Zusammenfassung:
Die morphologische Transition von der Knospung zum filamentösen Wachstum ist ein charakteristisches Merkmal vieler pathogener Pilze. Auch der Maisbrandpilz Ustilago maydis zeigt filamentöses Wachstum während seiner sexuellen Vermehrung. Daher kann er als gutes Modellsystem zum Studium der Mechanismen dienen, die dieser morphologischen Transition zugrunde liegen. Dabei hängt das filamentöse Wachstum von dem kleinen GTP-bindenden Protein Rac1 und seinem Effektor, der p21-aktivierten Kinase Cla4 ab. Kleine GTP-bindende Proteine der Rho-Familie werden durch Guaninnukleotid Austauschfaktoren (GEFs) aktiviert und durch GTPase aktivierende Proteine inaktiviert. Guaninnukleotid Dissoziationsinhibitoren (GDIs) können die Rho-GTPasen aus der Membran extrahieren und im Zytosol zurückhalten. In dieser Arbeit wurde gezeigt, dass die durch den b Kreuzungstyp kontrollierte morphologische Transition von U. maydis zur Stimulation der Rac1-Aktivität durch den GEF Cdc24 führt. Während des polaren Wachstums rekrutiert Cdc24 Rac1 in einen durch das Gerüstprotein Bem1 koordinierten Komplex mit Cla4, der an der polar wachsenden Spitze lokalisiert. Die Komplexbildung führt zur Degradierung von Cdc24, die durch die Cla4-abhängige Phosphorylierung des GEFs induziert wird. Die Expression von stabilisierten Cdc24 Varianten interferiert mit dem filamentösen Wachstum und der Pflanzeninfektion, was auf eine bedeutende Rolle des Cdc24 Abbaus während des polaren Wachstums von U. maydis hinweist. Es kann gefolgert werden, dass die Degradierung von Cdc24 die Aktivität des Bem1/Rac1-GTP/Cla4 Komplexes auf die apikale Wachstumszone beschränkt. Diese negative Rückkopplungsregulation ist von der Fähigkeit von Rac1 abhängig, zwischen der inaktiven GDP-gebundenen Konformation und dem aktiven GTP-gebundenen Zustand zu wechseln. Aus diesem Grund wurden die distinkten Funktionen von drei Rac1-GAPs und dem GDI Rdi1 während des polaren Wachstums untersucht. Es konnte gezeigt werden, dass die GAP-katalysierte Inaktivierung des Bem1/Rac1-GTP/Cla4 Komplexes und die Internalisierung von membrangebundenem Rac1 durch Rdi1, in Zusammenarbeit mit der aktinabhängigen Endozytose, für das polare Spitzenwachstum von essentieller Bedeutung sind.
Die Rho-GTPasen Rac1 und Cdc42 sind eng verwandte hoch konservierte Regulatoren des Zytoskeletts und haben in U. maydis spezifische Funktionen. In dieser Arbeit konnte gezeigt werden, dass Rac1 im Komplex mit Bem1 und Cla4 durch die Mutante Cdc42F56W, die eine hohe Affinität zu Cdc24 besitzt, substituiert werden kann. Daraus lässt sich folgern, dass während des polaren Wachstums von U. maydis allein die selektive Aktivierung durch den GEF Cdc24 bestimmt, welches Rho-Protein als zentrale GTPase des Signalmoduls fungiert.
Bibliographie / References
- Annette Bauer, Dissertation, 2011, Titel: " Die Rolle von Ras1 bei der Regulation des polaren Wachstums in Ustilago maydis " Philipps-Universität Marburg, Fachbereich Biologie, Genetik Sabrina Patzak, Diplomarbeit, 2007
- Guipponi, M., Scott, H. S., Chen, H., Schebesta, A., Rossier, C. and Antonarakis, S. E. (1998) Two isoforms of a human intersectin (ITSN) protein are produced by brain-specific alternative splicing in a stop codon. Genomics, 53, 369–376.
- Wedlich-Söldner, R., Wai, S. C., Schmidt, T. and Li, R. (2004) Robust cell polarity is a dynamic state established by coupling transport and GTPase signaling. J Cell Biol, 166, 889–900.
- Virag, A., Lee, M. P., Si, H. and Harris, S. D. (2007) Regulation of hyphal morphogenesis by cdc42 and rac1 homologues in Aspergillus nidulans. Mol Microbiol, 66, 1579–1596.
- Iwase, M., Luo, J., Nagaraj, S., Longtine, M., Kim, H. B., Haarer, B. K., Caruso, C., Tong, Z., Pringle, J. R. and Bi, E. (2006) Role of a Cdc42p effector pathway in recruitment of the yeast septins to the presumptive bud site. Mol Biol Cell, 17, 1110–1125.
