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Amyloids in bacteria

A collaboration involving Iramis and the Institut Joliot has revealed the spontaneous aggregation into amyloid fibers of a bacterial protein called Hfq and non-coding RNA strands. Furthermore, the collaborators demonstrated the ability of these fibers to penetrate a lipid membrane. This study paves the way for a better understanding of bacterial communication in addition to new approaches in antibiotic development.

Published on 21 November 2017

Certain proteins can fold up so as to agglutinate into fibers with a nanoscale cross-section and microscale length. These so-called amyloid structures are involved in a number of pathologies, including Alzheimer's disease. In other situations, they have a physiological function. This is the case of the bacterial protein Hfq, which associates with non-protein-coding RNAs.

The researchers demonstrated that Hfq proteins and RNA segments can self-assemble under certain conditions into amyloid fibers. They were also able to observe the interaction of these fibers with a lipid membrane, and were able to destroy it.

These results, obtained in particular using small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) at the LLB in addition to molecular microscopy (cryogenic electron transmission microscopy and atomic force microscopy), suggest that Hfq could participate in exporting nucleic acids out of the cell by forming pores in the bacterial membrane. This process could explain the presence of genetic material outside of the cell and could lead to a better understanding of the communication between bacteria. Ultimately, this could lead to the development of new antibacterial agents.   

This work was conducted in collaboration with the I2BC, the Soleil synchrotron and the Centre de protonthérapie at the Institut Curie in Orsay. It should be noted that they used the cryogenic microscopy technique honored by the 2017 Nobel Prize in Chemistry.

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