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OzTracs: Optical Osmolality Reporters Engineered from Mechanosensitive Ion Channels.
Thomas J Kleist1,2, I Winnie Lin2,3, Sophia Xu2,3,4
1Institute for Molecular Physiology, Heinrich Heine University, 40225 Düsseldorf, Germany.
Biomolecules
|June 24, 2022
Summary
Researchers developed genetically encoded osmolality sensors (OzTracs) by fusing fluorescent proteins to mechanosensitive ion channels. These OzTrac sensors report changes in osmolality via fluorescence, enabling new ways to study cellular responses.
Area of Science:
- Biophysics
- Cell Biology
- Molecular Biology
Background:
- Physical forces and membrane proteins are crucial for environmental sensing and acclimation in organisms.
- Mechanically gated ion channels and osmolyte transporters help microbes adapt to osmotic stress.
- Plant mechanosensitive ion channels play roles in defense signaling.
Purpose of the Study:
- To engineer genetically encoded osmolality sensors (OzTracs) for reporting cellular osmolality changes.
- To investigate the function of these sensors in living cells.
Main Methods:
- Fusion of fluorescent protein spectral variants to mechanosensitive ion channels (MscL from E. coli, MSL10 from A. thaliana).
- Expression of engineered OzTrac sensors in yeast cells.
- Live-cell imaging to observe sensor behavior and localization.
Main Results:
- OzTrac sensors successfully reported osmolality changes as proportional shifts in fluorescence emission ratios.
- Accumulation of fluorescent sensors in internal aggregates within yeast cells was observed.
- The sensors function as osmolality-dependent reporters through indirect mechanisms.
Conclusions:
- Genetically encoded OzTrac sensors provide a novel tool for monitoring cellular osmolality.
- The indirect reporting mechanism involves factors like molecular crowding or fluorophore solvation.
- OzTrac technology has potential applications in studying cellular stress responses and adaptation.
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