- Brachmann, A., König, J., Julius, C. and Feldbrügge, M. (2004) A reverse genetic approach for gene- rating gene replacement mutants in Ustilago maydis. Mol Genet Genomics, 272, 216–226.
- Kämper, J., Reichmann, M., Romeis, T., Bölker, M. and Kahmann, R. (1995) Multiallelic recognition: nonself-dependent dimerization of the bE and bW homeodomain proteins in Ustilago maydis. Cell, 81, 73–83.
- Seabra, M. C. and Wasmeier, C. (2004) Controlling the location and activation of Rab GTPases. Curr Opin Cell Biol, 16, 451–457.
- García-Pedrajas, M. D., Nadal, M., Bölker, M., Gold, S. E. and Perlin, M. H. (2008) Sending mixed signals: redundancy vs. uniqueness of signaling components in the plant pathogen, Ustilago maydis. Fungal Genet Biol, 45 Suppl 1, S22–S30.
- García-Mata, R. and Burridge, K. (2007) Catching a GEF by its tail. Trends Cell Biol, 17, 36–43.
- Marinissen, M. J. and Gutkind, J. S. (2005) Scaffold proteins dictate Rho GTPase-signaling specificity. Trends Biochem Sci, 30, 423–426.
- Raftopoulou, M. and Hall, A. (2004) Cell migration: Rho GTPases lead the way. Dev Biol, 265, 23–32.
- Shimada, Y., Gulli, M. P. and Peter, M. (2000) Nuclear sequestration of the exchange factor Cdc24 by Far1 regulates cell polarity during yeast mating. Nat Cell Biol, 2, 117–124.
- Irazoqui, J. E., Gladfelter, A. S. and Lew, D. J. (2003) Scaffold-mediated symmetry breaking by Cdc42p. Nat Cell Biol, 5, 1062–1070.
- Rossman, K. L., Der, C. J. and Sondek, J. (2005) GEF means go: turning on RHO GTPases with guanine nucleotide-exchange factors. Nat Rev Mol Cell Biol, 6, 167–180.
- Iden, S. and Collard, J. G. (2008) Crosstalk between small GTPases and polarity proteins in cell polarization. Nat Rev Mol Cell Biol, 9, 846–859.
- Schmidt, A. and Hall, A. (2002) Guanine nucleotide exchange factors for Rho GTPases: turning on the switch. Genes Dev, 16, 1587–1609.
- Gulli, M. P. and Peter, M. (2001) Temporal and spatial regulation of Rho-type guanine-nucleotide exchange factors: the yeast perspective. Genes Dev, 15, 365–379.
- Leveleki, L., Mahlert, M., Sandrock, B. and Bölker, M. (2004) The PAK family kinase Cla4 is required for budding and morphogenesis in Ustilago maydis. Mol Microbiol, 54, 396–406.
- Mahlert, M., Leveleki, L., Hlubek, A., Sandrock, B. and Bölker, M. (2006) Rac1 and Cdc42 regulate hyphal growth and cytokinesis in the dimorphic fungus Ustilago maydis. Mol Microbiol, 59, 567–578.
- Hlubek, A., Schink, K. O., Mahlert, M., Sandrock, B. and Bölker, M. (2008) Selective activation by the guanine nucleotide exchange factor Don1 is a main determinant of Cdc42 signalling specificity in Ustilago maydis. Mol Microbiol, 68, 615–623.
- Kwon, M. J., Arentshorst, M., Roos, E. D., van den Hondel, C. A. M. J. J., Meyer, V. and Ram, A. F. J. (2011) Functional characterization of Rho GTPases in Aspergillus niger uncovers conserved and diverged roles of Rho proteins within filamentous fungi. Mol Microbiol, 79, 1151–1167.
- Castillo-Lluva, S., Alvarez-Tabarés, I., Weber, I., Steinberg, G. and Pérez-Martín, J. (2007) Sustained cell polarity and virulence in the phytopathogenic fungus Ustilago maydis depends on an essential cyclin-dependent kinase from the Cdk5/Pho85 family. J Cell Sci, 120, 1584–1595.
- Castagnetti, S., Novák, B. and Nurse, P. (2007) Microtubules offset growth site from the cell centre in fission yeast. J Cell Sci, 120, 2205–2213.
- Cales, C., Hancock, J. F., Marshall, C. J. and Hall, A. (1988) The cytoplasmic protein GAP is impli- cated as the target for regulation by the ras gene product. Nature, 332, 548–51.
- Stress-induced response, localization, and regulation of the Pmk1 cell integrity pathway in Schizosaccharomyces pombe. J Biol Chem, 281, 2033–2043.
