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Immobilization of plasminogen on Escherichia coli flagella
K Lähteenmäki1, B Westerlund, P Kuusela
1Department of General Microbiology, University of Helsinki, Finland.
Abstract:
The interaction of plasminogen with flagella of Escherichia coli was investigated. Plasminogen bound to flagella purified from E. coli LE392, a commonly used cloning host, and E. coli IH3069, an O25H1 strain isolated from a case of newborn bacteremia. The binding was inhibited by the lysine analog epsilon-aminocaproic acid, suggesting involvement of the lysine-binding Kringle domains of plasminogen in the binding. Purified flagella enhanced the formation of plasmin activity in the presence of tissue-type plasminogen activator; a similar enhancement was observed with flagella-expressing LE392 cells.
Insights
Escherichia coli flagella bind plasminogen, a key protein in blood clot breakdown. This interaction, mediated by plasminogen's Kringle domains, enhances plasmin activity, potentially impacting bacterial virulence.
Area of Science:
- Microbiology
- Biochemistry
- Molecular Biology
Background:
- Plasminogen is a crucial protein in the fibrinolytic system, responsible for breaking down blood clots.
- Escherichia coli flagella are complex protein structures involved in bacterial motility and adhesion.
- The interaction between bacterial components and host proteins can significantly influence infection processes.
Purpose of the Study:
- To investigate the interaction between plasminogen and flagella of Escherichia coli.
- To determine the mechanism of plasminogen binding to E. coli flagella.
- To assess the functional consequences of this interaction on plasmin activity.
Main Methods:
- Purification of flagella from E. coli strains (LE392 and IH3069).
- Plasminogen binding assays using purified flagella and whole bacterial cells.
- Inhibition studies using epsilon-aminocaproic acid, a lysine analog.
- Assays to measure plasmin activity in the presence of flagella and tissue-type plasminogen activator.
Main Results:
- Plasminogen demonstrated binding to purified flagella from both E. coli LE392 and IH3069 strains.
- The binding was significantly inhibited by epsilon-aminocaproic acid, indicating the involvement of plasminogen's lysine-binding Kringle domains.
- Both purified flagella and flagella-expressing E. coli cells enhanced plasmin formation in the presence of tissue-type plasminogen activator.
Conclusions:
- E. coli flagella possess binding sites for plasminogen, primarily involving its Kringle domains.
- This interaction can modulate the host's fibrinolytic system by enhancing plasminogen activation.
- The findings suggest a potential role for flagella-plasminogen interaction in the pathogenesis of E. coli infections.