Biochemistry, Biophysics, and Structural Biology Commons^™

The coat proteins of the RNA phages MS2 and Qβ are structurally homologous, yet they specifically bind different RNA structures. In an effort to identify the basis of RNA binding specificity we sought to isolate mutants that convert MS2 coat protein to the RNA binding specificity of Qβ. A library of mutations was created which selectively substitutes amino acids within the RNA binding site. Genetic selection for the ability to repress translation from the Qβ translational operator led to the isolation of several MS2 mutants that acquired binding activity for Qβ RNA. Some of these also had reduced abilities to …