- Marco, E., Wedlich-Söldner, R., Li, R., Altschuler, S. J. and Wu, L. F. (2007) Endocytosis optimizes the dynamic localization of membrane proteins that regulate cortical polarity. Cell, 129, 411–422.
- Snaith, H. A. and Sawin, K. E. (2003) Fission yeast mod5p regulates polarized growth through ancho- ring of tea1p at cell tips. Nature, 423, 647–651.
- Nakagawa, M., Fukata, M., Yamaga, M., Itoh, N. and Kaibuchi, K. (2001) Recruitment and activation of Rac1 by the formation of E-cadherin-mediated cell-cell adhesion sites. J Cell Sci, 114, 1829–1838.
- Pál, C., Papp, B. and Lercher, M. J. (2006) An integrated view of protein evolution. Nat Rev Genet, 7, 337–348.
- Lin, R., Bagrodia, S., Cerione, R. and Manor, D. (1997) A novel Cdc42Hs mutant induces cellular transformation. Curr Biol, 7, 794–797.
- Bradford, M. M. (1976) A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem, 72, 248–254.
- Nichols, C. B., Perfect, Z. H. and Alspaugh, J. A. (2007) A Ras1-Cdc24 signal transduction pathway mediates thermotolerance in the fungal pathogen Cryptococcus neoformans. Mol Microbiol, 63, 1118–1130.
- Lechler, T., Jonsdottir, G. A., Klee, S. K., Pellman, D. and Li, R. (2001) A two-tiered mechanism by which Cdc42 controls the localization and activation of an Arp2/3-activating motor complex in yeast. J Cell Biol, 155, 261–70.
- Xu, H. and Wickner, W. (2006) Bem1p is a positive regulator of the homotypic fusion of yeast vacuoles. J Biol Chem, 281, 27158–27166.
- Casamayor, A. and Snyder, M. (2002) Bud-site selection and cell polarity in budding yeast. Curr Opin Microbiol, 5, 179–86.
- Weiss, E. L., Bishop, A. C., Shokat, K. M. and Drubin, D. G. (2000) Chemical genetic analysis of the budding-yeast p21-activated kinase Cla4p. Nat Cell Biol, 2, 677–685.
- Onken, B., Wiener, H., Philips, M. R. and Chang, E. C. (2006) Compartmentalized signaling of Ras in fission yeast. Proc Natl Acad Sci U S A, 103, 9045–9050.
- Zheng, Y., Cerione, R. and Bender, A. (1994) Control of the yeast bud-site assembly GTPase Cdc42. Catalysis of guanine nucleotide exchange by Cdc24 and stimulation of GTPase activity by Bem3. J Biol Chem, 269, 2369–2372.
- Rittinger, K., Walker, P. A., Eccleston, J. F., Nurmahomed, K., Owen, D., Laue, E., Gamblin, S. J. and Smerdon, S. J. (1997a) Crystal structure of a small G protein in complex with the GTPase-activating protein rhoGAP. Nature, 388, 693–697.
- Southern, E. M. (1992) Detection of specific sequences among DNA fragments separated by gel elec- trophoresis. 1975. Biotechnology, 24, 122–139.
- Sharp, P. A., Sugden, B. and Sambrook, J. (1973) Detection of two restriction endonuclease activities in Haemophilus parainfluenzae using analytical agarose–ethidium bromide electrophoresis. Bioche- mistry, 12, 3055–63.
- Andrea Hlubek, Dissertation, 2008, Titel: " Die selektive Aktivierung der kleinen GTPasen Cdc42 und Rac1 durch Guaninnukleotid- Austauschfaktoren bestimmt deren Signalspezifität in Ustilago maydis " Philipps-Universität Marburg, Fachbereich Biologie, Genetik Kay Schink, Dissertation, 2010, Titel: " Funktionelle Analyse von Rho-spezifischen Guaninnukleotidaustauschfaktoren in Ustilago may- dis " Philipps-Universität Marburg, Fachbereich Biologie, Genetik
- (1997) Direct interaction of the Rho GDP dissociation inhibitor with ezrin/radixin/moesin initiates the activation of the Rho small G protein. J Biol Chem, 272, 23371–23375.
- Slaughter, B. D., Das, A., Schwartz, J. W., Rubinstein, B. and Li, R. (2009) Dual modes of cdc42 recycling fine-tune polarized morphogenesis. Dev Cell, 17, 823–835.
- Goryachev, A. B. and Pokhilko, A. V. (2008) Dynamics of Cdc42 network embodies a Turing-type mechanism of yeast cell polarity. FEBS Lett, 582, 1437–1443.
- Kim, S. H., Li, Z. and Sacks, D. B. (2000) E-cadherin-mediated cell-cell attachment activates Cdc42. J Biol Chem, 275, 36999–37005.
