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Thermoplasma acidophilum proteasomes degrade partially unfolded and ubiquitin‐associated proteins
Author(s) -
Wenzel Thorsten,
Baumeister Wolfgang
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)81793-y
Subject(s) - thermoplasma acidophilum , proteasome , ubiquitin , chaotropic agent , biochemistry , substrate (aquarium) , protein degradation , biology , proteolysis , chemistry , microbiology and biotechnology , enzyme , ecology , gene
It is shown that proteasomes from the archaebacterium Thermoplasma acidophilum selectively degrade substrate proteins partially unfolded by phenylhydrazine‐ or hydrogen peroxide‐treatment. Surprisingly, the pre‐incubation of the substrate proteins with ubiquitin is also sufficient to render them susceptible to proteolytic degradation by proteasomes. We propose that, upon spontaneously associating with the substrate protein, ubiquitin exerts a chaotropic effect on it; this may involve the exposure of hydrophobic segments of the polypeptide chain which are recognized by the binding sites of the proteasome.