The yeast protein kinase C cell integrity pathway mediates tolerance to the antifungal drug caspofungin through activation of Slt2p mitogen-activated protein kinase signaling.
The echinocandin caspofungin is a new antifungal drug that blocks cell wall synthesis through inhibition of beta-(1-3)-glucan synthesis. Saccharomyces cerevisiae cells are able to tolerate rather high caspofungin concentrations, displaying high viability at low caspofungin doses. To identify yeast genes implicated in caspofungin tolerance, we performed a genome-wide microarray analysis. Strikingly, caspofungin treatment rapidly induces a set of genes from the protein kinase C (PKC) cell integrity signaling pathway, as well as those required for cell wall maintenance and architecture. The mitogen-activated protein kinase Slt2p is rapidly activated by phosphorylation, triggering signaling through the PKC pathway. Cells lacking genes such as SLT2, BCK1, and PKC1, as well as the caspofungin target gene, FKS1, display pronounced hypersensitivity, demonstrating that the PKC pathway is required for caspofungin tolerance. Notably, the cell surface integrity sensor Wsc1p, but not the sensors Wsc2-4p and Mid2p, is required for sensing caspofungin perturbations. The expression modulation of PKC target genes requires the transcription factor Rlm1p, which controls expression of several cell wall synthesis and maintenance genes. Thus, caspofungin-induced cell wall damage requires Wsc1p as a dedicated sensor to launch a protective response through the activated salvage pathway for de novo cell wall synthesis. Our results establish caspofungin as a specific activator of Slt2p stress signaling in baker's yeast.
Reinoso-Martín
Cristina
C
Department of Medical Biochemistry, Division of Molecular Genetics, Max F. Perutz Laboratories, University and Biocenter of Vienna, A-1030 Vienna, Austria.
Schüller
Christoph
C
Schuetzer-Muehlbauer
Manuela
M
Kuchler
Karl
K
D000935:Antifungal Agents / Q000494:pharmacology*; D000077336:Caspofungin; D002457:Cell Extracts; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015536:Down-Regulation; D004361:Drug Tolerance / Q000235:genetics; D054714:Echinocandins; D004789:Enzyme Activation / Q000187:drug effects; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects; D005800:Genes, Fungal / Q000187:drug effects; D007700:Kinetics; D055666:Lipopeptides; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D020411:Oligonucleotide Array Sequence Analysis; D010455:Peptides / Q000494:pharmacology*; D010456:Peptides, Cyclic; D010766:Phosphorylation; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
D000935:Antifungal Agents; D002457:Cell Extracts; D004268:DNA-Binding Proteins; D054714:Echinocandins; D005656:Fungal Proteins; D055666:Lipopeptides; D010455:Peptides; D010456:Peptides, Cyclic; C489601:RIM101 protein, S cerevisiae; D012333:RNA, Messenger; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; C072724:SLT2 protein, S cerevisiae; D000077336:Caspofungin