Requirement of Bni5 phosphorylation for bud morphogenesis in Saccharomyces cerevisiae

J Microbiol. 2007 Feb;45(1):34-40.


In budding yeast, G2/M transition is tightly correlated with bud morphogenesis regulated by Swe1 and septin that plays as a scaffold to recruits protein components. BNI5 isolated as a suppressor for septin defect is implicated in septin organization and cytokinesis. The mechanism by which Bni5 regulates normal septin function is not completely understood. Here, we show that Bni5 phosphorylation is required for mitotic entry regulated by Swe1 pathway. Bni5 modification was evident from late mitosis to G1 phase, and CIP treatment in vitro of affinity-purified Bni5 removed the modification, indicative of phosphorylation on Bni5. The phosphorylation-deficient mutant of BNI5 (bni5-4A) was defective in both growth at semi-restrictive temperature and suppression of septin defect. Loss of Bni5 phosphorylation resulted in abnormal bud morphology and cell cycle delay at G2 phase, as evidenced by the formation of elongated cells with multinuclei. However, deletion of Swe1 completely eliminated the elongated-bud phenotypes of both bni5 deletion and bni5-4A mutants. These results suggest that the bud morphogenesis and mitotic entry are positively regulated by phosphorylation-dependent function of Bni5 which is under the control of Swe1 morphogenesis pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle
  • Cell Cycle Proteins / metabolism
  • Cytoskeletal Proteins / metabolism
  • G2 Phase
  • GTP Phosphohydrolases / metabolism
  • Membrane Proteins / metabolism
  • Microbial Viability
  • Mitosis
  • Morphogenesis
  • Mutagenesis
  • Phosphorylation
  • Profilins / metabolism
  • Protein-Tyrosine Kinases / metabolism
  • Saccharomyces cerevisiae / cytology*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / metabolism*


  • BNI5 protein, S cerevisiae
  • CDC11 protein, S cerevisiae
  • CDC12 protein, S cerevisiae
  • CDC3 protein, S cerevisiae
  • Cell Cycle Proteins
  • Cytoskeletal Proteins
  • Membrane Proteins
  • Profilins
  • SHS1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • SWE1 protein, S cerevisiae
  • Protein-Tyrosine Kinases
  • CDC10 protein, S cerevisiae
  • GTP Phosphohydrolases