Document Detail

Structure and role of sialic acids on the surface of Aspergillus fumigatus conidiospores.
MedLine Citation:
PMID:  17223648     Owner:  NLM     Status:  MEDLINE    
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.
Mark L Warwas; Jacqueline N Watson; Andrew J Bennet; Margo M Moore
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-01-12
Journal Detail:
Title:  Glycobiology     Volume:  17     ISSN:  0959-6658     ISO Abbreviation:  Glycobiology     Publication Date:  2007 Apr 
Date Detail:
Created Date:  2007-03-15     Completed Date:  2007-06-26     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9104124     Medline TA:  Glycobiology     Country:  England    
Other Details:
Languages:  eng     Pagination:  401-10     Citation Subset:  IM    
Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.
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MeSH Terms
Aspergillus fumigatus / chemistry*,  growth & development,  physiology*
Candida tropicalis / chemistry,  growth & development,  physiology
Cell Membrane / chemistry,  physiology
Extracellular Matrix Proteins / metabolism
Fibronectins / metabolism
Fungal Proteins / metabolism
Polysaccharides / analysis,  chemistry
Protein Binding
Sialic Acids / chemistry,  metabolism*
Spores, Fungal / chemistry*
Reg. No./Substance:
0/Extracellular Matrix Proteins; 0/Fibronectins; 0/Fungal Proteins; 0/Lectins; 0/Polysaccharides; 0/Sialic Acids

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