Surface charge comparisons for halophilic and nonhalophilic proteins. Acidic character is indicated by red, basic character is indicated by blue, and neutral areas are indicated by white. (A) NRC-1 TFBe (left) and Human TFIIB (right) are shown with sites for BRE and TBP contacts indicated. (B) NRC-1 (left) and Escherichia coli GyrA (right) are shown with the binding site for the helix that is cleaved as well as the site for strand passage indicated for both molecules.