Molecular Biology

Regulation Revealed Under Stress

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Science  28 Sep 2007:
Vol. 317, Issue 5846, pp. 1834
DOI: 10.1126/science.317.5846.1834b

In most eukaryotic genes, the protein-coding sequences are interrupted by noncoding introns. These introns are removed from the pre-mRNA transcript by RNA splicing, a process that provides an additional and sometimes critical layer of gene regulation. Unlike more complex organisms, few genes in the yeast Saccharomyces cerevisiae contain introns. In those that do, the splice site sequences often conform to a strict consensus, making it unlikely that the use of alternative splice sites figures in the differential expression of genes. Intriguingly, though, ribosomal protein genes (RPGs)—components of the mRNA translation machinery—are the largest class of intron-containing genes.

Pleiss et al. show that amino acid starvation, which induces a general repression of translation, also results in a rapid and specific reduction in the splicing efficiency of nearly all intron-containing RPG transcripts. This is not merely an effect of stressful circumstances, because exposure to high levels of ethanol does not have an effect on RPG splicing; rather the splicing of distinct sets of transcripts is either down- or up-regulated. The yet-to-be-discovered regulatory mechanisms, which other evidence suggests could be mediated by core, rather than accessory, spliceosomal components, probably explain the evolutionary retention of introns in these groups of yeast genes and, given the conservation of the RNA splicing machinery, similar mechanisms may pervade pre-mRNA splicing in higher eukaryotes. — GR

Mol. Cell 27, 10.1016/j.molcel.2007.07.018 (2007).

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