The first representatives of the third domain of life, Archaea, were isolated from particularly harsh environments. Long it was thought that all archaea are ‘extremophiles’, but recently archaea were discovered in many temperate habitats, including the human gut, sea and soil, where they perform key roles in biochemical cycles.Archaea are the least explored domain of life and little is known about the mechanisms underlying motility and adhesion. Understanding these processes is especially timely since the widespread occurrence of archaeal species in environments including the human body is becoming more and more apparent.Archaeal motility has initially been studied using a thermophilic model organism, which has revealed that the structure responsible for swimming behavior of archaea is the ‘archaellum’. The archaellum has structural homology with bacterial type IV pili, which are at the basis of the pathogenicity of many Gram negative bacteria. However, the archaellum is rotating and thereby functionally resembles the bacterial flagellum.Taking advantage of this initial expertise and knowledge on archaeal motility available in the host laboratory, this project aims to focus on the mesophilic euryarchaeal model: Haloferax volcanii. This model is very appealing to study the molecular mechanism underlying motility, because genes encoding the archaellum components are linked with those of the bacterial chemotaxis pathway in haloarchaea. In addition, this model is one of the few genetically tractable archaeal systems that allows for advanced engineering, offering the unique option to study the mechanism of rotational switching, which influences the cells ‘decision’ to move or stay.The proposed research is important from both fundamental and medical perspective. In addition it opens the exiting possibility to develop a stable minimal nano-motor for synthetic biology, because the archaellum represents the biological rotating filament with lowest complexity