let-7 miRNAs control the timing of development of the nematode C. elegans. They bind two times in the 3’-UTR of lin-41 mRNAs and downregulate gene expression. We have determined by solution-state NMR the structure of a 34-nt RNA construct, which illustrates the interaction of let-7 miRNA to the first complementary binding site. Structure shows two non-canonical parts characteristic for the seed region: an asymmetric internal loop and a bulge. The internal loop demonstrates residues G23 and U25 bulged-out and the residue U24 looped-in. Residue A30 is not stacked-in but points into the minor groove.
COBISS.SI-ID: 4554778
In this review article we describe the preparation of the 33-nt RNA model construct mimicking interaction between let-7 miRNA and lin-41 mRNA. We explain NMR experiments used for assignment of 1H, 13C, 15N and 31P resonances and acquisition of NOE derived restraints and torsion angle restraints. Structural calculation showed that the isotopically labeled RNA construct folds into a stable structure consisting of two stem regions separated by a defined asymmetric internal loop. Solution-state NMR makes important contribution toward deeper understanding of structural features of miRNA:mRNA complexes.
COBISS.SI-ID: 4508698