title: Rga2 is a Rho2 GAP that regulates morphogenesis and cell integrity in S. pombe.
abstract: Schizosaccharomyces pombe Rho2 GTPase regulates alpha-D-glucan synthesis and acts upstream of Pck2 to activate the MAP kinase pathway for cell integrity. However, little is known about its regulation. Here we describe Rga2 as a Rho2 GTPase-activating protein (GAP) that regulates cell morphology. rga2+ gene is not essential for growth but its deletion causes longer and thinner cells whereas rga2+ overexpression causes shorter and broader cells. rga2+ overexpression also causes abnormal accumulation of Calcofluor-stained material and cell lysis, suggesting that it also participates in cell wall integrity. Rga2 localizes to growth tips and septum region. The N-terminal region of the protein is required for its correct localization whereas the PH domain is necessary exclusively for Rga2 localization to the division area. Also, Rga2 localization depends on polarity markers and on actin polymerization. Rga2 interacts with Rho2 and possesses in vitro and in vivo GAP activity for this GTPase. Accordingly, rga2Delta cells contain more alpha-D-glucan and therefore partially suppress the thermosensitivity of mok1-664 cells, which have a defective alpha-D-glucan synthase. Additionally, genetic interactions and biochemical analysis suggest that Rga2 regulates Rho2-Pck2 interaction and might participate in the regulation of the MAPK cell integrity pathway.
authors.affiliation: Instituto de Microbiología Bioquímica, Consejo Superior de Investigaciones Científicas (CSIC)/Departamento de Microbiología y Genética, Universidad de Salamanca, Edificio Departamental, 37007 Salamanca, Spain.
authors.forename: M Antonia
authors.initials: MA
authors.lastname: Villar-Tajadura
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Coll
authors.forename: Marisa
authors.initials: M
authors.lastname: Madrid
authors.forename: Jose
authors.initials: J
authors.lastname: Cansado
authors.forename: Beatriz
authors.initials: B
authors.lastname: Santos
authors.forename: Pilar
authors.initials: P
authors.lastname: Pérez
mesh_terms: D000199:Actins / Q000378:metabolism; D016764:Cell Polarity; D002473:Cell Wall / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D005936:Glucans / Q000378:metabolism; D020935:MAP Kinase Signaling System; D008856:Microscopy, Fluorescence; D009024:Morphogenesis; D012568:Schizosaccharomyces / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D004271:DNA, Fungal; D020690:GTPase-Activating Proteins; D005936:Glucans; C092804:Rho2 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; D020741:rho GTP-Binding Proteins