Rvs161p and sphingolipids are required for actin repolarization following salt stress.
In Saccharomyces cerevisiae, the actin cytoskeleton is depolarized by NaCl stress. In this study, the response was maximal after 30 min, and then actin patches repolarized. Rvs161p was required for actin repolarization because the rvs161delta mutant did not repolarize actin patches after growth in a salt medium. Mutations suppressing the rvs161delta-related salt sensitivity all occurred in genes required for sphingolipid biosynthesis: FEN1, SUR4, SUR2, SUR1, and IPT1. These suppressors also suppressed act1-1-related salt sensitivity and the defect in actin repolarization of the rvs161delta mutant, providing a link between sphingolipids and actin polarization. Indeed, deletion of the suppressor genes suppressed the rvs161delta defect in actin repolarization in two ways: either actin was not depolarized at the wild-type level in a set of suppressor mutants, or actin was repolarized in the absence of Rvs161p in the other suppressor mutants. Rvs161p was localized as cortical patches that concentrated at polarization sites, i.e., bud emergence and septa, and was found to be associated with lipid rafts. An important link between sphingolipids and actin polarization is that Rvs161p was required for actin repolarization and was found to be located in lipid rafts.
Balguerie
Axelle
A
Institut de Biochimie et Génétique Cellulaires, CNRS UMR 5095, F-33077 Bordeaux Cedex, France.
Bagnat
Michel
M
Bonneu
Marc
M
Aigle
Michel
M
Breton
Annick M
AM
D000199:Actins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism / Q000502:physiology*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D021962:Membrane Microdomains; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism / Q000502:physiology*; D012492:Salts / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D013107:Sphingolipids / Q000378:metabolism / Q000502:physiology*; D013696:Temperature; D013997:Time Factors
D000199:Actins; D003598:Cytoskeletal Proteins; D008164:Luminescent Proteins; C089181:RVS161 protein, S cerevisiae; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D012492:Salts; D013107:Sphingolipids; D049452:Green Fluorescent Proteins; D012965:Sodium Chloride