Figure 3.

Comparing the catalytic property of Alr1240 with those of the Escherichia coli exoribonucleases RNase II (EcRnb) and RNase R (EcRnr). Activity assays were performed using 16ss (A), 30ss (B), 16-mer and its complement (16-16ds) (C) or a 30-mer hybridized to the complement 16-mer (30-16ds) (D) as substrates at 30°C (see Materials and methods for details). In each reaction, the same amount of RNA substrate (50 nM) and different amounts of purified proteins (shown at the top of each lane) were used. The 16-mer and 30-mer RNA strands were labeled the 5′-end with the FAM fluorescein-based dye. The control reactions, which contained only the RNA substrates (Ctrl) and the reaction buffer, were incubated for either 0 min (left lane) or 30 min (right lane), while all the other reactions were incubated for 30 min. The FAM-labeled substrate strands are indicated by arrows (S).