Lmo1656 is a secreted virulence factor of Listeria monocytogenes that interacts with the sorting nexin 6–BAR complex

<i>Listeria monocytogenes</i> (<i>Lm</i>) is a facultative intracellular bacterial pathogen and the causative agent of listeriosis, a rare but fatal disease. During infection, <i>Lm</i> can traverse several physiological barriers; it can cross the intestine and placenta barrier and, in immunocompromised individuals, the blood-brain barrier. With the recent plethora of sequenced genomes available for <i>Lm</i>, it is clear that the complete repertoire of genes used by <i>Lm</i> to interact with its host remains to be fully explored. Recently, we focused on secreted <i>Lm</i> proteins because they are likely to interact with host cell components. Here, we investigated a putatively secreted protein of <i>Lm</i>, Lmo1656, that is present in most sequenced strains of <i>Lm</i> but absent in the nonpathogenic species <i>Listeria innocua. lmo1656</i> gene is predicted to encode a small, positively charged protein. We show that Lmo1656 is secreted by <i>Lm</i> Furthermore, deletion of the <i>lmo1656</i> gene (Δ<i>lmo1656</i>) attenuates virulence in mice infected orally but not intravenously, suggesting that Lmo1656 plays a role during oral listeriosis. We identified sorting nexin 6 (SNX6), an endosomal sorting component and BAR domain-containing protein, as a host cell interactor of Lmol656. SNX6 colocalizes with WT <i>Lm</i> during the early steps of infection. This colocalization depends on Lmo1656, and RNAi of SNX6 impairs infection in infected tissue culture cells, suggesting that SNX6 is utilized by <i>Lm</i> during infection. Our results reveal that Lmo1656 is a novel secreted virulence factor of <i>Lm</i> that facilitates recruitment of a specific member of the sorting nexin family in the mammalian host.