Related Experiment Videos
Expression and identification of a laminin-binding protein in Aspergillus fumigatus conidia
G Tronchin1, K Esnault, G Renier
1Groupe d'Etude des Interactions Hôte-Parasite, Laboratoire de Parasitologie-Mycologie, Centre Hospitalier Universitaire, Angers, France.
Abstract:
Adhesion of Aspergillus fumigatus, the causative agent of human aspergillosis, to the extracellular matrix protein laminin has been previously demonstrated. This study investigated the expression of laminin receptors during swelling of conidia, a step leading to germination and subsequent colonization of tissues. Scanning electron microscopy showed that the laminin binding sites were distributed over the external rodlet layer of resting conidia. During swelling, the characteristic rodlet layer progressively disintegrated and conidia surrounded by a smooth cell wall layer appeared. Flow cytometry using fluorescein isothiocyanate-conjugated laminin demonstrated that expression of laminin receptors at the surface of conidia was swelling dependent. Resting conidia expressed high levels of laminin receptors on their surface. A gradual decrease of laminin binding was then observed as swelling occurred, reaching a minimum for 4-h-swollen conidia. This correlated with a loss of adherence of swollen conidia to laminin immobilized on microtiter plates. Trypsin pretreatment of conidia reduced laminin binding. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and ligand blotting with laminin identified in a cell wall extract a major 72-kDa cell wall glycoprotein which binds laminin. Thus, one of the initial events in the host colonization may be the recognition of basement membrane laminin by this 72-kDa cell wall surface component.
Insights
Aspergillus fumigatus conidia express surface laminin receptors that decrease during swelling, impacting adherence. A 72-kDa glycoprotein is identified as a key laminin-binding component involved in fungal colonization.
Area of Science:
- Mycology
- Cell Biology
- Infectious Diseases
Background:
- Aspergillus fumigatus causes human aspergillosis.
- Fungal adhesion to extracellular matrix proteins like laminin is crucial for tissue colonization.
- Laminin receptor expression on fungal surfaces is a key factor in host-pathogen interactions.
Purpose of the Study:
- To investigate the expression of laminin receptors on Aspergillus fumigatus conidia during swelling.
- To understand the role of laminin binding in fungal adherence and colonization.
- To identify the specific fungal component responsible for laminin binding.
Main Methods:
- Scanning electron microscopy to visualize conidial surface changes.
- Flow cytometry with fluorescently labeled laminin to quantify receptor expression.
- Microtiter plate assays to measure fungal adherence.
- Proteomic analysis (SDS-PAGE and ligand blotting) to identify binding proteins.
Main Results:
- Laminin binding sites are present on the rodlet layer of resting conidia.
- Conidial swelling leads to rodlet layer disintegration and a decrease in surface laminin receptor expression.
- Reduced laminin receptor expression correlates with decreased adherence to laminin.
- A 72-kDa cell wall glycoprotein was identified as a major laminin-binding component.
Conclusions:
- Laminin receptor expression on Aspergillus fumigatus conidia is swelling-dependent.
- The decrease in receptor expression during swelling affects fungal adherence.
- A 72-kDa glycoprotein is likely involved in recognizing basement membrane laminin during initial host colonization.