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

蒙大拿大学的斯科特·R·米勒博士获得了一项资助，用于研究耐温性不同的密切相关的光合作用温泉细菌群体成员之间的生理适应机制。由于生物体不可能在所有可能的环境中都表现得同样好，因此了解微生物表现的极限以及微生物之间的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要么在较高温度下更稳定，要么在较低温度下工作得更快，但不能两者兼而有之。本项目专门针对光合作用过程中的一种关键蛋白质：核酮糖二磷酸羧化酶(Rubisco)在蛋白质水平上对这些细菌的生理和热生态的贡献：(1)Rubisco在不同温度下的稳定性和功能将通过从这些细菌分离的该蛋白质的现代版本的生理、生化和生物物理方法来确定；(2)代表这些细菌多样化过程中该蛋白质进化增量步骤的特定祖先版本的Rubisco将使用有针对性的突变方法从基因上构建；(3)将确定这些祖先Rubisco版本的稳定性和功能，以测试其进化过程中的特定组成变化是否导致在较高温度下的稳定性和/或在较低温度下性能的降低。

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.