Disruption of the Candida albicans TPS2 Gene Encoding Trehalose-6-Phosphate Phosphatase Decreases Infectivity without Affecting Hypha Formation

Abstract

Deletion of trehalose-6-phosphate phosphatase, encoded by TPS2, in Saccharomyces cerevisiae results in accumulation of trehalose-6-phosphate (Tre6P) instead of trehalose under stress conditions. Since trehalose is an important stress protectant and Tre6P accumulation is toxic, we have investigated whether Tre6P phosphatase could be a useful target for antifungals in Candida albicans. We have cloned the C. albicans TPS2 (CaTPS2) gene and constructed heterozygous and homozygous deletion strains. As in S. cerevisiae, complete inactivation of Tre6P phosphatase in C. albicans results in 50-fold hyperaccumulation of Tre6P, thermosensitivity, and rapid death of the cells after a few hours at 44°C. As opposed to inactivation of Tre6P synthase by deletion of CaTPS1, deletion of CaTPS2 does not affect hypha formation on a solid glucose-containing medium. In spite of this, virulence of the homozygous deletion mutant is strongly reduced in a mouse model of systemic infection. The pathogenicity of the heterozygous deletion mutant is similar to that of the wild-type strain. CaTPS2 is a new example of a gene not required for growth under standard conditions but required for pathogenicity in a host. Our results suggest that Tre6P phosphatase may serve as a potential target for antifungal drugs. Neither Tre6P phosphatase nor its substrate is present in mammals, and assay of the enzymes is simple and easily automated for high-throughput screening.

Characterization and Regulation of the Trehalose Synthesis Pathway and Its Importance in the Pathogenicity of Cryptococcus neoformans

“…In C. albicans, the tps2 mutant flocculates during stationary growth, while in A. nidulans, the mutant produces nonviable germination of spores through a deficiency in chitin production. Furthermore, both of these phenotypes can be suppressed by the addition of osmoprotectants to the culture medium (7,53,59). We did not observe a flocculation phenotype in a C. neoformans-like tps2 strain of C. albicans, but we did find different phenotypes between tps1 and tps2 mutants at low and high temperatures.…”

“…T6P is an intermediate in trehalose biosynthesis that has been shown to possess regulatory potential (5,26 (7,21,22,47,53,59) and give further insights into T6P. In C. albicans, the tps2 mutant flocculates during stationary growth, while in A. nidulans, the mutant produces nonviable germination of spores through a deficiency in chitin production.…”

Combined Inactivation of the Candida albicans GPR1 and TPS2 Genes Results in Avirulence in a Mouse Model for Systemic Infection

“…All strains used in this study derive from the KAR5 (TPS2/tps2 ura Ϫ ) and the EL17 (tps2⌬/tps2⌬ ura Ϫ ) strains (32) and are presented in Table 1. The construction of the different C. albicans gpr1⌬ strains is described below.…”

“…Interestingly, in this pathogen, the Tps1 enzyme is not essential for growth on glucose (38). Later, it was shown that deletion of TPS2 has an even stronger effect, probably because such a strain not only lacks trehalose but also accumulates high levels of T6P under stress conditions (32,39). As a result the tps2⌬ strain is also thermosensitive.…”

Distinct and Redundant Roles of the Two MYST Histone Acetyltransferases Esa1 and Sas2 in Cell Growth and Morphogenesis of Candida albicans

“…Trehalose, an important stress protectant, is synthesized in a two-step process in fungi by trehalose-6-phosphate (Tre6P) synthase and Tre6P phosphatase, which are encoded by TPS1 and TPS2, respectively (43). C. albicans Tps1 and Tps2 are proteins that are enriched during and play roles in osmotic and thermal stresses (44)(45)(46). Under exponential growth conditions at 25°C, the expression levels of both TPS1 and TPS2 were derepressed in the esa1/esa1 mutant cells compared to the wild-type cells (Fig.…”