title: Identification of Genes in Candida glabrata Conferring Altered Responses to Caspofungin, a Cell Wall Synthesis Inhibitor.
abstract: Candida glabrata is an important human fungal pathogen whose incidence continues to rise. Because many clinical isolates are resistant to azole drugs, the drugs of choice to treat such infections are members of the echinocandin family, although there are increasing reports of resistance to these drugs as well. In efforts to better understand the genetic changes that lead to altered responses to echinocandins, we screened a transposon-insertion library of mutants for strains to identify genes that are important for cellular responses to caspofungin, a member of this drug family. We identified 16 genes that, when disrupted, caused increased tolerance, and 48 genes that, when disrupted, caused increased sensitivity compared to the wild-type parental strain. Four of the genes identified as causing sensitivity are orthologs of Saccharomyces cerevisiae genes encoding proteins important for the cell wall integrity (CWI) pathway. In addition, several other genes are orthologs of the high affinity Ca(2+) uptake system (HACS) complex genes. We analyzed disruption mutants representing all 64 genes under 33 different conditions, including the presence of cell wall disrupting agents and other drugs, a variety of salts, increased temperature, and altered pH. Further, we generated knockout mutants in different genes within the CWI pathway and the HACS complex, and found that they too exhibited phenotypes consistent with defects in cell wall construction. Our results indicate that small molecules that inhibit the CWI pathway, or that the HACS complex, may be an important means of increasing the efficacy of caspofungin.
authors.affiliation: Department of Biology, Georgetown University, Washington, DC 20057 anne.rosenwald@georgetown.edu.
authors.forename: Anne G
authors.identifier: 0000-0002-0144-8515
authors.initials: AG
authors.lastname: Rosenwald
authors.affiliation: Department of Biology, Georgetown University, Washington, DC 20057.
authors.forename: Gaurav
authors.initials: G
authors.lastname: Arora
authors.affiliation: Department of Biology, Georgetown University, Washington, DC 20057.
authors.forename: Rocco
authors.initials: R
authors.lastname: Ferrandino
authors.affiliation: Department of Biology, Georgetown University, Washington, DC 20057.
authors.forename: Erica L
authors.initials: EL
authors.lastname: Gerace
authors.affiliation: Department of Biology, Georgetown University, Washington, DC 20057.
authors.forename: Maedeh
authors.initials: M
authors.lastname: Mohammednetej
authors.affiliation: Department of Biology, Georgetown University, Washington, DC 20057.
authors.forename: Waseem
authors.initials: W
authors.lastname: Nosair
authors.affiliation: Department of Biology, Georgetown University, Washington, DC 20057.
authors.forename: Shemona
authors.initials: S
authors.lastname: Rattila
authors.affiliation: Department of Biology, Georgetown University, Washington, DC 20057.
authors.forename: Amanda Zirzow
authors.initials: AZ
authors.lastname: Subic
authors.affiliation: Department of Biology, Georgetown University, Washington, DC 20057.
authors.forename: Ronda
authors.initials: R
authors.lastname: Rolfes
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D041221:Candida glabrata / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D002177:Candidiasis / Q000188:drug therapy / Q000235:genetics* / Q000382:microbiology; D000077336:Caspofungin; D002473:Cell Wall / Q000187:drug effects / Q000235:genetics*; D025141:Drug Resistance, Fungal / Q000235:genetics; D054714:Echinocandins / Q000494:pharmacology*; D006801:Humans; D055666:Lipopeptides / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000235:genetics
chemical_list: D000935:Antifungal Agents; D054714:Echinocandins; D055666:Lipopeptides; D000077336:Caspofungin
keywords: caspofungin; cell wall integrity pathway; echinocandins; high affinity calcium uptake system