Yeast G-proteins mediate directional sensing and polarization behaviors in response to changes in pheromone gradient direction

Travis I. Moore, Hiromasa Tanaka, Hyung Joon Kim, Noo Li Jeon, Tau Mu Yi

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Yeast cells polarize by projecting up mating pheromone gradients, a classic cell polarity behavior. However, these chemical gradients may shift direction. We examine how yeast cells sense and respond to a 180° switch in the direction of microfluidically generated pheromone gradients. We identify two behaviors: at low concentrations of a-factor, the initial projection grows by bending, whereas at high concentrations, cells form a second projection toward the new source. Mutations that increase heterotrimeric G-protein activity expand the bending-growth morphology to high concentrations;mutations that increase Cdc42 activity result in second projections at low concentrations. Gradient-sensing projection bending requires interaction between Gβγand Cdc24, whereas gradient-nonsensing projection extension is stimulated by Bem1 and hyperactivated Cdc42. Of interest, a mutation in Ga affects both bending and extension. Finally, we find a genetic perturbation that exhibits both behaviors. Overexpression of the formin Bni1, a component of the polarisome, makes both bending- growth projections and second projections at low and high a-factor concentrations, suggesting a role for Bni1 downstream of the heterotrimeric G-protein and Cdc42 during gradient sensing and response. Thus we demonstrate that G-proteins modulate in a ligand-dependent manner two fundamental cell-polarity behaviors in response to gradient directional change.

Original languageEnglish (US)
Pages (from-to)521-534
Number of pages14
JournalMolecular biology of the cell
Volume24
Issue number4
DOIs
StatePublished - Feb 15 2013

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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