Hijack of surface structures by archaeal viruses

• Applicant: Dr. Tessa Quax
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 411069969

Archaea are micro-organisms that are ubiquitously present in the environment and form a separate domain of life. They can be found in diverse habitats, spanning from the deep sea ocean to the human digestive tract. As most living cells, archaea can be infected by viruses. The morphological and genetic diversity displayed by isolated archaeal viruses is very high in comparison with bacterial and eukaryotic viruses. Bacterial viruses can hijack filamentous surface structures for attachment and infection. They bind for example to pili or the bacterial motility structure, the flagellum, and employ these structures to 'travel' to the cell surface. There are indications that archaeal viruses might also employ filamentous surface structures for attachment and cell entry. However, the molecular mechanism underlying viral entry via archaeal surface structures has not been studied. Archaea possess some surface structures, like pili, that are similar to those of bacteria. In contrast, the composition and structural organisation of the archaeal motility structure, the archaellum, is fundamentally different from the bacterial flagellum. This project aims to address if and how archaeal viruses hijack archaeal surface structures for infection. For this project the genetically accessible euryarchaeon Haloferax volcanii will be used for in vivo infection studies and microscopy analysis. This combination of techniques allows for the study of fundamental questions about the structural organisation and spatial temporal positioning of archaeal surface structures, which is relevant to understand where and when viruses could infect. In addition, the isolation of new archaeal viruses and study of their infection strategies, should shed light on the possible selective pressure that viruses assert on the presentation of filamentous structures on the cell surface. Together, this project is aimed at increasing our understanding of the still relatively unexplored archaeal viruses and their interaction with cellular surface structures in particular. This information aids in understanding of viral diversity and evolution. In addition, it addresses basic questions about archaeal cell biology and the interaction with the extracellular environment, which is important for the colonization of new habitats.

• DFG Programme: Independent Junior Research Groups