Chemical signaling is a mechanism employed by several bacterial species to interact within surrounding microbiota and their host. Upon this interaction the pathogenic bacteria regulate their virulence traits. The two-component system QseBC was described on chemical signaling in Salmonella enterica serovar Typhimurium, and a novel branch of pathogenic cascade regulation was revealed. Among these mechanisms a novel protein was described, VisP (Virulence and stress related Periplasmic protein). Previously, it was demonstrated the role of VisP on stress response and its relevance on pathogenicity mediated by SPI-1 and SPI-2 (Salmonella Patogenicity Island I and II). VisP is encoded by a gene inside a operon, which also presents ygiV, translated in a AraC-family transcriptional regulator. The O-antigen of the LPS layer provides protection against host defenses, and particularly its chain's length plays an essential role. O-antigen assembly is mediated by a group of periplasmic proteins, which mechanism of action was not completely elucidated. Preliminary data shows elevated levels of long and very-long O-antigen (L-Oag and VL-Oag) chains on visP mutant. The present study aims to better understand VisP role on O-antigen chains assembly and modality, as also presets the transcriptional regulation mediated by YgiV, correlating with pathogenicity. The full comprehension of this mechanisms of bacterial membrane homeostasis and the complex relationship amongst pathogenic bacteria, the microbiota, and the host is an essential topic in microbial pathogenesis. The complete elucidation of these signals will be essential to understand their relationship, develop novel technologies and therapies.
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