Transcriptomic and chemogenomic analyses unveil the essential role of Com2-regulon in response and tolerance of Saccharomyces cerevisiae to stress induced by sulfur dioxide

Microb Cell. 2019 Sep 30;6(11):509-523. doi: 10.15698/mic2019.11.697.

Abstract

During vinification Saccharomyces cerevisiae cells are frequently exposed to high concentrations of sulfur dioxide (SO2) that is used to avoid overgrowth of unwanted bacteria or fungi present in the must. Up to now the characterization of the molecular mechanisms by which S. cerevisiae responds and tolerates SO2 was focused on the role of the sulfite efflux pump Ssu1 and investigation on the involvement of other players has been scarce, especially at a genome-wide level. In this work, we uncovered the essential role of the poorly characterized transcription factor Com2 in tolerance and response of S. cerevisiae to stress induced by SO2 at the enologically relevant pH of 3.5. Transcriptomic analysis revealed that Com2 controls, directly or indirectly, the expression of more than 80% of the genes activated by SO2, a percentage much higher than the one that could be attributed to any other stress-responsive transcription factor. Large-scale phenotyping of the yeast haploid mutant collection led to the identification of 50 Com2-targets contributing to the protection against SO2 including all the genes that compose the sulfate reduction pathway (MET3, MET14, MET16, MET5, MET10) and the majority of the genes required for biosynthesis of lysine (LYS2, LYS21, LYS20, LYS14, LYS4, LYS5, LYS1 and LYS9) or arginine (ARG5,6, ARG4, ARG2, ARG3, ARG7, ARG8, ORT1 and CPA1). Other uncovered determinants of resistance to SO2 (not under the control of Com2) included genes required for function and assembly of the vacuolar proton pump and enzymes of the antioxidant defense, consistent with the observed cytosolic and mitochondrial accumulation of reactive oxygen species in SO2-stressed yeast cells.

Keywords: Com2 (YER130c); Saccharomyces cerevisiae; Sulfur dioxide tolerance; stress response; wine preservation.

Grant support

This work was funded by INNOVINE&WINE, Norte-01-0145-FEDER-000038, co-financed by the European Regional Development Fund (ERDF) through Norte 2020 and by ERFD through POCI-COMPETE 2020. Support received by FCT-Portuguese Foundation for Science and Technology (PTDC/EXPL/AGR-TEC/1823/2013 and PTDC/AGR-TEC/3315/2014) and by INTERACT project – “Integrated Research in Environment, Agro-Chain and Technology”, no. NORTE-01-0145-FEDER-000017, in its line of research entitled VitalityWine. Support received by Biosystems and Integrative Sciences Institute (BioISI; FCT/UID/Multi/04046/2018) and iBB-Institute for Bioengineering and Biosciences (UID/BIO/04565/2019) by FCT and from Programa Operacional Regional de Lisboa 2020 (project no. 007317 and PTDC/AGR-TEC/3315/2014_LISBOA-01-0145-FEDER-016834) is also acknowledged. The authors thank Professor Isabel Sá-Correia for the help and guidance in conducting the chemogenomic analysis.