Transmembrane Protein LMxysn_ of Serovar 4h Is Associated with Bile Salt Resistance and Intestinal Colonization.

(Lm) is a ubiquitous foodborne pathogen comprising of 14 serotypes, of which serovar 4h isolates belonging to hybrid sub-lineage Ⅱ exhibit hypervirulent features. LMxysn_ of serovar 4h Lm XYSN, a member of genomic island-7 (GI-7), is predicted to a membrane protein with unknown function, which is conserved in serovar 4h . Under bile salts stress, Lm XYSN strain lacking LMxysn_ (XYSN∆) exhibited a stationary phase growth defect as well as a reduction in biofilm formation and strikingly down-regulated bile-salts-resistant genes and virulent genes. Particularly, LMxysn_1693 protein plays a crucial role in Lm XYSN adhesion and invasion to intestinal epithelial cells, as well as colonization in the ileum of mice. Taken together, these findings indicate that the LMxysn_ gene encodes a component of the putative ABC transporter system, synthetically interacts with genes involved in bile resistance, biofilm formation and virulence, and thus contributes to survival within and outside the host.