In situ single-particle Cryo-EM methods: Principle and applications

Area of Science:

• Structural Biology
• Cellular Imaging
• Biophysics

Background:

• Cryo-electron microscopy (cryo-EM) is advancing from in vitro protein analysis to in situ cellular visualization.
• Conventional cryo-electron tomography (cryo-ET) with subtomogram averaging faces resolution limitations due to complex workflows and low throughput.
• Emerging in situ single-particle cryo-EM offers a promising alternative for high-resolution cellular imaging.

Purpose of the Study:

• To review the principles, workflows, and advantages of in situ single-particle cryo-EM methods.
• To highlight key applications of these advanced cryo-EM techniques.
• To discuss future perspectives in in situ structural biology.

Main Methods:

• Collecting high-dose, untilted images of cellular lamellae using in situ single-particle cryo-EM.
• Utilizing high-resolution templates for particle identification and refinement.
• Overcoming limitations of conventional cryo-electron tomography (cryo-ET) and subtomogram averaging.

Main Results:

• Significant advancements in data throughput for in situ cryo-EM.
• Substantial improvements in achievable resolution for macromolecular architecture.
• Enabling direct visualization of cellular structures with unprecedented detail.

Conclusions:

• In situ single-particle cryo-EM methods represent a major leap in visualizing cellular architecture.
• These methods address key limitations of traditional cryo-ET, offering higher resolution and throughput.
• The review provides a comprehensive overview and outlook for this rapidly evolving field.