FELIX: an algorithm for indexing multiple crystallites in X-ray free-electron laser snapshot diffraction images

Area of Science:

• Crystallography
• Structural Biology
• Biophysics

Background:

• Serial crystallography enables the study of dynamic biological processes using X-ray diffraction.
• Indexing multiple crystals per diffraction image is crucial for maximizing data collection efficiency.
• Current indexing methods can be limited in handling complex datasets with numerous crystals.

Purpose of the Study:

• To introduce FELIX, a novel algorithm for indexing multiple crystals in X-ray diffraction images.
• To demonstrate FELIX's capability in handling diverse crystal systems and high crystal densities.
• To evaluate the impact of indexing multiple crystals on data quality and collection efficiency in serial crystallography.

Main Methods:

• Development of FELIX, an algorithm based on a generalized parametrization of Rodrigues-Frank space.
• Simulation of diffraction patterns for cubic, tetragonal, and monoclinic crystal systems with multiple crystals.
• Application of FELIX to an experimental serial crystallography dataset of lysozyme microcrystals.

Main Results:

• FELIX successfully indexes over ten crystals per image in simulations across various crystal systems.
• The algorithm effectively processed an experimental serial crystallography dataset.
• Indexing multiple crystals per image significantly improved the signal-to-noise ratio.
• Fewer images were required to achieve the same data quality compared to single-crystal indexing.

Conclusions:

• FELIX offers a robust solution for indexing multiple crystals in serial crystallography.
• The algorithm enhances data collection efficiency and quality by maximizing information from each X-ray diffraction image.
• Analysis of lysozyme microcrystals revealed a tendency for crystals to adhere on specific facets.