AI Article Synopsis
- The study explores how helical membrane proteins, like Escherichia coli rhomboid protease GlpG, fold and unfold in environments that mimic their natural lipid membranes.
- Using magnetic tweezers for single-molecule forced unfolding experiments, the researchers found that these proteins unfold in a coordinated manner when subjected to mechanical tension.
- They characterized the energy landscape of GlpG, noting moderate thermodynamic stability but a significant energy barrier that helps maintain its folded state and prevent the formation of partially unfolded states.
Article Abstract
Membrane proteins are designed to fold and function in a lipid membrane, yet folding experiments within a native membrane environment are challenging to design. Here we show that single-molecule forced unfolding experiments can be adapted to study helical membrane protein folding under native-like bicelle conditions. Applying force using magnetic tweezers, we find that a transmembrane helix protein, Escherichia coli rhomboid protease GlpG, unfolds in a highly cooperative manner, largely unraveling as one physical unit in response to mechanical tension above 25 pN. Considerable hysteresis is observed, with refolding occurring only at forces below 5 pN. Characterizing the energy landscape reveals only modest thermodynamic stability (ΔG = 6.5 kBT) but a large unfolding barrier (21.3 kBT) that can maintain the protein in a folded state for long periods of time (t1/2 ∼3.5 h). The observed energy landscape may have evolved to limit the existence of troublesome partially unfolded states and impart rigidity to the structure.
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Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4986997 | PMC |
| http://dx.doi.org/10.1038/nchembio.1939 | DOI Listing |
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