Related Experiment Videos
Binding of extracellular matrix proteins to Aspergillus fumigatus conidia
M L Gil1, M C Peñalver, J L Lopez-Ribot
1Departamento de Microbiología y Ecología, Facultad de Farmacia, Universitat de València, Spain.
Abstract:
As detected by confocal immunofluorescence microscopy, binding of fibronectin and laminin appeared to be associated with the protrusions present on the outer cell wall layer of resting Aspergillus fumigatus conidia. Flow cytometry confirmed that binding of laminin to conidia was dose dependent and saturable. Laminin binding was virtually eliminated in trypsin-treated organisms, thus suggesting the protein nature of the binding site. Conidia were also able to specifically adhere to laminin immobilized on microtiter plates. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting (immunoblotting) with laminin and antilaminin antibody of whole conidial homogenates allowed identification, among the complex array of protein and glycoprotein species, of one polypeptide with an apparent molecular mass of 37 kDa which specifically interacts with laminin. The fact that binding of conidia to soluble or immobilized laminin or fibronectin was inhibited by fibronectin or laminin, respectively, suggests the existence of common binding sites for both ligands on the surface of conidia. Intact conidia were also able to adhere to type I and IV collagen immobilized on microtiter plates; adhesion was found to be dose dependent and saturable. Adhesion to immobilized type I and IV collagen was markedly inhibited by laminin and weakly inhibited by fibronectin. Coincubation of conidia with Arg-Gly-Asp (RGD) peptides caused a dose-dependent decrease in binding of cells to immobilized or soluble fibronectin, yet interaction of cells with soluble or immobilized laminin and type I and IV collagen remained unaffected. Interactions described here could be important in mediating attachment of the fungus to host tissues, thus playing a role in the establishment of the disease.
Insights
Aspergillus fumigatus conidia bind to host proteins like laminin and fibronectin via specific surface sites. These interactions are crucial for fungal attachment to host tissues and disease establishment.
Area of Science:
- Medical Mycology
- Molecular Biology
- Cell Adhesion
Background:
- Aspergillus fumigatus is a significant opportunistic fungal pathogen.
- Understanding fungal adhesion mechanisms is key to combating invasive infections.
Purpose of the Study:
- To investigate the molecular interactions between Aspergillus fumigatus conidia and host extracellular matrix proteins.
- To identify specific binding sites and their role in fungal adhesion.
Main Methods:
- Confocal immunofluorescence microscopy to visualize binding.
- Flow cytometry for quantitative analysis of ligand binding.
- Biochemical assays including SDS-PAGE and Western blotting.
- Adhesion assays using immobilized proteins and RGD peptides.
Main Results:
- Conidia bind to fibronectin and laminin on cell wall protrusions.
- Laminin binding is dose-dependent, saturable, and protein-mediated.
- A 37 kDa polypeptide on conidia specifically interacts with laminin.
- Conidia adhere to type I and IV collagen, inhibited by laminin and fibronectin.
- RGD peptides inhibit fibronectin binding but not laminin or collagen binding.
Conclusions:
- Aspergillus fumigatus conidia possess specific binding sites for fibronectin, laminin, and collagen.
- These interactions, potentially involving common binding sites, are vital for fungal adherence to host tissues.
- The identified binding mechanisms may play a critical role in the pathogenesis of invasive aspergillosis.