RESUMO
Trypanosomes encode a family of proteins known as Major Surface Metalloproteases (MSPs). We have identified six putative MSPs encoded within the partially sequenced T. congolense genome. Phylogenic analysis indicates that T. congolense MSPs belong to five subfamilies that are conserved among African trypanosome species. Molecular modeling, based on the known structure of Leishmania Major GP63, reveals subfamily-specific structural variations around the putative active site despite conservation of overall structure, suggesting that each MSP subfamily has evolved to recognize distinct substrates. We have cloned and purified a protein encoding the amino-terminal domain of the T. congolense homologue TcoMSP-D (most closely related to Leishmania GP63). We detect TcoMSP-D in the serum of T. congolense-infected mice. Mice immunized with the amino-terminal domain of TcoMSP-D generate a persisting IgG1 antibody response. Surprisingly, a low-dose challenge of immunized mice with T. congolense significantly increases susceptibility to infection, indicating that immunity to TcoMSP-D is a factor affecting virulence.
Assuntos
Metaloproteases/fisiologia , Proteínas de Protozoários/fisiologia , Trypanosoma congolense/enzimologia , Sequência de Aminoácidos , Análise de Variância , Animais , Anticorpos Antiprotozoários/metabolismo , Antígenos de Protozoários/genética , Antígenos de Protozoários/imunologia , Antígenos de Protozoários/metabolismo , Modelos Animais de Doenças , Feminino , Imunoglobulina G/metabolismo , Metaloproteases/genética , Metaloproteases/imunologia , Metaloproteases/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Modelos Moleculares , Dados de Sequência Molecular , Filogenia , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , Proteínas de Protozoários/metabolismo , Coelhos , Alinhamento de Sequência , Tripanossomíase AfricanaRESUMO
The sensitivity of delta red-gam delta ren mutants of bacteriophage lambda to Rex exclusion by lambda rexA+ rexB+ lysogens is modulated by the prophage cI repressor allele. We show the following: (i) lambda spi156 delta nin5 forms plaques on a cI+-rexA+-rexB+ lysogen with 10(5)-fold higher efficiency than on cI[Ts]-rexA+-rexB+ derivatives. (ii) The cI[Ts]857 allele augmentation of Rex exclusion is recessive to cI+. (iii) The cI857-mediated increase in Rex exclusion activity involves the participation of a genetic element mapping outside of cI-rexA-rexB.