Effects of lipids over DesK, the Bacillus subtillis thermosensor

MARTÍN, M.; DE MENDOZA, D.

Pueto Madryn

Congreso; XLVI Reunión Anual SAIB; 2010

The DesK thermosensor from B. subtilis belongs to the group of histidine kinases (HK) with sensing mechanisms linked to the transmembrane segments (TMS). It is a polytopic protein containing five TMS and controls the phosphorylation state of DesR, which in turn regulates the expression of the cold shock-inducible des gene which codifies the D5- Des. As temperature sensing is essential for the survival of living cells, a major challenge is to understand how thermal information is processed by a biological thermometer to restore cellular functions. Since DesK regulatory function is defined by interaction with the bilayer, it represents an ideal system for studying the molecular mechanism of thermodetection and signal transduction. We analyzed the effect of some aspects of membrane lipid structure including thickness, phase behavior and phospholipids head group on the autokinase activity of full-length DesK. To this end, we reconstituted DesK in vitro in a series of phosphatidylcholines containing monounsaturated or saturated fatty acyl chains of different lengths and also in lipids with other head groups. The three membrane aspects analyzed affected the autokinase activity of the HK. Thus, the results presented here suggest that transmission of the signal across the membrane by DesK is regulated by both, the properties of the acyl chains and the polar head of membrane phospholipids.