C-terminal domain of DREAM as a potential druggable target

Gessica St Louis and Jaroslava Miksovska

Department of Chemistry and Biochemistry
Florida International University

DREAM protein, also known as calsenilin or KCHIP-3 is a calcium sensor protein expressed in brain where it regulates diverse physiological processes. DREAM fulfills such functions by interactions with multiple intracellular partners including DNA, Kv4 channels and presenilin. Those interactions are regulated through Ca2⁺ binding to the EF hands of the proteins. Ca2+ binding to DREAM leads to a rearrangement of the tertiary structure resulting in increased exposure of the protein hydrophobic regions.  8-anilino- 1 –naphthalenesulfonic acid (ANS) is an extrinsic fluorescence probe that binds to hydrophobic patches on DREAM surface. Here we have developed a displacement approach using 1,8-ANS as a fluorescence probe to determine the DREAM affinity for hydrophobic molecules as well as kinetics parameters.  The data show that small hydrophobic molecules such as bezafibrate and cholesterol bind to DREAM C- terminus with micromolar affinity and displacement of the C-terminal helix 10 represent a rate limiting step for the drug assocaiton.  These results indicate that the C- terminal domain of DREAM may serve as “druggable” target for development of drugs for Alzheimer disease and other neuropathological conditions.