A PDMS-based Microfluidic Chip Assembly for Time-Resolved Cryo-EM (TRCEM) Sample Preparation.

Area of Science:

• Structural Biology
• Biochemistry
• Biophysics

Background:

• Time-resolved cryo-EM (TR-cryo-EM) enables structural and kinetic studies of biomolecular reactions before equilibrium.
• Existing TR-cryo-EM methods have limitations in capturing events on the millisecond timescale.
• Studying transient intermediates is crucial for understanding molecular mechanisms.

Purpose of the Study:

• To develop and validate a novel TR-cryo-EM setup for capturing pre-equilibrium biomolecular states.
• To demonstrate the setup's capability in addressing challenges like sample adsorption and inefficient mixing.
• To investigate the mechanism of ribosome recycling mediated by HflX.

Main Methods:

• Utilized a polydimethylsiloxane (PDMS)-based microfluidics chip assembly.
• Incorporated a SiO2-coated micromixer, a glass-capillary microreactor, and a microsprayer.
• Applied the method to study ribosome recycling by High frequency of lysogenization X (HflX).

Main Results:

• The developed TR-cryo-EM setup effectively prepares samples within the 10-1,000 ms time range.
• Demonstrated high reproducibility and addressed issues of sample adsorption and mixing.
• Provided biologically significant, reproducible structural and kinetic information on HflX-mediated ribosome recycling.

Conclusions:

• The novel microfluidics-based TR-cryo-EM protocol offers a powerful approach for studying fast biomolecular processes.
• This method yields crucial insights into pre-equilibrium intermediates, advancing our understanding of molecular mechanisms.
• The technique holds promise for diverse applications in structural and kinetic biology.