Structural insight into the mechanism of stabilization of the 7SK small nuclear RNA by LARP7.Uchikawa, E., Natchiar, K.S., Han, X., Proux, F., Roblin, P., Zhang, E., Durand, A., Klaholz, B.P., Dock-Bregeon, A.C.
(2015) Nucleic Acids Res. 43: 3373-3388
- PubMed: 25753663
- DOI: 10.1093/nar/gkv173
- PubMed Abstract:
The non-coding RNA 7SK is the scaffold for a small nuclear ribonucleoprotein (7SKsnRNP) which regulates the function of the positive transcription elongation factor P-TEFb in the control of RNA polymerase II elongation in metazoans. The La-related pr ...
The non-coding RNA 7SK is the scaffold for a small nuclear ribonucleoprotein (7SKsnRNP) which regulates the function of the positive transcription elongation factor P-TEFb in the control of RNA polymerase II elongation in metazoans. The La-related protein LARP7 is a component of the 7SKsnRNP required for stability and function of the RNA. To address the function of LARP7 we determined the crystal structure of its La module, which binds a stretch of uridines at the 3'-end of 7SK. The structure shows that the penultimate uridine is tethered by the two domains, the La-motif and the RNA-recognition motif (RRM1), and reveals that the RRM1 is significantly smaller and more exposed than in the La protein. Sequence analysis suggests that this impacts interaction with 7SK. Binding assays, footprinting and small-angle scattering experiments show that a second RRM domain located at the C-terminus binds the apical loop of the 3' hairpin of 7SK, while the N-terminal domains bind at its foot. Our results suggest that LARP7 uses both its N- and C-terminal domains to stabilize 7SK in a closed structure, which forms by joining conserved sequences at the 5'-end with the foot of the 3' hairpin and has thus functional implications.
Department of Integrated Structural Biology, Centre for Integrative Biology (CBI), IGBMC (Institute of Genetics and of Molecular and Cellular Biology, 67404 Illkirch, France Centre National de la Recherche Scientifique (CNRS) UMR 7104, Illkirch, France Institut National de la Santé et de la Recherche Médicale (INSERM) U964, Illkirch, France Université de Strasbourg, 67000 Strasbourg, France.