Bni1p implicated in cytoskeletal control is a putative target of Rho1p small GTP binding protein in Saccharomyces cerevisiae

EMBO J. 1996 Nov 15;15(22):6060-8.


The RHO1 gene encodes a homolog of mammalian RhoA small GTP binding protein in the yeast Saccharomyces cerevisiae. Rho1p is localized at the growth sites, including the bud tip and the cytokinesis site, and is required for bud formation. We have recently shown that Pkc1p, a yeast homolog of mammalian protein kinase C, and glucan synthase are targets of Rho1p. Using the two-hybrid screening system, we cloned a gene encoding a protein which interacted with the GTP-bound form of Rho1p. This gene was identified as BNI1, known to be implicated in cytokinesis or establishment of cell polarity in S.cerevisiae. Bni1p shares homologous domains (FH1 and FH2 domains) with proteins involved in cytokinesis or establishment of cell polarity, including formin of mouse, capu and dia of Drosophila and FigA of Aspergillus. A temperature-sensitive mutation in which the RHO1 gene was replaced by the mammalian RhoA gene showed a synthetically lethal interaction with the bni1 mutation and the RhoA bni1 mutant accumulated cells with a deficiency in cytokinesis. Furthermore, this synthetic lethality was caused by the incapability of RhoA to activate Pkc1p, but not glucan synthase. These results suggest that Rho1p regulates cytoskeletal reorganization at least through Bni1p and Pkc1p.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Cell Division / genetics
  • Cell Polarity / drug effects
  • Cell Polarity / genetics
  • Cloning, Molecular
  • DNA Primers / genetics
  • Drosophila Proteins
  • Fungal Proteins / chemistry
  • Fungal Proteins / metabolism*
  • GTP-Binding Proteins / metabolism*
  • Genes, Fungal / genetics
  • Glucans / biosynthesis
  • Glucans / metabolism
  • Glucosyltransferases / metabolism
  • Guanosine Diphosphate / metabolism
  • Guanosine Triphosphate / metabolism
  • Microfilament Proteins*
  • Molecular Sequence Data
  • Mutation / genetics
  • Protein Kinase C*
  • Saccharomyces cerevisiae / chemistry*
  • Saccharomyces cerevisiae Proteins*
  • rho GTP-Binding Proteins*
  • rhoA GTP-Binding Protein


  • Bni1 protein, S cerevisiae
  • DNA Primers
  • Drosophila Proteins
  • Fungal Proteins
  • Glucans
  • Microfilament Proteins
  • Saccharomyces cerevisiae Proteins
  • Guanosine Diphosphate
  • Guanosine Triphosphate
  • Glucosyltransferases
  • glucan synthase
  • Pkc1 protein, Trichoderma reesei
  • Protein Kinase C
  • GTP-Binding Proteins
  • RHO1 protein, S cerevisiae
  • Rho1 protein, Drosophila
  • rho GTP-Binding Proteins
  • rhoA GTP-Binding Protein