The ternary microplasmin-staphylokinase-microplasmin complex is a proteinase-cofactor-substrate complex in action.
The serine proteinase plasmin is the key fibrinolytic enzyme that dissolves blood clots and also promotes cell migration and tissue remodeling. Here, we report the 2.65 A crystal structure of a ternary complex of microplasmin-staphylokinase bound to a second microplasmin. The staphylokinase 'cofactor' does not affect the active-site geometry of the plasmin 'enzyme', but instead modifies its subsite specificity by providing additional docking sites for enhanced presentation of the plasminogen 'substrate' to the 'enzymes's' active site. The activation loop of the plasmin 'substrate', cleaved in these crystals, can be reconstructed to show how it runs across the active site of the plasmin 'enzyme' prior to activation cleavage. This is the first experimental structure of a productive proteinase-cofactor-macromolecular substrate complex. Furthermore, it provides a template for the design of improved plasminogen activators and plasmin inhibitors with considerable therapeutical potential.
Max-Planck Institute of Biochemistry, Department for Structural Research, Martinsried, Germany. parry@biochem.mpg.de
M A
MA
Parry
C
C
Fernandez-Catalan
A
A
Bergner
R
R
Huber
K P
KP
Hopfner
B
B
Schlott
K H
KH
Gührs
W
W
Bode
D000595:Amino Acid Sequence; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D005341:Fibrinolysin / Q000737:chemistry*; D006801:Humans; D046911:Macromolecular Substances; D008666:Metalloendopeptidases / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation; D016415:Sequence Alignment; D013379:Substrate Specificity
D046911:Macromolecular Substances; D010446:Peptide Fragments; C054561:microplasmin; D005341:Fibrinolysin; D008666:Metalloendopeptidases; C022653:auR protein, Staphylococcus aureus