Modulation of an Outer Membrane Protease Contributes to the Virulence Defect of <i>Shigella flexneri</i> Strains Carrying a Mutation in the <i>virK</i> Locus

Abstract

The Shigella actin assembly protein IcsA is removed from the bacterial surface by the protease IcsP. We show that decreased intracellular spreading of virK::Tn10 mutants is due in part to significant increases in IcsP and IcsP-mediated cleavage of IcsA and that IcsP expression is a critical determinant of Shigella virulence.