INVESTIGADORES
KLINKE Sebastian
congresos y reuniones científicas
Título:
Structural studies on the protein LOV-Histidine kinase from Brucella abortus
Autor/es:
SEBASTIÁN KLINKE; JIMENA RINALDI; GABRIELA SYCZ; GASTÓN PARIS; FERNANDO A. GOLDBAUM
Lugar:
Bariloche
Reunión:
Congreso; VII Reunión Anual de la Asociación Argentina de Cristalografía; 2011
Institución organizadora:
Asociación Argentina de Cristalografía
Resumen:
LOV (Light,
Oxygen, Voltage) sensory domains are found in Archaea, Eukarya and
Bacteria. In the latter, most of the LOV domain-containing proteins are
associated with histidine kinase (HK) output domains involved in signal
transduction. The HK protein is the first component of two-component systems,
which are involved in environmental sensing in bacteria regulating gene
expression, chemotaxis and virulence. LOV domains bind FMN as cofactor and
undergo a photocycle upon illumination. Blue light excites the FMN molecule to
the triplet state, giving rise to a covalent adduct between the ligand and a
cysteine residue from the protein. In the darkness, the covalent adduct decays
thermally to the basal state. Recent evidence suggests that the cysteinyl
adduct is the signal state of prokaryotic LOV-HKs.
Bacteria from the genus Brucella
are intracellular pathogens that cause a worldwide zoonosis named brucellosis.
A protein containing a LOV domain followed by a PAS and an HK domain has been
recently identified in Brucella abortus.
This protein binds FMN and undergoes a photocycle but it does not decay upon
incubation in the darkness. Infection of macrophage cells with a Brucella mutant lacking the LOV gene
shows an attenuated phenotype suggesting that the LOV-HK protein is a virulence
factor [1]. Macrophage infection with Brucella
wild type cells grown in the dark also shows a decrease in the number of
intracellular bacteria when compared with wild type cells grown in light,
confirming the effect of light in bacterial virulence.
As part of this
project we aim to solve the crystallographic structure of LOV-HK, which will
allow us a better understanding of the signal transduction effect between the
LOV and HK domains, giving clues about the light sensing mechanism of LOV
proteins and the general activation of histidine kinases. Additionally, we aim
to explain the virulence enhancement by light in Brucella.
In this talk we
will show our recent progress in the project, describing the LOV domain
structure at 1.64 Å resolution and preliminary results on HK domain crystals.
In addition, we will also illustrate the different strategies that are being
followed at the moment to cover as much as possible of the whole LOV-HK protein
in single constructs.
[1] Swartz,
T.E. et al. (2007). Science317, 1090-1093.