Protease Trafficking in Two Primitive Eukaryotes Is Mediated by a Prodomain Protein Motif

Trypanosome protozoa, an early lineage of eukaryotic cells, have proteases homologous to mammalian lysosomal cathepsins, but the precursor proteins lack mannose 6-phosphate. Utilizing green fluorescent protein as a reporter, we demonstrate that the carbohydrate-free prodomain of a trypanosome cathep...

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Bibliographic Details
Published in:The Journal of biological chemistry 1999-06, Vol.274 (23), p.16249-16256
Main Authors: Huete-Pérez, J A, Engel, J C, Brinen, L S, Mottram, J C, McKerrow, J H
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Amino Acid Substitution
Animals
Biological Transport
Cell Compartmentation
Cysteine Endopeptidases - genetics
Cysteine Endopeptidases - metabolism
Enzyme Precursors - genetics
Enzyme Precursors - metabolism
Green Fluorescent Proteins
Leishmania mexicana - enzymology
Luminescent Proteins
Microscopy, Confocal
Molecular Sequence Data
Mutagenesis, Site-Directed
Protozoan Proteins - genetics
Protozoan Proteins - metabolism
Sequence Alignment
Structure-Activity Relationship
Trypanosoma
Trypanosoma cruzi - enzymology
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Summary:Trypanosome protozoa, an early lineage of eukaryotic cells, have proteases homologous to mammalian lysosomal cathepsins, but the precursor proteins lack mannose 6-phosphate. Utilizing green fluorescent protein as a reporter, we demonstrate that the carbohydrate-free prodomain of a trypanosome cathepsin L is necessary and sufficient for directing green fluorescent protein to the lysosome/endosome compartment. A proper prodomain/catalytic domain processing site sequence is also required to free the mature protease for delivery to the lysosome/endosome compartment. A nine-amino acid prodomain loop motif, implicated in prodomain-receptor interactions in mammalian cells, is conserved in the protozoa. Site-directed mutagenesis now confirms the importance of this loop to protease trafficking and suggests that a protein motif targeting signal for lysosomal proteases arose early in eukaryotic cell evolution.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.274.23.16249