Project description:Structure probing combined with next-generation sequencing (NGS) has provided novel insights into RNA structure-function relationships. To date such studies have focused largely on bacteria and eukaryotes, with little attention given to the third domain of life, archaea. Furthermore, functional RNAs have not been extensively studied in archaea, leaving open questions about RNA structure and function within this domain of life. With archaeal species being diverse and having many similarities to both bacteria and eukaryotes, the archaea domain has the potential to be an evolutionary bridge. In this study, we introduce a method for probing RNA structure in vivo in the archaea domain of life. We investigated the structure of ribosomal RNA (rRNA) from Methanosarcina acetivorans, a well-studied anaerobic archaeal species, grown with either methanol or acetate. After probing the RNA in vivo with dimethyl sulfate (DMS), Structure-seq2 libraries were generated, sequenced, and analyzed. We mapped the reactivity of DMS onto the secondary structure of the ribosome, which we determined independently with comparative analysis, and confirmed the accuracy of DMS probing in M. acetivorans. Accessibility of the rRNA to DMS in the two carbon sources was found to be quite similar, although some differences were found. Overall, this study establishes the Structure-seq2 pipeline in the archaea domain of life and informs about ribosomal structure within M. acetivorans.
Project description:Ribosome assembly in eukaryotes involves the activity of hundreds of assembly factors that direct the hierarchical assembly of ribosomal proteins and numerous ribosomal RNA folding steps. However, detailed insights into the function of assembly factors and ribosomal RNA folding events are lacking. To address this, we have developed ChemModSeq, a method that combines structure probing, high throughput sequencing and statistical modeling, to quantitatively measure RNA structural rearrangements during the assembly of macromolecular complexes. By applying ChemModSeq to purified 40S assembly intermediates we obtained nucleotide-resolution maps of ribosomal RNA flexibility revealing structurally distinct assembly intermediates and mechanistic insights into assembly dynamics not readily observed in cryo-electron microscopy reconstructions. We show that RNA restructuring events coincide with the release of assembly factors and predict that completion of the head domain is required before the Rio1 kinase enters the assembly pathway. Collectively, our results suggest that 40S assembly factors regulate the timely incorporation of ribosomal proteins by delaying specific folding steps in the 3M-bM-^@M-^Y major domain of the 20S pre-ribosomal RNA. Three datasets of yeast ribosomal samples subjected to different chemical modifications; 1M7 dataset contains 8 different modified samples and 2 control samples; NAI dataset contains 3 different modified samples and 2 control samples; DMS dataset contains 1 modified sample and 1 control sample. Each sample consists of at least two replicates.
Project description:Structure probing experiments were performed on in vitro transcripts and E. coli and human cell cultures under natively extracted (cell-free) and in-cell conditions to benchmark the performance of the newly introduced PAIR-MaP correlated chemical probing strategy for detecting RNA duplexes. Multiple-hit dimethyl sulfate (DMS) probing was done using new buffer conditions that facilitate DMS modification of all four nucleotides.
Project description:To investigate the role of translation in the decay of cytoplasmic lncRNAs, we performed RNA-Seq in WT and upf1-delta yeast cells, treated or not with CHX.
Project description:To investigate the role of translation in the decay of cytoplasmic lncRNAs, we performed RNA-Seq in WT and upf1-delta yeast cells, treated or not with CHX.
Project description:Trypanosomes are unicellular parasites that cycle between the insect and mammalian host and is the causative agent of African sleeping sickness and the wasting disease, nagana, in cattle. Previous studies from our lab suggested that individual rRNA modification such as pseudouridine (Y) and 2’-O-methylation are developmentally regulated during the complex life cycle of these parasites. In this study we identified that the Y composition of translating ribosomes are different from rRNA derived from total RNA. Ablation of single snoRNA guiding Y in one of the inter-subunit bridges of the ribosome affects its affinity to translate specific mRNA. Mutational analysis in the pseudouridylation pocket of this snoRNA supports for the notion that the guided modification and not the chaperonic activity, is essential for the observed phenotype. Structural probing of rRNA using DMS-seq suggested that a single modification can affect the rRNA structure locally as wells as globally. Quantitative profiling of the composition of mutant ribosomes suggested the absence of eS12 ribosomal protein in the mature ribosomes. Addback experiments validated the role of eS12 during the loss of a single Y in these mutant cells. Orthologous experiments in related leishmania spp. also verify importance of a single Y in the function of ribosome. Ongoing experiments intend to visualize such ribosomes lacking a single RNA modification and decipher their significance towards ribosome structure.