Model system mimicking the cell envelope of archaea

Archaea are one of the oldest life-forms existing on Earth. These unicellular organisms are often adapted to extreme habitats. Many representatives of archaea are capable to live at very high temperatures (i.e., above 80 °C), very low or high pH values, high salt concentrations or high pressures. Since the cell envelope of many archaea consists only of a very thin layer of fat (lipid membrane), into which an outermost crystalline protein layer is anchored, the question arises how Nature can accomplish this high resistance to extreme environmental conditions.

The project "Generation and characterization of artificial archaeal cell envelope structures and their relevance as model membrane platforms" will study the reassembly of cell envelopes of archaea using previously isolated biological components, i.e., lipids and proteins. It aims to clarify the question how the self-organization of ether lipids and surface layer proteins proceeds in detail and which anchoring strategies are available for the formation of an artificial cell membrane. In addition, the question is addressed which properties of the biomolecules themselves and their assembly into macroscopic cell envelopes cause this amazing resistance to the extreme habitat conditions. Hence, selected archaea strains will be bred in the bioreactor and subsequently the basic building blocks, which are surface layer proteins and fats (so-called etherlipids) will be isolated from the biomass. In addition, the surface layer proteins can also be genetically produced by host cells. Moreover, if desired anchoring groups for the specific binding to etherlipids can be genetically inserted. This is a new approach, which has previously not attempted by another research group. By the application of Nature’s construction principle, the cell envelope structure of archaea will be reconstructed layer by layer. Each step will be tracked and analyzed using modern microscopial and surfaces sensitive techniques. Next to high-resolution light and fluorescence microscopy also electron and atomic force microscopy will be used as imaging methods. The main surface-sensitive methods include surface plasmon resonance spectroscopy and quartz crystal microbalance with dissipation monitoring. These methods are used for determining the morphology, thickness in the nanometer range and quality of each layer.

The results of this project will provide valuable insights into the isolation and in particular the self-assembly of cell envelope components. This knowledge can be applied to produce surface coatings with very specific properties (e.g., anti-foulingor self-cleaning). Further fields of application are biomimetic membrane systems, which can be used to study and model the cell walls of archaea. The latter have also a great potential to serve as model systems into which membrane-active peptides and membrane proteins can be incorporated and systematically investigated. In future it might be even possible to develop highly sensitive diagnostic and sensor systems.

Duration: 01.10.2016-30.09.2019

Funding agency: Austrian Science Fund (FWF): P 29399

Project leader: Prof. Dr. Bernhard Schuster (BOKU)

National collaborators: Prof. Dr. Christa Schleper, Dr. Simon K.-M. R. Rittmann