Structural study of a two-component signal transduction system activated by light in Brucella abortus (Comunicación Oral)

SEBASTIÁN KLINKE; JUAN M. PAZ; FERNANDO A. GOLDBAUM; GABRIELA SYCZ; JIMENA RINALDI; IGNACIO FERNÁNDEZ; LISANDRO OTERO

Iquique

Congreso; XLI Reunión Anual de la Sociedad de Bioquímica y Biología Molecular de Chile; 2018

Sociedad de Bioquímica y Biología Molecular de Chile

The pathogenic bacterium Brucella abortus codes for a cytoplasmic blue light-activated histidine kinase called LOV-HK, which is a key virulence factor that belongs to a two-component signal transduction system involved in the modulation of the general stress response in this microorganism [1], together with two response regulators called PhyR and LovR. With the goal of understanding at the atomic level the activation and signal transduction events of this system, we aimed to solve the three-dimensional structures of these proteins by means of X-ray crystallography. The following structures will be presented: (i) the core of the blue-light sensor FMN-binding LOV domain (at 1.64 A resolution in the dark) [2], (ii) the LOV core domain plus an N-terminal capping helix at 2.34 A resolution (N-LOV), (iii) the two-domain N-LOV-PAS structure at 2.74 A resolution bearing the intermediate PAS domain, (iv) the isolated HK domain at 2.51 A resolution solved by sulfur SAD in a challenging procedure [3,4], (v) the structure of the PhyR response regulator at 2.05 A resolution, and (vi) the structure of the complete LOV-HK protein in its activated form at 3.25 A resolution. All these protein structures, together with spectroscopic, activity and biophysical assays, allowed us for a better understanding of this crucial system for the pathogenicity of Brucella. [1] Sycz, G. et al. (2015). PLoS One 10, e0124058. [2] Rinaldi, J. et al. (2012). J. Mol. Biol. 420, 112-127. [3] Klinke, S. et al. (2015). Acta Cryst. D 71, 1433-1443. [4] Rinaldi, J. et al. (2016). J. Mol. Biol. 428, 1165-1179.