Fig. 4.

Identification of nuclease active-site residues. (A) Mutated residues of CdiA-CT^EC536. (B) Growth inhibition activity of CdiA-CT^EC536 variants. Arabinose-inducible expression plasmids were introduced into E. coli cysK⁺ and ∆cysK cells, and transformants were selected on media supplemented with glucose or arabinose. Plasmid pCH450 is the empty vector. (C) In vitro nuclease activity of CdiA-CT^EC536 variants. Purified CdiA-CT^EC536 proteins were incubated with total cellular RNA in the presence of CysK and CdiI^EC536 where indicated. Reactions were run on denaturing polyacrylamide gels and visualized by ethidium bromide staining (Top) and Northern blot hybridization (Bottom).