Observing Proteins in their Natural Environment

Björn Burmann and Johannes Thoma at the Department of Chemistry & Molecular Biology and the Wallenberg Centre of Molecular and Translational Medicine have developed a new method to examine proteins within their natural environment.

“Using our new method, we can now gain a deeper understanding of bacterial cell wall proteins. Because many of these proteins are involved in the uptake and the resistance to antibiotics, our research has a great potential to lead to better insight into these mechanisms and presumably aid the development of novel antibiotics” concludes senior author Björn Burmann.

Proteins are affected by their surrounding environment

The three-dimensional structure of proteins, which determines their function, is directly influenced by their surrounding environment. Within the natural cellular context, this means that proteins are constantly in contact with a large variety of diverse molecules, such as salts, carbohydrates, lipids and of course many different proteins.

So far, proteins needed to be extracted and isolated from their natural environment in order to be studied with structure-biological tools, such as nuclear magnetic resonance spectroscopy (NMR). During this purification process important molecules, which normally interact with these proteins inside the living cell, are removed.

Found new method

In their recent work, assistant professor Björn Burmann and post-doctoral fellow Johannes Thoma utilize bacterial outer membrane vesicles (OMVs) to circumvent this limitation. These vesicles are naturally produced by bacteria and contain cellular components surrounded by a lipid membrane. Bacteria can be manipulated to produce large amounts one specific protein of interest and to direct this protein to outer membrane vesicles. The resulting vesicles thus contain the protein of interest together with the natural cellular environment.

Johannes Thoma says: “Our recent work shows, that these vesicles contain enough of the protein of interest to probe its structural features with biophysical tools that are traditionally used to study proteins in isolation, allowing us to examine how the protein behaves and interacts within its natural cellular environment.”

The full article, featured on the cover of this month’s issue of Biochemistry, can be found here: https://pubs.acs.org/doi/10.1021/acs.biochem.9b01123

Figure: Proteins in OMVs, artwork by Johannes Thoma.

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