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Mycoplasma cells stimulate in vitro activation of plasminogen by purified tissue-type plasminogen activator
1Department of Clinical Biochemistry, Hadassah University Hospital, Jerusalem, Israel.
Abstract:
In an in vitro direct assay with tissue-type plasminogen activator (tPA), plasminogen and the chromogenic substrate S-2251, the ability of Mycoplasma fermentans KL4 to stimulate tPA-mediated activation of plasminogen to plasmin was studied. Mycoplasma cells markedly enhanced the activation of plasminogen by tPA in a concentration-, temperature- and pH-dependent manner. Nonidet P-40 (0.01%), sonication, and freezing and thawing of the cells substantially increased the stimulatory effect of mycoplasma on tPA activity. In contrast, the activation of plasminogen by urokinase was refractory to mycoplasma cells. The mycoplasma-mediated stimulation of tPA activity was prevented by epsilon-aminocaproic acid (EACA), a lysine analogue known to block lysine-binding sites (LBS) in plasminogen and tPA. Among several Mycoplasma fermentans strains tested, incognitus strain demonstrated the highest stimulation activity. These results suggest that mycoplasma cells interact with LBS in tPA and plasminogen to enhance plasminogen activation.
Insights
Mycoplasma fermentans KL4 significantly boosts tissue-type plasminogen activator (tPA)-mediated plasminogen activation. This interaction involves lysine-binding sites and is specific to tPA, not urokinase.
Area of Science:
- Microbiology
- Biochemistry
- Hematology
Background:
- Plasminogen activation is crucial for fibrinolysis.
- Tissue-type plasminogen activator (tPA) is a key enzyme in this process.
- The role of microbial agents in modulating tPA activity is not fully understood.
Purpose of the Study:
- To investigate the effect of Mycoplasma fermentans KL4 on tPA-mediated plasminogen activation.
- To determine the mechanism underlying this interaction.
Main Methods:
- In vitro direct assay using tPA, plasminogen, and a chromogenic substrate (S-2251).
- Assessed Mycoplasma fermentans KL4 concentration, temperature, and pH dependency.
- Investigated the effect of cell treatments (Nonidet P-40, sonication, freeze-thaw) and epsilon-aminocaproic acid (EACA).
- Compared tPA activity with urokinase-mediated activation.
Main Results:
- Mycoplasma fermentans KL4 markedly enhanced tPA-driven plasminogen activation in a dose-, temperature-, and pH-dependent manner.
- Cell treatments and EACA (a lysine analogue) significantly influenced the stimulatory effect.
- Urokinase-mediated plasminogen activation was not affected by Mycoplasma fermentans.
- Mycoplasma fermentans incognitus strain showed the highest stimulatory activity.
Conclusions:
- Mycoplasma fermentans cells interact with lysine-binding sites (LBS) on both plasminogen and tPA.
- This interaction enhances plasminogen activation by tPA.
- The findings suggest a novel mechanism by which Mycoplasma fermentans can influence the fibrinolytic system.