Losac, the First Hemolin that Exhibits Procogulant Activity through Selective Factor X Proteolytic Activation

Autor(es)

Alvarez-Flores, Miryam Paola ^[1] ; Furlin, Daniel ^[1] ; Ramos, Oscar H. P. ^[1] ; Balan, Andrea ^[2] ; Konno, Katsuhiro ^[3] ; Chudzinski-Tavassi, Ana Marisa ^{[1, 3]}

Afiliação do(s) autor(es)

^[1] Inst Butantan, Lab Bioquim & Biofis, BR-05503900 Sao Paulo - Brazil

^[2] Ctr Pesquisa Energia & Mat, Lab Nacl Biociencias, BR-13083970 Campinas, SP - Brazil

^[3] Inst Butantan, Ctr Toxinol Aplicada, BR-05503900 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Biological Chemistry; v. 286, n. 9, p. 6918-6928, MAR 4 2011.
• Citações Web of Science: 9

Resumo

Envenoming by the contact of human skin with Lonomia obliqua caterpillars promotes a hemorrhagic syndrome characterized by a consumptive coagulopathy. Losac (Lonomia obliqua Stuart factor activator) is a component of the bristle of L. obliqua that is probably partially responsible for the observed syndrome because it activates factor X and is recognized by an effective antilonomic serum. Here we unveil the proteolytic activity of Losac and demonstrate the feasibility of its recombinant production. On the other hand, Losac has no homology to known proteases, but it can be inhibited by PMSF, a serine protease inhibitor. Instead, it shows closer homology to members of the hemolin family of proteins, a group of cell adhesion molecules. The recombinant protein (rLosac) shortened the coagulation time of normal and deficient plasmas, whereas it was ineffective in factor X-deficient plasma unless reconstituted with this protein. rLosac was able to activate factor X in a dose-and time-dependent manner but not gamma-carboxyglutamic acid domainless factor X. Moreover, phospholipids and calcium ions increased rLosac activity. Also, rLosac had no effect on fibrin or fibrinogen, indicating its specificity for blood coagulation activation. Linear double reciprocal plots indicate that rLosac follows a Michaelis-Menten kinetics. Cleavage of factor X by rLosac resulted in fragments that are compatible with those generated by RVV-X (a well known factor X activator). Together, our results validate Losac as the first protein from the hemolin family exhibiting procoagulant activity through selective proteolysis on coagulation factor X. (AU)

• Processo FAPESP: 07/51813-0 - Clonagem, analises e predicao estrutural do losac, uma nova hemolina da lonomia obliqua.
• Beneficiário: Miryam Paola Alvarez Flores
• Modalidade de apoio: Auxílio à Pesquisa - Reunião - Exterior
• Processo FAPESP: 07/51889-7 - Expressão e caracterização bioquímica do rLosac, um ativador de fator X recombinante das cerdas da lagarta Lonomia obliqua: mecanismos celulares envolvidos na atividade proliferativa e antiapoptótica
• Beneficiário: Miryam Paola Alvarez Flores
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 08/54092-5 - Expressão e caracterização bioquímica do rLosac, um ativador de fator X recombinante das cerdas da lagarta Lanomia obliqua: mecanismos celulares envolvidos na atividade proliferativa e antiapoptótica
• Beneficiário: Ana Marisa Chudzinski-Tavassi
• Modalidade de apoio: Auxílio à Pesquisa - Regular