Yeast G-proteins mediate directional sensing and polarization behaviors in response to changes in pheromone gradient direction.
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(o) switch in the direction of microfluidically generated pheromone gradients. We identify two behaviors: at low concentrations of α-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 Gβγ and Cdc24, whereas gradient-nonsensing projection extension is stimulated by Bem1 and hyperactivated Cdc42. Of interest, a mutation in Gα 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 α-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.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Cell Cycle Proteins, Cell Polarity, Chemotaxis, Gene Expression Regulation, Fungal, Guanine Nucleotide Exchange Factors, Microfilament Proteins, Microfluidics, Mutation, Peptides, Pheromones, Protein Binding, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Signal Transduction, cdc42 GTP-Binding Protein, Saccharomyces cerevisiae
Adaptor Proteins, Signal Transducing, Cell Cycle Proteins, Cell Polarity, Chemotaxis, Gene Expression Regulation, Fungal, Guanine Nucleotide Exchange Factors, Microfilament Proteins, Microfluidics, Mutation, Peptides, Pheromones, Protein Binding, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Signal Transduction, cdc42 GTP-Binding Protein, Saccharomyces cerevisiae
Mol. Biol. Cell
Date: Feb. 01, 2013
PubMed ID: 23242998
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