FIGURE 3.

Sso-RNase J is an exoribonuclease displaying 5′-to-3′ directionality. (A) Zymogram assays performed with purified Sso-RNase J (lane 1) and S. solfataricus S100 extracts (lane 2) at 65°C. The arrow indicates the band corresponding to the RNase activity of Sso-RNase J. (B, left panel) [α-³²P]ATP was loaded on the gel (lane 1). 5′-PPP-GGA*-″-3′ RNA was incubated for 0 to 60 min at 65°C in the absence of Sso-RNase J (lanes 2–6). (Middle panel) Incubation of 5′-PPP-GGA*-″-3′ RNA with Sso-RNase J in the presence (lanes 7–11) and absence of Mg⁺⁺ (lanes 12–16). (Right panel) Incubation of 5′-PPP-GG-″-A*-3′ RNA with Sso-RNase J for 0 to 60 min in the presence of Mg⁺⁺ (lanes 17–21). The filled arrow indicates the full-length RNA, and the open arrow the single A nucleotide.