Figure 5. Immunity proteins display varying non-cognate effector neutralization.

(A) Tai3^TY is an exception to a simple cognate effector–immunity protection model. All panels in this figure show the growth of E. coli harboring vectors co-expressing the indicated effector and immunity proteins. Immunity proteins were induced identically in all panels. Error bars represent ± s.d. (n=3). Expression data for all experiments are provided in Figure S2. Asterisks in (A), (B), and (C) indicate immunity proteins that provided significant protection above the empty vector control (p < 0.05).

(B) The immunity provided by Tai3^TY against Tae2^BT does not extend to all family 2 effectors. Data demonstrating the catalytic activity of Tae2^TY on peptidoglycan are shown in Figure S5.

(C, D) Effector proteins of the same family are not always recognized by all immunity proteins of that family. (C) Co-expression of either Tae2^BT or Tae2^TY with Tai2^BT or Tai2^TY. (D) Co-expression of Tse1^PA with Tsi1^PA or Tsi1^BP with either lower (10μM IPTG) or higher (25μM IPTG) induction of Tse1^PA. Asterisks denote instances in which immunity proteins provided significantly lower protection against Tse1^PA at higher induction levels of the effector (p < 0.05).