The Mediator co-activator complex regulates Ty1 retromobility by controlling the balance between Ty1i and Ty1 promoters
Fig 2
Mediator subunit deletions influence Ty1 mobility in a module-specific manner.
(A) The Mediator transcriptional coactivator complex is composed of head (red), middle (blue), tail (yellow), and kinase (grey) modules (figure based on recent cryo-EM structure [50]). Individual subunits investigated in this study are labeled. (B) Schematic of the retromobility assay [19]. The HIS3 ORF is inserted downstream of POL in the opposite orientation of Ty1 and contains an intron that is in the sense orientation relative to Ty1. Splicing of this intron from the Ty1his3AI transcript, followed by integration, results in His+ colonies. (C) The frequency of retrotransposition, shown on a log scale, of the chromosomal Ty1his3AI-3114 element was measured in congenic WT, spt3Δ and Mediator subunit deletion strains. Error bars represent standard deviation for three biological replicates, except for med18Δ (n = 2), where the range of measurement is indicated (but is too small to be visible). Blue circles denote values that represent upper limit retrotransposition estimates in strains with no retrotransposition events among the total number of cells assayed. Bars are color-coded to match structural organization as shown in (A).