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Rho5p downregulates the yeast cell integrity pathway.
Hans-Peter Schmitz1, Stefanie Huppert, Anja Lorberg
1Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Universitätsstr. 1, Geb. 26. 12, D-40225 Düsseldorf, Germany. heinisch@uni-hohenheim.de
Journal of Cell Science
|July 16, 2002
Summary
Deleting Rho5p in yeast activates the protein kinase C (Pkc1p) pathway, increasing drug resistance. Rho5p acts as an off-switch for the MAP-kinase cascade, regulating cell functions.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Rho family proteins regulate crucial eukaryotic cell functions.
- In yeast (Saccharomyces cerevisiae), Rho proteins like Rho1p-Rho5p and Cdc42p control growth, morphogenesis, and secretion.
- Rho5p's specific role remained largely uncharacterized.
Purpose of the Study:
- To investigate the function of Rho5p in Saccharomyces cerevisiae.
- To determine Rho5p's role in the protein kinase C (Pkc1p) signaling pathway.
- To elucidate Rho5p's regulation of the MAP-kinase cascade.
Main Methods:
- Gene deletion and overexpression of Rho5p and its mutants.
- Assessing drug sensitivity (caffeine, Calcofluor white, Congo red).
- Analyzing actin cytoskeleton dynamics (depolarization/repolarization) after heat shock.
Main Results:
- Deletion of Rho5p (rho5 deletion) increased Pkc1p pathway activity and drug resistance.
- Overexpression of an activated RHO5Q91H mutant increased sensitivity to these drugs.
- Rho5 deletion and RHO5Q91H overexpression altered actin dynamics post-heat shock.
Conclusions:
- Rho5p functions as an inhibitor (off-switch) of the MAP-kinase cascade.
- Rho5p distinguishes between MAP-kinase-dependent and -independent Pkc1p functions.
- Rho5p plays a regulatory role in yeast cell signaling and cytoskeleton organization.