Baliga, C and Selmke, B and Worobiew, I and Borbat, P and Sarma, SP and Trommer, WE and Varadarajan, R and Aghera, N (2019) CcdB at pH 4 Forms a Partially Unfolded State with a Dry Core. In: Biophysical Journal, 116 (5). pp. 807-817.
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Abstract
pH is an important factor that affects the protein structure, stability, and activity. Here, we probe the nature of the low-pH structural form of the homodimeric CcdB (controller of cell death B) protein. Characterization of CcdB protein at pH 4 and 300 K using circular dichroism spectroscopy, 8-anilino-1-naphthalene-sulphonate binding, and Trp solvation studies suggests that it forms a partially unfolded state with a dry core at equilibrium under these conditions. CcdB remains dimeric at pH 4 as shown by multiple techniques, such as size-exclusion chromatography coupled to multiangle light scattering, analytical ultracentrifugation, and electron paramagnetic resonance. Comparative analysis using two-dimensional 15 N- 1 H heteronuclear single-quantum coherence NMR spectra of CcdB at pH 4 and 7 suggests that the pH 4 and native state have similar but nonidentical structures. Hydrogen-exchange-mass-spectrometry studies demonstrate that the pH 4 state has substantial but anisotropic changes in local stability with core regions close to the dimer interface showing lower protection but some other regions showing higher protection relative to pH 7.
| Item Type: | Journal Article |
|---|---|
| Publication: | Biophysical Journal |
| Publisher: | Biophysical Society |
| Additional Information: | The copyright for this article belongs to the Author(s). |
| Keywords: | bacterial protein; CcdB protein, Plasmid F, anisotropy; chemistry; hydrogen bond; molecular model; pH; protein multimerization; protein quaternary structure; protein unfolding, Anisotropy; Bacterial Proteins; Hydrogen Bonding; Hydrogen-Ion Concentration; Models, Molecular; Protein Multimerization; Protein Structure, Quaternary; Protein Unfolding |
| Department/Centre: | Division of Biological Sciences > Molecular Biophysics Unit |
| Date Deposited: | 31 Oct 2022 11:11 |
| Last Modified: | 31 Oct 2022 11:11 |
| URI: | https://eprints.iisc.ac.in/id/eprint/77706 |
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