Medicinal genetics approach towards identifying the molecular target of a novel inhibitor of fungal cell wall assembly.
Glycosylphosphatidylinositol (GPI)-anchored cell wall mannoproteins are required for the adhesion of pathogenic fungi, such as Candida albicans, to human epithelium. Small molecular inhibitors of the cell surface presentation of GPI-anchored mannoproteins would be promising candidate drugs to block the establishment of fungal infections. Here, we describe a medicinal genetics approach to identifying the gene encoding a novel target protein that is required for the localization of GPI-anchored cell wall mannoproteins. By means of a yeast cell-based screening procedure, we discovered a compound, 1-[4-butylbenzyl]isoquinoline (BIQ), that inhibits cell wall localization of GPI-anchored mannoproteins in Saccharomyces cerevisiae. Treatment of C. albicans cells with this compound resulted in reduced adherence to a rat intestine epithelial cell monolayer. A previously uncharacterized gene YJL091c, named GWT1, was cloned as a dosage-dependent suppressor of the BIQ-induced phenotypes. GWT1 knock-out cells showed similar phenotypes to BIQ-treated wild-type cells in terms of cell wall structure and transcriptional profiles. Two different mutants resistant to BIQ each contained a single missense mutation in the coding region of the GWT1 gene. These results all suggest that the GWT1 gene product is the primary target of the compound.
Tsukahara
Kappei
K
Tsukuba Research Laboratories, Eisai Co, Ltd, Tsukuba 300-2635, Ibaraki, Japan. k-tsukahara@hhc.eisai.co.jp
Hata
Katsura
K
Nakamoto
Kazutaka
K
Sagane
Koji
K
Watanabe
Nao-Aki
NA
Kuromitsu
Junro
J
Kai
Junko
J
Tsuchiya
Mamiko
M
Ohba
Fuminori
F
Jigami
Yoshifumi
Y
Yoshimatsu
Kentaro
K
Nagasu
Takeshi
T
D000595:Amino Acid Sequence; D002176:Candida albicans / Q000187:drug effects* / Q000378:metabolism; D002448:Cell Adhesion; D002473:Cell Wall / Q000187:drug effects* / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000096:biosynthesis* / Q000378:metabolism; D007294:Inositol / Q000378:metabolism; D007546:Isoquinolines / Q000494:pharmacology*; D008969:Molecular Sequence Data; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D017386:Sequence Homology, Amino Acid
C479572:1-(4-butylbenzyl)isoquinoline; C476345:GWT1 protein, S cerevisiae; D017261:Glycosylphosphatidylinositols; D007546:Isoquinolines; D029701:Saccharomyces cerevisiae Proteins; D007294:Inositol