PMID:12000756
| Citation |
Que, X, Ngo, H, Lawton, J, Gray, M, Liu, Q, Engel, J, Brinen, L, Ghosh, P, Joiner, KA and Reed, SL (2002) The cathepsin B of Toxoplasma gondii, toxopain-1, is critical for parasite invasion and rhoptry protein processing. J. Biol. Chem. 277:25791-7 |
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| Abstract |
Cysteine proteinases play a major role in invasion and intracellular survival of a number of pathogenic parasites. We cloned a single copy gene, tgcp1, from Toxoplasma gondii and refolded recombinant enzyme to yield active proteinase. Substrate specificity of the enzyme and homology modeling identified the proteinase as a cathepsin B. Specific cysteine proteinase inhibitors interrupted invasion by tachyzoites. The T. gondii cathepsin B localized to rhoptries, secretory organelles required for parasite invasion into cells. Processing of the pro-rhoptry protein 2 to mature rhoptry proteins was delayed by incubation of extracellular parasites with a cathepsin B inhibitor prior to pulse-chase immunoprecipitation. Delivery of cathepsin B to mature rhoptries was impaired in organisms with disruptions in rhoptry formation by expression of a dominant negative micro1-adaptin. Similar disruption of rhoptry formation was observed when infected fibroblasts were treated with a specific inhibitor of cathepsin B, generating small and poorly developed rhoptries. This first evidence for localization of a cysteine proteinase to the unusual rhoptry secretory organelle of an apicomplexan parasite suggests that the rhoptries may be a prototype of a lysosome-related organelle and provides a critical link between cysteine proteinases and parasite invasion for this class of organism. |
| Links |
PubMed Online version:10.1074/jbc.M202659200 |
| Keywords |
Amino Acid Sequence; Animals; Base Sequence; Cloning, Molecular; Cysteine Endopeptidases/chemistry; Cysteine Endopeptidases/genetics; Cysteine Endopeptidases/metabolism; Cysteine Proteinase Inhibitors/pharmacology; DNA Primers; Membrane Proteins/chemistry; Membrane Proteins/metabolism; Microscopy, Immunoelectron; Molecular Sequence Data; Protein Conformation; Protein Processing, Post-Translational; Protozoan Proteins/chemistry; Protozoan Proteins/metabolism; Sequence Homology, Amino Acid; Toxoplasma/enzymology; Toxoplasma/physiology |
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