Cell cycle entry triggers a switch between two modes of Cdc42 activation during yeast polarization

Abstract
Article and author information
Metrics

Abstract

Cell polarization underlies many cellular and organismal functions. The GTPase Cdc42 orchestrates polarization in many contexts. In budding yeast, polarization is associated with a focus of Cdc42•GTP which is thought to self sustain by recruiting a complex containing Cla4, a Cdc42-binding effector, Bem1, a scaffold, and Cdc24, a Cdc42 GEF. Using optogenetics, we probe yeast polarization and find that local recruitment of Cdc24 or Bem1 is sufficient to induce polarization by triggering self-sustaining Cdc42 activity. However, the response to these perturbations depends on the recruited molecule, the cell cycle stage, and existing polarization sites. Before cell cycle entry, recruitment of Cdc24, but not Bem1, induces a metastable pool of Cdc42 that is sustained by positive feedback. Upon Cdk1 activation, recruitment of either Cdc24 or Bem1 creates a stable site of polarization that induces budding and inhibits formation of competing sites. Local perturbations have therefore revealed unexpected features of polarity establishment.

Article and author information

Author details

Kristen L Witte

Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, United States

Competing interests
The authors declare that no competing interests exist.
Devin Strickland

Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, United States

Competing interests
The authors declare that no competing interests exist.
Michael Glotzer

Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, United States

For correspondence
mglotzer@uchicago.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-8723-7232

Funding

National Institute of General Medical Sciences (R01GM85087)

Michael Glotzer

American Cancer Society (119248-PF-10-134-01-CCG)

Devin Strickland

National Institute of General Medical Sciences (T32 GM007183)

Kristen L Witte

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.