Papel dos sistemas de dois componentes SsrAB e QseCB na regulação das Ilhas de Patogenicidade 1 e 2 de Salmonella enterica subsp. enterica sorovar Typhimurium pelo ácido 3,4-dimetilbenzoico

Abstract

The gastrointestinal tract is colonized by a wide diversity of microorganisms, collectively known as microbiota. Over millions of years of evolution, this community has established a mutualistic symbiotic relationship with its host, which is essential for maintaining homeostasis. Among the numerous interactions occurring in the microbiota, the recognition of molecules is crucial for cellular communication and the coordination of collective behaviors. One such molecule, 3,4-dimethylbenzoic acid (DMB), has been associated with the inhibition of virulence genes located in the Salmonella Pathogenicity Islands (SPI) 1 and 2, genetic clusters essential for the survival and adaptation of Salmonella enterica in both phagocytic and non-phagocytic cells. This suggests that the microbiota may play an important role in modulating the virulence of this pathogen. Therefore, this study investigated the impact of DMB on gene expression in SPI-1 and SPI-2, as well as the role of the Two-Component Systems (TCSs) SsrAB and QseCB in Salmonella enterica serovar Typhimurium's response to this compound. The results show that DMB continuously represses genes located in SPI-1 and SPI-2. Mutant strains with deletions in ssrB and qseB genes were generated to explore the signaling of these systems. The deletion of qseB repressed the expression of hilA – the main regulator of genes in SPI-1 – in response to DMB, while the deletion of ssrB affected the regulation of genes such as ssrA and sipA, which are important for the adaptation and pathogenicity of S. Typhimurium. These results suggest that DMB exerts a repressive action, modulating the expression of virulence genes through specific sensory systems. Thus, this study contributes to the understanding of the mechanisms by which the microbiota can influence the pathogenic behavior of Salmonella in the intestinal environment.