Copper Metabolism in Marine Synechococcus

University Of California-San Diego Scripps Inst Of Oceanography, La Jolla CA

Investigators

Abstract

Trace metal sample handling and analysis have led to the discovery that tiny (nanomolar) levels of metals such as iron are having profound influences on the diversity, abundance, and carbon fixation of primary producers in the oceans. One of these important primary producers, marine cyanobacteria, have similarly been shown to be affected, positively and negatively, by copper (natural and anthropogenic) levels and may also be influenced by cobalt and nickel levels. At the same time, cyanobacteria and other phytoplankton are changing the distributions of metals and their reactivity through uptake, which causes measurable depletion of metals in surface waters, and through the extra-cellular production of metal binding ligands. Because of the importance of copper in aquatic environments, the PIs will characterize copper metabolism in marine cyanobacteria using model Synechococcus strains from oligotrophic environments and from coastal environments that have very different metal physiologies revealed by the whole genome sequencing projects. They will characterize how the strains respond to different copper levels using whole genome microarrays that probe the global response of the cell and will combine these studies with state of the art characterization of intracellular metal levels and other measures of cellular physiology and photosynthetic capacity. Molecular genetics studies of diverse copper associated genes will be undertaken to determine their function in the cell. Preliminary results have found a potential candidate for an intracellular copper binding protein that is conserved in all marine cyanobacteria. At the same time, preliminary results have found that coastal cyanobacteria have greater resistance to copper than open ocean species and this might be due to a novel copper binding or efflux system. The PIs will illustrate the importance of copper in aquatic environments by developing hands-on lab components that will communicate some basic concepts around metal nutrition/pollution in the marine environment to middle school students. This will be undertaken in collaboration with Aquatic Adventures, who provide educational programs that connect underserved youth to science. Broader Impacts This research will reveal some of the major mechanisms by which marine cyanobacteria have adapted to metal levels in coastal and oligotrophic environments. Thus these results will help us understand the distribution and diversity of these organisms in relation to global primary productivity. They should lead to more robust biomarkers for metal stress and pollution in coastal environments. The PIs will expand on a previous outreach activity like their museum exhibit on marine genomics at the Birch Aquarium, La Jolla CA, by developing hands-on lab components that will communicate some basic concepts around metal nutrition/pollution in the marine environment to middle school students. This will be undertaken in collaboration with Aquatic Adventures, who provide educational programs that connect underserved youth to science, inspire environmental action, and increase exposure to marine habitats. In addition an undergraduate and graduate student in the interdisciplinary field of the metal physiology of microbes will be trained.