Transcriptional YgiV role and VisP protein-protein interaction on chemical signaling and LPS assembly in Salmonella enterica sorovar Typhimurium pathogenesis

Author(s)

Patrick da Silva

• Document type: Doctoral Thesis
• Press: Araraquara. 2021-03-05.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Farmacêuticas. Araraquara
• Defense date: 2020-11-06
• Advisor: Cristiano Gallina Moreira

Abstract

Pathogenic bacteria employ proteins to respond to external stimuli and activate pathogenicity. Salmonella enterica serovar Typhimurium presents the VisP protein, which plays an important role in the response to stress and in the activation of the pathogenicity islands SPI-1 and 2 (Salmonella Patogenicity Island 1 and 2). The visP gene is contained in an operon which also has ygiV, which encodes an AraC family transcriptional regulator. The present study evaluated and investigated the transcriptional regulation carried out by YgiV and its correlation with the two-component QseBC system. A transcriptomic analysis of the ΔygiV mutant was performed, identifying 379 differentially expressed genes compared to the wild-type. Among the genes with increased expression in ΔygiV, 33 belong to SPI-1 with the role of epithelial cell invasion. Most genes with reduced expression code for catabolism associated proteins in general, as sugar, aminoacids and nucleic acids catabolism. A massive in silico analysis was performed to predict YgiV function, as well as the determination of a recognition and transcription factor interaction consensus sequence. A probable YgiV interaction with the 1,2-propanediol molecule was determined. Furthermore, by identifying the consensus sequence of cis elements that undergo YgiV regulatory action, the likely YgiV regulon was predicted. Confirming the transcriptomic analysis data, SPI-1 genes and the fucose fermentation pathway to propionate were identified. Gene expression analysis assays under YgiV overexpression confirmed the in silico prediction data. The gene expression of some SPI-1 targets and the pdu operon, responsible for the degradation of 1,2-propanediol to propionate, was also evaluated. The results showed that the natural performance of YgiV is accentuated in an anaerobic environment and that the presence of fucose strongly affects the effect of its function. Finally, HeLa cell invasion assays have shown that YgiV can play the role of transcriptional repressor, a function that can be enhanced as the 1,2-propanediol concentration increases. These results demonstrated the transcriptional regulation role of YgiV in in the pathogenic process of epithelial cell invasion mediated by S. Typhimurium and its relationship with sugars present in the intestinal lumen. As well as the propionate production pathway being essential for an effective intestinal colonization by S. Typhimurium, a process that depends on regulation by QseBC and YgiV. (AU)

• FAPESP's process: 16/12744-2 - Transcriptional YgiV role and VisP protein-protein interaction on chemical signaling and LPS assembly in Salmonella enterica sorovar Typhimurium pathogenesis
• Grantee: Patrick da Silva
• Support Opportunities: Scholarships in Brazil - Doctorate