Effects of mini-vRNAP amino acid substitutions on promoter interaction. (A) Effects of mini-vRNAP amino acid substitutions in the N-terminal, intercalating β-hairpin, Fingers, and specificity loop on promoter binding. Asterisks indicate amino acid substitutions that render the promoter complex salt-sensitive. (B) Effects of amino acid substitutions on promoter binding (Upper) and salt-resistance (Lower). (C) Effects of mini-vRNAP amino acid substitutions on RNAP cross-linking to −11 5IdU-, −11/−12 AzPh-, and −5/−6 AzPh-substituted promoters.