COMPOSITON AND DYNAMICS OF RIBOPROTEOME IN SACCHAROMYCES CEREVISIAE DURING QUIESCENCE AND TRANSLATIONAL RECOVERY

MORENO S; VALACCO P; SOLARI C; PORTELA P

Congreso; LV Annual SAIB Meeting and XIV PABMB Congress; 2019

SAIB and PABMB

Ribosomal heterogeneity describes the existence of different populations of ribosomes, which provides translational selectivity for mRNAs. Ribosomal heterogeneity is evident in ribosomopathies, in which specific-tissue diseases are associated with mutations in ribosomal proteins. To study ribosomal heterogeneity, we used label-free quantitative proteomics and characterized the relative abundance and composition of proteins that belong to monosomal and polysomal ribosomes during the transition from quiescence to yeast cell proliferation. We identified 315 proteins belonging to different functional groups as analyzed by Gene Ontology: translation, protein folding, α-amino acid metabolism, cellular response to oxidative stress and glycolytic process. We characterized a specific repertoire of protein complexes that were fractionated with polysomes or monosomes. In addition, we identified 69 of the 79 ribosomal proteins of the 80S: 18 ribosomal proteins encoded by a single copy gene and 51 ribosomal proteins that are encoded by paralogous genes. Our results show that there is an exchange between protein paralogs and differential distribution of relative abundance resulting, in some cases, in undetectable levels of some ribosomal proteins either in the monosome or the polysome. In addition, 28 pairs of ribosomal protein paralogous show differences in translational fitness. Our results suggest that ribosomal heterogeneity is achieved by changes in the ribosomal core proteins and accessory proteins that could modify ribosomal function depending on growth conditions and the number of ribosomes associated to an mRNA.