Solving protein structure from sparse serial microcrystal diffraction data at a storage-ring synchrotron source

Area of Science:

• Structural Biology
• Biophysics
• Crystallography

Background:

• Serial microcrystallography (SMC) at synchrotron sources faces challenges with small crystals due to radiation damage and weak diffraction.
• Conventional indexing methods often fail for small crystals, leading to data loss.

Purpose of the Study:

• To introduce and validate a novel method, the expand-maximize-compress (EMC) algorithm, for analyzing weak diffraction data in SMC.
• To enable structure determination from data frames typically discarded by standard indexing software.

Main Methods:

• Development and application of the expand-maximize-compress (EMC) algorithm.
• Testing the EMC algorithm on a serial microcrystallography dataset with weak diffraction signals and significant background scatter.

Main Results:

• Successfully solved a protein structure at 2.1 Å resolution using the EMC algorithm on weak data.
• Demonstrated the algorithm's effectiveness despite challenging background noise from the sample delivery medium.

Conclusions:

• The EMC algorithm enhances serial microcrystallography by enabling analysis of weak diffraction data from small crystals.
• This method reduces sample consumption and expands the feasibility of SMC at storage-ring sources.