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Published on: January 30, 2016
Annealing synchronizes the TOM complex with Tom7 in a new orientation
Liuyan Yang1, Mingdong Liu2, Lei Qi3
1Marine Biotechnology Research Center, State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, China; School of Life Sciences, Department of Chemical Biology, Southern University of Science and Technology, Shenzhen, 518055, China; Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, 266237, China; Division of Healthy Oceans & Resource Sustainability, Laoshan Laboratory, Qingdao, 266237, China; Institute for Biological Electron Microscopy, Southern University of Science and Technology, Shenzhen, 518055, China.
Annealing improves membrane protein structural determination. Fast cooling of the translocase of the outer mitochondrial membrane (TOM) complex to 0°C enhances resolution and reveals new conformations for protein translocation.
Area of Science:
- Structural biology
- Membrane protein biophysics
- Cryo-electron microscopy
Background:
- Protein annealing synchronizes soluble proteins into minimum-energy states.
- Membrane proteins exhibit flexibility, hindering high-resolution structural determination.
- Applying annealing to membrane proteins is an unexplored area.
Purpose of the Study:
- Investigate ideal annealing conditions for membrane proteins.
- Determine the effect of annealing on the translocase of the outer mitochondrial membrane (TOM) complex structure.
- Explore novel conformations of the TOM complex.
Main Methods:
- Utilized the translocase of the outer mitochondrial membrane (TOM) complex as a model system.
- Applied annealing techniques involving controlled heating and rapid cooling (to 0°C).
- Determined high-resolution structures using cryo-electron microscopy.
Main Results:
- Fast cooling of the heated TOM complex to 0°C significantly improved local resolution compared to unannealed samples.
- Annealing induced a conformational change in the TOM complex.
- Observed a shift in the Tom7 α1 helix and a flip in the loop between β6 and β7 in Tom40, facilitating preprotein translocation.
Conclusions:
- Demonstrated the efficacy of annealing in synchronizing membrane proteins.
- Unveiled previously unidentified conformations of the TOM complex.
- Highlighted the potential of annealing for advancing membrane protein structural studies.
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