The Mediator co-activator complex regulates Ty1 retromobility by controlling the balance between Ty1i and Ty1 promoters
Fig 4
The Mediator tail acts on Ty1 mobility in an LTR promoter-dependent manner.
(A) Schematic of the PTEF1-Ty1his3AI element relative to a Ty1his3AI element with the standard LTR promoter. PTEF1-Ty1his3AI has a TEF1 promoter in place of Ty1 promoter elements in the U3 region of the 5′ LTR (See Fig 1C), while retaining the Ty1 TSS and R-U5 region of the 5′ LTR. (B) Retrotransposition frequency, shown on a log scale, for a plasmid-based Ty1his3AI (left) or PTEF1-Ty1his3AI (right) element in the WT and spt3Δ negative control strains (grey bars), Mediator head subunit gene deletion strains (red bars), middle subunit gene deletion strains (blue bars) and tail subunit gene deletion strains (yellow bars). (C) Retromobility frequencies, shown on a log scale, of a chromosomal Ty1kanMXAI element and a plasmid-borne PTEF1-Ty1his3AI element contained in the same wild type or med15Δ strain. All error bars represent s.d. Blue circles in (B) and (C) denote values that represent upper limit mobility estimates for strains in which most or all cultures had no His+ prototrophs (LTR-Ty1his3AI or PTEF1-Ty1his3AI) or G418R colonies (Ty1kanMXAI) per total number of Ura+ or Leu+ cells analyzed, respectively.