Figure 2.

Effects of substitutions at Y430 of σ⁷⁰ on stable complex formation. Duplex and Mismatch DNA bearing different substitutions at −11 (−11 2AP D = 2-Aminopurine Duplex; −11 Pur D = Purine Duplex; −11 Ab D = Abasic Duplex; −11G D = −11 Guanine Duplex; M is Mismatch) were incubated at room temperature with RNAP containing WT or mutant σ⁷⁰ with substitutions at position 430. Amounts of label in the complex and free DNA bands were determined by PhosphorImaging. The bars indicate the percentage of radioactivity in the complex bands (values are the averages of two or more independent experiments; errors were computed as half the differences between the duplicates for two experiments and standard deviations for three or more experiments). For details of the assay conditions see the Materials and Methods section and the legend to Figure 1C. Each group of bars represents the collection of σ⁷⁰ variants tested. (A) Duplex templates. (B) Mismatch templates.