Abstract
Molecular crowding, a ubiquitous feature of the cellular environment, has significant implications in the kinetics and equilibrium of biopolymer interactions. In this study, a single charged polypeptide is exposed to competing forces that drive it into a transmembrane protein pore versus forces that pull it outside. Using single-molecule electrophysiology, we provide compelling experimental evidence that the kinetic details of the polypeptide-pore interactions are substantially affected by high concentrations of less-penetrating polyethylene glycols (PEGs). At a polymer concentration above a critical value, the presence of these neutral macromolecular crowders increases the rate constant of association but decreases the rate constant of dissociation, resulting in a stronger polypeptide-pore interaction. Moreover, a larger-molecular weight PEG exhibits a lower rate constant of association but a higher rate constant of dissociation than those values corresponding to a smaller-molecular weight PEG. These outcomes are in accord with a lower diffusion constant of the polypeptide and higher depletion-attraction forces between the polypeptide and transmembrane protein pore under crowding and confinement conditions.
Original language | English (US) |
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Pages (from-to) | 4469-4477 |
Number of pages | 9 |
Journal | ACS nano |
Volume | 13 |
Issue number | 4 |
DOIs | |
State | Published - Apr 23 2019 |
Keywords
- free-energy landscape
- peptide-protein interactions
- polymer
- single-channel electrical recordings
- single-molecule kinetics
- α-hemolysin
ASJC Scopus subject areas
- General Materials Science
- General Engineering
- General Physics and Astronomy