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

智力优势：氮成本最小化（减少细胞结构中的氮，特别是蛋白质）是在贫营养沃茨中茁壮成长的海洋微生物的常见和重要的策略。最成功的生物体具有低G+C基因组，因此使用侧链中具有较少N原子的氨基酸，以及这种策略所需的必要权衡-蛋白质平均质量更大（需要更多非限制性碳），证明了这一点。该项目的核心假设是，成本最小化的生物体具有特定的基因组和分子适应性，促进氮节约并保持缓慢而稳定的生长方式。具体而言，这些生物体牺牲了翻译和调节的潜在效率，以在任何条件下保持生长。它们生长缓慢，无论底物的可用性-在代谢和细胞过程中有根本的限制。据推测，缓慢和稳定的增长硬连线到遗传密码，需要更复杂的转录调控和复杂的，蛋白质密集的氧化还原传感途径。该实验计划将通过量化在高氮和低氮条件下生长的原绿球藻菌株的初级转录组和局部翻译速率来测试这一核心假设。更广泛的影响：转录和翻译是基本的细胞过程，有助于设定生物体的最大生长速率。新技术将用于捕获原绿球藻转录景观的详细图像，这有可能产生关于地球上最丰富的微生物之一的成本最小化和转录复杂性之间关系的变革性信息。该项目产生的数据将成为许多领域研究人员的丰富资源;该项目产生的所有数据将发布到公共数据库。该项目包括研究生和中学教育部分。广泛的实验室和计算机工作提供了使用尖端的实验室和生物信息学技术的多样化的教育潜力。公共宣传将涉及PI和他的实验室继续努力参与，促进和改善内华达州最贫困学校的科学教育。这项工作也将有助于进一步发展的NSF-EPSCoR基础设施和研究活动在内华达州。

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.