MxiC is secreted by and controls the substrate specificity of the Shigella flexneri type III secretion apparatus.

Many gram-negative pathogenic bacteria use a type III secretion (T3S) system to interact with cells of their hosts. Mechanisms controlling the hierarchical addressing of needle subunits, translocators and effectors to the T3S apparatus (T3SA) are still poorly understood. We investigated the function of MxiC, the member of the YopN/InvE/SepL family in the Shigella flexneri T3S system.

MxiK and MxiN interact with the Spa47 ATPase and are required for transit of the needle components MxiH and MxiI, but not of Ipa proteins, through the type III secretion apparatus of Shigella flexneri.

The type III secretion (TTS) pathway is used by numerous Gram-negative pathogens to inject virulence factors into eukaryotic cells. The Shigella flexneri TTS apparatus (TTSA) spans the bacterial envelope and its assembly requires the products of approximately 20 mxi and spa genes. We present a functional analysis of the mxiK, mxiN and mxiL genes.

Role of Yops and adhesins in resistance of Yersinia enterocolitica to phagocytosis.

Yersinia enterocolitica is a pathogen endowed with two adhesins, Inv and YadA, and with the Ysc type III secretion system, which allows extracellular adherent bacteria to inject Yop effectors into the cytosol of animal target cells. We tested the influence of all of these virulence determinants on opsonic and nonopsonic phagocytosis by PU5-1.8 and J774 mouse macrophages, as well as by human polymorphonuclear leukocytes (PMNs).