GM/CA@APS: A Macromolecular Crystallography Resource

Uchicago Argonne, Llc, Chicago IL

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Abstract

The GM/CA@APS Resource provides user access to cutting-edge technologies for macromolecular crystallography at two insertion-device beamlines (23-ID-B and 23-ID-D) at the Advanced Photon Source (APS), Argonne National Laboratory (ANL). A major upgrade of beamline optics, endstations, computing resources, motion control, and data acquisition systems will be completed during the current funding period, simultaneously with an upgrade of the APS source. The new GM/CA optics provide an intense, micro-focused beam (1-50 microns) more than 1000-fold brighter than before the upgrades, with exceptionally stable position and intensity, over a wide energy range (5.0-35 keV,  = 2.48-0.35 Å), Precision goniometry and fast, low-noise detectors (Eiger X 16M and CdTe Eiger2 XE 16M) will enable users to take full advantage of the transformative new beamline capabilities. The GM/CA Macromolecular Crystallography Core provides a modern, powerful environment with sophisticated tools for sample screening, evaluation, data collection, and data analysis. Users will easily tailor the brilliant beam properties to match their scientific needs, making GM/CA an ideal facility for microcrystallography that is eminently suited for collecting data from weakly diffracting microcrystals. Cryo-protected samples are robotically mounted from a 288-sample Dewar and can be visualized and manipulated in the beam. Users control the beamlines and samples with the intuitive and biologist-friendly PyBluIce graphical user interface that includes functions for beamline control, sample centering, screening, data collection, energy scan, raster scan, and data analysis. The powerful raster scan feature can identify micro-crystals or find the best diffracting region of a larger crystal for automatic data collection. Data collection is automatically coupled to data processing pipelines, providing users with feedback in near real time. A serial crystallography capability is implemented and integrated into PyBluIce for automated collection from viscous injector and fixed-target delivery technologies. A computing cluster and storage array network provide high-speed data storage, retrieval, backup, and real time data processing. With the massively brighter new beam, most structures will be determined with multi-crystal datasets assembled from many small wedges of data or from serial crystallography. The expert staff will prepare the user community for the opportunities and challenges of the new APS through user workshops and new training materials for both remote and on-site users. Staff also contribute to a variety of community outreach activities including the annual CCP4/APS Crystallography School. GM/CA is led by Robert Fischetti (ANL, contact PI) and Janet Smith (U Michigan, PI). A proactive maintenance plan ensures the high level of performance and minimizes down time. During the 2020-2023 period, 624 unique individuals from 132 unique groups used GM/CA beamlines, deposited 225 structures in the PDB, and published 130 papers.