Assessment of Molecular Mechanisms involved in Nitrogen Cost Minimization of Oligotrophic Microorganisms

Nevada System Of Higher Education, Desert Research Institute, Reno NV

Investigators

Abstract

Intellectual Merit: Nitrogen cost-minimization (the reduction of nitrogen in cellular structures, especially protein) is a common and important strategy for marine microbes that thrive in oligotrophic waters. This is evidenced by the most successful organisms having low G+C genomes and thus using amino acids that have fewer N atoms in side chains and by the necessary trade-off this strategy entails - that proteins are, on average, larger in mass (require more non-limiting carbon). This project's core hypothesis is that cost-minimized organisms have specific genomic and molecular adaptations that promote nitrogen thrift and maintain a slow and steady approach to growth. Specifically, these organisms have sacrificed potential efficiencies in translation and regulation to maintain growth under any condition. They grow slowly regardless of substrate availability - there are fundamental limitations in metabolic and cell processes. It is posited that slow and steady growth hard-wired into the genetic code alleviates the need for more complex transcriptional regulation and complex, protein intensive redox sensing pathways. The experimental plan will test this core hypothesis by quantifying the primary transcriptome and local translation rates of a strain of Prochlorococcus grown under high and low nitrogen conditions. Broader Impacts: Transcription and translation are fundamental cellular processes that help set maximum growth rates of an organism. New techniques will be applied to capture a detailed picture of the transcriptional landscape of Prochlorococcus, and this has the potential to yield transformative information on the relationships between cost minimization and transcriptional complexity for one of the most abundant microbes on earth. The data generated during this project will be a rich resource to researchers in many fields; all of the data generated during this project will be released to public databases. This project has graduate and middle school educational components. The extensive laboratory and computer work offers a diverse educational potential using cutting-edge laboratory and bioinformatic techniques. Public outreach will involve a continued effort by the PI and his lab to engage, promote and improve science education in Nevada's poorest schools. This work will also contribute to the further development of the NSF-EPSCoR infrastructure and research activities in Nevada.