion mutants show severe cell integrity defects, indicating overlapping functions. The Klwsc1 Klmid2 double deletion phenotype can be suppressed by overexpression of the downstream components KlROM2, KlPKC1 and KlBCK1. KlWsc1 sensor domain analyses showed that an amino-terminal elongation as well as an extension within the cytoplasmic domain are dispensable for function. Heterologous complementation by KlMID2 and KlWSC1 in Saccharomyces cerevisiae is only achieved upon overexpression. In contrast to ScMID2, ScWSC1 complements in K. lactis. Functional studies with chimeric Mid2 constructs indicate that species specificity is mainly conferred by the extracellular domain. Sensor-GFP fusions localize to the plasma membrane, with a cell cycle dependent distribution of KlWsc1-GFP. Both Wsc-type sensors concentrate in discrete spots within the plasma membrane.
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Affiliation(s)
- Rosaura Rodicio
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, Barbarastr. 11, D-49076 Osnabrück, Germany
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Chen RE, Thorner J. Function and regulation in MAPK signaling pathways: lessons learned from the yeast Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1773:1311-40. [PMID: 17604854 PMCID: PMC2031910 DOI: 10.1016/j.bbamcr.2007.05.003] [Citation(s) in RCA: 442] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Revised: 05/02/2007] [Accepted: 05/04/2007] [Indexed: 10/23/2022]
Abstract
Signaling pathways that activate different mitogen-activated protein kinases (MAPKs) elicit many of the responses that are evoked in cells by changes in certain environmental conditions and upon exposure to a variety of hormonal and other stimuli. These pathways were first elucidated in the unicellular eukaryote Saccharomyces cerevisiae (budding yeast). Studies of MAPK pathways in this organism continue to be especially informative in revealing the molecular mechanisms by which MAPK cascades operate, propagate signals, modulate cellular processes, and are controlled by regulatory factors both internal to and external to the pathways. Here we highlight recent advances and new insights about MAPK-based signaling that have been made through studies in yeast, which provide lessons directly applicable to, and that enhance our understanding of, MAPK-mediated signaling in mammalian cells.
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Affiliation(s)
- Raymond E Chen
- Division of Biochemistry and Molecular Biology, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720-3202, USA
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Rodicio R, Koch S, Schmitz HP, Heinisch JJ. KlRHO1 and KlPKC1 are essential for cell integrity signalling in Kluyveromyces lactis. Microbiology (Reading) 2006; 152:2635-2649. [PMID: 16946259 DOI: 10.1099/mic.0.29105-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cell integrity in yeasts is ensured by a rigid cell wall whose synthesis is triggered by a MAP kinase-mediated signal-transduction cascade. Upstream regulatory components of this pathway inSaccharomyces cerevisiaeinvolve a single protein kinase C, which is regulated by interaction with the small GTPase Rho1. Here, two genes were isolated which encode these proteins fromKluyveromyces lactis(KlPKC1andKlRHO1). Sequencing showed ORFs which encode proteins of 1161 and 208 amino acids, respectively. The deduced proteins shared 59 and 85 % overall amino acid identities, respectively, with their homologues fromS. cerevisiae. Null mutants in both genes were non-viable, as shown by tetrad analyses of the heterozygous diploid strains. Overexpression of theKlRHO1gene under the control of theScGAL1promoter severely impaired growth in bothS. cerevisiaeandK. lactis. On the other hand, a similar construct withKlPKC1did not show a pronounced phenotype. Two-hybrid analyses showed interaction between Rho1 and Pkc1 for theK. lactisproteins and theirS. cerevisiaehomologues. A green fluorescent protein (GFP) fusion to the C-terminal end of KlPkc1 located the protein to patches in the growing bud, and at certain stages of the division process also to the bud neck. N-terminal GFP fusions to KlRho1 localized mainly to the cell surface (presumably the cytoplasmic side of the plasma membrane) and to the vacuole, with some indications of traffic from the former to the latter. Thus, KlPkc1 and KlRho1 have been shown to serve vital functions inK. lactis, to interact in cell integrity signalling and to traffic between the plasma membrane and the vacuole.
