Imperfect pseudo-merohedral twinning in crystals of fungal fatty acid synthase
- Institute of Molecular Biology and Biophysics, ETH Zurich, 8093 Zurich (Switzerland)
A case of imperfect pseudo-merohedral twinning in monoclinic crystals of fungal fatty acid synthase is discussed. A space-group transition during crystal dehydration resulted in a Moiré pattern-like interference of the twinned diffraction patterns. The recent high-resolution structures of fungal fatty acid synthase (FAS) have provided new insights into the principles of fatty acid biosynthesis by large multifunctional enzymes. The crystallographic phase problem for the 2.6 MDa fungal FAS was initially solved to 5 Å resolution using two crystal forms from Thermomyces lanuginosus. Monoclinic crystals in space group P2{sub 1} were obtained from orthorhombic crystals in space group P2{sub 1}2{sub 1}2{sub 1} by dehydration. Here, it is shown how this space-group transition induced imperfect pseudo-merohedral twinning in the monoclinic crystal, giving rise to a Moiré pattern-like interference of the two twin-related reciprocal lattices. The strategy for processing the twinned diffraction images and obtaining a quantitative analysis is presented. The twinning is also related to the packing of the molecules in the two crystal forms, which was derived from self-rotation function analysis and molecular-replacement solutions using a low-resolution electron microscopy map as a search model.
- OSTI ID:
- 22347972
- Journal Information:
- Acta Crystallographica. Section D: Biological Crystallography, Vol. 65, Issue Pt 2; Other Information: PMCID: PMC2631638; PMID: 19171964; PUBLISHER-ID: ba5132; OAI: oai:pubmedcentral.nih.gov:2631638; Copyright (c) Jenni & Ban 2009; This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0907-4449
- Country of Publication:
- Denmark
- Language:
- English
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