X - ray vs. NMR structure of N-terminal domain of ?-subunit of RNA polymerase.
Related Articles X - ray vs. NMR structure of N-terminal domain of ?-subunit of RNA polymerase.
J Struct Biol. 2014 Jun 14;
Authors: Demo G, Papoušková V, Komárek J, Kade?ávek P, Otrusinová O, Srb P, Rabatinová A, Krásný L, Zídek L, Sklená? V, Wimmerová M
Abstract
The crystal structure of the N-terminal domain of the RNA polymerase ? subunit (N?) from Bacillus subtilis solved at a resolution of 2.0 Ĺ is compared with the NMR structure determined previously. The molecule crystallizes in the space group C222(1) with a dimer in the asymmetric unit. Importantly, the X-ray structure exhibits significant differences from the lowest energy NMR structure. In addition to the overall structure differences, structurally important ? sheets found in the NMR structure are not present in the crystal structure. We systematically investigated the cause of the discrepancies between the NMR and X-ray structures of N?, addressing the pH dependence, presence of metal ions, and crystal packing forces. We convincingly showed that the crystal packing forces, together with the presence of Ni(2+) ions, are the main reason for such a difference. In summary, the study illustrates that the two structural approaches may give unequal results, which need to be interpreted with care to obtain reliable structural information in terms of biological relevance.
PMID: 24937760 [PubMed - as supplied by publisher]
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