期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 115, 期 45, 页码 11525-11530出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1803872115
关键词
proteases; mechanics; single molecule; enzymology; torsional free energy
资金
- Horizon 2020 Marie Sklodowska-Curie Actions Individual Fellowship [656721]
- Ministerio De Economia Y Competitividad (MINECO)
- Fonds Europeen de Developpement Economique et Regional (FEDER-EU) [BFU2016-77427-C2-2-R, SEV-2016-0644]
- Initiative d'Excellence program from the French State Grant DYNAMO [ANR-11-LABX-0011-01]
- Marie Curie Actions (MSCA) [656721] Funding Source: Marie Curie Actions (MSCA)
An immense repertoire of protein chemical modifications catalyzed by enzymes is available as proteomics data. Quantifying the impact of the conformational dynamics of the modified peptide remains challenging to understand the decisive kinetics and amino acid sequence specificity of these enzymatic reactions in vivo, because the target peptide must be disordered to accommodate the specific enzyme-binding site. Here, we were able to control the conformation of a single-molecule peptide chain by applying mechanical force to activate and monitor its specific cleavage by a model protease. We found that the conformational entropy impacts the reaction in two distinct ways. First, the flexibility and accessibility of the substrate peptide greatly increase upon mechanical unfolding. Second, the conformational sampling of the disordered peptide drives the specific recognition, revealing force-dependent reaction kinetics. These results support a mechanism of peptide recognition based on conformational selection from an ensemble that we were able to quantify with a torsional free-energy model. Our approach can be used to predict how entropy affects site-specific modifications of proteins and prompts conformational and mechanical selectivity.
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