Figure 5.

Minimum RNA requirement. (A) Substrates and cleavage sites. The ³²P label is denoted by •. Ribonucleotides are depicted in white on a black background. Principal sites of incision by M. smegmatis RnhA are indicated by black arrowheads. (B) Reaction mixtures (10 μl) containing 25 mM Tris–HCl (pH 7.5), 50 mM NaCl, 5 mM MgCl₂, 20 nM (200 fmol) duplex substrate as specified, and either no enzyme (lanes –) or 8 nM (80 fmol) RnhA were incubated at 37°C for 20 min. The products were analyzed by urea-PAGE and visualize by autoradiography. Alkaline hydrolysis ladders of the ³²P-labeled strands were analyzed in parallel in lanes OH.