Biology subjects

Latge, J.-P.

Publications and source records attributed to Latge, J.-P..

8 recordsLinked to original sources

bioRxiv2026

Distinguishing Polymer Turnover from De Novo Biosynthesis Reveals Dynamic Cell Wall Remodeling During Aspergillus fumigatus Conidial Germination

Dynamic remodeling of extracellular matrices underlies development, environmental adaptation, and host-pathogen interactions, yet distinguishing polymer turnover from de novo biosynthesis in intact cells remains a major challenge. Here, we combined high-resolution solid-state NMR with selective 13C-labeling strategies to distinguish pre-existing cell-wall polymers from newly synthesized polysaccharides during Aspergillus fumigatus conidial germination. Germination was accompanied by substantial remodeling of the rigid cell wall, characterized by decreased {beta}-1,3-glucan and increased chitin and -1,3-glucan, whereas the mobile wall fraction remained comparatively stable except for the emergence of galactosaminogalactan. Surprisingly, {beta}-1,3-glucan turnover proceeded independently of the major {beta}-1,3-glucanases encoded by the A. fumigatus genome and was dispensable for germination. Instead, isotope-labeling experiments revealed that newly assimilated carbon is preferentially directed toward -1,3-glucan biosynthesis, whereas deletion of the -1,3-glucan synthase genes triggered compensatory accumulation of chitin and {beta}-1,3-glucan. These results reveal a compartmentalized cell-wall remodeling program that coordinates selective turnover with de novo polysaccharide synthesis during fungal germination and establish isotope-edited solid-state NMR as a general approach for distinguishing inherited from newly synthesized polymers in complex carbohydrate matrices.

molecular biology↗

bioRxiv2026

Dynamic Reprogramming of Fungal Cell Walls Underlies Germination and Immune Exposure in Zygomycetous Fungal Pathogens

Fungal germination is a critical developmental transition that underlies environmental adaptation and pathogenicity, yet how the cell wall is molecularly reprogrammed during this process remains poorly understood. Here we show that germination of Rhizopus delemar involves a developmentally programmed transition from a {beta}-1,3-glucan-rich dormant scaffold to a chitin-chitosan-dominated polarized wall. Using solid-state nuclear magnetic resonance spectroscopy and cytochemistry approaches, we show that resting conidia contains a rigid {beta}-1,3-glucan- and chitosan-rich core beneath a persistent melanin layer. During swelling, this architecture is largely maintained, but germ tube emergence triggers complete shutdown of {beta}-1,3-glucan synthesis and extensive chitin-chitosan enrichment. Distinct chitosan polymorphs are selectively enriched, while mobile polysaccharides are progressively incorporated into the rigid scaffold. This remodeling enhances neutrophil recognition of swollen and germinating conidia. Our study reveals a molecular mechanism linking fungal morphogenesis, cell wall remodeling, and morphotype-specific immune exposure during mucormycosis.

biochemistry↗

bioRxiv2025

Kre6-Dependent β-1,6-glucan Biosynthesis Only Occurs in the Conidium of Aspergillus fumigatus

The structural role of {beta}-1,6-glucan has remained under-investigated in filamentous fungi compared to other fungal cell wall polymers, and previous studies have shown that the cell wall of the mycelium of A. fumigatus did not contain {beta}-1,6-glucans. In contrast, the current solid-state NMR investigations showed that the conidial cell wall contained a low amount of {beta}-1,6-glucan. ssNMR comparisons of the A. fumigatus and C. albicans {beta}-1,6-glucans showed they are structurally similar. Deletion of the KRE6 gene which is the only KRE gene in the A. fumigatus genome resulted in a mutant depleted of {beta}-1,6-glucan which has a growth phenotype similar to the parental strain. Even though it is not an essential polymer in A. fumigatus, {beta}-1,6-glucan play a role in cell wall organization since the kre6{Delta} mutant showed a higher sensitivity to Congo-red and Calcofluor white which are known to be general cell wall inhibitors. It is also another example of the significant structural differences seen between conidium and mycelium of filamentous fungi.

biochemistry↗

bioRxiv2024

Comparative Analysis of Polysaccharide and Cell Wall Structure in Aspergillus nidulans and Aspergillus fumigatus by Solid-State NMR

Invasive aspergillosis poses a significant threat to immunocompromised patients, leading to high mortality rates associated with these infections. Targeting the biosynthesis of cell wall carbohydrates is a promising strategy for antifungal drug development and will be advanced by a molecular-level understanding of the native structures of polysaccharides within their cellular context. Solid-state NMR spectroscopy has recently provided detailed insights into the cell wall organization of Aspergillus fumigatus, but genetic and biochemical evidence highlights species-specific differences among Aspergillus species. In this study, we employed a combination of 13C, 15N, and 1H-detection solid-state NMR, supplemented by Dynamic Nuclear Polarization (DNP), to compare the structural organization of cell wall polymers and their assembly in the cell walls of A. fumigatus and A. nidulans, both of which are key model organisms and human pathogens. The two species exhibited a similar rigid core architecture, consisting of chitin, -glucan, and {beta}-glucan, which contributed to comparable cell wall properties, including polymer dynamics, water retention, and supramolecular organization. However, differences were observed in the chitin, galactosaminogalactan, protein, and lipid content, as well as in the dynamics of galactomannan and the structure of the glucan matrix.

biophysics↗

bioRxiv2024

Molecular Architecture of Chitin and Chitosan-Dominated Cell Walls in Zygomycetous Fungal Pathogens by Solid-State NMR

