VirJ: An accesory protein of type IV secretion system involved in pathogenesis of Brucella abortus

DEL GIUDICE MG; DOHMER P.; SPERA JM; CZIBENER C; UGALDE JE.

Rosario

Congreso; SAIB 50th Annual Meeting.; 2014

Argentine Society for Biochemistry and Molecular Biology Research

Brucella abortus is a Gram-negative intracellular bacterium, responsible for brucellosis, a worldwide zoonosis of veterinary and human concern. Virulence of this pathogen is associated with the ability to survive and replicate within professional and nonprofessional phagocytes, avoid the fusion of the vacuole that contains it with the lysosomes, and redirect its traffic in order to generate a replicative niche where it will exponentially multiply. Many of these activities are completely dependent on the VirB system, a type IV secretion system that secretes and translocates into the host cell effector proteins that reprogram the fate of the Brucella-containing vacuole and allow the establishment of the replicative niche. Analysis of the genome of Brucella abortus allowed us to identify a homolog of the virJ gene of Agrobacterium tumefaciens that encodes a periplasmic protein necessary for the secretion of substrates of the A. tumefaciens VirB system. Our results show that the absence of this protein in B. abortus produces a negative effect in the intracellular cycle of the bacteria and negatively affects virulence in mice. We show that VirJ interacts in a direct or indirect manner with effector proteins, stimulating the VirB dependent secretion process.