GPI-Anchor Protein Disruption Alters Fungal Cell Wall and Growth Morphology
Researchers found that disrupting glycosylphosphatidylinositol (GPI)-anchor biosynthesis in the filamentous fungus Aspergillus oryzae alters cell wall composition and shifts growth from dense pellets to dispersed mycelium. The antifungal compound manogepix (MGX) inhibited the GPI pathway enzyme Gwt1, causing loss of a key adhesion molecule and downregulation of cell-fusion genes. This offers a potential strategy for rationally engineering fungal morphology to improve nutrient and oxygen transfer in industrial protein fermentation.
A new preprint study on bioRxiv demonstrates that perturbing GPI-anchored protein biosynthesis in Aspergillus oryzae fundamentally reorganizes the fungal cell wall and controls macroscopic growth morphology. Genetic disruption of the enzyme Mcd4 or chemical inhibition of Gwt1 with the antifungal drug manogepix (MGX) both induced hyper-branching and weakened the cell wall. Solid-state NMR analysis revealed that MGX treatment caused reorganization of two key cell wall polysaccharides—galactosaminogalactan (GAG) and galactomannan (GM)—including complete elimination of cationic galactosamine, a molecule critical for hyphal adhesion. Transcriptomic profiling corroborated these structural findings by showing downregulation of genes involved in somatic cell fusion, explaining why treated cells fail to aggregate into pellets. The shift from pelleted to dispersed mycelial growth is industrially significant because dense pellets restrict nutrient and oxygen diffusion, limiting fermentation yields. Notably, MGX produced distinct morphological outcomes across different industrially relevant fungal species, suggesting species-specific dependencies on GPI-anchored wall proteins. The authors propose that targeting the GPI biosynthesis pathway represents a rational, chemically controllable approach to morphology engineering in fungal cell factories.
What's missing
As a preprint, this work has not yet undergone formal peer review. The study does not report fermentation yield or productivity data demonstrating that the dispersed morphology induced by MGX actually improves industrial output in practice. The long-term effects of MGX on cell viability, metabolic burden, and product quality in scaled fermentation processes are not addressed. Additionally, the species-specific morphological outcomes in other fungi are described but not mechanistically explained, leaving open questions about generalizability.
What different sources said
- bioRxivCenter
Perturbing glycosylphosphatidylinositol (GPI)-anchor biosynthesis alters cell wall architecture and modulates fungal morphology
Related
Gut Bacteria Enzyme Found to Break Down Heat-Processed Food Compounds, Producing Novel Biogenic Amines
Researchers have discovered that an enzyme in common gut bacteria can degrade N-epsilon-carboxymethyllysine (CML), a compound formed during thermal food processing, producing previously unknown biogenic amines. The enzyme, ornithine decarboxylase SpeC from enterobacteria, acts on CML and related modified lysine derivatives through a low-level 'underground' catalytic activity. This finding suggests a previously unrecognized communication axis between thermally processed dietary compounds and gut microbial physiology, with potential implications for host health.
Full-Length Gene Sequencing Reveals Two Distinct Bacterial Communities in Black-Legged Ticks Expanding Into Canada
Researchers used Oxford Nanopore full-length 16S rRNA gene sequencing to characterize the microbiome of Ixodes scapularis black-legged ticks collected in Nova Scotia, Canada, distinguishing between tick-adapted bacteria and environmentally acquired bacteria. The study comes as I. scapularis — the primary vector of Lyme disease — is rapidly expanding northward into Canada due to climate change. The findings suggest that environmentally derived bacteria in tick microbiomes are not mere contamination, which has implications for how tick microbiome data is collected and interpreted across surveillance studies.
Study Identifies Metabolic Link Between Cell Envelope Stress and Biofilm Formation in Bacteria
Researchers have discovered that the metabolite acetyl-CoA directly inhibits enzymes that degrade the bacterial signaling molecule c-di-GMP, connecting cell envelope biosynthesis stress to biofilm formation in Pseudomonas aeruginosa. The study found that sub-inhibitory concentrations of antibiotics targeting early peptidoglycan biosynthesis — but not other antibiotic classes — elevate c-di-GMP levels by reducing phosphodiesterase activity, with acetyl-CoA competing for the enzyme active site. Because the relevant enzyme domain is broadly conserved across bacterial species, this checkpoint mechanism may be widespread and could have implications for understanding antibiotic-induced biofilm responses.