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Interactions between glycoconjugates from human respiratory airways and Pseudomonas aeruginosa
A Scharfman1, E Van Brussel, N Houdret
1Unité INSERM No. 377, Lille, France.
Abstract:
Pseudomonas aeruginosa binds to different glycoconjugates in vitro. As six other bacteria, it binds to several glycolipids, mainly asialo GM1 and asialo GM2. Asialo GM1 has been reported to exist at the surface of cystic fibrosis cells. The binding of P. aeruginosa to asialo GM1 involves the pili, especially the C-terminal part of pilin that recognizes the GaINAc(beta 1,4) Gal sequence of asialo GM1.P. aeruginosa may also bind to sialylated membrane-bound glycoproteins. Human salivary and respiratory mucins are also recognized by P. aeruginosa. Mucins represent the main components of mucus. The peptide part (apomucin) of this broad family of secreted glycoproteins is encoded by several mucin genes. The apomucins are covered by a large number of carbohydrate chains that can be remarkably different and represent a mosaic of sites for attachment of microorganisms. The binding of P. aeruginosa to mucins involves outer membrane proteins and mucin carbohydrate chains that are structurally different from the carbohydrate recognized by pillin. Airway and salivary mucins secreted by patients suffering from cystic fibrosis (CF) show alterations in their carbohydrate moiety. The increased sulfation of airway mucins seems to correspond to a primary defect. Other abnormalities such as increased sialylation or fucosylation have also been detected. The binding of P. aeruginosa to airway or salivary mucins is increased in CF. However, the precise link between the carbohydrate alterations and the increased binding of P. aeruginosa to CF mucins remains to be elucidated.
Insights
Pseudomonas aeruginosa binds to cystic fibrosis (CF) cells via glycolipids like asialo GM1 and altered mucins. This bacterial adhesion involves pili and outer membrane proteins, with CF mucin changes potentially increasing binding.
Area of Science:
- Microbiology
- Glycobiology
- Biochemistry
Background:
- Pseudomonas aeruginosa exhibits adherence to various host glycoconjugates.
- Specific glycolipids, such as asialo GM1 and asialo GM2, are recognized by P. aeruginosa.
- Asialo GM1 is present on cystic fibrosis (CF) cells, suggesting a role in CF pathogenesis.
Purpose of the Study:
- To investigate the molecular mechanisms of Pseudomonas aeruginosa binding to host glycoconjugates.
- To explore the interaction between P. aeruginosa and mucins, particularly in the context of cystic fibrosis.
Main Methods:
- In vitro binding assays using purified glycoconjugates and bacterial components.
- Analysis of P. aeruginosa interactions with human salivary and respiratory mucins.
- Characterization of carbohydrate alterations in mucins from CF patients.
Main Results:
- P. aeruginosa binds to asialo GM1 and asialo GM2 glycolipids via its pili, specifically recognizing the GaINAc(beta 1,4) Gal sequence.
- The bacterium also binds to human salivary and respiratory mucins through outer membrane proteins and mucin carbohydrate chains.
- Mucins from CF patients display altered carbohydrate structures, including increased sulfation, sialylation, and fucosylation, correlating with increased P. aeruginosa binding.
Conclusions:
- P. aeruginosa utilizes distinct molecular mechanisms, including pili and outer membrane proteins, to adhere to host glycoconjugates like glycolipids and mucins.
- Alterations in mucin glycosylation in cystic fibrosis patients enhance P. aeruginosa binding.
- Further research is needed to fully elucidate the relationship between CF-associated mucin changes and bacterial adhesion.