Wellcome Principal Research Fellow, Professor of RNA Biology and Director, Wellcome Centre for Cell Biology
David Tollervey studied for a BSc in Microbiology in Edinburgh and then for a PhD in Genetics at Cambridge in the lab of Herb Arst. He then moved to the University of California, San Francisco, as a postdoctoral fellow in the laboratory of Christine Guthrie. In 1983 he relocated to a permanent post at the Institut Pasteur in Paris, which he left in 1988 to move to the European Molecular Biology Laboratory (EMBL) in Heidelberg as a group leader. He returned to Edinburgh in 1997 as Professor of RNA Biology and a Wellcome Trust Principal Research Fellow. Since 2011 he has served as Director of the Wellcome Centre for Cell Biology. He is a Fellow of the Royal Society, and of the Royal Society of Edinburgh, a member of EMBO and Past President of the international RNA Society. The aim of the Tollervey group is to understand the nuclear pathways that process newly transcribed RNAs and assemble RNA-protein complexes, the mechanisms that regulate these pathways and the surveillance activities that monitor their fidelity. His current research combines in vivo UV crosslinking and high-throughput sequencing to precisely identify sites of RNA-protein interaction and RNA-RNA basepairing, with genetics, biochemistry, transcriptomics and bioinformatics.
With the arrival of the COVID-19 pandemic, we have commenced work on SARS-CoV-2: https://spark.adobe.com/page/wl1eLDI6JEind/
RNA Processing and Quality Control
RNA-binding proteins (RBPs) have important functions at all steps in gene expression, including transcription, RNA processing and mRNA translation. Defects in RBPs underpin many genetic diseases, while responses to environmental stress are frequently mediated by altered RNA-protein interactions.
We examined global RBP dynamics in Saccharomyces cerevisiae in response to stress, using our recently developed technique of total RNA-associated protein purification (TRAPP). Stresses induced very rapid remodeling of the RNA-protein interactome, without corresponding changes in RBP abundance (Bresson et al., 2020). A set of “scanning” translation initiation factors (eIF4A, eIF4B, and Ded1), were remarkably rapidly evicted from mRNAs (<30 sec after glucose withdrawal) driving translation shutdown (Fig). Selective mRNA 5'-degradation by the exonuclease Xrn1 was seen following heat shock, particularly for translation-related factors, reinforcing translational inhibition. Notably, these responses are distinct from previously characterized pathways for stress-induced translation inhibition.
An outstanding question in nuclear RNA quality control is how “defective” RNAs are identified and targeted for degradation. During surveillance, the RNA exosome functions together with the TRAMP complexes (Delan-Forino et al., 2020). These include the DEAH-box RNA helicase Mtr4 together with an RBP (Air1 or Air2) and a poly(A) polymerase (Trf4 or Trf5). TRAMP acts to make substrates more susceptible to degradation, by addition of a single-stranded “tail”, and also targets them to the exosome. Combining biochemistry, genetics and genomics, we identified three distinct TRAMP complexes formed in yeast, which preferentially assemble on different classes of transcripts. Surprisingly, the poly(A) polymerases Trf4 and Trf5 emerged as crucial in TRAMP targeting and recruitment.
Transcription elongation rates are important for many aspects of RNA processing, defining the “window of opportunity” for interaction and folding. However, sequence-specific regulation of elongation rates is poorly understood. Notably, elongation by RNA polymerases is only moderately processive, being based on a "Brownian Ratchet" rather than an energy-driven mechanism. To analyse RNA polymerase I elongation in S.cerevisiae (Turowski et al., 2020) we combined in vivo RNAPI profiling, in vitro biochemical analyses and a quantitative, mechanistic model of transcription elongation. Unexpectedly, these revealed that folding of the nascent pre-rRNA close to the transcribing polymerase has a major effect on the elongation rate, with a modest contribution from the stability of the RNA-DNA duplex in the active site. RNAPI from S.pombe was similarly sensitive to transcript folding, as were S.cerevisiae RNAPII and RNAPIII. For RNAPII, unstructured RNA, which favours slowed elongation, was associated with faster cotranscriptional splicing and proximal splice site usage, indicating regulatory significance for transcript folding.
Bresson, S., Shchepachev, V., Spanos, C., Turowski, T., Rappsilber, J., and Tollervey, D. (2020). Stress-induced translation inhibition through rapid displacement of scanning initiation factors. Molecular Cell 80, 470-484.
Delan-Forino, C., Spanos, C., Rappsilber, J., and Tollervey, D. (2020). Substrate specificity of the TRAMP nuclear surveillance complexes. Nature Communications 11, 3122-3122.
Turowski, T.W., Petfalski, E., Goddard, B.D., French, S.L., Helwak, A., and Tollervey, D. (2020). Nascent transcript folding plays a major role in determining RNA polymerase elongation rates. Molecular Cell 79, 488-503.
Stress induces very rapid translation and selective mRNA degradation.
Following glucose starvation or heat shock, translation initiation factors rapidly dissociate from the 5'-end of mRNAs, halting translation initiation. Already-initiated ribosomes continue translating, leaving unprotected mRNAs. Following heat shock, Xrn1 is involved in degradation of a subset of these transcripts.