FIGURE 5.

Analysis of the splicing efficiency or pre-mRNA leakage of different reporters in wild-type or ΔWW-Prp40 strains. (A) Histogram reporting the results of β-galactosidase assays from the reporters carrying no LacZ gene (“background”), the LacZ reporter gene with no intron (“No intron”), the LacZ reporter gene interrupted by a simple intron (“Wild type RP51A intron”), a weak synhetic intron or pre-mRNA leakage expressed either in a wild type yeast strain (hatched bars), or in a ΔWWPrp40 strain (gray bars). The reporter constructs were described earlier (Legrain and Rosbash 1989). (B) Histogram reporting the results of β-galactosidase assays from reporters either in a wild-type yeast strain (hatched bars) or in a ΔWWPrp40 strain (gray bars). Control reporters carry no LacZ coding sequence (“background”) or the LacZ reporter gene with no intron (“No intron”). A first set of reporters described earlier (Séraphin and Rosbash 1990) contains the LacZ reporter gene interrupted by a simple intron with GG at nucleotides −3 and −4 in the upstream exon, combined with either wild-type or mutant 5′ splice site (5′II, GUAUaU) (Jacquier et al. 1985) and either wild-type or frameshifted exon 2 (WT GG, 5′ II GG, WT GG – FS, 5′II GG – FS). A second set of reporters contain the LacZ reporter gene interrupted by an intron carrying duplicated 5′ splice sites (Séraphin and Kandels-Lewis 1993) either with AA at positions −1 and −2 in the upstream exon and combinations of wild-type or mutant 5′ splice site (5′II, GUAUaU) (Jacquier et al. 1985) or with combinations of AG and UC at positions −1 and −2 in the upstream exon. Finally, the last reporter contained the LacZ reporter gene interrupted by an intron with a duplicated branchpoint and 3′ splice site (Goguel and Rosbash 1993). Constructs carrying the 5′II mutant 5′ splice site have previously been shown to be poorly spliced in the absence of Nam8 (Puig et al. 1999; data not shown quoted therein).