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Affiliation(s)
- Rosaura Rodicio
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, 33006 Oviedo, Spain
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, Barbarastr. 11, 49076 Osnabrück, Germany
| | - Sabrina Koch
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, Barbarastr. 11, 49076 Osnabrück, Germany
| | - Hans-Peter Schmitz
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, Barbarastr. 11, 49076 Osnabrück, Germany
| | - Jürgen J Heinisch
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, Barbarastr. 11, 49076 Osnabrück, Germany
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Tang RJ, Breger J, Idnurm A, Gerik KJ, Lodge JK, Heitman J, Calderwood SB, Mylonakis E. Cryptococcus neoformans gene involved in mammalian pathogenesis identified by a Caenorhabditis elegans progeny-based approach. Infect Immun 2006; 73:8219-25. [PMID: 16299318 PMCID: PMC1307092 DOI: 10.1128/iai.73.12.8219-8225.2005] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Caenorhabditis elegans can serve as a substitute host for the study of microbial pathogenesis. We found that mutations in genes of the fungal pathogen Cryptococcus neoformans involved in mammalian virulence allow C. elegans to produce greater numbers of progeny than when exposed to wild-type fungus. We used this property to screen a library of C. neoformans mutants for strains that permit larger C. elegans brood sizes. In this screen, we identified a gene homologous to Saccharomyces cerevisiae ROM2. C. neoformans rom2 mutation resulted in a defect in mating and growth defects at elevated temperature or in the presence of cell wall or hyperosmolar stresses. An effect of the C. neoformans rom2 mutation in virulence was confirmed in a murine inhalation infection model. We propose that a screen for progeny-permissive mutants of microorganisms can serve as a high-throughput method for identifying novel loci related to mammalian pathogenesis.
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Affiliation(s)
- Robin J Tang
- Division of Infectious Diseases, Massachusetts General Hospital, Gray-Jackson 504, 55 Fruit Street, Boston, MA 02114, USA
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Uccelletti D, Staneva D, Rufini S, Venkov P, Palleschi C. Enhanced secretion of heterologous proteins in Kluyveromyces lactis by overexpression of the GDP-mannose pyrophosphorylase, KlPsa1p. FEMS Yeast Res 2005; 5:735-46. [PMID: 15851102 DOI: 10.1016/j.femsyr.2005.01.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2004] [Revised: 11/26/2004] [Accepted: 01/19/2005] [Indexed: 11/30/2022] Open
Abstract
GDP-mannose is the mannosyl donor for the glycosylation reactions and is synthesized by GDP-mannose pyrophosphorylase from GTP and d-mannose-1-phosphate; in Saccharomyces cerevisiae this enzyme is encoded by the PSA1/VIG9/SRB1 gene. We isolated the Kluyveromyces lactis KlPSA1 gene by complementing the osmotic growth defects of S. cerevisiae srb1/psa1 mutants. KlPsa1p displayed a high degree of similarity with other GDP-mannose pyrophosphorylases and was demonstrated to be the functional homologue of S. cerevisiae Psa1p. Phenotypic analysis of a K. lactis strain overexpressing the KlPSA1 gene revealed changes in the cell wall assembly. Increasing the KlPSA1 copy number restored the defects in O-glycosylation, but not those in N-glycosylation, that occur in K. lactis cells depleted for the hexokinase Rag5p. Overexpression of GDP-mannose pyrophosphorylase also enhanced heterologous protein secretion in K. lactis as assayed by using the recombinant human serum albumin and the glucoamylase from Arxula adeninivorans.
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Affiliation(s)
- Daniela Uccelletti
- Department of Developmental and Cell Biology, University of Rome La Sapienza, Rome, Italy
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Gerik KJ, Donlin MJ, Soto CE, Banks AM, Banks IR, Maligie MA, Selitrennikoff CP, Lodge JK. Cell wall integrity is dependent on the PKC1 signal transduction pathway in Cryptococcus neoformans. Mol Microbiol 2005; 58:393-408. [PMID: 16194228 DOI: 10.1111/j.1365-2958.2005.04843.x] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cell wall biogenesis and integrity are crucial for fungal growth, pathogenesis and survival, and are attractive targets for antifungal therapy. In this study, we identify, delete and analyse mutant strains for 10 genes involved in the PKC1 signal transduction pathway and its regulation in Cryptococcus neoformans. The kinases Bck1 and Mkk2 are critical for maintaining integrity, and deletion of each of these causes severe phenotypes different from each other. In stark contrast to results seen in Saccharomyces cerevisiae, a deletion in LRG1 has severe repercussions for the cell, and one in ROM2 has little effect. Also surprisingly, the phosphatase Ppg1 is crucial for cell integrity. These data indicate that the mechanisms of maintaining cell integrity differ between the two fungi. Deletions in SSD1 and PUF4, potential alternative regulators of cell integrity, also exhibit phenotypes. This is the first comprehensive analysis examining genes involved the maintenance of cell integrity in C. neoformans and sets the foundation for future biochemical and virulence studies.
