Now that the structure of the N-terminal domain of exotoxin S has been revealed, perhaps a drug target will present itself.
Pseudomonas aeruginosa continues to develop antibiotic resistance, remaining potentially fatal to patients with cystic fibrosis. It appears to escape host defences by activating the GTPase activity of small G proteins that are involved in rearranging the cytoskeleton. However, researchers in Germany have revealed the structure of the N-terminal domain of the exotoxin responsible, exotoxin S (ExoS-N), hopefully providing clues for new drugs that could attenuate the bacteria (Nat Struct Biol 2001 8;23-26).
Dr Alfred Wittinghofer et al of the Max-Planck-Institut für Molekulare Physiologie in Dortmund, Germany, found that the GAP domain of ExoS is an all-helical protein, and that its interactions with Rac, a human G protein, are different from those of other GTPase-activating proteins in the host cell. Disruption of the gene encoding ExoS significantly reduces the virulence of the bacteria. Knowing the structure of ExoS-N should make it possible to find drugs to block its function.