Recognition of the TACTAAC box during mRNA splicing in yeast involves base pairing to the U2-like snRNA.
The U2 snRNP binds to the site of branch formation during splicing of mammalian pre-mRNA in vitro. In Saccharomyces cerevisiae the branch site is within the so-called TACTAAC box (UACUAAC box), an absolutely conserved intron sequence required for splicing. Based on the identification and sequence of a U2 analogue in yeast, a specific base pairing interaction between the UACUAAC box and a highly conserved region of this snRNA can be proposed. To test this hypothesis, we have taken advantage of two mutations constructed previously in the UACUAAC box of an actin-HIS4 fusion. These mutant strains were transformed with stable plasmids bearing U2-like snRNAs into which changes predicted to restore base pairing had been introduced. Allele-specific suppression of biological and biochemical phenotypes was observed in both cases. Recognition of the UACUAAC box thus relies, at least in part, on Watson-Crick base pairing with the yeast U2 analogue.
D000483:Alleles; D001483:Base Sequence; D006860:Hydrogen Bonding; D007438:Introns; D012326:RNA Splicing; D012342:RNA, Small Nuclear / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development; D012689:Sequence Homology, Nucleic Acid; D013489:Suppression, Genetic
D012342:RNA, Small Nuclear