NARILIS microbiologists unravel secrets of Brucella abortus cell envelope, a complex multilayered structure

The research group of Prof. Xavier De Bolle (UNamur, Research Unit in Biology of Microorganisms, URBM) just made an important discovery on the complex structure of Brucella abortus cell envelope. Brucella pathogens, responsible for brucellosis, are Gram-negative bacteria surrounded by a multilayered cell envelope comprising an outer membrane and an inner membrane. The space between these two membranes, termed periplasm, contains the peptidoglycan. The PhD thesis work of Pierre Godessart attempted to answer long-standing questions regarding the architecture and cell wall biogenesis of Brucella abortus. His investigations brought to light how the outer membrane is connected to the peptidoglycan. The results have just been published in the prestigious journal Nature Microbiology (Godessart et al., 2020) and show that the outer membrane is attached to peptidoglycan by covalent cross-links between the N termini of outer membrane β-barrel-shaped proteins and the peptide stems of peptidoglycan. The study also reveals that this covalent attachment of the outer membrane to the peptidoglycan plays a crucial role in maintaining cell envelope stability of Brucella abortus.

This work was made possible thanks to the support of the UNamur Mass Spectrometry Facility (Dr. Marc Dieu and Prof. Patsy Renard). Moreover, this research is also the fruit of a collaboration with the VUB (Prof. Han Remaut) and the UCLouvain (Prof. Jean-François Collet and Prof. Patrick Soumillion) in the framework of a Collective Research Initiative (ARC 17/22-087).

With this discovery, NARILIS scientists demonstrate once more their cutting-edge expertise in molecular microbiology. Capitalizing on this outstanding know-how, the UNamur is organizing a new Master in Molecular Microbiology (MMM) since 2019. This research-oriented program, entirely given in English, is unique in Belgium and is anchored in the strong research environment of NARILIS. Moreover, it operates as an international master degree jointly developed with two other European universities recognized in the field of bacteriology, the University of Marburg (Germany) and the Aix-Marseille University (France).

Contact: xavier.debolle@unamur.be

More info: Xavier De Bolle's research group

Outer membrane proteins - PG interactions

Beta-barrel proteins (blue) are embdded in the outer membrane and have a N-terminal extension facing the peptidoglycan (grey). Enzymes (L,D-transpeptidases, green) can attach those N-terminal extension to the peptidoglycan.