- Liu, Y., Shah, K., Yang, F., Witucki, L. and Shokat, K. M. (1998) Engineering Src family protein kinases with unnatural nucleotide specificity. Chem Biol, 5, 91–101.
- Minc, N., Bratman, S. V., Basu, R. and Chang, F. (2009) Establishing new sites of polarization by microtubules. Curr Biol, 19, 83–94.
- Bourne, H. R. (1997) G proteins. The arginine finger strikes again. Nature, 389, 673–674.
- Smith, G. R., Givan, S. A., Cullen, P. and Sprague, G. F. (2002) GTPase-activating proteins for Cdc42. Eukaryot Cell, 1, 469–480.
- Brachmann, A., Weinzierl, G., Kämper, J. and Kahmann, R. (2001) Identification of genes in the bW/bE regulatory cascade in Ustilago maydis. Mol Microbiol, 42, 1047–1063.
- Prehoda, K. E., Scott, J. A., Mullins, R. D. and Lim, W. A. (2000) Integration of multiple signals through cooperative regulation of the N-WASP-Arp2/3 complex. Science, 290, 801–806.
- Martin, S. G. (2009) Microtubule-dependent cell morphogenesis in the fission yeast. Trends Cell Biol, 19, 447–454.
- Masuda, T., Tanaka, K., Nonaka, H., Yamochi, W., Maeda, A. and Takai, Y. (1994) Molecular cloning and characterization of yeast rho GDP dissociation inhibitor. J Biol Chem, 269, 19713–19718.
- Nash, P., Tang, X., Orlicky, S., Chen, Q., Gertler, F. B., Mendenhall, M. D., Sicheri, F., Pawson, T. and Tyers, M. (2001) Multisite phosphorylation of a CDK inhibitor sets a threshold for the onset of DNA replication. Nature, 414, 514–521.
- Salazar, C. and Höfer, T. (2009) Multisite protein phosphorylation–from molecular mechanisms to kinetic models. FEBS J, 276, 3177–3198.
- Hayakawa, M., Matsushima, M., Hagiwara, H., Oshima, T., Fujino, T., Ando, K., Kikugawa, K., Tanaka, H., Miyazawa, K. and Kitagawa, M. (2008) Novel insights into FGD3, a putative GEF for Cdc42, that undergoes SCF(FWD1/beta-TrCP)-mediated proteasomal degradation analogous to that of its homologue FGD1 but regulates cell morphology and motility differently from FGD1. Genes Cells, 13, 329–342.
- Klahre, U., Becker, C., Schmitt, A. C. and Kost, B. (2006) Nt-RhoGDI2 regulates Rac/Rop signaling and polar cell growth in tobacco pollen tubes. Plant J, 46, 1018–1031.
- Shen, Y., Li, N., Wu, S., Zhou, Y., Shan, Y., Zhang, Q., Ding, C., Yuan, Q., Zhao, F., Zeng, R. and Zhu, X. (2008) Nudel binds Cdc42GAP to modulate Cdc42 activity at the leading edge of migrating cells. Dev Cell, 14, 342–353.
- Nishimura, T., Yamaguchi, T., Kato, K., Yoshizawa, M., ichi Nabeshima, Y., Ohno, S., Hoshino, M. and Kaibuchi, K. (2005) PAR-6-PAR-3 mediates Cdc42-induced Rac activation through the Rac GEFs STEF/Tiam1. Nat Cell Biol, 7, 270–277.
- Yamanaka, T., Horikoshi, Y., Suzuki, A., Sugiyama, Y., Kitamura, K., Maniwa, R., Nagai, Y., Yama- shita, A., Hirose, T., Ishikawa, H. and Ohno, S. (2001) PAR-6 regulates aPKC activity in a novel way and mediates cell-cell contact-induced formation of the epithelial junctional complex. Genes Cells, 6, 721–731.
- Kemphues, K. (2000) PARsing embryonic polarity. Cell, 101, 345–348.
- Gulli, M. P., Jaquenoud, M., Shimada, Y., Niederhäuser, G., Wiget, P. and Peter, M. (2000) Phospho- rylation of the Cdc42 exchange factor Cdc24 by the PAK-like kinase Cla4 may regulate polarized growth in yeast. Mol Cell, 6, 1155–1167.
- O´Donnel, K. L. and McLaughlin, D. (1984) Postmeiotic mitosis, basidiospore development, and sep- tation in Ustilago maydis. Mycologica, 76, 486–502.
- Zhang, F. L. and Casey, P. J. (1996) Protein prenylation: molecular mechanisms and functional con- sequences. Annu Rev Biochem, 65, 241–269.
