Identification of genome-wide binding sites of heat shock factor 1, Hsf1, under basal conditions in the human pathogenic yeast, Candida albicans

Abstract

The master regulator of thermal stress response, Hsf1, is also an essential determinant for viability and virulence in Candida albicans. Our recent studies highlighted that apart from ubiquitous roles of Hsf1 at higher temperatures, it also has myriad non-heat shock responsive roles essential under iron deprivation and drug defense. Here, we further explored its implications in the normal cellular functioning, by profiling its genome-wide occupancy using chromatin immuno-precipitation coupled to high-density tiling arrays under basal and iron deprived conditions. Hsf1 recruitment profiles revealed that it binds to promoters of 660 genes of varied functions, under both the conditions, however, elicited variability in intensity of binding. For instance, Hsf1 binding was observed on several genes of oxidative and osmotic stress response, cell wall integrity, iron homeostasis, mitochondrial, hyphal and multidrug transporters. Additionally, the present study divulged a novel motif under basal conditions comprising, -GTGn3GTGn3GTG- where, Hsf1 displays strong occupancy at significant number of sites on several promoters distinct from the heat induced motif. Hence, by binding to and regulating major chaperones, stress responsive genes and drug resistance regulators, Hsf1 is imperative in regulating various cellular machineries. The current study provides a framework for understanding novel aspects of how Hsf1 coordinates diverse cellular functions.Electronic supplementary materialThe online version of this article (10.1186/s13568-018-0647-7) contains supplementary material, which is available to authorized users.

The Heat Shock Transcription Factor HsfA Is Essential for Thermotolerance and Regulates Cell Wall Integrity in Aspergillus fumigatus

“…Again, the lipid and ergosterol biosynthetic processes were also found downregulated only in the wild-type strain. The iron assimilation and cellular response to iron ion starvation categories were also downregulated exclusively in the wild type ( Figure 8C ), which is in agreement with previous studies that have shown a relationship between Hsf1 and the cellular iron pool in C. albicans ( Nair et al, 2017 , 2018 ).…”

“…Again, the lipid and ergosterol biosynthetic processes were also found downregulated only in the wild-type strain. The iron assimilation and cellular response to iron ion starvation categories were also downregulated exclusively in the wild type (Figure 8C), which is in agreement with previous studies that have shown a relationship between Hsf1 and the cellular iron pool in C. albicans (Nair et al, 2017(Nair et al, , 2018. Subsequently, to identify genes whose expression was directly influenced by hsfA, we compared the xylP::hsfA mutant grown on repressive conditions with the wild-type strain, and we observe that several genes are modulated either at the non-HS control condition (30 • C) or during temperature stress (Figures 9A,B).…”

Response and regulatory mechanisms of heat resistance in pathogenic fungi

“…C. albicans Hsf1 binds nGAAn elements in at least three configurations in different dimeric and trimeric forms. The TTCnnGAAnnTTC element has the strongest binding ability, whereas GAAnnTTC and TTCn7TTC have lower but still significant binding affinity (Leach et al 2016 ; Nair et al 2018 ). HSF1 of C .…”