A d-Amino Acid at the N-Terminus of a Protein Abrogates Its Degradation by the N-End Rule Pathway
Eukaryotes have evolved the ubiquitin (Ub)/proteasome system to degrade polypeptides. The Ub/proteasome system is one way that cells regulate cytosolic protein and amino acids levels through the recognition and ubiquitination of a protein's N-terminus via E1, E2, and E3 enzymes. The process by...
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| Format: | Article |
| Language: | English |
| Published: |
American Chemical Society (ACS),
2017-07-10T19:22:29Z.
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| Online Access: | Get fulltext |
| Summary: | Eukaryotes have evolved the ubiquitin (Ub)/proteasome system to degrade polypeptides. The Ub/proteasome system is one way that cells regulate cytosolic protein and amino acids levels through the recognition and ubiquitination of a protein's N-terminus via E1, E2, and E3 enzymes. The process by which the N-terminus stimulates intracellular protein degradation is referred to as the N-end rule. Characterization of the N-end rule has been limited to only the natural l-amino acids. Using a cytosolic delivery platform derived from anthrax lethal toxin, we probed the stability of mixed chirality proteins, containing one d-amino acid on the N-terminus of otherwise all l-proteins. In all cases, we observed that one N-terminal d-amino acid stabilized the cargo protein to proteasomal degradation with respect to the N-end rule. We found that since the mixed chirality proteins were not polyubiquitinated, they evaded N-end-mediated proteasomal degradation. Evidently, a subtle change on the N-terminus of a natural protein can enhance its intracellular lifetime. MIT Faculty Start-up Fund Massachusetts Institute of Technology. Charles E. Reed Faculty Initiative Fund National Science Foundation (U.S.) (CAREER Award CHE-1351807) Damon Runyon Cancer Research Foundation National Science Foundation (U.S.). Graduate Research Fellowship Program |
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