Conserved and acquired: decoding YbjX and VirK in the pathogenicity of Shigella flexneri
Description
Bacterial pathogens use a variety of strategies to evade the host’s defences and reach their replicative niches. Among these pathogens, Shigella flexneri is responsible for bacillary dysentery in developing countries, making the study of all the virulence factors important for designing effective treatments. All Shigella spp. carry a virulence plasmid where most of the genes encoding those factors are located. Here, we describe the characterisation of the proteins YbjX and VirK, whose genes are on the chromosome and the virulence plasmid, respectively. The structures of these proteins are highly similar, so we investigated whether their functions are somehow related. After defining their promoters and common regulation of their expression, we performed a functional study. We found that YbjX and VirK are involved in maintaining the integrity of the outer membrane, in resistance to antimicrobial peptides and the modulation of the host immune response, pivotal in the infection process and, more broadly, in host-pathogen interaction. We evidenced that, while VirK plays the leading role, YbjX provides an important supporting function.