Expression of mammalian cytokines by Trypanosoma cruzi indicates unique signal sequence requirements and processing

• Published in: Molecular and biochemical parasitology 1995-12, Vol.75 (1), p.25-31
• Main Authors: La Flamme, Anne C., Buckner, Frederick S., Swindle, John, Ajioka, Janet, Van Voorhis, Wesley C.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Biological Assay; Chromatography, Affinity; Cytokines - biosynthesis; Cytokines - isolation & purification; Cytokines - pharmacology; Enzyme-Linked Immunosorbent Assay; Gene Expression; Interferon-gamma - biosynthesis; Interferon-gamma - isolation & purification; Interferon-gamma - pharmacology; Interleukin-2 - biosynthesis; Interleukin-2 - isolation & purification; Interleukin-2 - pharmacology; Mammals; Mice; Molecular Sequence Data; Protein Sorting Signals - metabolism; Rats; Recombinant Proteins - biosynthesis; Recombinant Proteins - isolation & purification; Recombinant Proteins - pharmacology; Signal peptide; T-Lymphocytes, Cytotoxic - drug effects; T-Lymphocytes, Cytotoxic - immunology; Transfection; Trypanosoma cruzi; Trypanosoma cruzi - metabolism
• ISSN: 0166-6851; 1872-9428
• DOI: 10.1016/0166-6851(95)02506-5

A vector based upon the calmodulin-ubiquitin 2.65 locus of Trypanosoma cruzi has enabled the expression and secretion of the murine cytokines interleukin-2 (IL-2) and gamma-interferon (γ-IFN) by transfected T. cruzi. The T. cruzi-derived cytokines were bioactive and produced by both epimastigotes and mammalian forms. The native coding sequence of IL-2 was sufficient to cause secretion of the protein, but the γ-IFN signal sequence had to be replaced by the IL-2 signal sequence (IL-2/γ-IFN) to allow efficient secretion of γ-IFN. The amino acid sequences at the N-termini of the secreted T. cruzi-derived cytokines were different from the expected murine secreted protein. The secreted IL-2 was cleaved six amino acids downstream from the murine signal sequence cleavage site, and the hybrid IL-2/γ-IFN molecule was cleaved three amino acids downstream from the predicted signal cleavage site in the IL-2/γ-IFN molecule. These apparent differences in signal peptide sequence requirements and cleavage sites most likely indicate that the signal sequence processing in trypanosomes is distinct from that of higher eukaryotes.