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Time-resolved heat stress response of Saccharomyces cerevisiae

ABSTRACT: Whole-genome transcriptional response of S. cerevisiae to an increase in temperature from 28°C to 41°C under well-controlled conditions. Two subsequent phases of response with very different dynamics: a short term response for the first hour after the temperature increase and a long term one for up to six hours. The initial response was strongest with almost half of the ORFs being induced or repressed to a statistically significant level (here 1.5 fold). The data was grouped based on the function of the encoded proteins. Analysis showed that the cells overexpressed genes involved in energy conservation processes. Genes encoding molecular chaperones were overexpressed as well, presumably to counteract the effect of the temperature increase on protein denaturation. Furthermore, genes encoding parts of the translation and transcription systems were repressed temporarily, in line with the observed lag in growth. More detailed analysis of certain small groups of genes involved in energy metabolism supported the notion that, although the expression level of genes represent a part of the stress response, they cannot be directly linked to the level of activity of their products.

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE25503 | GEO | 2013/12/01

SECONDARY ACCESSION(S): PRJNA134643

REPOSITORIES: GEO

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Project description:Carbon catabolite repression (CCR) is a gene regulation process that allows bacteria to use carbon-energy sources in a hierarchical manner. Thus, the presence of a preferred sugar, usually D-glucose, results in downregulation of genes participating in the transport and catabolic pathways of secondary carbon sources. Further, CCR controls the expression of global regulators that control expression of many genes involved in multiple aspects of bacterial physiology such as stress response proteins and virulence factors. The human-restricted pathogen Neisseria gonorrhoeae can rely upon a limited number of carbon-energy sources, including glucose and lactate and both are available within its infection niches. We recently reported that expression of the L-lactate permease-encoding gene lctP is subjected to glucose repression within physiological concentrations. However, the transducing mechanism or the gene that connect glucose with lctP promoter repression remained unknown. To address this issue, we performed an RNA-Seq analysis to determine the transcriptional landscape of gonococci due to changes in glucose or lactate concentrations in the growth media. Glucose was found to regulate 144 genes (5.5% of total genes in the genome) while lactate influenced the expression of 434 (16.5%) genes with an overlap of 97 genes between the two sugars. Both, glucose and lactate were found to upregulate genes involved in protein translation, a high energy consumption cellular function. Individually, glucose enhanced genes participating in glycolysis and repressed genes in the tricarboxylic acid (TCA) cycle, while lactate enhanced genes encoding respiratory enzymes and ATP synthase. Interestingly, lactate was found to repress expression of several genes encoding known gonococcal virulence factors such as tbpAB encoding the transferrin-binding proteins; the tonB and exbBD genes encoding the membrane energy transfer complex TonB-ExbB-ExbD required for many outer membrane transport systems; katA encoding an important H2O2-inducible catalase and to upregulate mtrR encoding the master repressor of the mtrCDE antimicrobial efflux pump genes. Moreover, glucose repressed mntC encoding a Zn/Mn ABC transporter and lctP, both required for resistance to killing by H2O2. These results set the framework to determine important gonococci virulent factor genes whose expression can be modulated by CCR as well as to discover the corresponding CCR regulators that control such genes.

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Time-resolved heat stress response of Saccharomyces cerevisiae

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