2023-06-05 18:59:58
The spores of fungal pathogens such asAspergillus fumigatus his allow them to spread through the air and thus be inhaled by hosts such as humans. In healthy hosts, they will be eliminated by the immune system but in vulnerable hosts (immunocompromised for example), they lead to a fatal disease called pulmonary aspergillosis. Hence the interest of scientists in the composition of the wall of these spores throughout their life cycle during the germination process, because it is this wall that interacts with the external environment.
But understanding the atomic-scale molecular organization of this cell wall remains a challenge. It is indeed made up of many biomolecules such as sugars, proteins, pigments and lipids, which are often difficult to identify and quantify. Moreover, the majority of the analytical approaches developed to study these cell walls are destructive because they require a selective extraction of these biomolecules.
Scientists from the Institute of Chemistry and Biology of Membranes and Nanoobjects (CNRS/University of Bordeaux/Bordeaux INP) and the European Institute of Chemistry and Biology (CNRS/University of Bordeaux/Inserm), in collaboration with the Molecular Mycology Unit of the Institut Pasteur (CNRS/Paris Cité University) have developed a new non-destructive analysis method using nuclear magnetic resonance (NMR) spectroscopy to characterize the molecular organization of fungal spores of the pathogen Aspergillus fumigatus
and their evolution throughout the germination process.
They were thus able to compare the composition and abundance of polysaccharides such as glucans and chitins at three morphological stages of germination. More advanced methods using so-called “magic angle” rotation have revealed the role of the sugar called galactosaminogalactan, synthesized during germination, as well as the presence of mobile triglycerides. By combining these solid-state NMR data allowing the identification and quantification of sugars with surface accessibility measurements, models of molecular organization of ’A. fumigatus
might be offered.
This new solid-state NMR methodology provides essential information to better understand the morphology of its spores throughout the germination process and therefore the interactions they are likely to have with their environment. Beyond that, it might also be used to study the action of antifungal compounds on this molecular organization.
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Study of the cell wall of spores of the fungal pathogen Aspergillus fumigatus by solid-state NMR spectroscopy. © Antoine Locket
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