1qc0
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(New page: 200px<br /><applet load="1qc0" size="450" color="white" frame="true" align="right" spinBox="true" caption="1qc0, resolution 1.55Å" /> '''CRYSTAL STRUCTURE OF...)
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Revision as of 01:48, 25 November 2007
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CRYSTAL STRUCTURE OF A 19 BASE PAIR COPY CONTROL RELATED RNA DUPLEX
Overview
The structures of two RNA duplexes, whose sequences correspond to portions, of the ColE1 plasmid copy control RNA I and RNA II, have been determined., Crystals containing the 18mers 5'-CA CCGUUGGUAGCGGUGC-3' and, 5'-CACCGCUACCAACGGUGC-3' diffract to 1.20 A resolution while those, containing the 19mers 5'-GCACCGUUGGUAGCGGUGC-3' and, 5'-GCACCGCUACCAACGGUGC-3' diffract to 1.55 A resolution. Both duplexes are, standard A form, with Watson-Crick base pairing throughout. Use of, anisotropic atomic displacement factors in refinement of the 1.20 A, structure dramatically improved refinement statistics, resulting in a, final R(free) of 15.0% and a crystallographic R-factor of 11.6%. Perhaps, surprisingly, these crystals of the 18 base pair RNA exhibit a 36-fold, static disorder, resulting in a structure with a single sugar-phosphate, backbone conformation and an averaged base composition at each residue., Since the sugar-phosphate backbone structure is identical in the 36, different nucleotides that are superimposed, there can be no, sequence-dependent variation in the structure. The average ribose pucker, amplitude is 45.8 degrees for the 18 base pair structure and 46.4 degrees, for the 19 base pair structure; these values are respectively 19% and 20%, larger than the average pucker amplitude reported from nucleoside crystal, structures. A standard RNA water structure, based on analysis of the, hydration of these crystal structures and that of the TAR RNA stem, [Ippolito, J. A., and Steitz, T. A. (1998) Proc. Natl. Acad. Sci. U.S.A., 95, 9819-9824], has been derived, which has allowed us to predict water, positions in lower resolution RNA crystal structures. We report a new RNA, packing motif, in which three pro-S(p) phosphate oxygens interact with an, ammonium ion.
About this Structure
1QC0 is a Protein complex structure of sequences from [1] with NH4 as ligand. Full crystallographic information is available from OCA.
Reference
Crystal structures of two plasmid copy control related RNA duplexes: An 18 base pair duplex at 1.20 A resolution and a 19 base pair duplex at 1.55 A resolution., Klosterman PS, Shah SA, Steitz TA, Biochemistry. 1999 Nov 9;38(45):14784-92. PMID:10555960
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