- Sasaki, T., Kikuchi, A., Araki, S., Hata, Y., Isomura, M., Kuroda, S. and Takai, Y. (1990) Purification and characterization from bovine brain cytosol of a protein that inhibits the dissociation of GDP from and the subsequent binding of GTP to smg p25A, a ras p21-like GTP-binding protein. J Biol Chem, 265, 2333–7.
- Titel: " Regulation der Zellknospung durch Rsr1 in Ustilago maydis " Philipps-Universität Marburg, Fachbereich Biologie, Genetik Britta Tillmann, Diplomarbeit, 2008, Titel: " Funktionelle Analyse des BAR-Domänen Rho-GEFs Hot1 in Ustilago maydis " Philipps-Universität Marburg, Fachbereich Biologie, Genetik Florian Rosenthal, Diplomarbeit, 2009,
- Burridge, K. and Wennerberg, K. (2004) Rho and Rac take center stage. Cell, 116, 167–79. 0092-8674 Comment Journal Article Review.
- Perez, P. and Rincón, S. A. (2010) Rho GTPases: regulation of cell polarity and growth in yeasts. Biochem J, 426, 243–253.
- Glynn, J. M., Lustig, R. J., Berlin, A. and Chang, F. (2001) Role of bud6p and tea1p in the interaction between actin and microtubules for the establishment of cell polarity in fission yeast. Curr Biol, 11, 836–845.
- Glomset, J. A. and Farnsworth, C. C. (1994) Role of protein modification reactions in programming interactions between ras-related GTPases and cell membranes. Annu Rev Cell Biol, 10, 181–205.
- Mullis, K., Faloona, F., Scharf, S., Saiki, R., Horn, G. and Erlich, H. (1986) Specific enzymatic ampli- fication of DNA in vitro: the polymerase chain reaction. Cold Spring Harb Symp Quant Biol, 51, 263–73.
- Wedlich-Söldner, R., Altschuler, S., Wu, L. and Li, R. (2003) Spontaneous cell polarization through actomyosin-based delivery of the Cdc42 GTPase. Science, 299, 1231–1235.
- Liu, Y., Bishop, A., Witucki, L., Kraybill, B., Shimizu, E., Tsien, J., Ubersax, J., Blethrow, J., Morgan, D. O. and Shokat, K. M. (1999) Structural basis for selective inhibition of Src family kinases by PP1. Chem Biol, 6, 671–678.
- Snyder, J. T., Worthylake, D. K., Rossman, K. L., Betts, L., Pruitt, W. M., Siderovski, D. P., Der, C. J. and Sondek, J. (2002) Structural basis for the selective activation of Rho GTPases by Dbl exchange factors. Nat Struct Biol, 9, 468–475.
- Wu, S. K., Zeng, K., Wilson, I. A. and Balch, W. E. (1996b) Structural insights into the function of the Rab GDI superfamily. Trends Biochem Sci, 21, 472–476.
- Rittinger, K., Walker, P. A., Eccleston, J. F., Smerdon, S. J. and Gamblin, S. J. (1997b) Structure at 1.65 A of RhoA and its GTPase-activating protein in complex with a transition-state analogue. Nature, 389, 758–762.
- Mata, J. and Nurse, P. (1997) tea1 and the microtubular cytoskeleton are important for generating global spatial order within the fission yeast cell. Cell, 89, 939–949.
- Martin, S. G., McDonald, W. H., Yates, J. R. and Chang, F. (2005) Tea4p links microtubule plus ends with the formin for3p in the establishment of cell polarity. Dev Cell, 8, 479–491.
- Merla, A. and Johnson, D. I. (2000) The Cdc42p GTPase is targeted to the site of cell division in the fission yeast Schizosaccharomyces pombe. Eur J Cell Biol, 79, 469–477.
- Joberty, G., Petersen, C., Gao, L. and Macara, I. G. (2000) The cell-polarity protein Par6 links Par3 and atypical protein kinase C to Cdc42. Nat Cell Biol, 2, 531–539.
- Toenjes, K. A., Sawyer, M. M. and Johnson, D. I. (1999) The guanine-nucleotide-exchange factor Cdc24p is targeted to the nucleus and polarized growth sites. Curr Biol, 9, 1183–1186.
- Kim, H., Yang, P., Catanuto, P., Verde, F., Lai, H., Du, H., Chang, F. and Marcus, S. (2003) The kelch repeat protein, Tea1, is a potential substrate target of the p21-activated kinase, Shk1, in the fission yeast, Schizosaccharomyces pombe. J Biol Chem, 278, 30074–30082.
- Tippit, D. H., Fields, C. T., O'Donnell, K. L., Pickett-Heaps, J. D. and McLaughlin, D. J. (1984) The organization of microtubules during anaphase and telophase spindle elongation in the rust fungus Puccinia. Eur J Cell Biol, 34, 34–44.
