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

蒙大拿大学（University of Montana）的斯科特·r·米勒（Scott R. Miller）博士获得了一项资助，用于研究一种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，这些细菌对温度的耐受性不同。由于生物体不可能在所有可能的环境中都表现得同样好，因此了解性能的限制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，但不是两者兼而有之。该项目特别解决了这种权衡在蛋白质水平上对这些细菌的生理和热生态的贡献，因为光合过程中的关键蛋白质：核酮糖二磷酸羧化酶（Rubisco）：(1) Rubisco在不同温度下的稳定性和功能将通过从这些细菌中分离出的这种蛋白质的现代版本的生理，生化和生物物理方法来确定；(2) Rubisco的特定祖先版本代表了该蛋白在这些细菌多样化过程中的渐进进化步骤，将使用靶向突变方法从基因上构建；(3)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成分变化是否赋予其在高温下的稳定性和/或在低温下的性能下降率。

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.