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Copper transport: molecular and cellular mechanisms

In recent years it became clear that transition metals, particularly copper, are essential for normal development and function of human cells. Disruption of copper metabolism causes severe neurodegenerative diseases, such as Wilson's disease and Menkes disease, with symptoms that range from psychiatric abnormalities, and motor dysfunction, to poor temperature control, and liver and kidney abnormalities. In order to understand how copper deficiency or copper overload can lead to these various pathologies, we study the structure, function, and regulation of molecules that are involved in binding and transport of copper within human cells. The research in the laboratory is focused on two proteins crucial for normal copper metabolism: the copper-transporting ATPase (or Wilson's disease protein) and human copper chaperone ATOX1.

Wilson's disease protein, or human copper-transporting ATPase, is a large transmembrane protein, that utilizes the energy of ATP-hydrolysis to transport copper from the cytosol through various cell membranes. In order to understand how the Wilson's disease protein works, and how mutations in this protein alter its function, we express and characterize the Wilson's disease protein and its important functional domains. Following expression, we analyze the structural properties of these proteins, their ability to bind physiological ligands, such as copper and ATP, and their ability to be involved in ligand-dependent protein-protein interactions.

Another important direction in the laboratory is the analysis of the molecular mechanisms that regulate the Wilson's disease protein function and its targeting to various cell membranes. In a cell, the Wilson's disease protein receives copper from a small cytosolic protein, copper-chaperone ATOX1. Our current goal is to understand how the chaperone and copper-transporting ATPase find each other in a cell, and how copper is transferred from the chaperone to the Wilson's disease protein. Finally, we elucidate how copper-dependent posttranslational modification of the Wilson's disease protein is linked to its intracellular targeting and trafficking. In our studies, we use a large arsenal of techniques including molecular cloning and site-directed mutagenesis, protein purification, chemical modification, ligand-binding analysis, UV, X-ray absorption, and fluorescent spectroscopy.
 

Recent Publications:

1. Barnes, N., Tsivkovskii, R., Tsivkovskaia, N., Lutsenko, S. (2005) The copper-transporting ATPases, Menkes and Wilson disease proteins, have distinct roles in adult and developing cerebellum J. Biol. Chem. Epub:ahead of print. Pubmed  
    
2. Efremov, R., Kosinsky, Y.A., Nolde, D.E., Tsivkovskii, R., Arseniev, A.S., Lutsenko, S. (2004) Molecular modeling of the nucleotide-binding domain of the Wilson' disease protein: location of the ATP-binding site, domain dynamics, and potential effects of the major disease mutations. Biochem J. :Epub. Pubmed  
    
3. Morgan, C.T., Tsivkovskii, R., Kosinsky, Y.A., Efremov, R., Lutsenko, S. (2004) The distinct functional properties of the nucleotide-binding domain of ATP7B, the human Copper-transporting ATPase. Analysis of the wilson disease mutations E1064A, H1069Q, R1151H, and C1104F. J. Biol. Chem. :Epub. Pubmed  
    
4. Ralle, M., Lutsenko, S., Blackburn, N.J. (2004) Copper transfer to the N-terminal domain of the Wilson disease protein (ATP7B): X-ray absorption spectroscopy of reconstituted and chaperone-loaded metal binding domains and their interaction with exogenous ligands J. Inorg. Biochem. 98:765-74. Pubmed