Evidence for the Supramolecular Organization of a Bacterial Outer-Membrane Protein from In-Vivo Pulse EPR Spectroscopy

• Published in: Journal of the American Chemical Society 2020-06, Vol.142 (24), p.10715-10722
• Main Authors: Nyenhuis, David A., Nilaweera, Thushani D., Niblo, Jessica K., Nguyen, Nhu Q., DuBay, Kateri H., Cafiso, David S.
• Format: Article
• Language: English
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/jacs.0c01754

In the outer membrane of gram-negative bacteria, membrane proteins are thought to be organized into domains or islands that play a role in the segregation, movement and turnover of membrane components. However, there is presently limited information on the structure of these domains or the molecular interactions that mediate domain formation. In the present work, the Escherichia coli outer membrane vitamin B 12 transporter, BtuB, was spin labeled and double electron-electron resonance was used to measure the distances between proteins in intact cells. These data together with Monte Carlo simulations provide evidence for the presence of specific intermolecular contacts between BtuB monomers that could drive the formation of string-like oligomers. Moreover, the EPR data provide evidence for the location of the interacting interfaces and indicate that lipopolysaccharide mediates the contacts between BtuB monomers.