The crystal structure of the N-terminal domain of the RNA polymerase δ subunit (Nδ) from Bacillus subtilis solved at a resolution of 2.0Å 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 β 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 Nδ, 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.

• MeSH
• Bacillus subtilis enzymologie   MeSH
• DNA řízené RNA-polymerasy chemie   MeSH
• koncentrace vodíkových iontů MeSH
• konformace proteinů * MeSH
• krystalografie rentgenová metody   MeSH
• nukleární magnetická rezonance biomolekulární metody   MeSH
• sekundární struktura proteinů MeSH
• sekvence aminokyselin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH