title: Structural Insights into the HWE Histidine Kinase Family: The Brucella Blue Light-Activated Histidine Kinase Domain.
abstract: In response to light, as part of a two-component system, the Brucella blue light-activated histidine kinase (LOV-HK) increases its autophosphorylation, modulating the virulence of this microorganism. The Brucella histidine kinase (HK) domain belongs to the HWE family, for which there is no structural information. The HWE family is exclusively present in proteobacteria and usually coupled to a wide diversity of light sensor domains. This work reports the crystal structure of the Brucella HK domain, which presents two different dimeric assemblies in the asymmetric unit: one similar to the already described canonical parallel homodimers (C) and the other, an antiparallel non-canonical (NC) dimer, each with distinct relative subdomain orientations and dimerization interfaces. Contrary to these crystallographic structures and unlike other HKs, in solution, the Brucella HK domain is monomeric and still active, showing an astonishing instability of the dimeric interface. Despite this instability, using cross-linking experiments, we show that the C dimer is the functionally relevant species. Mutational analysis demonstrates that the autophosphorylation activity occurs in cis. The different relative subdomain orientations observed for the NC and C states highlight the large conformational flexibility of the HK domain. Through the analysis of these alternative conformations by means of molecular dynamics simulations, we also propose a catalytic mechanism for Brucella LOV-HK.
authors: Fundación Instituto Leloir, IIBBA-CONICET, Avenida Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina.
authors: Jimena
authors: J
authors: Rinaldi
authors: Departamento de Química Inorgánica, Analítica y Química Física e INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires , Ciudad Universitaria, Pabellón 2, C1428EHA, Buenos Aires, Argentina.
authors: Mehrnoosh
authors: M
authors: Arrar
authors: Fundación Instituto Leloir, IIBBA-CONICET, Avenida Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina.
authors: Gabriela
authors: G
authors: Sycz
authors: Fundación Instituto Leloir, IIBBA-CONICET, Avenida Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina; Plataforma Argentina de Biología Estructural y Metabolómica PLABEM, Avenida Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina.
authors: María Laura
authors: ML
authors: Cerutti
authors: Fundación Instituto Leloir, IIBBA-CONICET, Avenida Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina.
authors: Paula M
authors: PM
authors: Berguer
authors: Fundación Instituto Leloir, IIBBA-CONICET, Avenida Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina.
authors: Gastón
authors: G
authors: Paris
authors: Departamento de Química Inorgánica, Analítica y Química Física e INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires , Ciudad Universitaria, Pabellón 2, C1428EHA, Buenos Aires, Argentina.
authors: Darío Ariel
authors: DA
authors: Estrín
authors: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA, Buenos Aires, Argentina.
authors: Marcelo Adrián
authors: MA
authors: Martí
authors: Fundación Instituto Leloir, IIBBA-CONICET, Avenida Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina; Plataforma Argentina de Biología Estructural y Metabolómica PLABEM, Avenida Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina.
authors: Sebastián
authors: S
authors: Klinke
authors: Fundación Instituto Leloir, IIBBA-CONICET, Avenida Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina; Plataforma Argentina de Biología Estructural y Metabolómica PLABEM, Avenida Patricias Argentinas 435, C1405BWE, Buenos Aires, Argentina. Electronic address: fgoldbaum@leloir.org.ar.
authors: Fernando Alberto
authors: FA
authors: Goldbaum
mesh_terms: D002002:Brucella / Q000201:enzymology*; D018360:Crystallography, X-Ray; D004252:DNA Mutational Analysis; D000071677:Histidine Kinase; D056004:Molecular Dynamics Simulation; D010766:Phosphorylation; D011487:Protein Conformation; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D055503:Protein Multimerization; D011499:Protein Processing, Post-Translational
chemical_list: D011494:Protein Kinases; D000071677:Histidine Kinase
keywords: X-ray crystallography; autophosphorylation mechanism; molecular dynamics simulations; signal transduction; two-component system