FIGURE 2.

The structure of the complex of L7Ae bound to Kt-7. Stereoscopic pairs (A,D,E) are shown as parallel-eye stereoscopic pairs. Electron density is taken from the composite omit map and contoured at 2σ. (A) An overall view of the complex. The basic β-strand:turn:helix and hydrophobic loop sections are colored blue, with hydrogen bonds between amino acid side chains and the RNA highlighted in red. The nucleotides of the k-turn are colored in our conventional scheme (loop purple; G•A pairs green; NC helix gray; C helix yellow), with the NC and C helices indicated. (B,C) Nonstereoscopic images of the structures of the two recognition elements of the protein, i.e., the α-helix (B) and the hydrophobic loop (C). (D,E) The interaction between the α-helix (D) and the hydrophobic loop (E) of the k-turn RNA. The electron density map is shown for the protein. Hydrogen bonds between amino acid side chains and the RNA are highlighted in red. Note that the N-terminal end of the α-helix is directed toward O6 of G1b.