Elucidating the signalome profile of industrial S. cerevisiae strains and the convergences between xylose-fermenting pathways to convert agroindustrial residues

Abstract

The global concerns about climate change due to anthropogenic use of fossil sources have driven the search for renewable energy sources, one of which is plant lignocellulosic biomass. The lignocellulosic biomass is mostly composed of carbohydrates, with glucose and xylose making up a majority of its dry mass, and the conversion of all biomass sugars into bioproducts is essential for the feasibility of biorefineries. Although the most used yeast in the industry, Saccharomyces cerevisiae, excels at consuming glucose, it does not consume xylose naturally. Strategies of metabolic engineering and adaptive evolution have been employed over the years to construct xylose-fermenting strains, however, xylose consumption by these strains is still much lower than glucose consumption. Studies exploring the reason for this low xylose consumption demonstrated that this pentose is not sensed as a fermentable sugar by the yeast, pointing to xylose sensing and signaling as a bottleneck in pentose consumption improvement. In this project, we will, for the first time, integrate a real-time single-cell biosensor to monitor the sugar signaling in an industrial strain of S. cerevisiae, elucidating the convergences of xylose isomerase (XI) and the xylose reductase/xylitol dehydrogenase (XR-XDH) pathways for xylose metabolism, while also analyzing the signalome profile of the single and double mutants of YFH1, YPR1, ZWF1, CLN3, and SSK2 genes. The results will help to develop strategies to improve extracellular xylose sensing and signaling for the efficient conversion of biomass-derived sugars into value-added products. (AU)