Structural basis of cholesterol binding by a novel clade of dendritic cell modulators from ticks.
Roversi P., Johnson S., Preston SG., Nunn MA., Paesen GC., Austyn JM., Nuttall PA., Lea SM.
Two crystal structures of Japanin, an 18 kDa immune-modulatory lipocalin from the Brown Ear Tick (Rhipicephalus appendiculatus), have been determined at 2.2 and 2.4 Å resolution. In both crystal forms the protein is in complex with cholesterol, which sits in a closed pocket at the centre of the lipocalin barrel. Both crystal forms are dimers, which are also observed in solution. Molecular modelling suggests that previously-described members of a tick protein family bearing high sequence homology to Japanin are also likely to bind cholesterol or cholesterol derivatives.