Archaeal Sec-Dependent Protein Translocation

所有的细胞都需要将蛋白质转移到疏水的膜中，并通过疏水膜与环境相互作用。大多数蛋白质通过SEC途径通过普遍保守的蛋白质孔以未折叠的构象转运。一些在细菌和真核生物中不同的非保守附属成分也是通过这一途径有效运输所必需的。令人惊讶的是，古生菌的SEC机制包含细菌和真核SEC成分的同源物的组合，这就提出了关于古生菌易位机制的问题。此外，在细菌和酵母中，需要不同的易位ATPase来为蛋白质运输提供能量，但这两种ATPase的古生代同源物尚未被鉴定。因此，推动蛋白质通过古生菌SEC孔进行单向净移动的能量学仍然未知。该项目的目标是利用两种互补的遗传选择策略，分离和鉴定模式盐生考古中的古生菌SEC易位突变体。重要的是，这些选择有可能识别新的SEC成分，包括古细菌特有的成分(如新的易位ATPase)以及具有细菌和/或真核同源物的成分，这些成分以前并不知道参与SEC易位。总之，这项研究可能会进一步加深对生命各个领域中SEC易位途径的了解。此外，更好地了解通常生活在“极端”环境中的古生菌，将使研究人员能够确定生物圈中生物过程的边界，并有可能揭示关于生命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向城际学校伸出手，作为大学课程的一部分，以演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.