Candida albicans SNO1 and SNZ1 expressed in stationary-phase planktonic yeast cells and base of biofilm

Abstract

The Candida albicans homologues of the most studied Saccharomyces cerevisiae stationaryphase genes, SNO1 and SNZ1, were used to test the hypothesis that, within a biofilm, some cells reach stationary phase within continuously fed, as well as static, C. albicans biofilms grown on dental acrylic. The authors first studied the expression patterns of these two genes in planktonic growth conditions. Using real-time RT-PCR (RT-RTPCR), increased peak expression of both SNZ1 and SNO1 was observed at 5 and 6 days, respectively, in C. albicans grown in suspension culture. SNZ1-yellow fluorescent protein (YFP) and SNO1-YFP were constructed to study expression at the cellular level and protein localization in C. albicans. Snz1p-YFP and Sno1p-YFP localized to the cytoplasm with maximum expression (>90 %) at 5 and 6 days, respectively, in planktonic conditions. When yeast growth was reinitiated, loss of fluorescence began immediately. Germ tubes and hyphae were non-fluorescent. Pseudohyphae began appearing at 9 days in planktonic yeast culture and expressed each protein by 11 days; however, the cells budding from pseudohyphae were not fluorescent. Biofilm was formed in vitro under either static or continuously fed conditions. Increased expression of the two genes was shown by RT-RTPCR, beginning by day 3 and increasing through to day 15 (continuously fed biofilm). Only the bottommost layer of acrylic-adhered cells in the biofilm showed 25 and 40 % fluorescence at 6 and 15 days, respectively. These observations suggest that only a few cells in C. albicans biofilms express genes associated with the planktonic stationary phase and that these are found at the bottom of the biofilm adhered to the surface.

A proteomic view of Candida albicans yeast cell metabolism in exponential and stationary growth phases

“…Nevertheless, we identified proteins as stationary phase specific in agreement with prior publications. For instance, SNZ1 was described to have its maximum expression in 5-6-day-old suspension cultures of C. albicans (Uppuluri et al, 2006). We identified the corresponding protein Snz1p only in the stationary phase.…”

Exposure of ELF-EMF and RF-EMF Increase the Rate of Glucose Transport and TCA Cycle in Budding Yeast

“…SNZ1 , a member of a highly conserved gene family, was first identified through studies of proteins synthesized in stationary-phase yeast cells (Braun et al, 1996). The highly conserved gene SNO1 ( SNZ1 proximal Open reading frame) is located downstream of SNZ1 , and its regulation is coordinated with the neighboring gene through the same promoter (Uppuluri et al, 2006). Snz proteins contain no distinct functional motifs but exhibit very distant relationships with proteins involved in amino acid, vitamin, and nucleic acid biosynthesis (Dong et al, 2004).…”

Photodynamic inactivation of clinical isolates ofCandidausing Photodithazine®

“…This complex structure can be divided in three different layers: the basal layer, the middle layer, and the superficial layer. Studies have shown that cells of Candida biofilms have distinct metabolic activity in the different layers (La Fleur et al 2006;Uppuluri et al 2006). Thus, this variety of physiological states of biofilm cells can influence the penetration of PS and promote poor cell sensitization.…”