Determination of the NMR structure of the complex between U1A protein and its RNA polyadenylation inhibition element.

RNA-protein recognition is critical to post-transcriptional regulation of gene expression, yet poorly understood at the molecular level. The relatively slow progress in understanding this important area of molecular biology is due to difficulties in obtaining good-quality crystals and derivatives, and in preparing samples suitable for NMR investigation. The determination of the structure of the complex between the human U1A protein and its polyadenylation inhibition element is described here. In this paper, we describe the sample preparation, spectral assignments, construction of the NOE-based distance constraints and methodology for calculating the structure of the complex. The structure was determined to an overall precision of 2.03 A (for all ordered regions), and 1.08 A for the protein-RNA interface. The patterns of hydrogen bonding and hydrophobic interactions at the interface were analysed statistically using the final ensemble of 31 structures.