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Protein crystals can be incommensurately modulated

Author

  • Jeffrey J Lovelace
  • Cameron R Murphy
  • Lee Daniels
  • Kartik Narayan
  • Clarence E Schutt
  • Uno Lindberg
  • Christer Svensson
  • Gloria E. O. Borgstahl

Summary, in English

For a normal periodic crystal, the X-ray diffraction pattern can be described by an orientation matrix and a set of three integers that indicate the reciprocal lattice points. Those integers determine the spacing along the reciprocal lattice directions. In aperiodic crystals, the diffraction pattern is modulated and the standard periodic main reflections are surrounded by satellite reflections. The successful indexing and refinement of the main unit cell and q vector using TWINSOLVE, developed by Svensson [(2003). Lund University, Sweden], are reported here for an incommensurately modulated, aperiodic crystal of a profilin: actin complex. The indexing showed that the modulation is along the b direction in the crystal, which corresponds to an 'actin ribbon' formed by the crystal lattice. Interestingly, the transition to the aperiodic state was shown to be reversible and the diffraction pattern returned to the periodic state during data collection. It is likely that the protein underwent a conformational change that affected the neighbouring profilin: actin molecules in such a way as to produce the observed modulation in the diffraction pattern. Future work will aim to trap the incommensurately modulated crystal state, for example using cryocooling or chemical crosslinking, thus allowing complete X-ray data to be collected.

Department/s

Publishing year

2008

Language

English

Pages

600-605

Publication/Series

Journal of Applied Crystallography

Volume

41

Issue

Part 3

Document type

Journal article

Publisher

International Union of Crystallography

Topic

  • Physical Sciences
  • Natural Sciences

Keywords

  • modulated protein crystals
  • profilin
  • actin
  • modulated diffraction
  • satellite reflections
  • incommensurate crystallography

Status

Published

ISBN/ISSN/Other

  • ISSN: 1600-5767