Redox Photochemistry in Genomes of Microorganisms

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The Chemistry of Life Processes Program in the Division of Chemistry is awarding funding to Dr. Cynthia Burrows at the University of Utah. Her research team plans to investigate how the genomes of microorganisms adapt to environmental stress. Many species of plants, algae and bacteria have adapted to live under extreme conditions of heat, salt, drought or intense UV light, all of which place chemical stress on the cell's DNA. Other organisms, such as the coral symbiont zooxanthellae, a close cousin of algae, have not adapted to stress, and rising ocean temperatures are leading to coral 'bleaching' due to loss of their algae, a food source for the coral. Research supported by this grant investigates the hypothesis that sequences of DNA that can fold into a motif termed "G-quadruplex" may help the organism respond to oxidative stress caused by an increase in temperature and increased photosynthesis. Students involved in this work are to learn how the chemistry of the environment influences the chemistry of the cell at the level of the organism's genetic code. In addition, the PI is developing a series of lectures, "Beyond Watson and Crick," that communicate the importance of changes in the DNA to life processes.To address the question of why certain microorganisms, notably algae and thermophilic bacteria, have dense potential G-quadruplex sequences (PQS) in their genomes, a reporter plasmid assay is to be developed in the model algal organism Chlamydomonas. Synthetically altered DNA sequences is to be inserted into promoter sequences of a reporter gene, and gene expression will be monitored as a function of oxidative stress. In addition, the PQS density in Thermus bacteria is to be investigated. The sites of oxidative damage are to be mapped onto the promoter regions and PQS sites to discover correlations between G-quadruplex sequences, regulation of oxidative damage, and adaptive responses to environmental stress. These studies help define the circumstances under which chemically-modified bases in DNA, such as 8-oxoguanine, serve as epigenetic markers.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.