Figure 2.

Effects of point mutations in the 5′end stem–loop on 30S-IC formation and ribosome/ S1 binding. (A) 30S-IC complex formation was monitored on +42 tisB mRNA (WT) and three mutant mRNAs with 5′ apical loop mutations (see Figure 1C). Toeprint signals at position 15, the signature of 30S-IC complex formation at the tisB RBS (SD and AUG – black bars), are indicated by a black arrow. (B) Fluorescence anisotropy change of 5′-end FAM-labeled +42 tisB mRNA in presence of a 10-fold molar excess of either 30S (grey columns) or purified protein S1 (blue). These complexes were challenged by a 50-fold molar excess of unlabeled wild-type +42 tisB mRNA or the corresponding G57C mutant variant. *: P-value < 0.05 (triplicate).