Effects of mutations in the Saccharomyces cerevisiae RNA14 gene on the abundance and polyadenylation of its transcripts.

In the yeast Saccharomyces cerevisiae, the RNA14 and RNA15 gene products have been implicated in RNA cleavage and polyadenylation in vitro and in the choice of polyadenylation site of ACT1 mRNA in vivo. The RNA14 gene produces three transcripts that differ in their 3' end, suggesting the use of different polyadenylation sites. The appearance of the three RNA14 transcripts was examined in different rna14 and/or rna15 mutant strains. In the rna14-1 or rna15-2 mutant strains, only the large transcript is present at the non-permissive temperature, showing that the rna14-1 and rna15-2 mutations lead to the use of the most distal RNA14 polyadenylation site, which turns out to be the most efficient. The rna14-5 mutation, which does not primarily modify the choice of poly(A) site, increases the global amount of RNA14 transcript. Surprisingly, this RNA14 mRNA overproduction is also observed in the double rna14-1 rna15-2 mutant strain. Moreover, in the strains in which the RNA14 transcripts are overproduced, short heterogeneous polyadenylated antisense RNAs are detected in the 3' region of the RNA14 large transcript. Taken together these observations suggest that, in addition to poly(A) site choice, Rna14 protein has another function involved in the control of global RNA14 mRNA level.