Temperature Sensing in Membranes: Lessons learned from DesK

FERNÁNDEZ, PILAR; ALBANESI, DANIELA; DE MENDOZA, DIEGO; MANSILLA, MARÍA CECILIA

Boston

Conferencia; Membrane Protein Folding-Gordon Research Conference; 2019

Gordon Research Conferences (GRC)

In this talk I will focus on Bacillus subtilis DesK, a membrane-bound histidine kinase (HK) that senses changes in membrane fluidity, initiating an adaptive response. Throughout the years, genetic, biochemical, structural, and computational studies on wild-type, mutant, and truncated versions of DesK allowed us to dissect several aspects of DesK?s functioning, pushing forward a more general understanding of its own structure/function relationships as well as those of other HKs. We have shown that the sensing mechanism is rooted in temperature-dependent membrane properties and we have proposed possible mechanisms by which DesK senses these properties and transduces the signals. X-ray structures and computational models have revealed structural features of TM and cytoplasmic regions in DesK?s kinase- and phosphatase-competent states. Biochemical and genetic experiments and molecular simulations further showed that reversible formation of a two-helix coiled coil in the fifth TM segment and the N-terminus of the cytoplasmic domain is essential for the sensing and signal transduction mechanisms. We propose that membrane thickening is the main driving force for signal sensing and that it acts by inducing helix stretching and rotation prompting an asymmetric kinase-competent state. Finally, we advance an important role for TM prolines in transducing the initial signals to the cytoplasmic coiled coils, based on simulations of DesK?s TM helices and site-directed mutants. Overall, the known structural changes of DesK, as well as further dynamic rearrangements that we predict, consistently link structure determinants to activity modulation.