1. Different Endosomal Proteolysis Requirements for Antigen Processing of Two T-cell Epitopes of the M5 Protein from ViableStreptococcus pyogenes
- Author
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John H. Robinson and Alexei A. Delvig
- Subjects
Streptococcus pyogenes ,T-Lymphocytes ,Proteolysis ,Molecular Sequence Data ,Endosomes ,Biology ,medicine.disease_cause ,Major histocompatibility complex ,Biochemistry ,Epitope ,Serine ,Epitopes ,Mice ,Bacterial Proteins ,medicine ,Animals ,Amino Acid Sequence ,Molecular Biology ,Antigens, Bacterial ,medicine.diagnostic_test ,Antigen processing ,Hydrolysis ,Cell Biology ,Hydrogen-Ion Concentration ,Cysteine Endopeptidases ,biology.protein ,Intracellular ,Cysteine - Abstract
We studied endosomal proteolysis of the surface fibrillar M5 protein from viable Streptococcus pyogenes as an essential step involved in major histocompatibility complex class II-restricted antigen processing of two immunodominant CD4(+) T-cell epitopes (17-31/Ed and 308-319/Ad). Intracellular proteolysis of viable streptococci for presentation of 17-31, bound by serine proteinase cleavage sites, was mediated by serine proteinases, whereas processing of soluble recombinant M5 protein required in addition cysteine proteinases. Furthermore, processing of 17-31 was resistant to ammonium chloride and thus was not dependent on endosome acidification. Cysteine and serine proteinase cleavage sites were located adjacent to 308-319, and its processing was dependent on serine, cysteine, and aspartic proteinases, as well as on endosomal acidification. The data suggest that antigen processing of two major T-cell epitopes on streptococcal M5 protein occurred in different endosomal compartments by different classes of intracellular proteinases.
- Published
- 1998
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