posted on 2016-09-14, 00:00authored byJames
Allen Frank, Henri G. Franquelim, Petra Schwille, Dirk Trauner
Ceramide
is a pro-apoptotic sphingolipid with unique physical characteristics.
Often viewed as a second messenger, its generation can modulate the
structure of lipid rafts. We prepared three photoswitchable ceramides, ACes, which contain an azobenzene photoswitch allowing for
optical control over the N-acyl chain. Using combined
atomic force and confocal fluorescence microscopy, we demonstrate
that the ACes enable reversible switching of lipid domains
in raft-mimicking supported lipid bilayers (SLBs). In the trans-configuration, the ACes localize into
the liquid-ordered (Lo) phase. Photoisomerization to the cis-form triggers a fluidification of the Lo domains,
as liquid-disordered (Ld) “lakes” are formed
within the rafts. Photoisomerization back to the trans-state with blue light stimulates a rigidification inside the Ld phase, as the formation of small Lo domains. These
changes can be repeated over multiple cycles, enabling a dynamic spatiotemporal
control of the lipid raft structure with light.