Data for: Divergence of alternative sugar preferences through modulation of the expression and activity of the Gal3 sensor in yeast

Optimized nutrient utilization is crucial for the progression of
microorganisms in competing communities. Here we investigate how different
budding yeast species and ecological isolates have established divergent
preferences for two alternative sugar substrates: Glucose, which is
fermented preferentially by yeast, and galactose, which is alternatively
used upon induction of the relevant GAL metabolic genes. We
quantified the dose-dependent induction of the GAL1 gene encoding the
central galactokinase enzyme, and found that a very large diversification
exists between different yeast ecotypes and species. The sensitivity of
GAL1 induction correlates with the growth performance of the respective
yeasts with the alternative sugar. We further define some of the
mechanisms, which have established different glucose/galactose consumption
strategies in representative yeast strains by modulating the activity of
the Gal3 inducer. (1) Optimal galactose consumers, such as Saccharomyces
uvarum, contain a hyperactive GAL3 promoter, sustaining highly sensitive
GAL1 expression, which is not further improved upon repetitive galactose
encounters. (2) Desensitized galactose consumers, such as S. cerevisiae
Y12, contain a less sensitive Gal3 sensor, causing a shift of the
galactose response towards higher sugar concentrations even in galactose
experienced cells. (3) Galactose insensitive sugar consumers, such as S.
cerevisiae DBVPG6044, contain an interrupted GAL3 gene, causing extremely
reluctant galactose consumption, which however still is improved upon
repeated galactose availability. In summary, different yeast strains and
natural isolates have evolved galactose utilization strategies, which
cover the whole range of possible sensitivities by modulating the
expression and/or activity of the inducible galactose sensor Gal3.