Conformational Ensembles from Experimental Data and Computer Simulations

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Conformational Ensembles from Experimental Data
and Computer Simulations Poster Abstracts
153
116-POS Board 36
A Direct Interaction of Cholesterol with Monoamine Transporters Prevents Their Out-to-
Inward Transition
Talia Zeppelin1, Lucy K. Ladefoged3, Steffen Sinning2, Xavier Periole1, Birgit Schioett1,3.
1Aarhus University, Aarhus C, Denmark, 2Translational Neuropsychiatry Unit, Aarhus C,
Denmark, 3Aarhus University, Aarhus C, Denmark.
Monoamine transporters (MATs) carry out neurotransmitter reuptake from the synaptic cleft,
which is a key step targeted in treatment of neurological disorders. Cholesterol, a major
component of the synaptic plasma membrane, has been shown to exhibit a modulatory effect on
MATs, and recent crystal structures of the dopamine transporter (DAT) in the presence of two
conserved cholesterol molecules substantiate the hypothesis of a direct protein-cholesterol
interaction. We performed extensive all-atom molecular dynamics (MD) simulations of DAT
with and without cholesterol bound. In the absence of cholesterol, DAT undergoes structural
changes reflecting early events of transport: transition to an inward-facing conformation. In
contrast, in the presence of cholesterol these conformational changes are inhibited presumably by
a stabilizing interaction of cholesterol at the intracellular side of TM5. We further provide
evidence, from using coarse-grained MD simulations, that the cholesterol sites observed in the
DAT crystal structures are conserved in all human MATs, suggesting that this effect might
extend to the entire family.