Discovery of a Well-Folded Protein Interaction Hub Within the Human Long Non-Coding RNA NORAD
The long non-coding RNA NORAD functions in maintaining genomic stability in humans via sequestering Pumilio proteins from the cytoplasm, and thereby modulating the gene expression of mRNA targets of Pumilio proteins. Despite its role in fundamental cellular pathways including chromosome segregation and DNA damage response, there have been limited structural and biophysical descriptions of NORAD. Here, using an integrative approach combining chemical probing coupled to high throughput sequencing, and RNA-pull downs coupled with mass spectrometry, we discovered a well-folded and structured protein interaction hub within the functional core of NORAD. Our in vitro biochemical reconstitutions using purified recombinant proteins and a NORAD repeat unit region within this hub reveal the assembly of a higher-order multimeric RNA-protein complex.