Jaramillo-Martinez, Valeria, Dominguez, Matthew J, Bell, Gemma M, Souness, Megan E, Carhart, Anna H, Cuibus, M Adriana, Masoumzadeh, Elahe, Lantz, Benjamin J, Adkins, Aaron J, Latham, Michael P et al (show 2 more authors)
(2023)
How a highly acidic SH3 domain folds in the absence of its charged peptide target.
Protein science : a publication of the Protein Society, 32 (5).
e4635-e4635.
Abstract
Charged residues on the surface of proteins are critical for both protein stability and interactions. However, many proteins contain binding regions with a high net-charge that may destabilize the protein but are useful for binding to oppositely charged targets. We hypothesized that these domains would be marginally stable, as electrostatic repulsion would compete with favorable hydrophobic collapse during folding. Furthermore, by increasing the salt concentration we predict that these protein folds would be stabilized by mimicking some of the favorable electrostatic interactions that take place during target binding. We varied the salt and urea concentrations to probe the contributions of electrostatic and hydrophobic interactions for the folding of the yeast SH3 domain found in Abp1p. The SH3 domain was significantly stabilized with increased salt concentrations due to Debye-Huckel screening and a non-specific territorial ion binding effect. Molecular dynamics and NMR show that sodium ions interact with all 15 acidic residues but do little to change backbone dynamics or overall structure. Folding kinetics experiments show that the addition of urea or salt primarily affects the folding rate, indicating that almost all the hydrophobic collapse and electrostatic repulsion occurs in the transition state. After the transition state formation, modest yet favorable short-range salt-bridges are formed along with hydrogen bonds, as the native state fully folds. Thus, hydrophobic collapse offsets electrostatic repulsion to ensure this highly charged binding domain can still fold and be ready to bind to its charged peptide targets, a property that is likely evolutionarily conserved over one billion years. This article is protected by copyright. All rights reserved.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Debye-Huckel, domain-peptide binding, electrostatic interactions, folding kinetics, protein folding, protein-ion interactions, SH3 domain, transition state |
| Divisions: | Faculty of Health and Life Sciences Faculty of Health and Life Sciences > Institute of Systems, Molecular and Integrative Biology Faculty of Health and Life Sciences > Institute of Systems, Molecular and Integrative Biology > School of Life Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 21 Apr 2023 09:11 |
| Last Modified: | 13 Jul 2023 07:44 |
| DOI: | 10.1002/pro.4635 |
| Open Access URL: | https://doi.org/10.1002/pro.4635 |
| Related URLs: | |
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3169832 |
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