Mechanobiology: what makes bacterial pathogens so stiff?

Bacteria are surrounded by mechanically rigid cell envelopes, which play important roles in controlling cellular processes like growth, division, adhesion as well as resistance to drugs and environmental stresses. In the prototypical pathogen Escherichia coli, it has long been believed that peptidoglycan was the only biopolymer that conveys mechanical strength to the cell envelope. However, in a study published in Nature Communications, the teams of Yves Dufrêne and Jean-François Collet (WELBIO investigator) at the UCLouvain have identified the key roles of the lipoprotein Lpp in defining the E. coli cell envelope mechanics, using state-of-the-art nanoimaging techniques combined with genetic manipulation. They discovered that Lpp has a dual function, by covalently connecting peptidoglycan to the outermost cellular membrane and by precisely tuning the size of the periplasmic space. The researchers also found that Lpp-dependent cell mechanics has a major impact on antibiotic sensitivity, functional mutations in the protein increasing drastically the efficacy of vancomycin. This study, funded by the Excellence of Science (EOS), WELBIO and ERC fundings, demonstrates the power of coupling nanotechnology and molecular biology methods for understanding the molecular details behind bacterial stiffness, and for linking cellular mechanics to function, a grand challenge in current mechanobiology. The results show promise for the design of innovative antibacterial drugs targeting the molecular machineries that stabilize the cell envelope.
See the Nature Microbiology blog for more details.
See Daily Science.

Published on April 15, 2020