RNA polymerase I stability couples cellular growth to metal availability.

Zinc is an essential cofactor of all major eukaryotic RNA polymerases. How the activity of these enzymes is coordinated or regulated according to cellular zinc levels is largely unknown. Here we show that the stability of RNA polymerase I (RNAPI) is tightly coupled to zinc availability in vivo.

Widespread impact of nonsense-mediated mRNA decay on the yeast intronome.

Nonsense-mediated mRNA decay (NMD) eliminates transcripts carrying premature translation termination codons, but the role of NMD on yeast unspliced pre-mRNA degradation is controversial. Using tiling arrays, we show that many unspliced yeast pre-mRNAs accumulate in strains mutated for the NMD component Upf1p and the exonuclease Xrn1p. Intron identity and suboptimal splicing signals resulting in weak splicing were found to be important determinants in NMD targeting.

The roles of endonucleolytic cleavage and exonucleolytic digestion in the 5'-end processing of S. cerevisiae box C/D snoRNAs.

Small nucleolar RNAs (snoRNAs) play important roles in ribosomal RNA metabolism. In Saccharomyces cerevisiae, box C/D snoRNAs are synthesized from excised introns, polycistronic precursors, or independent transcription units. Previous studies have shown that only a few independently transcribed box C/D snoRNAs are processed at their 5' end.

RNAse III-mediated degradation of unspliced pre-mRNAs and lariat introns.

Double-stranded RNA (dsRNA) has emerged as a modulator of gene expression, from gene silencing to antiviral responses. Here we show that dsRNA stem-loop structures found in intronic regions of the S. cerevisiae RPS22B and RPL18A transcripts trigger degradation of unspliced pre-mRNAs and lariat introns and can control the level of mRNA produced from these intron-containing genes.