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Binding of human fibronectin to Aspergillus fumigatus conidia
M C Peñalver1, J E O'Connor, J P Martinez
1Departamento de Microbiología y Ecología, Facultad de Farmacia, Universitat de Valencia, Spain.
Abstract:
Aspergillus fumigatus conidia exhibited the ability to bind purified human fibronectin, whereas mycelial forms did not bind the ligand, as detected by an indirect immunofluorescence assay with an antifibronectin polyclonal antibody after incubation of the cells with fibronectin. Flow cytometry confirmed that binding of the ligand to conidia was dose dependent and saturable. Pretreatment of the cells with trypsin markedly reduced binding, which suggested a protein nature for the binding sites present at the surface of conidia. Intact conidia were also able to adhere to fibronectin or antifibronectin antibodies, a significant reduction (from 88 to 92%) in the binding of conidia was noticed, thus suggesting that adhesion to the immobilized ligand was specific. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western immunoblotting with fibronectin and antifibronectin antibody of whole conidial homogenates and 2-mercaptoethanol extracts from isolated conidial cell walls allowed identification, among the complex array of protein and glycoprotein species present in both cell-free preparations, of two polypeptides with apparent molecular masses of 23 and 30 kDa which specifically interact with fibronectin.
Insights
Aspergillus fumigatus conidia bind human fibronectin, a protein interaction mediated by specific surface polypeptides. This binding is crucial for understanding fungal adhesion mechanisms.
Area of Science:
- Medical Mycology
- Molecular Biology
- Immunology
Background:
- Aspergillus fumigatus is an opportunistic fungal pathogen.
- Fibronectin is a key extracellular matrix protein involved in cell adhesion and immune responses.
- Understanding fungal-host interactions is critical for treating invasive infections.
Purpose of the Study:
- To investigate the interaction between Aspergillus fumigatus conidia and human fibronectin.
- To identify the molecular components of A. fumigatus involved in fibronectin binding.
Main Methods:
- Indirect immunofluorescence assay to detect fibronectin binding.
- Flow cytometry for quantitative analysis of ligand binding.
- Enzymatic treatment (trypsin) to assess the nature of binding sites.
- SDS-PAGE and Western immunoblotting to identify interacting proteins.
Main Results:
- A. fumigatus conidia, but not mycelial forms, bind purified human fibronectin.
- Conidial fibronectin binding is dose-dependent, saturable, and reduced by trypsin, indicating proteinaceous binding sites.
- Conidia adhere specifically to immobilized fibronectin and antifibronectin antibodies.
- Two polypeptides of 23 and 30 kDa in conidial extracts specifically interact with fibronectin.
Conclusions:
- A. fumigatus conidia possess specific surface proteins that bind human fibronectin.
- This interaction is likely important for fungal adhesion and pathogenesis.
- The identified 23 and 30 kDa polypeptides are potential targets for therapeutic intervention.