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Durham University

Department of Biosciences


Publication details for Prof. Ehmke Pohl

Freitag-Pohl, Stefanie, Jasilionis, Andrius, Håkansson, Maria, Svensson, L. Anders, Kovačič, Rebeka, Welin, Martin, Watzlawick, Hildegard, Wang, Lei, Altenbuchner, Josef, Płotka, Magdalena, Kaczorowska, Anna Karina, Kaczorowski, Tadeusz, Nordberg Karlsson, Eva, Al-Karadaghi, Salam, Walse, Björn, Aevarsson, Arnthór & Pohl, Ehmke (2019). Crystal structures of the Bacillus subtilis prophage lytic cassette proteins XepA and YomS. Acta Crystallographica Section D Structural Biology 75(11): 1028-1039.

Author(s) from Durham


For the extraction of the best possible X-ray diffraction data from macromolecular crystals, accurate positioning of the crystals with respect to the X-ray beam is crucial. In addition, information about the shape and internal defects of crystals allows the optimization of data-collection strategies. Here, it is demonstrated that the X-ray beam available on the macromolecular crystallo­graphy beamline P14 at the high-brilliance synchrotron-radiation source PETRA III at DESY, Hamburg, Germany can be used for high-energy phase-contrast microtomography of protein crystals mounted in an optically opaque lipidic cubic phase matrix. Three-dimensional tomograms have been obtained at X-ray doses that are substantially smaller and on time scales that are substantially shorter than those used for diffraction-scanning approaches that display protein crystals at micrometre resolution. Adding a compound refractive lens as an objective to the imaging setup, two-dimensional imaging at sub-micrometre resolution has been achieved. All experiments were performed on a standard macromolecular crystallography beamline and are compatible with standard diffraction data-collection workflows and apparatus. Phase-contrast X-ray imaging of macromolecular crystals could find wide application at existing and upcoming low-emittance synchrotron-radiation sources.