A general method for phasing novel complex RNA crystal structures without heavy-atom derivatives
Using idealized known RNA secondary-structural fragments, it is demonstrated that it is possible to solve novel complex RNA structures without resort to heavy-atom phasing methods. The crystallographic phase problem [Muirhead & Perutz (1963 ▶), Nature (London), 199, 633–638] remains the single major impediment to obtaining a three-dimensional structure of a macromolecule once suitable crystals have been obtained. Recently, it was found that it was possible to solve the structure of a 142-nucleotide L1 ligase ribozyme heterodimer that possesses no noncrystallographic symmetry without heavy-atom derivatives, anomalous scattering atoms or other modifications and without a model of the tertiary structure of the ribozyme [Robertson & Scott (2007 ▶), Science, 315, 1549–1553]. Using idealized known RNA secondary-structural fragments such as A-form helices and GNRA tetraloops in an iterative molecular-replacement procedure, it was possible to obtain an estimated phase set that, when subjected to solvent flattening, yielded an interpretable electron-density map with minimized model bias, allowing the tertiary structure of the ribozyme to be solved. This approach has also proven successful with other ribozymes, structured RNAs and RNA–protein complexes.
- OSTI ID:
- 22347987
- Journal Information:
- Acta Crystallographica. Section D: Biological Crystallography, Vol. 64, Issue Pt 7; Other Information: PMCID: PMC2507861; PUBLISHER-ID: wd5091; PMID: 18566509; OAI: oai:pubmedcentral.nih.gov:2507861; Copyright (c) International Union of Crystallography 2008; Country of input: International Atomic Energy Agency (IAEA); ISSN 0907-4449
- Country of Publication:
- Denmark
- Language:
- English
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