Journal of Cell Science, Vol 111, Issue 4 479-494, Copyright © 1998 by Company of Biologists

JOURNAL ARTICLES

The Spa2-related protein, Sph1p, is important for polarized growth in yeast

T Roemer, L Vallier, YJ Sheu and M Snyder
Department of Biology, Yale University, New Haven, CT 06520-8103, USA.

The Saccharomyces cerevisiae protein Sph1p is both structurally and functionally related to the polarity protein, Spa2p. Sph1p and Spa2p are predicted to share three 100-amino acid domains each exceeding 30% sequence identity, and the amino-terminal domain of each protein contains a direct repeat common to Homo sapiens and Caenorhabditis elegans protein sequences. sph1- and spa2-deleted cells possess defects in mating projection morphology and pseudohyphal growth. sph1(Delta) spa2(Delta) double mutants also exhibit a strong haploid invasive growth defect and an exacerbated mating projection defect relative to either sph1(Delta) or spa2(Delta) single mutants. Consistent with a role in polarized growth, Sph1p localizes to growth sites in a cell cycle-dependent manner: Sph1p concentrates as a cortical patch at the presumptive bud site in unbudded cells, at the tip of small, medium and large buds, and at the bud neck prior to cytokinesis. In pheromone-treated cells, Sph1p localizes to the tip of the mating projection. Proper localization of Sph1p to sites of active growth during budding and mating requires Spa2p. Sph1p interacts in the two-hybrid system with three mitogen-activated protein (MAP) kinase kinases (MAPKKs): Mkk1p and Mkk2p, which function in the cell wall integrity/cell polarization MAP kinase pathway, and Ste7p, which operates in the pheromone and pseudohyphal signaling response pathways. Sph1p also interacts weakly with STE11, the MAPKKK known to activate STE7. Moreover, two-hybrid interactions between SPH1 and STE7 and STE11 occur independently of STE5, a proposed scaffolding protein which interacts with several members of this MAP kinase module. We speculate that Spa2p and Sph1p may function during pseudohyphal and haploid invasive growth to help tether this MAP kinase module to sites of polarized growth. Our results indicate that Spa2p and Sph1p comprise two related proteins important for the control of cell morphogenesis in yeast.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				X.-M. Zhao, R.-S. Wang, L. Chen, and K. Aihara Uncovering signal transduction networks from high-throughput data by integer linear programming Nucleic Acids Res., May 1, 2008; 36(9): e48 - e48. [Abstract] [Full Text] [PDF]

				J. B. Moseley and B. L. Goode The Yeast Actin Cytoskeleton: from Cellular Function to Biochemical Mechanism Microbiol. Mol. Biol. Rev., September 1, 2006; 70(3): 605 - 645. [Abstract] [Full Text] [PDF]

				A. Virag and S. D. Harris Functional Characterization of Aspergillus nidulans Homologues of Saccharomyces cerevisiae Spa2 and Bud6 Eukaryot. Cell, June 1, 2006; 5(6): 881 - 895. [Abstract] [Full Text] [PDF]

				S. E. Tcheperegine, X.-D. Gao, and E. Bi Regulation of Cell Polarity by Interactions of Msb3 and Msb4 with Cdc42 and Polarisome Components Mol. Cell. Biol., October 1, 2005; 25(19): 8567 - 8580. [Abstract] [Full Text] [PDF]

				P. Knechtle, F. Dietrich, and P. Philippsen Maximal Polar Growth Potential Depends on the Polarisome Component AgSpa2 in the Filamentous Fungus Ashbya gossypii Mol. Biol. Cell, October 1, 2003; 14(10): 4140 - 4154. [Abstract] [Full Text] [PDF]

				R. E. Lamson, M. J. Winters, and P. M. Pryciak Cdc42 Regulation of Kinase Activity and Signaling by the Yeast p21-Activated Kinase Ste20 Mol. Cell. Biol., May 1, 2002; 22(9): 2939 - 2951. [Abstract] [Full Text] [PDF]

				S. P. Palecek, A. S. Parikh, and S. J. Kron Sensing, signalling and integrating physical processes during Saccharomyces cerevisiae invasive and filamentous growth Microbiology, April 1, 2002; 148(4): 893 - 907. [Full Text] [PDF]

				G. A. G. Dittmar, C. R. M. Wilkinson, P. T. Jedrzejewski, and D. Finley Role of a Ubiquitin-Like Modification in Polarized Morphogenesis Science, March 29, 2002; 295(5564): 2442 - 2446. [Abstract] [Full Text] [PDF]

				K. B. Lengeler, R. C. Davidson, C. D'souza, T. Harashima, W.-C. Shen, P. Wang, X. Pan, M. Waugh, and J. Heitman Signal Transduction Cascades Regulating Fungal Development and Virulence Microbiol. Mol. Biol. Rev., December 1, 2000; 64(4): 746 - 785. [Abstract] [Full Text] [PDF]

				Y.-J. Sheu, Y. Barral, and M. Snyder Polarized Growth Controls Cell Shape and Bipolar Bud Site Selection in Saccharomyces cerevisiae Mol. Cell. Biol., July 15, 2000; 20(14): 5235 - 5247. [Abstract] [Full Text]

				B. Santos and M. Snyder Sbe2p and Sbe22p, Two Homologous Golgi Proteins Involved in Yeast Cell Wall Formation Mol. Biol. Cell, February 1, 2000; 11(2): 435 - 452. [Abstract] [Full Text]

				H. Jin and D. C. Amberg The Secretory Pathway Mediates Localization of the Cell Polarity Regulator Aip3p/Bud6p Mol. Biol. Cell, February 1, 2000; 11(2): 647 - 661. [Abstract] [Full Text]

				D Pruyne and A Bretscher Polarization of cell growth in yeast. I. Establishment and maintenance of polarity states J. Cell Sci., January 2, 2000; 113(3): 365 - 375. [Abstract] [PDF]

				D Pruyne and A Bretscher Polarization of cell growth in yeast J. Cell Sci., January 2, 2000; 113(4): 571 - 585. [Abstract] [PDF]

				M. A. Leza and E. A. Elion POG1, a Novel Yeast Gene, Promotes Recovery From Pheromone Arrest via the G1 Cyclin CLN2 Genetics, February 1, 1999; 151(2): 531 - 543. [Abstract] [Full Text]

				M. C. Gustin, J. Albertyn, M. Alexander, and K. Davenport MAP Kinase Pathways in the Yeast Saccharomyces cerevisiae Microbiol. Mol. Biol. Rev., December 1, 1998; 62(4): 1264 - 1300. [Abstract] [Full Text] [PDF]

				Y.-J. Sheu, B. Santos, N. Fortin, C. Costigan, and M. Snyder Spa2p Interacts with Cell Polarity Proteins and Signaling Components Involved in Yeast Cell Morphogenesis Mol. Cell. Biol., July 1, 1998; 18(7): 4053 - 4069. [Abstract] [Full Text]

				J. M. Atienza, M. Suh, I. Xenarios, R. Landgraf, and J. Colicelli Human ERK1 Induces Filamentous Growth and Cell Wall Remodeling Pathways in Saccharomyces cerevisiae J. Biol. Chem., June 30, 2000; 275(27): 20638 - 20646. [Abstract] [Full Text] [PDF]