Project description:When eukaryotic cells are deprived of amino acids, uncharged tRNAs accumulate and activate the conserved GCN2 protein kinase. We examine how yeast growth and tRNA charging or aminoacylation is affected during amino acid depletion in the presence and absence of GCN2. tRNA charging is measured using a microarray technique which allows for simultaneous measurement of all cytosolic tRNAs. A fully prototrophic and its isogenic GCN2 deletion strain were used. We measured relative tRNA charging levels in yeast strains with an intact and deleted GCN2.
Project description:When eukaryotic cells are deprived of amino acids, uncharged tRNAs accumulate and activate the conserved GCN2 protein kinase. We examine how yeast growth and tRNA charging or aminoacylation is affected during amino acid depletion in the presence and absence of GCN2. tRNA charging is measured using a microarray technique which allows for simultaneous measurement of all cytosolic tRNAs. A fully prototrophic and its isogenic GCN2 deletion strain were used.
Project description:Protein binding is essential to the transport, decay and regulation of almost all RNA molecules. However, the structural preference of protein binding on RNAs and their cellelar functions and dynamics upon changing environmental condictions are poorly understood. Here, we integrated various high-throughput data and introduced a computational framework to describe the global interactions between RNA binding proteins (RBPs) and structured RNAs in yeast at single-nucleotide resolution. We found that on average, in terms of percent total lengths, ~15% of mRNA untranslated regions (UTRs), ~37% of canonical ncRNAs and ~11% of long ncRNA (lncRNAs) are bound by proteins. The RBP binding sites, in general, tend to occur at single-stranded loops, with evolutionarily conserved signatures, and often facilitate a specific RNA structure conformation in vivo. We found that four nucleotide modifications of tRNA are significantly associated with RBP binding. We also identified various structural motifs bound by RBPs in the UTRs of mRNAs, associated with localization, degradation and stress responces. Moreover, we identified >200 novel lncRNAs bound by RBPs, and about half of them contain conserved secondary structures. We present the first ensemble pattern of RBP binding sites in the structured noncoding regions of a eukaryotic genome, emphasizing their structural context and cellular functions.
Project description:The goal of these experiments was to define the targets of Ty3 transposition in Saccharomyces cerevisiae. Ty3 is a retroviruslike element that is found at the transcription initiation site of chromosomal tRNA genes.
Project description:O-Mannosylation is a vital protein modification conserved from fungi to humans. In an essential step towards the full understanding of O-mannosylation we mapped the O mannose glycoproteome in baker´s yeast.
Project description:Aminoacyl-tRNA synthetases (aaRSs) are essential enzymes that ligate amino acids to tRNAs, and often require editing to ensure accurate protein synthesis. Recessive mutations in aaRSs cause various neurological disorders in humans, yet the underlying mechanism remains poorly understood. Pathogenic aaRS mutations frequently cause protein destabilization and aminoacylation deficiency. In this study, we report that combined aminoacylation and editing defects cause severe proteotoxicity. We show that a C268A mutation in yeast threonyl-tRNA synthetase (ThrRS) abolishes editing and causes heat sensitivity. Surprisingly, directed-evolution of the C268A mutant result in intragenic mutations that restore heat resistance but not editing. C268A destabilizes ThrRS and decreases overall Thr-tRNAThr synthesis, and the suppressor mutations in the evolved strains improve aminoacylation. We further show that deficiency in ThrRS aminoacylation or editing alone is not sufficient to cause heat sensitivity, and that C268A impairs ribosome-associated quality control. Our results suggest that aminoacylation deficiency predisposes cells to proteotoxic stress.