Structure and role of sialic acids on the surface of Aspergillus fumigatus conidiospores
| Autor: | Mark L. Warwas, Andrew J. Bennet, Jacqueline N. Watson, Margo M. Moore |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Glycan
Sialidase Biochemistry Aspergillus fumigatus Microbiology Fungal Proteins chemistry.chemical_compound Polysaccharides Lectins Neuraminic acid Candida tropicalis skin and connective tissue diseases chemistry.chemical_classification Extracellular Matrix Proteins biology Hydrolysis Cell Membrane Spores Fungal biology.organism_classification Fibronectins Sialic acid carbohydrates (lipids) Fibronectin Kinetics Enzyme chemistry Galactose Sialic Acids biology.protein Protein Binding |
| Zdroj: | Glycobiology. 17:401-410 |
| ISSN: | 1460-2423 0959-6658 |
| DOI: | 10.1093/glycob/cwl085 |
| Popis: | Aspergillus fumigatus is an opportunistic fungal pathogen that causes a life-threatening invasive fungal disease (invasive aspergillosis, IA) in immunocompromised individuals. The first step of pathogenesis is thought to be the attachment of conidia to proteins in lung tissue. Previous studies in our laboratory have shown that conidia adhere to basal lamina proteins via negatively charged sugars on their surface, presumably sialic acids. Sialic acids are a family of more than 50 substituted derivatives of a nine-carbon monosaccharide, neuraminic acid. The purpose of this study was 2-fold: (1) to determine the structure of sialic acids and the glycan acceptor on A. fumigatus oligosaccharides and (2) to determine the effect on the removal of sialic acids from conidia on conidial binding to the extracellular matrix protein fibronectin and phagocytosis of conidia by cultured macrophages and type 2 pneumocytes. Surface sialic acids were removed using Micromonospora viridifaciens sialidase or using acetic acid, mild acid hydrolysis. Lectin binding studies revealed that the majority of conidial sialic acids are alpha2,6-linked to a galactose residue. High-pressure liquid chromatography of derivatized sialic acids released from conidia revealed that unsubstituted N-acetylneuraminic acid is the predominant sialic acid on the surface of conidia. Enzymatic removal of sialic acid significantly decreased the binding of conidia to fibronectin by greater than 65% when compared with sham-treated controls. In addition, removal of sialic acids decreased conidial uptake by cultured murine macrophages and Type 2 pneumocytes by 33% and 53%, respectively. Hence, sialylated molecules on A. fumigatus conidia are ligands for both professional and nonprofessional phagocytes. |
| Databáze: | OpenAIRE |
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