Abstract 1374 Licensed to kill: Post-translational activation of an antibacterial effector protein

All bacteria compete for growth niches and other limited resources in the environment. These existential battles are waged at several levels, but one common strategy entails the direct transfer of toxic effector proteins between competing cells. Antibacterial effectors are invariably encoded with immunity proteins, which neutralize the effector to protect the cell from auto-inhibition and intoxication by neighboring siblings. Here, I show that an immunity protein from Enterobacter cloacae is also required to activate its cognate effector prior to delivery into target bacteria. Genetic, biochemical and structural analyses reveal that the toxic effector is subject to a novel post-translational modification when bound to its immunity protein. This modification stabilizes the effector fold and is absolutely required for toxic enzymatic activity in vitro and in vivo. Join us on Tuesday afternoon to learn the identity of this new post-translational modification. This work was supported by grant R01 GM117930 from the National Institutes of Health.