Fig. 4.

Low-energy intermediate conformational states (I1, I2 and I3) and “Bound” state as identified from the 2D PMF profile of the MSI1-RNA simulation system started from the Unbound state. The MSI1 protein and Numb RNA are shown in green and red, respectively. The NMR structure of the MSI1-Numb complex is shown in blue for comparison. MSI1 protein residues Arg99 and Arg61, and nucleotide A106 of Numb RNA are highlighted in balls and sticks. The hydrogen bonds between the side-chain of residues in the MSI1 protein and Numb RNA are shown in red. The salt-bridge interactions between the side-chain of residues in the MSI1 protein and backbone (oxygen atom) of the Numb RNA are shown in black.