Archaea with a cell wall: a multidisciplinary approach to understand a major evolutionary convergence
The Archaea display major differences from Bacteria, not only concerning their molecular machineries for transmission of genetic information, but also their cell envelope architecture. While most archaea contain a proteinaceous S-layer as major component of the cell envelope (1), only two clades, the Methanobacteriales and the closely related Methanopyrales, possess a cell wall made of pseudopeptidoglycan (pPG). It structurally resembles its bacterial counterpart, but is chemically distinct (2), indicating an independent evolutionary origin. How these archaea “reinvented” a pPG cell wall, and what were the consequences at the cellular level are fascinating open questions.
We have recently started investigating this issue by developing the first experimental model of walled archaea, Methanobrevibacter smithii, the main species of methanogen from the human gut microbiome. We demonstrated that M. smithii is an ovococcoid that divides binarily using a homologue of FtsZ and its anchor SepF (3). However, the archaeal machineries involved in cell growth and division in the presence of a pPG cell wall remain largely unknown.
This project aims at identifying and characterizing additional components of the M. smithii divisome and elongasome, and understanding how the cell wall is synthesized and modified during the cell cycle. A wide range of approaches will be used, including immunolabeling and high-resolution microscopy, co-IP, protein-protein interaction, biochemistry, and bioinformatics analysis.
The results obtained will allow to elucidate a major evolutionary convergence in the prokaryotic world and have strong impact on the rapidly expanding field of archaeal cell biology. Moreover, by identifying the elements driving cell growth and division in this major and yet neglected component of the human microbiome, the project will contribute essential information to further research on the role of archaea in health and disease.
Applicants should hold (or expect shortly) a PhD in Life Sciences and a strong background in prokaryotic cell biology and/or biochemistry.
Previous work on Archaea is not mandatory. All the necessary training to work with methanogens will be provided by current postdoc Nika Pende and by permanent staff. Previous experience with sequence analysis is a plus, but also not strictly necessary, as all members of the group are encouraged to acquire expertise through formation either by staff bioinformaticians or frequent classes at Institut Pasteur.
The successful candidate will join the group “Evolutionary Biology of the Microbial Cell” headed by Professor Simonetta Gribaldo at the Department of Microbiology.
We are a highly interdisciplinary team working on large-scale evolution of Bacteria and Archaea, with a strong interest in the cell envelope. We combine different approaches merging in silico analysis (phylogenomics, metagenomics) with wet lab approaches (molecular biology, cell biology, microscopy, biochemistry) to understand major and ancient evolutionary events on the Tree of Life. The group has all the equipment and expertise to grow and manipulate methanogens and many other ongoing lines of research on their evolution, diversity, and role in health and disease. Other than M. smithii, our second experimental model is the bacterium Veillonella parvula, a member of the Firmicutes with an outer membrane. The postdoctoral fellow will therefore be exposed to a wide range of topics and the possibility to learn different techniques.
The Institute Pasteur is located in center Paris and provides state-of-the-art technology with its multiple technical platforms, and full administrative support for foreign candidates.
How to apply ?
The position is immediately available and should ideally start between January and March 2022. The contract is extendable through application to postdoctoral fellowships and pending funding requests. Applications should be sent to simonetta.gribaldo(at)pasteur.fr and nika.pende(at)pasteur.fr and include a full CV and motivation letter, as well as two names of referents.
Deadline for application is December 31st, 2021, but the earlier the better.
1. Meyer, B. H. and Albers, S.-V., Archaeal Cell Walls. eLS 1–14 (2020)
2. König, H., Hartmann, E. and Kärcher. Pathways and Principles of the Biosynthesis of Methanobacterial Cell Wall Polymers. Syst. Appl. Microbiol. 16, 510–517 (1993)
3. Pende, N., Sogues, A., et al., SepF is the FtsZ anchor in archaea, with features of an ancestral cell division system. Nat. Comm. (2021)