7 research outputs found
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Innate Immune Messenger 2-5A Tethers Human RNase L into Active High-Order Complexes
2′,5′-linked oligoadenylates (2-5As) serve as conserved messengers of pathogen presence in the mammalian innate immune system. 2-5As induce self-association and activation of RNase L, which cleaves cytosolic RNA and promotes the production of interferons (IFNs) and cytokines driven by the transcription factors IRF-3 and NF-κB. We report that human RNase L is activated by forming high-order complexes, reminiscent of the mode of activation of the phylogenetically related transmembrane kinase/RNase Ire1 in the unfolded protein response. We describe crystal structures determined at 2.4 Å and 2.8 Å resolution, which show that two molecules of 2-5A at a time tether RNase L monomers via the ankyrin-repeat (ANK) domain. Each ANK domain harbors two distinct sites for 2-5A recognition that reside 50 Å apart. These data reveal a function for the ANK domain as a 2-5A-sensing homo-oligomerization device and describe a nonlinear, ultrasensitive regulation in the 2-5A/RNase L system poised for amplification of the IFN response
Structural mechanism of sensing long dsRNA via a noncatalytic domain in human oligoadenylate synthetase 3
Human RNase L tunes gene expression by selectively destabilizing the microRNA-regulated transcriptome
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Controlling the material properties and rRNA processing function of the nucleolus using light
The nucleolus is a prominent nuclear condensate that plays a central role in ribosome biogenesis by facilitating the transcription and processing of nascent ribosomal RNA (rRNA). A number of studies have highlighted the active viscoelastic nature of the nucleolus, whose material properties and phase behavior are a consequence of underlying molecular interactions. However, the ways in which the material properties of the nucleolus impact its function in rRNA biogenesis are not understood. Here we utilize the Cry2olig optogenetic system to modulate the viscoelastic properties of the nucleolus. We show that above a threshold concentration of Cry2olig protein, the nucleolus can be gelled into a tightly linked, low mobility meshwork. Gelled nucleoli no longer coalesce and relax into spheres but nonetheless permit continued internal molecular mobility of small proteins. These changes in nucleolar material properties manifest in specific alterations in rRNA processing steps, including a buildup of larger rRNA precursors and a depletion of smaller rRNA precursors. We propose that the flux of processed rRNA may be actively tuned by the cell through modulating nucleolar material properties, which suggests the potential of materials-based approaches for therapeutic intervention in ribosomopathies.SCOPUS: ar.jinfo:eu-repo/semantics/publishe