title: The mannoprotein TIR3 (CAGL0C03872g) is required for sterol uptake in Candida glabrata.
abstract: Sterol uptake in the pathogenic fungus, Candida glabrata, occurs via the sterol transporter, CgAus1p. Azole inhibition of sterol biosynthesis can under certain circumstances be reversed by adding exogenously sterol. Here we demonstrate that the CgTIR3 (CAGL0C03872g) gene product is also required for sterol uptake, since Cgtir3Δ strains fail to take up sterol both aerobically and under hypoxic conditions. Western analysis using an HA-tagged TIR3 strain showed that CgTir3p localizes to the cell wall, and its expression is induced by serum. Semi-quantitative reverse transcriptase-PCR also showed that two transcription regulatory genes, CgUPC2A and CgUPC2B, control CgTIR3 as well as CgAUS1 gene expression. Interestingly, complementation studies using Cgtir3Δ showed that ScDAN1, a mannoprotein required for sterol uptake in Saccharomyces cerevisiae, could not complement the C. glabrata TIR3 function. Furthermore, sterol analyses, in which both the CgAUS1 and CgTIR3 genes were constitutively expressed, resulted in aerobic sterol uptake although the amount of uptake was considerably less than that of cells cultured aerobically with serum. These results suggest that additional factors other than CgAUS1 and CgTIR3 are required for sterol uptake in C. glabrata.
authors.affiliation: Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Japan; Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, Japan; Division of Pathology, Immunology and Microbiology, Graduate School of Medicine, The University of Tokyo, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Inukai
authors.affiliation: Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Nagi
authors.affiliation: Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Morita
authors.affiliation: Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Tanabe
authors.affiliation: Department of Electronic and Information Engineering, Suzuka National College of Technology, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Aoyama
authors.affiliation: Department of Chemotherapy and Mycoses, National Institute of Infectious Diseases, Japan.
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Miyazaki
authors.affiliation: Department of Biology, Indiana University-Purdue University Indianapolis, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Bard
authors.affiliation: Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science, Japan. Electronic address: nakayamh@suzuka-u.ac.jp.
authors.forename: Hironobu
authors.initials: H
authors.lastname: Nakayama
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology; D001692:Biological Transport; D041221:Candida glabrata / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015687:Cell Hypoxia; D002784:Cholesterol / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015725:Fluconazole / Q000494:pharmacology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D044967:Serum / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D000935:Antifungal Agents; D005656:Fungal Proteins; D008562:Membrane Glycoproteins; C025363:mannoproteins; D015725:Fluconazole; D002784:Cholesterol
keywords: Candida glabrata; DAN/TIR; Mannoprotein; Sterol uptake; UPC2