Processing of Multicrystal Diffraction Patterns in Macromolecular Crystallography Using Serial Crystallography Programs

Ki Hyun Nam

doi:10.3390/cryst12010103

Abstract

Cryocrystallography is a widely used method for determining the crystal structure of macromolecules. This technique uses a cryoenvironment, which significantly reduces the radiation damage to the crystals and has the advantage of requiring only one crystal for structural determination. In standard cryocrystallography, a single crystal is used for collecting diffraction data, which include single-crystal diffraction patterns. However, the X-ray data recorded often may contain diffraction patterns from several crystals. The indexing of multicrystal diffraction patterns in cryocrystallography requires more precise data processing techniques and is therefore time consuming. Here, an approach for processing multicrystal diffraction data using a serial crystallography program is introduced that allows for the integration of multicrystal diffraction patterns from a single image. Multicrystal diffraction data were collected from lysozyme crystals and processed using the serial crystallography program CrystFEL. From 360 images containing multicrystal diffraction patterns, 1138 and 691 crystal lattices could be obtained using the XGANDALF and MOSFLM indexing algorithms, respectively. Using this indexed multi-lattice information, the crystal structure of the lysozyme could be determined successfully at a resolution of 1.9 Å. Therefore, the proposed approach, which is based on serial crystallography, is suitable for processing multicrystal diffraction data in cryocrystallography.

Highlights

Cryocrystallography is a widely used X-ray crystallographic technique for determining the structure of macromolecules and has the advantage of significantly reducing the radiation damage experienced by the crystals during data collection [1,2]
In the case of the multicrystal diffraction pattern images generated from crystals of different sizes or through partial multicrystal diffraction, crystal lattice indexing can be performed successfully by selecting only the diffraction patterns containing high-intensity Bragg peaks
To process multicrystal diffraction data, which is even more challenging, multicrystal diffraction patterns were obtained by exposing crystals of similar sizes to X-rays such that the individual crystal diffraction patterns could not be distinguished with ease

Summary

Introduction

Cryocrystallography is a widely used X-ray crystallographic technique for determining the structure of macromolecules and has the advantage of significantly reducing the radiation damage experienced by the crystals during data collection [1,2]. In such instances, when the crystals are exposed to X-rays, the diffraction images recorded could contain diffraction patterns from multiple crystals From these multicrystal diffraction patterns, a single-crystal lattice must be distinguished and indexed to determine the structure factor. In such cases, it is generally possible to index the crystal lattice by selecting the highestintensity Bragg peak detected in the multicrystal diffraction pattern [7]. Several lysozyme crystals were exposed to an X-ray beam to produce multicrystal diffraction patterns These diffraction patterns were successfully processed using the CrystFEL program and the XGANDALF and MOSFLM indexing algorithms, and the crystal structure of the lysozyme could be determined successfully at a resolution of 1.9 Å. The results obtained confirmed that SX programs can be employed for the data processing of multicrystal diffraction patterns obtained from conventional cryocrystallography

Sample Preparation

Data Collection

Structural Determination

Results

Discussion

Conclusions