Projects and Grants

Molecular Mechanism of b-amyloid Peptide Production

gamma-Secretase is a human membrane protein complex responsible for the activation of pools of membrane-bound latent transcriptional activators through a process termed regulated intramembrane proteolysis (RIP). The cleaved domains are then released to the cytosol as active transcriptional activators. Examples of transcriptional activators processed by gamma-Secretase include the developmental signaling molecule Notch and the human epidermal growth factor receptor-like protein ErbB-4. gamma-Secretase also plays a prominent role in the pathogenesis of Alzheimer's disease, through the processing of the amyloid precursor protein (APP) and the generation of beta-amyloid peptides (Ab). An understanding of the molecular mechanism of Ab production could enable the development of new therapeutics against Alzheimer's disease.

Structure and Function of Rhomboid Intramembrane Proteases

Rhomboids are serine intramembrane proteases found in organisms ranging from bacteria to humans and shown to play a role intercellular signaling. In Drosophila melanogaster, Rhomboid cleaves the membrane bound epidermal growth factor receptor (EGFR) ligands - Spitz, Keren and Gurken, leading to their extracellular release and activation of the single EGF receptor pathway in a neighboring cell. We are using Rhomboids from eukaryotic and prokaryotic origin to gain insight shed light into the general mechanism of proteolysis within biological membranes.

Structure Determination of Membrane Proteins by Electron Crystallography

The overall goal of this project is to foster membrane protein structure determination by electron crystallography, which involves the application of cryo-electron microscopy (cryo-EM) on two-dimensional (2D) crystals. Electron crystallography has developed into a powerful tool to elucidate the 3D structure of membrane proteins at medium and high-resolution. This methodology has yielded the medium-resolution structure (5-8 Ã…) of approximately 20 unique membrane proteins and atomic structures in the case of bacteriorhodopsin, light harvesting complex, aquaporin and glutathione transferase. 2D crystals are formed by achieving high density of a single protein species constrained to a 2D lipid bilayer that resembles the native biological membrane and thus offer a unique advantage for structure determination of delicate membrane protein complexes from eukaryotic sources. By implementing technologies for automated screening of 2D crystallization trials, we aim to make electron crystallography a viable alternative for membrane protein structure determination.