RESUMO
Enolase is a glycolytic and gluconeogenic enzyme also found on the surface of several eukaryotic and prokaryotic cells where it acts as plasminogen binding protein. Leishmania mexicana, one of the causative agents of Leishmaniasis, binds plasminogen and, in this parasite, enolase has been previously found associated with the external face of the plasma membrane. In this work, we show that the purified recombinant enolase has plasminogen binding activity indicating that, at the surface of the parasite, the protein may function as one of the plasminogen receptors. An internal motif (249)AYDAERKMY(257), similar to the nine amino-acid internal plasminogen-binding motif in Streptococcus pneumoniae enolase, is responsible for plasminogen interaction with the parasite enolase. Anti-enolase antibodies inhibited up to 60% of plasminogen binding on live parasites indicating that enolase act as a plasminogen receptor on the parasite. The fact that enolase acts as a possible plasminogen receptor in vivo makes this protein a promising target for therapy.
Assuntos
Leishmania mexicana/enzimologia , Fosfopiruvato Hidratase/metabolismo , Plasminogênio/metabolismo , Proteínas de Protozoários/metabolismo , Sequência de Aminoácidos , Animais , Humanos , Leishmania mexicana/genética , Leishmania mexicana/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Fosfopiruvato Hidratase/química , Fosfopiruvato Hidratase/genética , Ligação Proteica , Proteínas de Protozoários/química , Proteínas de Protozoários/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMO
The ability of Trypanosoma cruzi to interact with plasminogen, the zimogenic form of the blood serin protease plasmin, was examined. Immunohistochemistry studies revealed that both forms, epimastigotes and metacyclic trypomastigotes, were able to fix plasminogen in a lysine dependant manner. This interaction was corroborated by plasminogen activation studies. Both forms of the parasite enhanced the plasminogen activation by tissue-type plasminogen activator. The maximal enhancements obtained were 15-fold and 3.4-fold with epimastigotes and metacyclic trypomastigotes, respectively, as compared to plasminogen activation in absence of cells. Ligand-blotting analysis of proteins extracted with Triton X-114 from a microsomal fraction of epimastigotes revealed at least five soluble proteins and one hydrophobic protein able to bind plasminogen.
Assuntos
Plasminogênio/metabolismo , Trypanosoma cruzi/metabolismo , Animais , Ativação Enzimática , Humanos , Imuno-Histoquímica , Ativador de Plasminogênio Tecidual/metabolismoRESUMO
The ability of Trypanosoma cruzi to interact with plasminogen, the zimogenic form of the blood serin protease plasmin, was examined. Immunohistochemistry studies revealed that both forms, epimastigotes and metacyclic trypomastigotes, were able to fix plasminogen in a lysine dependant manner. This interaction was corroborated by plasminogen activation studies. Both forms of the parasite enhanced the plasminogen activation by tissue-type plasminogen activator.The maximal enhancements obtained were 15-fold and 3.4-fold with epimastigotes and metacyclic trypomastigotes, respectively, as compared to plasminogen activation in absence of cells. Ligand-blotting analysis of proteins extracted with Triton X-114 from a microsomal fraction of epimastigotes revealed at least five soluble proteins and one hydrophobic protein able to bind plasminogen.