Fig 3. TthCsm binds and cleaves its ssRNA target optimally at high temperatures.

(A) TthCsm was pre-incubated in the absence of metal ions with complementary ssRNA at either 65°C or 37°C (pre-incubation), and then cleavage was initiated by addition of MgCl₂ and continued at either 65°C or 37°C, as indicated (assay). Reactions with (+) or without (-) TthCsm added are shown. (B) TthCsm was incubated with a ³²P-labeled complementary ssRNA target at 65°C or 37°C, and binding was measured by an EMSA, as in Fig 2A. TthCsm was added to a concentration of 0–1200 nM at 37°C or 0–300 nM at 65°C.