Archaeal Sec-Dependent Protein Translocation

所有的细胞都需要将蛋白质转移到疏水膜中并穿过疏水膜与环境相互作用。 大多数蛋白质通过Sec途径经由普遍保守的蛋白质孔以未折叠构象移位。 许多在细菌和真核生物中不同的非保守辅助组分也是通过该途径进行有效运输所必需的。 令人惊讶的是，古细菌的Sec机制包含细菌和真核生物的Sec组分的同源物的组合，这引起了关于古细菌中易位机制的问题。 此外，在细菌和酵母中，需要不同的易位ATP酶来为蛋白质运输提供能量，但尚未鉴定出这些ATP酶中任一种的古细菌同源物。 因此，驱动蛋白质通过古细菌Sec孔的净单向运动的能量学仍然未知。 本项目的目标是分离和表征古菌Sec易位突变体的模式Haloferax volcano ii使用两个互补的遗传选择策略。 重要的是，这些选择具有鉴定新的Sec组分的潜力，包括古细菌特有的组分（例如新的易位ATP酶）以及具有细菌和/或真核同源物的组分，其先前不知道参与Sec易位。 总之，这项研究可能会进一步了解Sec易位途径在生活的各个领域。 此外，更好地了解古生菌，往往居住在“极端”的环境，将使调查人员能够确定生物圈中的生物过程的边界，并有可能揭示有关生命的三个领域的起源和进化的信息。该项目正在促进对各级学生的培训。对教育感兴趣的本科生正在进行外联，作为大学课程的一部分，到城市间的学校展示微生物研究的基本原理。

All cells need to translocate proteins into and across hydrophobic membranes to interact with their environment. Most proteins are translocated in an unfolded conformation by the Sec pathway via a universally conserved proteinaceous pore. A number of non-conserved accessory components, which are distinct in bacteria and eukaryotes, are also necessary for efficient transport via this pathway. Surprisingly, the archaeal Sec machinery contains a combination of homologs of bacterial and eukaryotic Sec components, which raises questions regarding the mechanism of translocation in archaea. In addition, in bacteria and yeast, distinct translocation ATPases are required to provide energy for protein transport, yet no archaeal homolog of either of these ATPases has been identified. Thus, the energetics driving the net unidirectional movement of proteins through the archaeal Sec pore remains unknown. The goal of this project is to isolate and characterize archaeal Sec translocation mutants in the model haloarchaeon Haloferax volcanii using two complementary genetic selection strategies. Importantly, these selections have the potential to identify novel Sec components, including components that are unique to archaea (such as a novel translocation ATPase) as well as components that have bacterial and/or eukaryotic homologs, which were not previously known to participate in Sec translocation. Together, this research is likely to further the knowledge of the Sec translocation pathway in all domains of life. Moreover, a better understanding of archaea, which often inhabit "extreme" environments, will allow the investigator to define the boundaries of biological processes in the biosphere, and has the potential to reveal information about the origin and evolution of the three domains of life. This project is fostering the training of students at all levels. Undergraduate students interested in education are doing out reach as part of a university course to intercity schools to demonstrate basic principles of microbial research.