Genetic interactions among mutants affecting mRNA export factors Dbp5p/Rat8p, Mex67p, Sub2p and Yra1p, and the transcription factor Bur6p and truncated Rpb2tp. (A) Synthetic lethality between bur6-ts and yra1-1 or sub2-85. Double mutants yra1-1 bur6-ts [pYRA1/URA3] (yra1-1 in the Figure), sub2-85 bur6-ts [pSUB2/URA3] (sub2-85 in the Figure), mex67-5 bur6-ts [pMEX67/URA3] (mex67-5 in the Figure) and mex67-6 bur6-ts [pMEX67/URA3] (mex67-6 in the Figure) were streaked on SC-ura (as control) or 5′-FOA (to analyze synthetic lethality) and incubated at 30 °C for 4 days. (B) rat8-2 mutant was transformed with a C-terminal deletion of RPB2 carried on the multicopy plasmid YEplac181 (YEp-rpb2t), the wild type RPB2 gene cloned in YEplac181 (YEp-RPB2) or the empty vector (YEplac181). Serial dilutions (1:10) of transformed cells were spotted onto YPD plates and incubated for 3 days at different temperatures. A yeast strain carrying the DBP5 gene under the control of the regulatable promoter containing tetO (PtetO-DBP5) was transformed with the indicated plasmids. Transformed cells were spotted onto YPD or YPD containing 10 mg/L doxycycline and incubated for 3 days at 30 °C. sub2-85 and yra1-1 mutants were transformed with the YEp-rpb2t plasmid or the empty vector YEplac181 and growth was analyzed by spotting serial dilutions of the transformants on YPD plates and incubation at different temperatures.