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Receptors for human plasminogen on gram-negative bacteria
M Ullberg1, G Kronvall, I Karlsson
1Department of Clinical Microbiology, Karolinska Hospital, Stockholm, Sweden.
Infection and Immunity
|January 1, 1990
Summary
Gram-negative bacteria, including Haemophilus influenzae and Branhamella catarrhalis, readily interact with human plasminogen. Bacterial plasminogen uptake involves specific receptors and lysine-binding sites on plasminogen.
Area of Science:
- Microbiology
- Biochemistry
Background:
- Plasminogen is a key protein in the fibrinolytic system.
- Bacterial interactions with host proteins can influence pathogenicity.
Purpose of the Study:
- To investigate the interaction between human plasminogen and various gram-negative bacterial strains.
- To characterize the receptors involved in plasminogen uptake by bacteria.
Main Methods:
- Radiolabeling of human plasminogen with 125I.
- Quantification of bacterial plasminogen uptake.
- Scatchard analysis to determine receptor binding kinetics (Kd and site number).
Main Results:
- Haemophilus influenzae and Branhamella catarrhalis showed high plasminogen uptake.
- Proteus mirabilis and Pseudomonas aeruginosa also demonstrated significant plasminogen uptake.
- Receptor interactions varied, with H. influenzae and B. catarrhalis exhibiting two receptor types, while P. aeruginosa showed one.
- Plasminogen uptake was inhibited by plasmin-aprotinin, lysine, and epsilon-aminocaproic acid, indicating involvement of lysine-binding sites.
Conclusions:
- Gram-negative bacteria possess receptors that bind human plasminogen.
- The interaction involves specific lysine-binding sites on plasminogen.
- Bacterial species exhibit distinct receptor characteristics for plasminogen binding.