LIPID-PROTEIN INTERACTIONS GOVERNING COLD SENSING

LARISA E. CYBULSKI; MARÍA C. MANSILLA; MARIANA MARTÍN; DANIELA ALBANESI; DIEGO DE MENDOZA

Rosario, Argentina

Taller; Segundo Taller de Criobiología Aplicada a las Ciencias Biomédicas; 2007

Bacillus subtilis, a gram-positive bacterium, frequently encounters stress conditions in its natural environment, the soil. In order to detect and respond accordingly to these stressful conditions, it employs two-component signal transduction systems. Changes in the growth temperature or nutrient availability alter the membrane fluidity, and B. subtilis overcomes this situation by regulating the proportion of unsaturated fatty acids. The B. subtilis Des pathway has been identified as the system that mediates this response, and is the first described system that senses changes in membrane lipid fluidity. It is composed of a membrane histidin-kinase, DesK, a soluble response regulator, DesR, and the effector enzyme, D5-desaturase. This study aims to unveil the mechanistic details by which changes in the membrane fluidity due to temperature variations regulate the signaling state of the sensor protein DesK. The dissection of this molecular mechanism will provide important insights into the basic question of how the DesK transmembrane segments sense the lipid environment. This information might also be used to understand the role of membrane fluidity in bacterial pathogenesis.