title: The Rho1 GTPase-activating protein CgBem2 is required for survival of azole stress in Candida glabrata.
abstract: Invasive fungal infections are common clinical complications of neonates, critically ill, and immunocompromised patients worldwide. Candida species are the leading cause of disseminated fungal infections, with Candida albicans being the most prevalent species. Candida glabrata, the second/third most common cause of candidemia, shows reduced susceptibility to a widely used antifungal drug fluconazole. Here, we present findings from a screen of 9134 C. glabrata Tn7 insertion mutants for altered survival profiles in the presence of fluconazole. We have identified two components of RNA polymerase II mediator complex, three players of Rho GTPase-mediated signaling cascade, and two proteins implicated in actin cytoskeleton biogenesis and ergosterol biosynthesis that are required to sustain viability during fluconazole stress. We show that exposure to fluconazole leads to activation of the protein kinase C (PKC)-mediated cell wall integrity pathway in C. glabrata. Our data demonstrate that disruption of a RhoGAP (GTPase activating protein) domain-containing protein, CgBem2, results in bud-emergence defects, azole susceptibility, and constitutive activation of CgRho1-regulated CgPkc1 signaling cascade and cell wall-related phenotypes. The viability loss of Cgbem2Δ mutant upon fluconazole treatment could be partially rescued by the PKC inhibitor staurosporine. Additionally, we present evidence that CgBEM2 is required for the transcriptional activation of genes encoding multidrug efflux pumps in response to fluconazole exposure. Last, we report that Hsp90 inhibitor geldanamycin renders fluconazole a fungicidal drug in C. glabrata.
authors.affiliation: Centre for DNA Fingerprinting and Diagnostics, Building 7, Gruhakalpa, 5-4-399/B, Nampally, Hyderabad 500001, India.
authors.forename: Sapan
authors.initials: S
authors.lastname: Borah
authors.forename: Raju
authors.initials: R
authors.lastname: Shivarathri
authors.forename: Rupinder
authors.initials: R
authors.lastname: Kaur
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D016227:Benzoquinones / Q000494:pharmacology; D041221:Candida glabrata / Q000235:genetics / Q000378:metabolism*; D025141:Drug Resistance, Fungal / Q000187:drug effects / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015725:Fluconazole / Q000494:pharmacology*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000235:genetics / Q000378:metabolism*; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D009154:Mutation; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects* / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000935:Antifungal Agents; D016227:Benzoquinones; D004791:Enzyme Inhibitors; D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; D047029:Lactams, Macrocyclic; D015725:Fluconazole; D011493:Protein Kinase C; D020741:rho GTP-Binding Proteins; C001277:geldanamycin