Copper biology

Metals are vital for life as they are necessary for essential biological processes. Traditionally, metals are categorized as either dynamic signals or static cofactors. Redox-inactive metals such as calcium (Ca), potassium (K), sodium (Na), and zinc (Zn) signal through large fluctuations in their metal-ion pools. In contrast, redox-active transition metals such as copper (Cu) and iron (Fe) drive catalysis and are largely characterized as static cofactors that must be buried and protected within the active sites of proteins, due to their ability to generate damaging reactive-oxygen species through Fenton chemistry. Cu has largely been studied as a static cofactor in fundamental processes from cellular respiration to pigmentation, working through cytochrome c oxidase and tyrosinase, respectively. However, within the last decade, a new paradigm in nutrient sensing and protein regulation — termed ‘metalloallostery’ — has emerged, expanding the repertoire of Cu beyond the catalytic proteins to dynamic signaling molecules essential for cellular processes that impact normal physiology and disease states. In this Primer we introduce both the ‘traditional’ and emerging roles for Cu in biology and the many ways in which Cu intersects with human health. Copper is well known to serve as a static cofactor in a variety of fundamental cellular processes. However, within the last decade, a new role for redox-active copper has emerged in nutrient sensing and protein regulation. In this Primer, Tsang et al. highlight the diverse roles of copper in biology.