DOI: 10.5061/dryad.69p8cz8z8
title: Variation in the modality of a yeast signaling pathway is mediated by a single regulator

description: Bimodal gene expression by genetically identical cells is a pervasive
 feature of signaling networks, and has been suggested to allow organisms
 to hedge their "bets" in uncertain conditions. In the
 galactose-utilization (GAL) pathway of Saccharomyces cerevisiae, gene
 induction is unimodal or bimodal depending on natural genetic variation
 and pre-induction conditions. Here, we find that this variation in
 modality arises from regulation of two features of the pathway response:
 the fraction of cells that show induction, and their level of expression.
 GAL3, the galactose sensor, controls the fraction of induced cells, and
 titrating its expression is sufficient to control modality; moreover, all
 the observed differences in modality between different pre-induction
 conditions and amongst natural isolates can be explained by changes in
 GAL3's regulation and activity. The ability to switch modality by
 tuning the activity of a single protein may allow rapid adaptation of bet
 hedging to maximize fitness in complex environments.
description: <b>Dataset 1</b> GAL induction of natural isolates in
 galactose titration experiments (Figure 1B, Figure S1). Contains .fcs
 files of raw flow cytometry data. <b>Dataset 2</b> GAL
 induction of natural isolates in glucose titrations with a constant
 galactose concentration (Figure 1C-D, Figure 4A-E, Figure S2). Contains
 .fcs files of raw flow cytometry data. <b>Dataset 3</b> GAL
 induction of a S288C <i>mig1</i>Δ strain in glucose titrations
 with a constant galactose concentration (Figure 4F). Contains .fcs files
 of raw flow cytometry data. <b>Dataset 4</b> GAL
 induction of natural isolates in glucose titrations with a constant
 galactose concentration after growth in different carbon source (Figure
 1D, Figure 5, Figure S11-12). Contains .fcs files of raw flow cytometry
 data. <b>Dataset
 5</b> Steady-state expression of S288C GAL promoters in different
 carbon sources (Figure 6A). Contains .fcs files of raw flow cytometry
 data. <b>Dataset
 6</b> Expression of the S288C <i>GAL3</i> promoter in
 different carbon sources and different natural isolates (Figure 6B).
 Contains .fcs files of raw flow cytometry data. <b>Dataset 7</b> GAL
 induction of S288C with inducible <i>GAL3</i> expression in
 glucose titrations with a constant galactose concentration after growth in
 raffinose and mannose and quantification of inducible expression after
 pre-induction growth with a TetO7pr-YFP strain (Figure 6C). Contains .fcs
 files of raw flow cytometry data. <b>Dataset 8</b> GAL
 induction of a S288C <i>gal3</i>Δ strain with inducible
 <i>GAL3</i>-mCherry expression in glucose titrations with a
 constant galactose concentration after growth in different carbon sources
 (Figure 6D). Contains .fcs files of raw flow cytometry data.
 <b>Dataset
 9 </b><i>GAL3</i> levels of the S288C
 <i>gal3</i>Δ strain with inducible
 <i>GAL3</i>-mCherry expression (see Dataset 8) before the
 switch to glucose and galactose medium (Figure 6D). Contains .tif files of
 raw flow microscopy data. <b>Dataset 10</b> GAL
 induction of GAL3 allele swap strains in glucose titrations with a
 constant galactose concentration (Figure 7, Figure S13). Contains .fcs
 files of raw flow cytometry data.