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User-friendly, High-throughput, and Fully Automated Data Acquisition Software for Single-particle Cryo-electron Microscopy
Published on: July 29, 2021
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Practical considerations for using K3 cameras in CDS mode for high-resolution and high-throughput single particle
Ming Sun1, Caleigh M Azumaya1, Eric Tse2
1Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, United States.
Journal of Structural Biology
|May 13, 2021
Summary
The Gatan K3 direct detector camera, using correlated-double sampling (CDS) mode, significantly enhances cryo-electron microscopy (cryo-EM) resolution and throughput. Optimal dose rates and magnifications were identified for efficient high-resolution structure determination.
Area of Science:
- Cryo-electron microscopy (cryo-EM)
- Electron detector technology
- Structural biology
Background:
- High-resolution and high-throughput cryo-EM structure determination relies heavily on advanced detector technology.
- The Gatan K3 camera offers improvements over the K2, including higher speed, larger area, and correlated-double sampling (CDS) mode, leading to enhanced detective quantum efficiency (DQE) and throughput.
Purpose of the Study:
- To optimize camera data collection parameters for routine use in cryo-EM facilities.
- To investigate the trade-off between data collection throughput and achieved resolution using the Gatan K3 camera.
- To evaluate the performance of the Gatan K3 camera in CDS mode versus standard mode.
Main Methods:
- Collected eight datasets of murine heavy-chain apoferritin using the Gatan K3 camera.
- Employed varying dose rates and magnifications with a 9-hole image shift data collection strategy.
- Characterized camera performance by analyzing the resolution of resulting 3D reconstructions.
Main Results:
- The Gatan K3 camera in CDS mode consistently outperformed standard mode in reconstruction resolution across all tested conditions.
- An optimal dose rate of 8 electrons per pixel per second was identified.
- At low magnification (64kx), resolutions of 149% of the physical Nyquist limit (1.8 Å) were achieved.
- At moderate magnification (105kx), a resolution of 1.65 Å was obtained within 8 hours of data collection.
- For optimal samples like apoferritin, resolutions better than 2.5 Å can be achieved with just 5 minutes of data collection.
Conclusions:
- The Gatan K3 direct detector, particularly in CDS mode, significantly enhances cryo-EM data collection efficiency and resolution.
- Optimized data collection strategies, including dose rate and magnification selection, are crucial for maximizing throughput and resolution.
- These findings provide valuable guidance for cryo-EM facilities to efficiently image protein complexes and advance structural biology research.
