title: Cdc42 regulates multiple membrane traffic events in fission yeast.
abstract: Fission yeast Cdc42 regulates polarized growth and is involved in For3 formin activation and actin cable assembly. We show here that a thermosensitive strain carrying the cdc42L160S allele has membrane traffic defects independent of the actin cable defects. This strain has decreased acid phosphatase (AP) secretion, intracellular accumulation of vesicles and fragmentation of vacuoles. In addition, the exocyst is not localized to the tips of these cells. Overproduction of the scaffold protein Pob1 suppressed cdc42L160S thermosensitive growth and restored exocyst localization and AP secretion. The GTPase Rho3 also suppressed cdc42L160S thermosensitivity, restored exocyst localization and AP secretion. However, Rho3 did not restore the actin cables in these cells as Pob1 does. Similarly, overexpression of psy1(+) , coding a syntaxin (t-SNARE) homolog, or of ypt2(+) , coding an SEC4 homolog in fission yeast, rescued growth at high temperature but did not restore actin cables, nor the exocyst-polarized localization. cdc42L160S cells also have defects in vacuole formation that were rescued by Pob1, Rho3 and Psy1. All together, we propose that Cdc42 and the scaffold Pob1 are required for membrane trafficking and fusion, contributing to polarized secretion, endosome recycling, vacuole formation and growth.
authors: Instituto de Biología funcional y Genómica, Consejo Superior de Investigaciones Científicas CSIC/Departamento de Microbiología y Genética, Universidad de Salamanca, 30007 Salamanca, Spain.
authors: Miguel
authors: M
authors: Estravís
authors: Sergio A
authors: SA
authors: Rincón
authors: Beatriz
authors: B
authors: Santos
authors: Pilar
authors: P
authors: Pérez
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000199:Actins / Q000235:genetics / Q000378:metabolism; D000483:Alleles; D002268:Carboxypeptidases / Q000378:metabolism; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D016764:Cell Polarity / Q000235:genetics; D011992:Endosomes / Q000235:genetics / Q000378:metabolism; D005089:Exocytosis / Q000235:genetics; D020558:GTP Phosphohydrolases / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D008561:Membrane Fusion / Q000235:genetics; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D050765:Qa-SNARE Proteins / Q000235:genetics; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism; D014617:Vacuoles / Q000235:genetics / Q000378:metabolism; D020764:cdc42 GTP-Binding Protein / Q000235:genetics* / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000235:genetics; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000199:Actins; D026901:Membrane Transport Proteins; C510389:Psy1 protein, S pombe; D050765:Qa-SNARE Proteins; D050600:SNARE Proteins; D029702:Schizosaccharomyces pombe Proteins; C489566:rho3 protein, S pombe; D000135:Acid Phosphatase; D002268:Carboxypeptidases; C064393:ypt2 protein, S pombe; D020558:GTP Phosphohydrolases; C548057:Pob1 protein, S pombe; D020764:cdc42 GTP-Binding Protein; D020691:rab GTP-Binding Proteins; D020741:rho GTP-Binding Proteins