Superposition of the crystal structures of Aquifex aeolicus (Aa) NusB-NusE-BoxA and NusB-NusE-dsRNA, illustrating the contiguous binding regions for BoxA and dsRNA. The protein surface representation is colored by vacuum-electrostatic potential (red, negative; blue, positive), which depicts the BoxA- and dsRNA-binding sites as a contiguous positively-charged surface (Stagno, Altieri, Bubunenko, Tarasov, Court, Byrd, and Ji. Nucl. Acids Res. June 7, 2011; Full Text).