Procyclin gene expression and loss of the variant surface glycoprotein during differentiation of Trypanosoma brucei.
J Cell Biol
; 108(2): 737-46, 1989 Feb.
Article
em En
| MEDLINE
| ID: mdl-2645304
ABSTRACT
In the mammalian host, the unicellular flagellate Trypanosoma brucei is covered by a dense surface coat that consists of a single species of macromolecule, the membrane form of the variant surface glycoprotein (mfVSG). After uptake by the insect vector, the tsetse fly, bloodstream-form trypanosomes differentiate to procyclic forms in the fly midgut. Differentiation is characterized by the loss of the mfVSG coat and the acquisition of a new surface glycoprotein, procyclin. In this study, the change in surface glycoprotein composition during differentiation was investigated in vitro. After triggering differentiation, a rapid increase in procyclin-specific mRNA was observed. In contrast, there was a lag of several hours before procyclin could be detected. Procyclin was incorporated and uniformly distributed in the surface coat. The VSG coat was subsequently shed. For a single cell, it took 12-16 h to express a maximum level of procyclin at the surface while the loss of the VSG coat required approximately 4 h. The data are discussed in terms of the possible molecular arrangement of mfVSG and procyclin at the cell surface. Molecular modeling data suggest that a (Asp-Pro)2 (Glu-Pro)22-29 repeat in procyclin assumes a cylindrical shape 14-18 nm in length and 0.9 nm in diameter. This extended shape would enable procyclin to interdigitate between the mfVSG molecules during differentiation, exposing epitopes beyond the 12-15-nm-thick VSG coat.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Trypanosoma brucei brucei
/
Glicoproteínas Variantes de Superfície de Trypanosoma
/
Regulação da Expressão Gênica
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
1989
Tipo de documento:
Article