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J Synchrotron Radiat. 2015 Mar;22(2):225-38. doi: 10.1107/S1600577515002349. Epub 2015 Feb 17.

Indications of radiation damage in ferredoxin microcrystals using high-intensity X-FEL beams.

Author information

1
Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, D-69120 Heidelberg, Germany.
2
SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
3
European XFEL GmbH, Albert-Einstein-Ring 19, 22761 Hamburg, Germany.
4
Photon Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany.
5
Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany.
6
Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, Aarhus 8000, Denmark.
7
Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala 75120, Sweden.
8
Physikalisch-Technische Bundesanstalt (PTB), Abbestrasse 2-12, 10587 Berlin, Germany.
9
Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550, USA.

Abstract

Proteins that contain metal cofactors are expected to be highly radiation sensitive since the degree of X-ray absorption correlates with the presence of high-atomic-number elements and X-ray energy. To explore the effects of local damage in serial femtosecond crystallography (SFX), Clostridium ferredoxin was used as a model system. The protein contains two [4Fe-4S] clusters that serve as sensitive probes for radiation-induced electronic and structural changes. High-dose room-temperature SFX datasets were collected at the Linac Coherent Light Source of ferredoxin microcrystals. Difference electron density maps calculated from high-dose SFX and synchrotron data show peaks at the iron positions of the clusters, indicative of decrease of atomic scattering factors due to ionization. The electron density of the two [4Fe-4S] clusters differs in the FEL data, but not in the synchrotron data. Since the clusters differ in their detailed architecture, this observation is suggestive of an influence of the molecular bonding and geometry on the atomic displacement dynamics following initial photoionization. The experiments are complemented by plasma code calculations.

KEYWORDS:

SFX; free-electron laser; metalloprotein; protein crystallography; radiation damage; serial femtosecond crystallography

PMID:
25723924
DOI:
10.1107/S1600577515002349
[Indexed for MEDLINE]

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