Portrait of Candida albicans Adherence Regulators

Abstract

Cell-substrate adherence is a fundamental property of microorganisms that enables them to exist in biofilms. Our study focuses on adherence of the fungal pathogen Candida albicans to one substrate, silicone, that is relevant to device-associated infection. We conducted a mutant screen with a quantitative flow-cell assay to identify thirty transcription factors that are required for adherence. We then combined nanoString gene expression profiling with functional analysis to elucidate relationships among these transcription factors, with two major goals: to extend our understanding of transcription factors previously known to govern adherence or biofilm formation, and to gain insight into the many transcription factors we identified that were relatively uncharacterized, particularly in the context of adherence or cell surface biogenesis. With regard to the first goal, we have discovered a role for biofilm regulator Bcr1 in adherence, and found that biofilm regulator Ace2 is a major functional target of chromatin remodeling factor Snf5. In addition, Bcr1 and Ace2 share several target genes, pointing to a new connection between them. With regard to the second goal, our findings reveal existence of a large regulatory network that connects eleven adherence regulators, the zinc-response regulator Zap1, and approximately one quarter of the predicted cell surface protein genes in this organism. This limited yet sensitive glimpse of mutant gene expression changes had thus defined one of the broadest cell surface regulatory networks in C. albicans.

Phenotypic Consequences of a Spontaneous Loss of Heterozygosity in a Common Laboratory Strain of Candida albicans

“…Based on their reported GO functions in Candida and Saccharomyces (http://www.candidagenome.org/ and http:// www.yeastgenome.org/), four of these ORFs, SNF5, POL1, orf19.5854.1, and MBP1, were selected for further study. SNF5 (orf19.5871 ) encodes a component of the Swi/Snf chromatin remodeling complex and null mutants display increased MMS sensitivity in Saccharomyces cerevisiae (Chai et al 2005) and anomalous biofilm formation and other pleiotropic defects in C. albicans (Finkel et al 2012). We found that SNF5 homozygous deletants in the CAF2-1 background (TCS1038 and TCS1039) were more sensitive to MMS than its parent, but not as sensitive as CAI4 ( Figure S5A).…”

Plasticity of Candida albicans Biofilms

“…Profiling can be performed by assessing genome-wide transcription by using microarrays (195,200,(244)(245)(246)(247)(248), NanoString nCounter technology (249,250), and RNA sequencing (RNA-Seq) (197,200) or by using quantitative reverse transcription-PCR (RT-PCR) or Northern blot analysis of a smaller, select group of genes (251). Such comparisons are often made between biofilm preparations and planktonic cultures.…”

High Throughput Screening of Gene Expression for the Investigation of Multifactorial Dermatological Disorders

“…For this, the following conditions were used: control hyphae, model hyphae, and control hyphae Lack of induction of these three genes may be due to the fact that these cells were cultured in a mammalian culture medium containing glucose. These results are in agreement with a previous report, which showed that glucose did not significantly induce the expression of GlcNAc catabolism genes [14]. Furthermore, our results showed that the expression of all four genes (NGT1, DAC1, HXK1, and NAG1) genes involved in GlcNAc catabolism were all significantly upregulated in model hyphae and upon GlcNAc induction (Figure 4).…”

“…An important initial step during pathogenesis is adhesion. A large set of adhesins and a complex regulatory machinery have already been identified [14]. After adhesion and hyphal induction, penetration is facilitated by a set of secreted aspartic proteases [15].…”