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Affiliation(s)
- Kimberly J Gerik
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, 1402 S Grand Boulevard, Saint Louis, MO 63104, USA
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Heinisch JJ. Baker's yeast as a tool for the development of antifungal kinase inhibitors—targeting protein kinase C and the cell integrity pathway. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2005; 1754:171-82. [PMID: 16216564 DOI: 10.1016/j.bbapap.2005.07.032] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Revised: 07/15/2005] [Accepted: 07/16/2005] [Indexed: 01/27/2023]
Abstract
Today, the yeast Saccharomyces cerevisiae is probably the best-studied eukaryotic organism. This review first focuses on the signaling process which is mediated by the unique yeast protein kinase C (Pkc1p) and a downstream mitogen-activated protein kinase (MAPK) cascade. This pathway ensures cellular integrity by sensing cell surface stress and controlling cell wall biosynthesis and progression through the cell cycle. The domain structure of Pkc1p is conserved from yeast to humans. A yeast system for heterologous expression of specific domains in a chimeric yeast/mammalian PKC enzyme ("domain shuffling") is depicted. It is also proposed how this system could be employed for the study of protein kinase inhibitors in high-throughput screens. Moreover, a reporter assay that allows a quantitative readout of the activity of the cell integrity signaling pathway is introduced. Since a variety of protein kinases take part in the signal transduction, this broadens the range of targets for potential inhibitors.
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Affiliation(s)
- Jürgen J Heinisch
- Universität Osnabrück, Fachbereich Biologie/Chemie, AG Genetik, Barbarastr. 11, D-49069 Osnabrück, Germany.
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Klinner U, Schäfer B. Genetic aspects of targeted insertion mutagenesis in yeasts. FEMS Microbiol Rev 2004; 28:201-23. [PMID: 15109785 DOI: 10.1016/j.femsre.2003.10.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2003] [Revised: 08/20/2003] [Accepted: 10/02/2003] [Indexed: 11/16/2022] Open
Abstract
Targeted insertion mutagenesis is a main molecular tool of yeast science initially applied in Saccharomyces cerevisiae. The method was extended to fission yeast Schizosaccharomyces pombe and to "non-conventional" yeast species, which show specific properties of special interest to both basic and applied research. Consequently, the behaviour of such non-Saccharomyces yeasts is reviewed against the background of the knowledge of targeted insertion mutagenesis in S. cerevisiae. Data of homologous integration efficiencies obtained with circular, ends-in or ends-out vectors in several yeasts are compared. We follow details of targeted insertion mutagenesis in order to recognize possible rate-limiting steps. The route of the vector to the target and possible mechanisms of its integration into chromosomal genes are considered. Specific features of some yeast species are discussed. In addition, similar approaches based on homologous recombination that have been established for the mitochondrial genome of S. cerevisiae are described.
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Affiliation(s)
- U Klinner
- RWTH Aachen, Institut für Biologie IV (Mikrobiologie und Genetik), Worringer Weg, D-52056 Aachen, Germany.
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López ML, Redruello B, Valdés E, Moreno F, Heinisch JJ, Rodicio R. Isocitrate lyase of the yeast Kluyveromyces lactis is subject to glucose repression but not to catabolite inactivation. Curr Genet 2003; 44:305-16. [PMID: 14569415 DOI: 10.1007/s00294-003-0453-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2003] [Revised: 09/13/2003] [Accepted: 09/19/2003] [Indexed: 10/26/2022]
Abstract
KlICL1, encoding the isocitrate lyase of Kluyveromyces lactis, was isolated by complementation of the Saccharomyces cerevisiae icl1 deletion mutant. Sequence analysis revealed an open reading frame of 1626 nucleotides encoding a protein with 542 amino acids. The deduced protein shows extensive homologies to isocitrate lyases from various organisms, with an overall identity of 69% to the enzyme from S. cerevisiae. The KlICL1 gene has two major transcription start-points, located at -113 bp and -95 bp relative to the ATG translation start codon. The gene is expressed on ethanol medium only in respiratory-competent cells. Transcription is repressed by glucose. Mutants carrying a Klcat8 deletion lack the ability to derepress KlICL1 transcription. A Klicl1 deletion mutant does not grow on ethanol medium and lacks any isocitrate lyase activity. A strain lacking the gene KlFBP1, which encodes the gluconeogenic enzyme fructose 1,6-bisphosphatase, lacks the ability to grow on non-fermentable carbon sources. This implies that K. lactis does not contain additional isoenzymes catalyzing either of the reactions. Enzyme assays revealed that neither KlIcl1p nor KlFbp1p are subject to catabolite inactivation. However, the respective enzymes from S. cerevisiae are efficiently inactivated when expressed in K. lactis. Thus, despite the extensive sequence similarities of the enzymes involved, non-fermentative carbohydrate metabolism in the two yeasts displays distinct regulatory properties.
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Affiliation(s)
- M Luz López
- Departamento de Bioquímica y Biología Molecular, Universidad de Oviedo, Edificio Santiago Gascón, 33006 Oviedo, Spain
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Current awareness on yeast. Yeast 2003; 20:1151-8. [PMID: 14598808 DOI: 10.1002/yea.949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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