Figure 2.

Competitive binding of Bst S4 to the 16S 5′ domain RNA. (a) S4 binding measured by gel mobility shift. 0.5 nM ³²P-labeled and 0–400 nM unlabeled 5′domain RNAs were incubated with 31.5 nM Bst S4 in HKM4 buffer at 42°C. Gel is 8% polyacrylamide in TBE. NP, ³²P-5′domain RNA only. (b) The fraction of complexed ³²P-labeled 5′domain RNA versus competitor RNA was fit to Equation (1). Filled circles, 5′ domain (K_{d, 5′domain} = 5.5 ± 2.6 nM); filled squares, 16S rRNA (K_rel = 1.6 ± 0.8).