A synthetic lethal screen identifies a role for the cortical actin patch/endocytosis complex in the response to nutrient deprivation in Saccharomyces cerevisiae.
Saccharomyces cerevisiae whi2Delta cells are unable to halt cell division in response to nutrient limitation and are sensitive to a wide variety of stresses. A synthetic lethal screen resulted in the isolation of siw mutants that had a phenotype similar to that of whi2Delta. Among these were mutations affecting SIW14, FEN2, SLT2, and THR4. Fluid-phase endocytosis is severely reduced or abolished in whi2Delta, siw14Delta, fen2Delta, and thr4Delta mutants. Furthermore, whi2Delta and siw14Delta mutants produce large actin clumps in stationary phase similar to those seen in prk1Delta ark1Delta mutants defective in protein kinases that regulate the actin cytoskeleton. Overexpression of SIW14 in a prk1Delta strain resulted in a loss of cortical actin patches and cables and was lethal. Overexpression of SIW14 also rescued the caffeine sensitivity of the slt2 mutant isolated in the screen, but this was not due to alteration of the phosphorylation state of Slt2. These observations suggest that endocytosis and the organization of the actin cytoskeleton are required for the proper response to nutrient limitation. This hypothesis is supported by the observation that rvs161Delta, sla1Delta, sla2Delta, vrp1Delta, ypt51Delta, ypt52Delta, and end3Delta mutations, which disrupt the organization of the actin cytoskeleton and/or reduce endocytosis, have a phenotype similar to that of whi2Delta mutants.
Care
Alison
A
Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK.
Vousden
Katherine A
KA
Binley
Katie M
KM
Radcliffe
Pippa
P
Trevethick
Janet
J
Mannazzu
Ilaria
I
Sudbery
Peter E
PE
D000199:Actins / Q000235:genetics* / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D004705:Endocytosis / Q000235:genetics* / Q000502:physiology; D005656:Fungal Proteins / Q000378:metabolism; D005804:Genes, Lethal; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010641:Phenotype; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D027981:Symporters / Q000235:genetics / Q000378:metabolism
D000199:Actins; C436246:FEN2 protein, S cerevisiae; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D027981:Symporters; C470937:Whi2 protein, S cerevisiae; C491504:ARK1 protein, S cerevisiae; C061570:protein kinase N; D020794:Receptor Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; C072724:SLT2 protein, S cerevisiae; D017027:Protein Tyrosine Phosphatases; C528878:Siw14 protein, S cerevisiae