Crystal structure of the virulence protein J (VirJ) domain 1 from Brucella abortus.

Virulence protein J (VirJ) is a periplasmic protein encoded by the bacterial pathogen Brucella abortus and is important for its virulence. The VirJ homologue AcvB from Agrobacterium tumefaciens was found to be a lysyl-phosphatidylglycerol hydrolase that contains two domains, D1 and D2. Interestingly, both VirJ and AcvB are associated with the type IV secretion system (T4SS) activity in the respective bacteria. To date, no structural information is available for these proteins, limiting our understanding of their function. Here, we have purified, crystallized and determined the crystal structure of the N-terminal domain 1 of VirJ (VirJ) at a resolution of 1.7 Å. Our structural analysis shows that VirJ adopts an α/β-hydrolase fold but lacks the characteristic catalytic triad. The structure presented here may help to decipher the function of VirJ in Brucella spp. and other bacterial pathogens, as well as its contribution to the T4SS function.