MIP. Temperature Adaptation of Autotrophic Carbon Metabolism in Ecologically Diverse Hot Spring Synechococcus: An Integrative Study of Extreme Photosynthesis

斯科特·R博士获得了一笔赠款。蒙大拿大学的米勒研究了一组密切相关的光合温泉细菌的成员之间的生理适应机制，这些细菌在温度耐受性方面存在差异。 由于生物体不能在所有可能的环境中表现得同样好，因此了解微生物之间的性能限制和生理差异如何发展仍然是微生物多样性研究的基本目标。 影响性能的蛋白质通常可以在较高温度下更稳定，或者在较低温度下工作得更快，但不能两者兼而有之。 本项目主要研究光合作用过程中的一个关键蛋白--核酮糖二磷酸羧化酶（Rubisco）在蛋白质水平上的平衡对这些细菌生理学和热生态学的贡献：（1）Rubisco在不同温度下的稳定性和功能将通过生理学、生物化学和生物物理学方法来确定从这些细菌中分离的这种蛋白质的现代版本;（2）将使用靶向突变方法在遗传上构建Rubisco的特定祖先版本，其代表在这些细菌多样化期间该蛋白质进化的增量步骤;（3）将确定这些祖先Rubisco版本的稳定性和功能，以测试在其进化过程中的特定组成变化是否赋予了在较高温度下的稳定性，和/或或在较低温度下性能速率降低。

A grant has been awarded to Dr. Scott R. Miller of The University of Montana to investigate the mechanisms of physiological adaptation among members of a closely related group of photosynthetic hot spring bacteria that differ in temperature tolerance. Because organisms cannot perform equally well in all possible environments, understanding both the limits to performance and how physiological differences develop among microorganisms remains a fundamental goal for the study of microbial diversity. Proteins that affect performance can generally either be more stable at higher temperatures or work faster at lower temperatures, but not both. This project specifically addresses the contributions of this trade-off at the protein level to the physiology and thermal ecology of these bacteria for a key protein in the photosynthetic process: ribulose bis-phosphate carboxylase (Rubisco): (1) Rubisco stability and function at different temperatures will be determined by physiological, biochemical and biophysical approaches for modern-day versions of this protein isolated from these bacteria; (2) specific ancestral versions of Rubisco that represent incremental steps in the evolution of this protein during the diversification of these bacteria will be constructed genetically using a targeted mutational approach; (3) stability and function of these ancestral Rubisco versions will be determined to test whether particular compositional changes during its evolution have conferred stability at higher temperatures and/or a decreased rate of performance at lower temperatures.