Conformational Dynamics in RNA—Protein Interactions: Immobilization of the Functional Domains in tRNAfMet and Methionyl-tRNA Synthetase
RNA—protein interactions have been studied extensively. Conformational changes in both nucleic acids and proteins have been demonstrated and may play critical roles in the recognition processes. Conformational flexibility in proteins and its functional significance in some proteins have been elucidated (1). Relatively little is known about the segmental movement in RNA. Specific interactions of tRNA and cognate synthetases have provided model systems that have contributed to our understanding of the mechanisms in protein—RNA interactions (2). One of the particularly advantageous systems is the interaction of tRNAfMet and methionyl-tRNA synthetase (MetRS), as the crystal structures of both tRNAfMet (3) and an active fragment of MetRS (4) have been determined Although the crystal structure of the tRNA—synthetase complex is yet to be resolved, their interaction has been carefully examined using a variety of approaches including photo-cross-linking (5), chemical modification (6), base substitution (7), fluorescence spectroscopy (8), neutron scattering (9), and affinity chemical modification (10). These studies have provided extensive information on the recognition sites in the tRNA molecule. Furthermore, these studies suggest that conformational changes in interacting tRNA and synthetase are essential in the recognition process. Little is known about the nature of the conformational changes in tRNA and the cognate synthetase upon their association.
KeywordsEntropy Anisotropy Immobilization Tryptophan Macromolecule
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