Cloning of the RHO1 gene from Candida albicans and its regulation of beta-1,3-glucan synthesis

Glucan Synthase Complex of Aspergillus fumigatus

“…Synthesis occurs on the cytoplasmic side of the plasma membrane, and ␤(1-3) glucan chains are extruded towards the periplasmic space (15,35). The glucan synthase complex has been characterized at the molecular level almost exclusively in the yeast Saccharomyces cerevisiae (5,7,12,19,29) and has been shown to be composed of two proteins: (i) the putative catalytic subunit Fksp, a large-molecular-size (Ͼ200 kDa) polypeptide with 16 transmembrane domains (12,29,30), and (ii) the regulatory subunit Rho1p, a small-molecular-size GTPase, which stimulates ␤(1-3) glucan synthase activity in its prenylated form (1,11,17,18,24,28,33).If the ␤(1-3) glucan synthase has been extensively analyzed in yeast, then this enzymatic complex has been poorly studied in filamentous fungi. Only one FKS gene had been cloned and sequenced to date in Aspergillus nidulans (23), and neither has a regulatory partner been identified nor has the cellular localization of the glucan synthase complex been investigated.…”

Piperazine Propanol Derivative as a Novel Antifungal Targeting 1,3-.BETA.-D-Glucan Synthase

“…1,3-b-DGlucan synthase was partially purified by product entrapment from the pathogenic fungus C. albicans IFO1060. 11,13) We identified GSI578 [(2,6-Difluoro-phenyl)-carbamic acid 3-(4-benzothiazol-2-yl-piperazine-1-yl)-propyl ester] as a potent 1,3-b-D-glucan synthase inhibitor (Fig. 1).…”

“…1,3-b-D-Glucan synthase is composed of a putative catalytic subunit with sixteen putative transmembrane domains encoded by a pair of closely related genes, FKS1/GSC1/CWH53/ETG1/CND1/PBR1/YLR342W and FKS2/GSC2/G4074/YGRO32W, [3][4][5][6][7][8] and a regulatory subunit encoded by the RHO1 9,10) in Saccharomyces cerevisiae. In C. albicans, the catalytic and regulatory subunits are encoded by CaFKS1/GSC1, 11,12) and CaRHO1, 13) respectively. 1,3-b-D-Glucan synthase has three features of a promising target for an antifungal agent: 2,14,15) 1) its function is essential for growth, proven by the fact that the disruption of the genes for the catalytic subunit of 1,3-b-D-glucan synthase is a lethal event in S. cerevisiae, 6,8) C. albicans, 11,12) and Cryptococcus neoformans 16) ; 2) mammalian cells have no comparable cell wall, indicating that a 1,3-b-D-glucan synthase inhibitor would be highly selective to fungal cells; and 3) genes for catalytic subunits have been identified from several pathogenic fungi, such as C. albicans, 11,12) Cr.…”

Properties of Various RHO1 Mutant Alleles of Cryptococcus neoformans

“…Rho1p was also identified as the putative regulatory subunit of ␤-1,3-glucan synthase, which produces a major structural component of the yeast cell wall (10,32). The regulation of ␤-1,3-glucan synthesis by Rho1p has also been demonstrated in Schizosaccharomyces pombe (1) and Candida albicans (22).…”