Molecular biology of Pasteurella multocida toxin

Abstract

Pasteurella multocida toxin (PMT) is the causative agent of progressive atrophic rhinitis in swine. The 146 kDa single-chain toxin harbours discrete domains important for receptor binding, internalisation and biological activity. The molecular basis of the toxin's activity is the deamidation of a specific glutamine residue in the α-subunit of heterotrimeric G proteins. This results in an inhibition of the inherent GTPase activity leading to a constitutively active phenotype of the G protein. Due to the ability of the toxin to act on various families of heterotrimeric G proteins, a large subset of signal transduction pathways is stimulated.