Talk abstracts
Talk on Friday 01:45-02:00pm submitted by Taylor Ayers
How are RNA helicases recruited to their RNA substrates?
Taylor N. Ayers (Carnegie Mellon University), Fiona Fitzgerald (Carnegie Mellon University), Collin Bachert (Carnegie Mellon University), John L. Woolford (Carnegie Mellon University)
Abstract:
Ribosome assembly depends upon the stepwise folding of rRNA into its three-dimensional structure. Near-atomic resolution cryo-EM structures of ribosome assembly intermediates have uncovered the order in which domains of rRNA form their mature structures, yet the mechanisms underlying rRNA folding are not well understood. Assembly factors (AFs) and ribosomal proteins can reconfigure rRNA structures or stabilize rRNA conformations. A class of AF, called RNA helicases, actively remodels rRNA substrates and mediates irreversible transitions in pre-rRNA folding, critical for powering assembly forward. Nineteen phylogenetically conserved RNA helicases have been implicated in ribosome biogenesis in Saccharomyces cerevisiae (yeast). These proteins contain a structurally conserved catalytic core that recognizes RNA in a sequence-independent manner. This raises the question: how are these RNA helicases recruited to their specific rRNA substrates? Our molecular genetic, biochemical, and structural data indicate that the RNA helicase Drs1 is required for structural maturation of rRNA domain III during nucleolar stages of large subunit (60S) assembly in yeast. However, how Drs1 is recruited to the pre-60S is not clear. Here, we have identified a patch of residues on the AF Erb1 that is critical for recruiting Drs1 onto the pre-ribosome. Using a combination of genetic and biochemical approaches, we demonstrate that mutating these residues on Erb1 significantly diminishes the presence of Drs1 on the pre-60S, impairs direct interactions between Erb1 and Drs1, and results in a slow-growth phenotype. We have also examined the role of other AFs implicated in Drs1 recruitment based on protein-protein crosslinking data. Revealing the mechanism by which Drs1 acts is pivotal for linking how RNA helicases locate their substrates during ribosome biogenesis.
Keywords: RNA helicase, ribosome assembly