Reproducible radiation-damage processes in proteins irradiated by intense x-ray pulses

Area of Science:

• Structural Biology
• Biophysics
• Crystallography

Background:

• X-ray free-electron lasers (XFELs) enable femtosecond protein nanocrystallography for protein structure determination.
• This method allows time-resolved imaging of nanocrystals too small for conventional crystallography.
• Short XFEL pulse durations mitigate radiation damage by scattering before significant sample alteration.

Purpose of the Study:

• To investigate the damage cascade in ferredoxin crystals induced by high-intensity XFEL pulses.
• To determine if the diffraction process self-terminates due to radiation damage.
• To analyze the reproducibility and correlations within the damage process for imaging applications.

Main Methods:

• Computational modeling of damage cascades in ferredoxin crystals under XFEL irradiation.
• Analysis of atomic displacements and their effect on Bragg diffraction.
• Assessment of damage reproducibility and correlations among protein monomers.

Main Results:

• High-intensity XFEL pulses initiate a cascade of damage processes in ferredoxin crystals.
• The damage process exhibits initial non-random correlations among protein monomers.
• Bragg diffraction persists in damaged crystals despite significant atomic displacements.

Conclusions:

• The damage process in femtosecond protein nanocrystallography is reproducible to a degree.
• These findings have potential benefits for the orientation step in single-molecule imaging.
• Understanding radiation damage mechanisms is crucial for advancing XFEL-based structural biology.