INACTIVATION OF THE STREPTOKINASE GENE PREVENTS STREPTOCOCCUS-EQUISIMILIS H46A FROM ACQUIRING CELL-ASSOCIATED PLASMIN ACTIVITY IN THE PRESENCE OF PLASMINOGEN

The streptokinase gene of Streptococcus equisimilis H46 was inactivate d by plasmid insertion mutagenesis to study the relationship between e laboration of streptokinase and acquisition of cell-associated plasmin activity after incubation of wild-type and mutant cells in media cont aining plasminogen or plasmin. The results showed that H46A binds both the zymogen and active enzyme, generates surface-associated plasmin a ctivity in the presence of plasminogen when producing streptokinase, a nd expresses its plasmin(ogen) receptor(s) independently of a function al streptokinase gene. At least part of the plasmin(ogen) binding capa city may be due to the glyceraldehyde-3-phosphate dehydrogenase type o f receptor molecule, as judged by the detection of the corresponding g ene.