Staphylokinase

• UniProt: P68802

Staphylokinase is a prophage encoded pathogenicity of Staphylococcus aureus. It is a protein without enzymatic activity.

Staphylokinase interacts with defensins and with plasminogen. By interacting with them defensins neutralize the bactericidal effect of these substances and thus provides a means to subvert the innate immune system of the host. The interaction with plasminogen results in active plasmin, a serine protease that dissolves the fibrin in fibrinolysis in blood clots. Staphylokinase is an opponent of the coagulase, which is also produced by S. aureus. The effect of coagulase similar to that of the endogenous thrombin, the key enzyme of blood clotting, it leads to the polymerization of fibrinogen to fibrin.

This approach of S. aureus is very tricky:

• At the beginning of an infection, this bacterium utilizes the coagulase and creates through the activation of the coagulation system a space where it can multiply undisturbed. This differentiation site of infection, it is protected from the attacks of the immune system.
• Once it has reached a certain cell density in this niche, it switches, cell density dependent on quorum sensing regulated by the production of staphylokinase at. This dissolves the fibrin structures and blocks part of the immune system. This is a further spread of the pathogen into the surrounding tissue allows outside the original infection site.

In cardiology, the streptokinase is used in the treatment of heart attack and severe thrombosis. Is currently being tested in clinical tests whether staphylokinase is also suitable for therapeutic purposes.