Zygomycetous fungal infections pose an emerging medical threat among individuals with compromised immunity and metabolic abnormalities. Our pathophysiological understanding of these infections, particularly the role of fungal cell walls in growth and immune response, remains limited. Here we conducted multidimensional solid-state NMR analysis to examine cell walls in five Mucorales species, including key mucormycosis causative agents like Rhizopus and Mucor species. We show that the rigid core of the cell wall primarily comprises highly polymorphic chitin and chitosan, with minimal quantities of {beta}-glucans linked to a specific chitin subtype. Chitosan emerges as a pivotal molecule preserving hydration and dynamics. Some proteins are entrapped within this semi-crystalline chitin/chitosan layer, stabilized by the sidechains of hydrophobic amino acid residues, and situated distantly from {beta}-glucans. The mobile domain contains galactan- and mannan-based polysaccharides, along with polymeric -fucoses. Treatment with the chitin synthase inhibitor nikkomycin removes the {beta}-glucan-chitin/chitosan complex, leaving the other chitin and chitosan allomorphs untouched while simultaneously thickening and rigidifying the cell wall. These findings shed light on the organization of Mucorales cell walls and emphasize the necessity for a deeper understanding of the diverse families of chitin synthases and deacetylases as potential targets for novel antifungal therapies.

biophysics↗

bioRxiv2023

Structural Remodeling of Fungal Cell Wall Promotes Resistance to Echinocandins

The insufficient efficacy of existing antifungal drugs and the rise in resistance necessitate the development of new therapeutic agents with novel functional mechanisms1,2. Echinocandins are an important class of antifungals that inhibit {beta}-1,3-glucan biosynthesis to interfere with cell wall structure and function3,4. However, their efficacy is limited by the fungistatic activity against Aspergillus species and the trailing effect during clinical application. Here, we describe how echinocandins remodel the supramolecular assembly of carbohydrate polymers in the fungal cell wall in an unexpected manner, possibly resulting in a subsequent inhibition of the activity of these drugs. Solid-state nuclear magnetic resonance (ssNMR) analysis of intact cells from the human pathogenic fungus Aspergillus fumigatus showed that the loss of {beta}-1,3-glucan and the increase of chitin content led to a decrease in cell wall mobility and water-permeability, thus enhancing resistance to environmental stresses. Chitosan and -1,3-glucan were found to be important buffering molecules whose physical association with chitin maintained the wall integrity. These new findings revealed the difficult-to-understand structural principles governing fungal pathogens response to echinocandins and opened new avenues for designing novel antifungal agents with improved efficacy.

biophysics↗

bioRxiv2023

Structural Organization of the Cell Wall of Halophilic Fungi

Halophilic fungi, which thrive in hypersaline habitats and face a range of extreme conditions. These fungal species have gained considerable attention due to their potential applications in harsh industrial processes, such as bioremediation and fermentation under unfavorable conditions of hypersalinity, low water activity, and extreme pH. However, the role of the cell wall in surviving these environmental conditions remains unclear. Here we employ solid-state NMR spectroscopy to compare the cell wall architecture of Aspergillus sydowii across salinity gradients. Analyses of intact cells reveal that A. sydowii cell walls contain a rigid core comprising chitin, {beta}-glucan, and chitosan, shielded by a surface shell composed of galactomannan and galactosaminogalactan. When exposed to hypersaline conditions, A. sydowii enhances chitin biosynthesis and incorporates -glucan to create thick, stiff, and hydrophobic cell walls. Such structural rearrangements enable the fungus to adapt to both hypersaline and salt-deprived conditions, providing a robust mechanism for withstanding external stress. These molecular principles can aid in the optimization of halophilic strains for biotechnology applications.

biophysics↗

bioRxiv2020

Characterization of extracellular vesicles produced by Aspergillus fumigatus protoplasts

Extracellular vesicles (EVs) are outer membranous compartments produced by yeast and mycelial forms of several fungal species. One of the difficulties to perceive the role of EVs during the fungal life is the fact that an active secretion of these EVs has not been clearly demonstrated in situ due to the presence of a thick cell wall. One alternative to have a better access to these vesicles is to use protoplasts. This approach has been investigated here with Aspergillus fumigatus, one of the most common opportunistic fungal pathogens worldwide. Analysis of regenerating protoplasts by scanning electron microscopy and fluorescence microscopy indicated the occurrence of outer membrane projections in association with surface components and the release of particles with properties resembling those of fungal EVs. EVs in culture supernatants were characterized by transmission electron microscopy and nanoparticle tracking analysis. Proteomic and glycome analysis of EVs revealed the presence of a complex array of enzymes related to lipid / sugar metabolism, pathogenic processes, and cell wall biosynthesis. Our data indicate that i) EV production is a common feature of different morphological stages of this major fungal pathogen, and ii) protoplastic EVs are a promising tool to undertake studies of vesicle functions in fungal cells. IMPORTANCEFungal cells use extracellular vesicles (EVs) to export biologically active molecules to the outer space. Since fungal cells are encaged in a thick cell wall, it is reasonable to expect that this structure might impact the vesicle-mediated molecular export. In this study, we used protoplasts of Aspergillus fumigatus, a major fungal pathogen, as a model to evaluate EV production in the absence of a cell wall. Our results demonstrated that wall-less A. fumigatus exports plasma membrane-derived EVs containing a complex combination of proteins and glycans. Our study is the first to characterize fungal EVs in the absence of a cell wall. Our results suggest that protoplasts are a promising model for functional studies of fungal vesicles.

microbiology↗