Crystal structure of the histidine kinase domain from LOV-HK from the bacterium Brucella (poster)

JIMENA RINALDI; SEBASTIÁN KLINKE; GABRIELA SYCZ; GASTÓN PARIS; FERNANDO A. GOLDBAUM

Buenos Aires

Congreso; SAIB 2013 "Molecular mechanisms in cell signaling and gene expression"; 2013

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

The release of bacterial genomic sequences has greatly expanded the number of known two-component system histidine kinases (HK). A particular group, called the HWE family present in alpha- and gamma-proteobacteria was identified bioinformatically. A member of this group, LOV-HK from the bacterium Brucella, has been shown to mediate the light-induced increase of the virulence of this pathogen. As part of our project, we solved the three-dimensional structure of the histidine kinase domain from LOV-HK by X-ray crystallography. This is the first structure of a histidine kinase from the HWE family. Like other HKs, it presents a Dimerization and Histidine phosphotransfer subdomain (DHp) and a Catalytic and ATP-binding subdomain (CA). The structure shows two different dimer conformations. Both dimers differ in the parallel/antiparallel assembly of the monomers, the regions involved in the dimerization interface and the relative orientation between the DHp and CA subdomains. According to the interface area and the nature of their contacts, both dimers might exist in solution. SLS experiments indicate the HK domain is a monomer in solution. These observations suggest that the HK domain alternates between the two dimeric conformations, which dissociate during gel filtration in SLS experiments. The quaternary structures and their biological relevance will be the next focus of our efforts.