Detecting, Measuring and Manipulating Copper in Biological Systems

Copper is an essential micronutrient for eukaryotic systems and, thus, an essential mineral in the human diet. As a redox-active metal, copper plays a key role as a catalytic cofactor for a number of enzymes, including those responsible for cellular respiration, neurotransmitter synthesis, extracellular matrix crosslinking, and pigment synthesis. However, the one-electron chemistry that makes copper so valuable within enzymes also makes it potentially toxic to cells, as copper may also generate reactive oxygen species within biological systems. For copper to be loaded into enzymes without causing toxicity, it must be acquired by an organism from the environment and trafficked to the correct tissues, cells, organelles, and proteins. Understanding the complex system of proteins and small molecules that acquire and chaperone copper within vertebrate organisms is a fascinating and challenging puzzle, raising such questions as: Which tissues, cells, and organelles accumulate copper, and which exclude it? Which proteins handle copper during copper trafficking, and which receive copper at its final destination? Is there a role for copper in biological systems beyond enzyme catalysis? What are the functional consequences of copper overload and copper deficiency for an organism? And can copper or copper chelators be used as nutritional supplements to combat disease? Here, we address these questions in the following ways: Chapter 1 provides a review of techniques for mapping the distribution and localization of transition metals within biological systems. Chapter 2 outlines the application of laser ablation ICP-MS and nanoSIMS metal mapping to study the retinal tissue of the zebrafish model of Menkes disease. Chapter 3 explores proteomics methods to find proteins that bind copper transiently, outside enzyme active sites. Finally, Chapter 4 outlines efforts toward genetic tools to study the copper import protein, CTR1