title: Novel Rho GTPase involved in cytokinesis and cell wall integrity in the fission yeast Schizosaccharomyces pombe.
abstract: The Rho family of GTPases is present in all eukaryotic cells from yeast to mammals; they are regulators in signaling pathways that control actin organization and morphogenetic processes. In yeast, Rho GTPases are implicated in cell polarity processes and cell wall biosynthesis. It is known that Rho1 and Rho2 are key proteins in the construction of the cell wall, an essential structure that in Schizosaccharomyces pombe is composed of beta-glucan, alpha-glucan, and mannoproteins. Rho1 regulates the synthesis of 1,3-beta-D-glucan by activation of the 1,3-beta-D-glucan synthase, and Rho2 regulates the synthesis of alpha-glucan by the 1,3-alpha-D-glucan synthase Mok1. Here we describe the characterization of another Rho GTPase in fission yeast, Rho4. rho4Delta cells are viable but display cell separation defects at high temperature. In agreement with this observation, Rho4 localizes to the septum. Overexpression of rho4(+) causes lysis and morphological defects. Several lines of evidence indicate that both rho4(+) deletion or rho4(+) overexpression result in a defective cell wall, suggesting an additional role for Rho4 in cell wall integrity. Rho4Delta cells also accumulate secretory vesicles around the septum and are defective in actin polarization. We propose that Rho4 could be involved in the regulation of the septum degradation during cytokinesis.
authors.affiliation: Instituto Microbiología-Bioquímica, Departamento de Microbiología-Genética, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, 37007 Salamanca, Spain. bsr@usal.es
authors.forename: Beatriz
authors.initials: B
authors.lastname: Santos
authors.forename: Javier
authors.initials: J
authors.lastname: Gutiérrez
authors.forename: Teresa M
authors.initials: TM
authors.lastname: Calonge
authors.forename: Pilar
authors.initials: P
authors.lastname: Pérez
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D002455:Cell Division / Q000502:physiology*; D002473:Cell Wall / Q000378:metabolism*; D017353:Gene Deletion; D005800:Genes, Fungal; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D012568:Schizosaccharomyces; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D017386:Sequence Homology, Amino Acid; D013696:Temperature; D020741:rho GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D008164:Luminescent Proteins; D029702:Schizosaccharomyces pombe Proteins; D049452:Green Fluorescent Proteins; D020741:rho GTP-Binding Proteins