Histone modifying proteins Gcn5 and Hda1 affect flocculation in Saccharomyces cerevisiae during high-gravity fermentation

Abstract

The performance of yeast is often limited by the constantly changing environmental conditions present during high-gravity fermentation. Poor yeast performance contributes to incomplete and slow utilization of the main fermentable sugars which can lead to flavour problems in beer production. The expression of the FLO and MAL genes, which are important for the performance of yeast during industrial fermentations, is affected by complex proteins associated with Set1 (COMPASS) resulting in the induction of flocculation and improved maltose fermentation capacity during the early stages of high-gravity fermentation. In this study, we investigated a possible role for other histone modifying proteins. To this end, we tested a number of histone deacetylases (HDACs) and histone acetyltransferases and we report that flocculation is induced in absence of the histone deacetylase Hda1 or the histone acetyltransferase Gcn5 during high-gravity fermentation. The absence of Gcn5 protein also improved utilization of high concentrations of maltose. Deletion of SIR2 encoding the HDA of the silent informator regulator complex, did not affect flocculation under high-gravity fermentation conditions. Despite the obvious roles for Hda1 and Gcn5 in flocculation, this work indicates that COMPASS mediated silencing is the most important amongst the histone modifying components to control the expression of the FLO genes during high-gravity fermentation.

The yeast Cyc8–Tup1 complex cooperates with Hda1p and Rpd3p histone deacetylases to robustly repress transcription of the subtelomeric FLO1 gene

“…Previous reports have connected Cyc8–Tup1 to class I histone deacetylases (HDACs) Rpd3p and Hos2p [31] , and Tup1p has been linked to the class II HDAC Hda1p [33] . Flocculation was also reported to be induced during high-gravity fermentation in an hda1 mutant [60] . In order to identify which HDACs, if any, were involved in FLO1 gene repression in our system, mutations in various HDACs were prepared and screened for FLO1 transcription.…”

Flocculation in Saccharomyces cerevisiae: a review

“…It was proposed that COMPASS was involved in silencing the expression of FLO1 , FLO5 and FLO9 genes (Dietvorst and Brandt 2008). Recently, it was shown that in addition to COMPASS, the histone deacetylase (Hda1) and histone acetyltransferase (Gcn5) proteins are required to repress FLO genes in high‐gravity fermentations (Dietvorst and Brandt 2010). Histone deacetylases (HDACs) are transcriptional repressors; they reduce acetylation of histones, creating regions of repressed chromatin.…”

“…Other histone modification enzymes, like Gcn5, have also been shown to be involved in silencing. FLO1 gene is expressed in the absence of Had1, whereas the expression of FLO1 and FLO9 genes is induced in the absence of Gcn5 (Dietvorst and Brandt 2010).…”

Flocculation inSaccharomyces cerevisiae is regulated by RNA/DNA helicase Sen1p

“…Flocculation is governed by FLO genes and quite a few flocculation activators and suppressor genes have been described in literature[11]. FLO genes appears to be regulated by upstream genetic elements where different activator and repressor proteins are known to bind including Set1 (COMPASS) methylation complex[55] and Histone deacetylases (HDACs) such as Gcn5p, Had1[56]; however, the mechanisms that control this complex process is not fully understood. Our current study sheds light on the process of flocculation control by identifying Sen1p as a novel regulator.…”