IIBBA   05544
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Gaining insight into the activation mechanism of the response regulator NTRX from Brucella abortus
Autor/es:
FERNÁNDEZ, IGNACIO; OTERO, LISANDRO HORACIO; KLINKE, SEBASTIÁN; CARRICA, MARIELA C.; GOLDBAUM, FERNANDO A.
Lugar:
Rosario
Reunión:
Congreso; L Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2014
Institución organizadora:
Sociedad Argentina de Investigación en Bioquímica y Biología Molecular
Resumen:
Brucella abortus is a pathogen that has to overcome 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 that 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 beryllofluoride 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 α4 and sheet β5 from neighboring monomers. Also, major changes in the backbone of loop β4α4 were observed, allowing interactions between residues W55-H85, as well as repositioning of helix α5. To study the relevance of H85 we obtained the REC(H85A) mutant, which is not efficiently phosphorylated and autodephosphorylates 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 α5 as possible transducer events, and H85 as an important residue to determine phosphorylation efficiency and half-life of the activated response regulator