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Adaptor‐guided proteolysis initiates on the ribosome (932.1)
Author(s) -
Puri Neha,
Karzai Wali
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.932.1
Subject(s) - proteolysis , degron , ribosome , signal transducing adaptor protein , translation (biology) , biochemistry , biology , microbiology and biotechnology , proteases , chemistry , rna , ubiquitin , messenger rna , enzyme , signal transduction , gene , ubiquitin ligase
Adaptor proteins extend the substrate range and specificity of AAA+ proteases. The SspB adaptor protein enhances the efficiency of ClpXP mediated degradation of tmRNA‐tagged proteins. We have investigated the mechanism by which SspB captures tag‐bearing proteins. Our inquiries reveal that SspB associates with tmRNA‐rescued ribosomes in a trans‐translation dependent manner, in a process reliant on distinct recognition signals within the appended tmRNA degron. Specific alterations in the tmRNA peptide sequence or the peptide‐binding groove of SspB have adverse effects on the efficiency of SspB ribosome association and the subsequent degradation of marked proteins. Our studies have also unveiled the ability of SspB to capture additional nascent polypeptides that harbor genetically encoded yet degenerate forms of the tmRNA degron and modulate their intracellular levels through directed proteolysis. Based on these findings, we propose that SspB scans translating ribosomes to capture signal‐bearing proteins for guided proteolysis by the ClpXP protease. Grant Funding Source : Supported by NIH