Biochemical and Molecular Genetic Studies of the HMT-1-Dependent Heavy Metal Detoxification Pathway in C. Elegans

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This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). While metal polluted environments are a growing concern, much remains to be learned about the protective adaptations and mechanisms in all organisms. The ability to effectively develop bioremediation strategies for heavy metal-polluted environments is contingent on gaining a detailed understanding of these cellular detoxification and tolerance mechanisms. In this regard, HMT-1, a half molecule ATP-binding cassette (ABC) transporter in the nematode worm Caenorhabditis elegans is acutely required for heavy metal detoxification and has homologs in many other species including Chlamydomonas reinhardtii, Schizosaccharomyces pombe, Drosophila and humans. How the HMT-1-dependent pathway functions and the roles of other ABC transporters relative to HMT-1 are unknown. This project uses C. elegans as a simple and well-defined model system to study the HMT-1-dependent detoxification pathway using biochemical and genetic approaches. Objective 1 will focus on the identification and localization of proteins that functionally associate with HMT-1 in a complex. Parallel systematic genetic assays pursued in Objective 2 will identify ABC transporters that are required for heavy metal tolerance, and assess their functional relationships to HMT-1. Given the large and diverse nature of the C. elegans ABC transporter gene family, this work promises to be of considerable interest to the broader C. elegans community and beyond to learn the function of these genes and potential involvement with other stress responses and developmental pathways. In providing the first fundamental information about the HMT-1-dependent pathway, this project will identify and classify functional roles of the ABC transporters, identify new pathways, and ascribe functions to known pathways that have not previously been determined to be involved in metal detoxification, and thus will contribute to the long-term goal of understanding of cellular resources for metal tolerance. Broader Impacts. The research component of this project is integrated with the education of students, postdoctoral fellows and the general public about heavy metals and their toxicity as well as broader issues in environmental and agricultural biotechnology. First, a series of lectures discussing heavy metals and their toxicity is integrated into two upper-level lecture courses. Second, research is directed towards the training and mentoring of undergraduate, graduate students and postdoctoral fellows in the laboratory with special efforts to recruit women and minorities. The incorporation of modern genomic and biochemical approaches to study environmental issues will provide valuable experience for the next generation of scientists. Third, the project is designed to reach New York State (NYS) farmers and gardeners to increase their knowledge about heavy metals and their toxicity, and the importance of safe soil management for decreasing heavy metal entrance into the food chain. This outreach activity will consist of lecture presentations, and the development of user-friendly soil-test interpretation guidance documents, which will be summarized in a web module. This initiative has exciting potential for broad usage, going beyond the citizens of NYS, and may provide a paradigm for effective interfacing of scientific expertise and research with publicly-available information.