- Gérard, A., Mertens, A. E. E., van der Kammen, R. A. and Collard, J. G. (2007) The Par polarity complex regulates Rap1-and chemokine-induced T cell polarization. J Cell Biol, 176, 863–875.
- Wu, C., Lytvyn, V., Thomas, D. Y. and Leberer, E. (1997) The phosphorylation site for Ste20p-like protein kinases is essential for the function of myosin-I in yeast. J Biol Chem, 272, 30623–30626.
- Merla, A. and Johnson, D. I. (2001) The Schizosaccharomyces pombe Cdc42p GTPase signals through Pak2p and the Mkh1p-Pek1p-Spm1p MAP kinase pathway. Curr Genet, 39, 205–209.
- Heimel, K., Scherer, M., Vranes, M., Wahl, R., Pothiratana, C., Schuler, D., Vincon, V., Finkernagel, F., Flor-Parra, I. and Kämper, J. (2010b) The transcription factor Rbf1 is the master regulator for b-mating type controlled pathogenic development in Ustilago maydis. PLoS Pathog, 6.
- Gültekin, H. and Heermann, K. H. (1988) The use of polyvinylidenedifluoride membranes as a general blotting matrix. Anal Biochem, 172, 320–329.
- Wahl, R., Zahiri, A. and Kämper, J. (2010) The Ustilago maydis b mating type locus controls hyphal proliferation and expression of secreted virulence factors in planta. Mol Microbiol, 75, 208–220.
- TrCP-mediated degradation pathway establishes a 'turning off switch' of a Cdc42 guanine nucleotide exchange factor, FGD1. Genes Cells, 10, 241–251.
- Gao, Y., Xing, J., Streuli, M., Leto, T. L. and Zheng, Y. (2001) Trp(56) of rac1 specifies interaction with a subset of guanine nucleotide exchange factors. J Biol Chem, 276, 47530–47541.
- Brefort, T., Doehlemann, G., Mendoza-Mendoza, A., Reissmann, S., Djamei, A. and Kahmann, R. (2009) Ustilago maydis as a Pathogen. Annu Rev Phytopathol, 47, 423–445.
- Snetselaar, Bolker and Kahmann (1996) Ustilago maydis Mating Hyphae Orient Their Growth toward Pheromone Sources. Fungal Genet Biol, 20, 299–312.
- Wu, C., Lee, S. F., Furmaniak-Kazmierczak, E., Côté, G. P., Thomas, D. Y. and Leberer, E. (1996a) Activation of myosin-I by members of the Ste20p protein kinase family. J Biol Chem, 271, 31787– 31790.
- Carol, R. J., Takeda, S., Linstead, P., Durrant, M. C., Kakesova, H., Derbyshire, P., Drea, S., Zarsky, V. and Dolan, L. (2005) A RhoGDP dissociation inhibitor spatially regulates growth in root hair cells. Nature, 438, 1013–1016.
- Weinzierl, G., Leveleki, L., Hassel, A., Kost, G., Wanner, G. and Bölker, M. (2002) Regulation of cell separation in the dimorphic fungus Ustilago maydis. Mol Microbiol, 45, 219–231.
- Schwamborn, J. C. and Püschel, A. W. (2004) The sequential activity of the GTPases Rap1B and Cdc42 determines neuronal polarity. Nat Neurosci, 7, 923–929.
- White, T. J., Arnheim, N. and Erlich, H. A. (1989) The polymerase chain reaction. Trends Genet, 5, 185–9.
- Howell, A. S., Savage, N. S., Johnson, S. A., Bose, I., Wagner, A. W., Zyla, T. R., Nijhout, H. F., Reed, M. C., Goryachev, A. B. and Lew, D. J. (2009) Singularity in polarization: rewiring yeast cells to make two buds. Cell, 139, 731–743.
- Layton, A. T., Savage, N. S., Howell, A. S., Carroll, S. Y., Drubin, D. G. and Lew, D. J. (2011) Modeling vesicle traffic reveals unexpected consequences for Cdc42p-mediated polarity establishment. Curr Biol, 21, 184–194.
- Tatebe, H., Nakano, K., Maximo, R. and Shiozaki, K. (2008) Pom1 DYRK regulates localization of the Rga4 GAP to ensure bipolar activation of Cdc42 in fission yeast. Curr Biol, 18, 322–330.
- Zhang, X., Bi, E., Novick, P., Du, L., Kozminski, K. G., Lipschutz, J. H. and Guo, W. (2001) Cdc42 interacts with the exocyst and regulates polarized secretion. J Biol Chem, 276, 46745–46750.
