BIOL 128 |
| RNA recognition motifs or RRMs are among the most common eukaryotic protein sequences. They are found in hundreds of RNA-binding proteins and bind to different RNA substrates with varying affinities and specificities. The U1A protein is a component of the U1 snRNP and is involved in the splicing of pre-mRNA. Its N-terminal RRM in complex with the stem loop 2 of U1 snRNA is a model system for studying RRM-RNA interactions. The U1A and stem loop 2 RNA both undergo conformational changes upon binding. In the free state, the helix C of U1A is down and in contact with the beta sheet, while in complex, it is away from the beta sheet to accommodate the RNA. We are investigating the dynamics of the U1A protein to probe whether binding occurs by conformational capture or induced fit. We have incorporated tryptophan into helix C and are using time-resolved fluorescence anisotropy to probe the dynamics of helix C. Several mutants have been constructed in which residues that are proposed to be involved in maintaining the position of helix C have been mutated. The dynamics of helix C in these mutant proteins has been compared with that of the wild type protein. The effect of these mutations on binding affinity has been measured to establish whether there is a correlation between helix C dynamics and binding. |
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Poster Session
8:00 PM-10:00 PM, Monday, August 20, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Biological Chemistry |