Discipline: Chemistry and Chemical Sciences
Subcategory: Biochemistry (not Cell and Molecular Biology and Genetics)
Maria D. Santiago Estevez - Florida International University
Co-Author(s): Dr. Jaroslava Miksovska , Florida International University, Miami, FL
Neuronal calcium sensors regulate several physiological processes in the brain and are linked to numerous pathological conditions such as autism, Parkinson and Alzheimer disease. Downstream regulatory element antagonist modulator (DREAM) is among the neuronal calcium sensor family, it is an EF-hand protein highly expressed in the central nervous system in various areas such as the hippocampus and the neural cortex. DREAM is responsible for regulating the kinetics of potassium channels, gene expression, calcium homeostasis, and enzymatic activity of presenilin.in the cytoplasm. The characterization of the metal-binding properties of DREAM and how it affects DREAM structure and its interactions with effector proteins are fundamental to understand its biological function. Essential metals like Mg2+, Zn2+ and Ca2+ play extremely important roles in biological processes through direct interactions with proteins. DREAM carries out two Ca2+ binding EF hands and one Mg2+ binding EF hand, however, DREAM binding to other biologically significant metals is not very well known. Interactions of DREAM with Zn2+ have been monitored by using intrinsic and extrinsic fluorescent probes. Data obtained shows that Zn2+ associates to DREAM with Kd ~ 200 M. Zn2+ and it does not compete for the same binding site as Ca2+ as the changes in the protein tertiary structure are distinct from those observed upon Ca2+association. Considering increased concentration of Zn2+ in neuronal tissue (150 – 200 M), these results point towards the potential role of Zn2+ in modulating DREAM interactions with other intracellular proteins. Future studies include to isolate and purify DREAM constructs with individual residues replaced by Ala and characterize its structural properties and interactions with effector proteins using fluorescence, ITC, and mass spectrometry. In addition, considering the role of Pb2+ and Zn2+ in several neurological diseases, we will determine DREAM is a target of neurotoxicity for several metals that were shown previously to interact with EF –hands proteins using ITC, fluorescence, and mass spectrometry. References 1. Carrion, A. M., Link, W. A., Ledo, F., Mellstrom, B., and Naranjo, J. R. (1999) DREAM is a Ca2+-regulated transcriptional repressor. Nature. 398, 80-84. 2. Buxbaum, J. D., Choi, E., Luo, Y., Lilliehook, C., Crowley, A. C., Merriam, D. E., and Wasco, W. (1998) Calsenilin: A calcium-binding protein that interacts with the presenilins and regulates the levels of a presenilin fragment. Nat. Med. 4, 1177-1181. 3. An, W. F., Bowlby, M. R., Betty, M., Cao, J., Ling, H., Mendoza, G., Hinson, J. W., Mattsson, K. I., Strassle, B. W., Trimmer, J. S., and Rhodes, K. J. (2000) Modulation of A-type potassium channels by a family of calcium sensors. Nature. 403, 553-556.
Not SubmittedFunder Acknowledgement(s): Dr Jaroslava Miksovska
Faculty Advisor: Dr Jaroslava Miksovska, miksovsk@fiu.edu
Role: The research was completely performed by the student , under the guidance of the instructor