Quantitative analysis of prion-protein degradation by constitutive and immuno-20S proteasomes indicates differences correlated with disease susceptibility.
The main part of cytosolic protein degradation depends on the ubiquitin-proteasome system. Proteasomes degrade their substrates into small peptide fragments, some of which are translocated into the endoplasmatic reticulum and loaded onto MHC class I molecules, which are then transported to the cell surface for inspection by CTL. A reliable prediction of proteasomal cleavages in a given protein for the identification of CTL epitopes would benefit immensely from additional cleavage data for the training of prediction algorithms. To increase the knowledge about proteasomal specificity and to gain more insight into the relation of proteasomal activity and susceptibility to prion disease, we digested sheep prion protein with human constitutive and immuno-20S proteasomes. All fragments generated in the digest were quantified. Our results underline the different cleavage specificities of constitutive and immunoproteasomes and provide data for the training of prediction programs for proteasomal cleavages. Furthermore, the kinetic analysis of proteasomal digestion of two different alleles of prion protein shows that even small changes in a protein sequence can affect the overall efficiency of proteasomal processing and thus provides more insight into the possible molecular background of allelic variations and the pathogenicity of prion proteins.
Tenzer
Stefan
S
Department of Immunology, Institute for Cell Biology, University of Tübingen, Tübingen, Germany.
Stoltze
Lars
L
Schönfisch
Birgitt
B
Dengjel
Jörn
J
Müller
Margret
M
Stevanović
Stefan
S
Rammensee
Hans-Georg
HG
Schild
Hansjörg
H
D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D002461:Cell Line, Transformed; D003546:Cysteine Endopeptidases / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D004198:Disease Susceptibility / Q000276:immunology; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism; D010449:Peptide Mapping / Q000379:methods; D011328:Prions / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012756:Sheep
D009097:Multienzyme Complexes; D010446:Peptide Fragments; D011328:Prions; D011994:Recombinant Proteins; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex