Functional characterization of DesK, the Bacillus subtilis thermosensor

MARTÍN, M.; ALBANESI, D.; ALZARI, P.; DE MENDOZA, D.

Villa Carlos Paz- Córdoba- Argentina

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2008

The ability of bacteria to control the biophysical properties of their membranes allows them to thrive in a wide range of environments. When bacteria are exposed to lower temperatures than usual conditions, their membranes rigidify and as a consequence, cellular activities are suboptimal. One mechanism of adaptation involves the desaturation of acyl chains of membrane phospholipids. As a result, membrane fluidity is restored and normal cellular activities can take place at the lower temperature imposed. In Bacillus subtillis, there is only one Desaturase, a ƒ¢5- acyl lipid desaturase, whose expression is stringently controlled by DesR/K two component system. By means of its membrane component DesK, this system senses changes in membrane properties due to abrupt temperature changes. We undertook in vitro biochemical studies on DesK to answer the question of how does this membrane fluidity sensor perceive and transmit the signal. To this end, we first set up a one-step procedure to obtain functional DesK proteoliposomes. Then, we proceed to fully characterize DesK activities assaying DesK proteoliposomesLs autokinase, phosphotransfer and phosphatase activities at different temperatures. As a consequence, a biochemical-inspired hypothesis for signal perception and transduction through the membrane to the cytoplasmatic domain is discussed.