Induced conformational changes in the activation of the Pseudomonas aeruginosa type III toxin, ExoU.

ExoU is a 74-kDa, water-soluble toxin injected directly into mammalian cells through the type III secretion system of the opportunistic pathogen, Pseudomonas aeruginosa. Previous studies have shown that ExoU is a Ca(2+)-independent phospholipase that requires a eukaryotic protein cofactor. One protein capable of activating ExoU and serving as a required cofactor was identified by biochemical and proteomic methods as superoxide dismutase (SOD1).

Identification of Francisella tularensis Himar1-based transposon mutants defective for replication in macrophages.

Francisella tularensis, the etiologic agent of tularemia in humans, is a potential biological threat due to its low infectious dose and multiple routes of entry. F. tularensis replicates within several cell types, eventually causing cell death by inducing apoptosis.