These authors contributed equally to this work.
Dual energy landscape: The functional state of the β-barrel outer membrane protein G molds its unfolding energy landscape†
Article first published online: 5 NOV 2010
Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Special Issue: Focus on Physical Principles of Protein Behavior in the Cell
Volume 10, Issue 23, pages 4151–4162, No. 23 December 2010
How to Cite
Damaghi, M., Sapra, K. T., Köster, S., Yildiz, Ö., Kühlbrandt, W. and Muller, D. J. (2010), Dual energy landscape: The functional state of the β-barrel outer membrane protein G molds its unfolding energy landscape. Proteomics, 10: 4151–4162. doi: 10.1002/pmic.201000241
Colour Online: See the article online to view fig. 3 in colour.
- Issue published online: 26 NOV 2010
- Article first published online: 5 NOV 2010
- Accepted manuscript online: 30 SEP 2010 03:22AM EST
- Manuscript Accepted: 17 MAY 2010
- Manuscript Revised: 16 MAY 2010
- Manuscript Received: 13 APR 2010
- DFG. Grant Numbers: YI 96/3-1, MU 1791
- Atomic force microscopy;
- Mechanical properties;
- pH gating;
- Single-molecule force spectroscopy
We applied dynamic single-molecule force spectroscopy to quantify the parameters (free energy of activation and distance of the transition state from the folded state) characterizing the energy barriers in the unfolding energy landscape of the outer membrane protein G (OmpG) from Escherichia coli. The pH-dependent functional switching of OmpG directs the protein along different regions on the unfolding energy landscape. The two functional states of OmpG take the same unfolding pathway during the sequential unfolding of β-hairpins I–IV. After the initial unfolding events, the unfolding pathways diverge. In the open state, the unfolding of β-hairpin V in one step precedes the unfolding of β-hairpin VI. In the closed state, β-hairpin V and β-strand S11 with a part of extracellular loop L6 unfold cooperatively, and subsequently β-strand S12 unfolds with the remaining loop L6. These two unfolding pathways in the open and closed states join again in the last unfolding step of β-hairpin VII. Also, the conformational change from the open to the closed state witnesses a rigidified extracellular gating loop L6. Thus, a change in the conformational state of OmpG not only bifurcates its unfolding pathways but also tunes its mechanical properties for optimum function.