Figure 3. Csx1 binds cA₄ with high affinity and RNA with relatively low affinity.

(A) Phosphorimage of native gel electrophoresis visualising cA₄ (20 nM) binding by Csx1 (concentrations as indicated in the figure). The other bands visible are due to unreacted ATP and other linear nucleotide products. (B) Plot of fraction of cA₄ bound by Csx1. Error bars indicate the standard deviation of the mean of four technical replicates and the data were fitted to a quadratic equation incorporating a term for non-specific binding. The inset plot is a magnification of cA₄ binding between 0.01 and 5 µM Csx1 dimer concentrations. (C) Phosphorimage of native gel electrophoresis visualising A1 substrate RNA binding by Csx1 H345N protein dimer in the absence (left hand-side) or presence (right hand-side) of unlabelled cA₄ (20 µM). The image shown is representative of three technical replicates. Control c – RNA alone.