TABLE 1.

Yeast strains used

Strain	Genotype
FY1642	MATa his4-912δ lys2-128δ leu2Δ1 ura3-52 SPT5-FLAG
FY1668-uH	MATa his4-912δ lys2-128δ spt5-4 ura3::HIS3
FY1635	MATα his4-912δ lys2-128δ leu2Δ1 ura3-52 spt5-242
L615	MATa his4-912δ lys2-128δ ura3-52 ade2-1 trp5 can1-100 spt5-25
FY300	MATa his4-912δ lys2-128δ leu2Δ1 ura3-52 spt5-194
GHY180	MATα ura3-52 leu2Δ1 his4-912δ lys2-128δ spt4Δ2::HIS3
FY276-uT	MATa leu2Δ1 ura3::TRP1 his4-9128 lys2-128δ spt5-8
AYW3-1B1	MATa leu2 trp1 ura3 his3
AYW3-3D1	MATa leu2 his3 ura3 leu2-k::ADE2-URA3-leu2-k hpr1Δ3::HIS3
Z96	MATa ura3-52 leu2-3,112 his3Δ200 rpbΔ297::HIS3 [pRP214 (LEU2 RPB2)]
Z100	Isogenic to Z96 except [pRP2-4L (LEU2 rpb2-4)]
Z106	Isogenic to Z96 except [pRP2-10L (LEU2 rpb2-10)]
Z103	Isogenic to Z96 except [pRP2-7L (LEU2 rpb2-7)]
DY106-u	Isogenic to Z96 except dstl::hisG
DY108	Isogenic to Z106 except dst1::hisG