Fall 2018 Seminar Series, Dr. Megan McEvoy
Metals in Motion: Survival in Metal-Rich Environments through Sequestration and Export
When challenged with an environment containing potentially toxic compounds, organisms must respond in an appropriate manner to ensure their survival. Metal ions such as copper can be toxins that require a very fine tuned response, since low levels of copper are necessary for proper cellular function, yet a slight excess can cause cellular damage. Cellular systems that handle metal ions must prevent the toxic effects of free metals and correctly identify metal species with a high degree of specificity. As a basis for understanding cellular responses to metal ion excess, we are studying a model system from E. coli, the Cus system. This system includes an efflux system to transport copper and silver to the extracellular space, CusCFBA, as well as a two-component sensory system, CusRS, that detects metal ions and upregulates expression of the cus genes. We are interested in obtaining a molecular understanding of this system and how it leads to increased metal ion resistance. Through structural and functional characterization of the Cus proteins, we have developed an understanding of how metal ions are specifically recognized in this system, and how protein-protein interactions maintain the metal ion in a sequestered environment to prevent potential cellular damage before export from the cell. The general strategies employed to handle metal ions, as well as the molecular details employed by the Cus system will be discussed.