Suppression of the profilin-deficient phenotype by the RHO2 signaling pathway in Saccharomyces cerevisiae.
Profilin plays an important role in actin organization in all eukaryotic cells through mechanisms that are still poorly understood. We had previously shown that Mid2p, a transmembrane protein and a potential cell wall sensor, is an effective multicopy suppressor of the profilin-deficient phenotype in Saccharomyces cerevisiae. To better understand the role of Mid2p in the organization of the actin cytoskeleton, we isolated five additional multicopy suppressors of pfy1Delta cells that are Rom1p, Rom2p, Rho2p, Smy1p, and the previously uncharacterized protein Syp1p. The problems of caffeine and NaCl sensitivity, growth defects at 30 degrees and 37 degrees, the accumulation of intracellular vesicular structures, and a random budding pattern in pfy1Delta cells are corrected by all the suppressors tested. This is accompanied by a partial repolarization of the cortical actin patches without the formation of visible actin cables. The overexpression of Mid2p, Rom2p, and Syp1p, but not the overexpression of Rho2p and Smy1p, results in an abnormally thick cell wall in wild-type and pfy1Delta cells. Since none of the suppressors, except Rho2p, can correct the phenotype of the pfy1-111/rho2Delta strain, we propose a model in which the suppressors act through the Rho2p signaling pathway to repolarize cortical actin patches.
Marcoux
N
N
Pavillon Charles-Eugène Marchand, Laval University, Ste-Foy, Quebec G1K 7P4, Canada.
Cloutier
S
S
Zakrzewska
E
E
Charest
P M
PM
Bourbonnais
Y
Y
Pallotta
D
D
D000199:Actins / Q000378:metabolism; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000235:genetics; D016764:Cell Polarity; D003285:Contractile Proteins; D017931:DNA Primers; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D005838:Genotype; D006836:Hydro-Lyases / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000235:genetics; D008840:Microfilament Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins; D010641:Phenotype; D016133:Polymerase Chain Reaction; D051304:Profilins; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic; D020741:rho GTP-Binding Proteins
D000199:Actins; D002135:Calcium-Binding Proteins; D003285:Contractile Proteins; D017931:DNA Primers; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; C091625:MID2 protein, S cerevisiae; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D008840:Microfilament Proteins; D051304:Profilins; D029701:Saccharomyces cerevisiae Proteins; D020559:Monomeric GTP-Binding Proteins; C051303:RHO2 protein, S cerevisiae; D020741:rho GTP-Binding Proteins; D006836:Hydro-Lyases; C021434:imidazoleglycerolphosphate dehydratase