Expression of mammalian cytokines by Trypanosoma cruzi indicates unique signal sequence requirements and processing.
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 (gamma-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 gamma-IFN signal sequence had to be replaced by the IL-2 signal sequence (IL-2/gamma-IFN) to allow efficient secretion of gamma-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/gamma-IFN molecule was cleaved three amino acids downstream from the predicted signal cleavage site in the IL-2/gamma-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.
La Flamme
A C
AC
Department of Pathobiology, University of Washington, Seattle 98195, USA.
Buckner
F S
FS
Swindle
J
J
Ajioka
J
J
Van Voorhis
W C
WC
D000595:Amino Acid Sequence; D000818:Animals; D001681:Biological Assay; D002846:Chromatography, Affinity; D016207:Cytokines / Q000096:biosynthesis* / Q000302:isolation & purification / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D015870:Gene Expression; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000302:isolation & purification / Q000494:pharmacology; D007376:Interleukin-2 / Q000096:biosynthesis* / Q000302:isolation & purification / Q000494:pharmacology; D008322:Mammals; D051379:Mice; D008969:Molecular Sequence Data; D021382:Protein Sorting Signals / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000494:pharmacology; D013602:T-Lymphocytes, Cytotoxic / Q000187:drug effects / Q000276:immunology; D014162:Transfection; D014349:Trypanosoma cruzi / Q000378:metabolism*
D016207:Cytokines; D007376:Interleukin-2; D021382:Protein Sorting Signals; D011994:Recombinant Proteins; D007371:Interferon-gamma