18S and 25S Exonuclease Resistant Ribosomal RNA Molecules Are Produced by 5'-End Modification During TOR Inhibition.

ABSTRACT: Saccharomyces cerevisiae yeast cells have been shown to produce 18S and 25S ribosomal RNA molecules that are resistant to degradation by exonucleases, which require a 5' monophosphate for activity. These resistant RNA species accumulate during the diauxic shift, a phase marked by reduced TOR signaling. To further investigate the link between TOR activity and the accumulation of resistant rRNA, we examined the effects of pharmacological TOR inhibition. Treatment with rapamycin, an active TOR suppressor, led to increased levels of resistant 18S and 25S RNA. Importantly, this accumulation was also observed in cells with constitutively active RNA polymerase I (CARA), indicating that the resistant RNA species arise independently of RNA Pol I transcriptional regulation. Similarly, a TOR1-deleted

SUBMITTER: Rocha MA 

PROVIDER: S-EPMC12757822 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature