IBR   13079
INSTITUTO DE BIOLOGIA MOLECULAR Y CELULAR DE ROSARIO
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
A minimal sensor that responds to membrane fluidity
Autor/es:
CYBULSKI, LE; MARTIN M; MANSILLA MC; FERNÁNDEZ, A; DE MENDOZA, D
Lugar:
Carlos Paz, Argentina
Reunión:
Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2008
Resumen:
The B. subtilis DesKR two component system has been identified as
the first system that senses changes in membrane lipid fluidity and
responds accordingly. It is composed of a membrane histidin-kinase,
DesK, a cytoplasmic response regulator, DesR, and the effector
enzyme, delta5-desaturase. Under conditions of restricted
membrane fluidity DesK phosphorylates DesR, enabling its binding
to the desaturase promoter. A tetramer of phosphorylated DesR
positioned on Pdes recruits the RNAPolymerase to increase the
transcription of the acyl-lipid desaturase. This enzyme introduces
double bonds into the acyl chains of membrane lipids to decrease its
phase transition temperature.
To obtain a simple system to study the sensing mechanism of DesK
we constructed a series of fusion proteins composed of the
cytoplasmic domain of DesK and one of several chimerical
transmembrane segments (TMSs) envisioned as possessing the
critical elements involved in sensing. One of these fusion proteins
behaves as DesK wild type, so we called it DesK-Minimal Sensor
(DesK-MS).
The unique TMS of DesK-MS seems to harbor the essence of the
functioning of a biological sensor, having the required elements to
perceive and transmit the signal. The DesK-MS give us the
opportunity to test our hypothesis on its mode of action by the
construction of several site-directed mutants and analyze its
behavior in vitro