Structural and Biophysical Characterization of Prohibitin

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Trieu, Benchmen
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Prohibitin (PHB) is a multimeric protein found on lipid rafts of the eukaryotic inner-mitochondrial membrane. The protein is comprised of 3 domains: an N-terminal transmembrane helix, a PHB domain found at the center, and followed by a C-terminal coiled-coil domain. PHB has been shown to function as an intracellular signalling mediator in various cellular processes such as iron homeostasis, cell apoptosis, and mitochondrial DNA maintenance. Many of these processes are associated with the diseases that affect the general population ranging from cancer to obesity. Since no atomic resolution structure of PHB is known, such a determination will provide insight towards its function and furthermore the role it plays within the cell as well as the entire organism. X-ray Diffraction is the desired method for structure determination; therefore, preliminary data pertaining to the protein’s behaviour in various solvent conditions will facilitate protein crystallization. This study describes biophysical and structural aspects of (PHB1)-25-252-CHis6 from dynamic light scattering, analytical ultracentrifugation, transmission electron microscopy, and small angle X-ray solution scattering. CD data was used to determine the quality of refolding protein and showed that it was refolded but without functional assays available, it is unknown whether the protein is properly folded. Sedimentation and microscopy results indicate that the protein forms large oligomers. Further scattering and sedimentation data analysis showed that when protein concentrations were increased from 1-60mg/mL, the protein decreases in particle size. This may be due to large protein sizes, normally observed for proteins at greater concentrations, collapsing and forming smaller structures.
Biochemistry, Chemistry, Protein, Prohibitin, Dynamic Light Scattering, Analytical Ultracentrifugation, Small Angle X-ray Scattering, Transmission Electron Microscopy