Figure 3.

Influence of Cmr1α RNA-binding activity on the in vivo nucleic acid interference and in vitro RNA/DNA cleavage by the Cmr-α system. RNA interference (A) and transcription-dependent DNA interference (B) were determined for the cmr1α mutants as described in the legends of Figure 1B and C. RNA cleavage activity (C) and RNA-activated DNA cleavage activity (D) were assayed as described in the legends of Figure 2C and D. Δβ—S. islandicus Δβ, a reference strain carrying a deletion of the complete Cmr-β gene cassette; Δβ1α-M1—S. islandicus Δβ1α-M1: derived from S. islandicus Δβ with which substitution mutations of W58A and F59A were generated on the cmr1α gene. Δβ1α-M2—S. islandicus Δβ1α-M2: derived from S. islandicus Δβ with which substitution mutations of I52A, G54A, R57A and R61A were generated on the cmr1α gene. Cmr-α1M1: mutant Cmr-α complex purified from S. islandicus Δβ1α-M1 (containing Cmr1α^W58A,F59A); Cmr-α1M2: mutant Cmr-α complex purified from S. islandicus Δβ1α-M2 (carrying a much reduced level of Cmr1α^{I52A, G54A, R57A,R61A}).