INVESTIGADORES
CARRICA Mariela Del Carmen
congresos y reuniones científicas
Título:
GAINING INSIGHT INTO THE ACTIVATION MECHANISM OF THE RESPONSE REGULATOR NTRX FROM Brucella abortus
Autor/es:
FERNANDEZ IGNACIO; OTERO LISANDRO; KLINKE SEBASTIAN; CARRICA MARIELA; GOLDBAUM FERNANDO
Lugar:
Rosario
Reunión:
Congreso; 50th Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular; 2014
Resumen:
Brucella abortus is a pathogen that has to o vercome oxygen
deficiency during the course of infection. Our group identified the two - component system NtrY/X
that is activated under reducing conditions and is important for the induction of genes involved in the adaptation
to low oxygen tension. Given t hat NtrX has not been previously characterized, we decided to study the changes
induced in its isolated receiver domain (REC) upon phosphorylation. We solved the structure of the REC domain in
the absence and presence of the phosphoryl analog beryllofluori de by X - ray crystallography. We could determine
that phosphorylation promotes dimerization of the REC domain, and analysis of the structures showed the assembly
of an interface between helix α 4 and
sheet β 5 from neighboring monomers. Also, major changes in the backbone
of loop β 4 α 4 were observed, allowing
interactions between residues W55 - H85,
as well as repositioning of helix α 5 .
To study the relevance of H85 we obtained the REC(H85A) mutant, which is not
efficiently phosphorylated and is autodephosphorylated faster than the wild - type
domain. These results present a first
glimpse into the activation mechanism of NtrX, with changes in the interface
between monomers and movement of helix α 5 as p ossible transducer events, and H85 as
an important residue to determine phosphorylation efficiency and half - life of the activated
response regulator.