• A LOV-Domain Histidine Kinase is involved in Brucella abortus infection.

. PARIS, G.; SWARTZ, T.E.; SPERA, J.M.; COMERCI, D.; BOGOMOLNI, R.; GOLDBAUM, F.A.

Congreso; SAIB XLII; 2006

Brucella abortus is a facultative intracellular pathogen that causes brucellosis in domestic animals and humans. Brucella invades and replicates inside professional and non-professional phagocytes. Two-component proteins are widely recognized as environmental sensors in bacteria. Light, oxygen or voltage (LOV) belongs to the PAS domain superfamily. LOV domains bind a single molecule of FMN and undergo a self-contained photocycle that is dependent on the presence of a highly conserver cysteine residue. We identified a gen coding for a LOV domain protein in B.abortus (LOV-HPK). In addition to LOV domain this gene also has a PAS domain and an histidine kinase domains. The gene of LOV-HPK was cloned and expressed in E.coli. Illumination of recombinant purified LOV-HPK protein in presence of ATP conduce to autophosphorylation of kinase domain, showing that LOV-HPK is an active histidine kinase. In order to investigate the in vivo function of LOV-HPK this gene was knocked-out and mutation was checked by PCR. Cell infection assays in macrophages J774 shown that LOV-HPK mutant bacterias has a attenuated phenotype as compared with control. However, in HeLa cells, LOV-HPK mutant shown similar infection as compared with control. Taking together these results suggest that LOV-HPK protein from B.abortus is a virulence factor involved in the defense against oxidative killing in macrophages.