- Sikorski, R. S. and Hieter, P. (1989) A system of shuttle vectors and yeast host strains designed for efficient manipulation of DNA in Saccharomyces cerevisiae. Genetics, 122, 19–27.
- Gibson, R. M. and Wilson-Delfosse, A. L. (2001) RhoGDI-binding-defective mutant of Cdc42Hs targets to membranes and activates filopodia formation but does not cycle with the cytosol of mammalian cells. Biochem J, 359, 285–294.
- Snaith, H. A., Samejima, I. and Sawin, K. E. (2005) Multistep and multimode cortical anchoring of tea1p at cell tips in fission yeast. EMBO J, 24, 3690–3699.
- Lamson, R. E., Winters, M. J. and Pryciak, P. M. (2002) Cdc42 regulation of kinase activity and signaling by the yeast p21-activated kinase Ste20. Mol Cell Biol, 22, 2939–2951.
- Park, H.-O. and Bi, E. (2007) Central roles of small GTPases in the development of cell polarity in yeast and beyond. Microbiol Mol Biol Rev, 71, 48–96.
- Hirota, K., Tanaka, K., Ohta, K. and Yamamoto, M. (2003) Gef1p and Scd1p, the Two GDP-GTP exchange factors for Cdc42p, form a ring structure that shrinks during cytokinesis in Schizosaccha- romyces pombe. Mol Biol Cell, 14, 3617–3627.
- Romeis, T., Kämper, J. and Kahmann, R. (1997) Single-chain fusions of two unrelated homeodomain proteins trigger pathogenicity in Ustilago maydis. Proc Natl Acad Sci U S A, 94, 1230–1234.
- Martin, S. G., Rincón, S. A., Basu, R., Pérez, P. and Chang, F. (2007) Regulation of the formin for3p by cdc42p and bud6p. Mol Biol Cell, 18, 4155–4167.
- Knaus, M., Pelli-Gulli, M.-P., van Drogen, F., Springer, S., Jaquenoud, M. and Peter, M. (2007) Phos- phorylation of Bem2p and Bem3p may contribute to local activation of Cdc42p at bud emergence. EMBO J, 26, 4501–4513.
- Caviston, J. P., Longtine, M., Pringle, J. R. and Bi, E. (2003) The role of Cdc42p GTPase-activating proteins in assembly of the septin ring in yeast. Mol Biol Cell, 14, 4051–4066.
- Peterson, J., Zheng, Y., Bender, L., Myers, A., Cerione, R. and Bender, A. (1994) Interactions between the bud emergence proteins Bem1p and Bem2p and Rho-type GTPases in yeast. J Cell Biol, 127, 1395–1406.
- Takaishi, K., Sasaki, T., Kotani, H., Nishioka, H. and Takai, Y. (1997) Regulation of cell-cell adhesion by rac and rho small G proteins in MDCK cells. J Cell Biol, 139, 1047–1059.
- Nern, A. and Arkowitz, R. A. (2000) Nucleocytoplasmic shuttling of the Cdc42p exchange factor Cdc24p. J Cell Biol, 148, 1115–1122.
- Kozma, R., Sarner, S., Ahmed, S. and Lim, L. (1997) Rho family GTPases and neuronal growth cone re- modelling: relationship between increased complexity induced by Cdc42Hs, Rac1, and acetylcholine and collapse induced by RhoA and lysophosphatidic acid. Mol Cell Biol, 17, 1201–1211.
- Tong, Z., Gao, X.-D., Howell, A. S., Bose, I., Lew, D. J. and Bi, E. (2007) Adjacent positioning of cellular structures enabled by a Cdc42 GTPase-activating protein-mediated zone of inhibition. J Cell Biol, 179, 1375–1384.
- Schink, K. O. and Bölker, M. (2009) Coordination of cytokinesis and cell separation by endosomal targeting of a Cdc42-specific guanine nucleotide exchange factor in Ustilago maydis. Mol Biol Cell, 20, 1081–1088.
- Wai, S. C., Gerber, S. A. and Li, R. (2009) Multisite phosphorylation of the guanine nucleotide exchange factor Cdc24 during yeast cell polarization. PLoS One, 4, e6563.
- Wu, Y. I., Frey, D., Lungu, O. I., Jaehrig, A., Schlichting, I., Kuhlman, B. and Hahn, K. M. (2009) A genetically encoded photoactivatable Rac controls the motility of living cells. Nature, 461, 104–108.
- Kozubowski, L., Saito, K., Johnson, J. M., Howell, A. S., Zyla, T. R. and Lew, D. J. (2008) Symmetry- breaking polarization driven by a Cdc42p GEF-PAK complex. Curr Biol, 18, 1719–1726.
