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Genome Sequencing of Photosynthetic Prokaryotes

 

Intellectual Merit

Complete genome sequencing is proposed for four photosynthetic prokaryotes, Heliobacterium modesticaldum, Roseobacter denitrificans, Rhodocista centenaria and Acaryochloris marina. Finished genome sequences of these carefully selected organisms will fill large gaps in the available genomic data for photosynthetic prokaryotes and will help to understand the origin and early evolution of photosynthesis. Each organism also has individual characteristics that justify its inclusion in a genome-sequencing project, including agricultural applications and environmental aspects such as understanding global photosynthetic productivity. The project team includes experts on each organism, including Robert Blankenship, Michael Madigan, Thomas Beatty, Carl Bauer, Mamoro Mimuro and Hideaki Miyashita and a highly experienced sequencing center, directed by Jeffrey Touchman.

 

Broader Impacts

Photosynthesis has been a central force in the evolution of life on Earth. Only after oxygenevolving photosynthesis appeared about 2.7-2.5 billion years ago and free molecular oxygen began to accumulate beginning about 2.2 billion years ago did more advanced forms of life appear, which are absolutely dependent on aerobic respiration. Oxygenic photosynthesis clearly has its roots in anoxygenic (non-oxygen-evolving) photosynthesis, although the evolutionary processes that led to the existing diversity of both prokaryotic and eukaryotic photosynthetic organisms are complex and still very poorly understood. The transition from anoxygenic to oxygenic photosynthesis is especially enigmatic. Photosynthesis has a deep evolutionary connection to nitrogen fixation and many photosynthetic prokaryotes are also diazotrophic. Our ability to understand these complex evolutionary relationships and processes is very much limited by a lack of data, especially complete genome sequences. The proposed research offers a solution to this problem and will fill major gaps in the evolutionary picture of photosynthesis. The project will actively engage a large number of bioinformatics students in the annotation efforts. Bioinformatics graduate students at Arizona State University will use the raw genome data as part of “real world? class exercises. For example, they will use bioinformatics tools to identify metabolic pathways or families of transport proteins, using the newly acquired genome data. Following this classroom experience, four students per year, for a total of twelve students, will continue annotation efforts as summer interns. Three of these twelve students will be underrepresented minority students, who will be paid as a cost share from Arizona State University. Additional NSF supported student annotation will take place at Indiana University and Southern Illinois University, as well as non-NSF supported work at the University of British Columbia and Kyoto University. The team will also partner with the public science museum at the Arizona Science Center to develop public displays and teacher training materials aimed at communicating the excitement and benefits of microbial genomics to the general public and to school children, respectively.
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