Brucella abortus PrrB/A: a conserved redox-responsive two-component system

FERNÁNDEZ, IGNACIO; CARRICA, MARIELA DEL CARMEN; SIEIRA, RODRIGO; PARIS, GASTON; GOLDBAUM, FERNANDO

Mendoza

Congreso; XLVII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2012

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Brucella abortus is an intracellular bacterium that needs to adapt to an oxygen limited environment in order to achieve a successful infection. This prompted us to search putative systems that mediate the adaptation to the microaerobic conditions encountered by this pathogen. We identified in B. abortus genome the homologues to a conserved two-component system called PrrB/A. In other microorganisms, it has been shown that PrrB senses the redox status and, through PrrA, generates a global response which involves expression of high?affinity cytochrome oxidases and induction of enzymes that allow the use of alternative electron-accepting sources. We performed biochemical studies which indicate that PrrB is a histidine kinase more active under reductive conditions that phosphorylates PrrA, its cognate response regulator, as reported in other bacteria. We also demonstrated, using qRT?PCR, that under microaerobiosis PrrB is necessary to achieve the induction of high?affinity cytochrome oxidases and denitrification enzymes. By EMSA we found that PrrA directly regulates the nitrate reductase operon by binding to its promoter, and that phosphorylation of PrrA increases the affinity for this DNA fragment. Altogether, these results show that the homologues to PrrB/A in form a functional two-component system involved in the adaptation to microaerobic conditions.