Fromont-Racine, M. | Search bioRxiv

bioRxiv2023

Xrn1 biochemically associates to the eisosome after the post diauxic shift in yeast

mRNA degradation is one of the main steps of gene expression, and a key player is the 5-3 exonuclease Xrn1. In Saccharomyces cerevisiae, it was previously shown, by a microscopy approach, that Xrn1 is located to different cellular compartments, depending on physiological state. During exponential growth, Xrn1 is distributed in the cytoplasm, while it is present in the eisosomes after the post-diauxic shift (PDS). Here, we biochemically characterized the Xrn1-associated complexes in different cellular states. We demonstrate that, after PDS, Xrn1 but not the decapping (DCP), nor Lsm1-7/Pat1 complexes, was sequestered in the eisosomes, thus preserving mRNAs from degradation.

biochemistry↗

bioRxiv2018

A SKI subcomplex specifically required for the degradation of ribosome-free RNA regions

The Ski2-Ski3-Ski8 (SKI) complex assists the RNA exosome during the 3-5 degradation of cytoplasmic transcripts. Previous reports showed that the SKI complex is involved in the 3-5 degradation of mRNA, including 3 untranslated regions (UTRs), devoid of ribosomes. Paradoxically, we recently showed that the SKI complex directly interacts with ribosomes during the co-translational mRNA decay and that this interaction is necessary for its RNA degradation promoting activity. Here, we characterized a new SKI-associated factor, Ska1, which antagonizes the SKI-ribosome interaction. We showed that the SKI-Ska1-subcomplex is specifically involved in the degradation of ribosome-free RNA regions such as long mRNA 3UTRs and cytoplasmic lncRNAs. We propose a model in which the SKI-exosome complex first targets ribosome-free RNA 3ends in its Ska1-associated form. When the complex reaches the mRNA coding sequence, the Ska1-SKI-exosome complex is exchanged for the SKI-exosome, which interacts directly with ribosomes in order to resume the degradation process.

molecular biology↗