- Boulter, E., Garcia-Mata, R., Guilluy, C., Dubash, A., Rossi, G., Brennwald, P. J. and Burridge, K. (2010) Regulation of Rho GTPase crosstalk, degradation and activity by RhoGDI1. Nat Cell Biol, 12, 477–483.
- Heimel, K., Scherer, M., Schuler, D. and Kämper, J. (2010a) The Ustilago maydis Clp1 protein orche- strates pheromone and b-dependent signaling pathways to coordinate the cell cycle and pathogenic development. Plant Cell, 22, 2908–2922.
- Terenna, C. R., Makushok, T., Velve-Casquillas, G., Baigl, D., Chen, Y., Bornens, M., Paoletti, A., Piel, M. and Tran, P. T. (2008) Physical mechanisms redirecting cell polarity and cell shape in fission yeast. Curr Biol, 18, 1748–1753.
- Wang, T. and Bretscher, A. (1995) The rho-GAP encoded by BEM2 regulates cytoskeletal structure in budding yeast. Mol Biol Cell, 6, 1011–1024.
- Takemoto, D., Kamakura, S., Saikia, S., Becker, Y., Wrenn, R., Tanaka, A., Sumimoto, H. and Scott, B. (2011) Polarity proteins Bem1 and Cdc24 are components of the filamentous fungal NADPH oxidase complex. Proc Natl Acad Sci U S A, 108, 2861–2866.
- Wedlich-Söldner, R., Bölker, M., Kahmann, R. and Steinberg, G. (2000) A putative endosomal t- SNARE links exo-and endocytosis in the phytopathogenic fungus Ustilago maydis. EMBO J, 19, 1974–1986.
- Freitag, J., Lanver, D., Böhmer, C., Schink, K. O., Bölker, M. and Sandrock, B. (2011) Septation of infectious hyphae is critical for appressoria formation and virulence in the smut fungus ustilago maydis. PLoS Pathog, 7, e1002044.
- Brown, J. L., Jaquenoud, M., Gulli, M. P., Chant, J. and Peter, M. (1997) Novel Cdc42-binding proteins Gic1 and Gic2 control cell polarity in yeast. Genes Dev, 11, 2972–2982.
- Smith, D. G., Garcia-Pedrajas, M. D., Hong, W., Yu, Z., Gold, S. E. and Perlin, M. H. (2004) An ste20 homologue in Ustilago maydis plays a role in mating and pathogenicity. Eukaryot Cell, 3, 180–189.
- Ziman, M., O'Brien, J. M., Ouellette, L. A., Church, W. R. and Johnson, D. I. (1991) Mutational analysis of CDC42Sc, a Saccharomyces cerevisiae gene that encodes a putative GTP-binding protein involved in the control of cell polarity. Mol Cell Biol, 11, 3537–3544.
- Stacey, D. W., Feig, L. A. and Gibbs, J. B. (1991) Dominant inhibitory Ras mutants selectively inhibit the activity of either cellular or oncogenic Ras. Mol Cell Biol, 11, 4053–4064.
- Gibbs, J. B., Sigal, I. S., Poe, M. and Scolnick, E. M. (1984) Intrinsic GTPase activity distinguishes normal and oncogenic ras p21 molecules. Proc Natl Acad Sci U S A, 81, 5704–8.
- Karnoub, A. E., Der, C. J. and Campbell, S. L. (2001) The insert region of Rac1 is essential for membrane ruffling but not cellular transformation. Mol Cell Biol, 21, 2847–2857.
- Bourne, H. R., Sanders, D. A. and McCormick, F. (1990) The GTPase superfamily: a conserved switch for diverse cell functions. Nature, 348, 125–32.
- Bourne, H. R., Sanders, D. A. and McCormick, F. (1991) The GTPase superfamily: conserved structure and molecular mechanism. Nature, 349, 117–27.
- Sanger, F., Nicklen, S. and Coulson, A. R. (1977) DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A, 74, 5463–7.
- West, M., Kung, H. F. and Kamata, T. (1990) A novel membrane factor stimulates guanine nucleotide exchange reaction of ras proteins. FEBS Lett, 259, 245–8. 0014-5793 Journal Article.
- Schulz, B., Banuett, F., Dahl, M., Schlesinger, R., Schäfer, W., Martin, T., Herskowitz, I. and Kahmann, R. (1990) The b alleles of U. maydis, whose combinations program pathogenic development, code for polypeptides containing a homeodomain-related motif. Cell, 60, 295–306.
- Mionnet, C., Bogliolo, S. and Arkowitz, R. A. (2008) Oligomerization regulates the localization of Cdc24, the Cdc42 activator in Saccharomyces cerevisiae. J Biol Chem, 283, 17515–17530.