The human U1A RNA-binding domain (RBD1) adopts one of the most common protein folds, the RNA-recognition motif, and is a paradigm for understanding RNA-protein interactions. A 2.8 A resolution structure of the unbound RBD1 has previously been determined [Nagai et al. (1990). Nature (London), 348, 515-520] and revealed a well defined alpha/beta core with disordered termini. Using a longer construct, a 1.8 A resolution structure of the unbound domain was determined that reveals an ordered C-terminal helix. The presence of this helix is consistent with a solution structure of the free domain [Avis et al. (1996). J. Mol. Biol. 257, 398-411]; however, in the solution structure the helix occludes the RNA-binding surface. In the present structure, the helix occupies a position similar to that seen in a 1.9 A resolution RNA-RBD1 complex structure [Oubridge et al. (1994). Nature (London), 372, 432-438]. The crystals in this study were grown from 2.2 M sodium malonate. It is possible that the high salt concentration helps to orient the C-terminal helix in the RNA-bound conformation by strengthening hydrophobic interactions between the buried face of the helix and the alpha/beta core of the protein. Alternatively, the malonate (several molecules of which are bound in the vicinity of the RNA-binding surface) may mimic RNA.
U1A RNA-binding domain at 1.8 A resolution.,Rupert PB, Xiao H, Ferre-D'Amare AR Acta Crystallogr D Biol Crystallogr. 2003 Aug;59(Pt 8):1521-4. Epub 2003, Jul 23. PMID:12876372
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Rupert PB, Xiao H, Ferre-D'Amare AR. U1A RNA-binding domain at 1.8 A resolution. Acta Crystallogr D Biol Crystallogr. 2003 Aug;59(Pt 8):1521-4. Epub 2003, Jul 23. PMID:12876372