1t4x
From Proteopedia
(New page: 200px<br /><applet load="1t4x" size="450" color="white" frame="true" align="right" spinBox="true" caption="1t4x" /> '''The first left-handed RNA structure of (CGCG...) |
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'''The first left-handed RNA structure of (CGCGCG)2, Z-RNA, NMR, 12 structures, determined in high salt'''<br /> | '''The first left-handed RNA structure of (CGCGCG)2, Z-RNA, NMR, 12 structures, determined in high salt'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Right-handed RNA duplexes of (CG)n sequence undergo salt-induced helicity | + | Right-handed RNA duplexes of (CG)n sequence undergo salt-induced helicity reversal, forming left-handed RNA double helices (Z-RNA). In contrast to the thoroughly studied Z-DNA, no Z-RNA structure of natural origin is known. Here we report the NMR structure of a half-turn, left-handed RNA helix (CGCGCG)2 determined in 6 M NaClO4. This is the first nucleic acid motif determined at such high salt. Sequential assignments of non-exchangeable proton resonances of the Z-form were based on the hitherto unreported NOE connectivity path [H6(n)-H5'/H5''(n)-H8(n+1)-H1'(n+1)-H6(n+2)] found for left-handed helices. Z-RNA structure shows several conformational features significantly different from Z-DNA. Intra-strand but no inter-strand base stacking was observed for both CpG and GpC steps. Helical twist angles for CpG steps have small positive values (4-7 degrees), whereas GpC steps have large negative values (-61 degrees). In the full-turn model of Z-RNA (12.4 bp per turn), base pairs are much closer to the helix axis than in Z-DNA, thus both the very deep, narrow minor groove with buried cytidine 2'-OH groups, and the major groove are well defined. The 2'-OH group of cytidines plays a crucial role in the Z-RNA structure and its formation; 2'-O-methylation of cytidine, but not of guanosine residues prohibits A to Z helicity reversal. |
==About this Structure== | ==About this Structure== | ||
| - | 1T4X is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ]. Full crystallographic information is available from [http:// | + | 1T4X is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1T4X OCA]. |
==Reference== | ==Reference== | ||
High salt solution structure of a left-handed RNA double helix., Popenda M, Milecki J, Adamiak RW, Nucleic Acids Res. 2004 Aug 3;32(13):4044-54. Print 2004. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=15292450 15292450] | High salt solution structure of a left-handed RNA double helix., Popenda M, Milecki J, Adamiak RW, Nucleic Acids Res. 2004 Aug 3;32(13):4044-54. Print 2004. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=15292450 15292450] | ||
[[Category: Protein complex]] | [[Category: Protein complex]] | ||
| - | [[Category: Adamiak, R | + | [[Category: Adamiak, R W.]] |
[[Category: Milecki, J.]] | [[Category: Milecki, J.]] | ||
[[Category: Popenda, M.]] | [[Category: Popenda, M.]] | ||
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[[Category: z-rna]] | [[Category: z-rna]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:09:55 2008'' |
Revision as of 13:09, 21 February 2008
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The first left-handed RNA structure of (CGCGCG)2, Z-RNA, NMR, 12 structures, determined in high salt
Overview
Right-handed RNA duplexes of (CG)n sequence undergo salt-induced helicity reversal, forming left-handed RNA double helices (Z-RNA). In contrast to the thoroughly studied Z-DNA, no Z-RNA structure of natural origin is known. Here we report the NMR structure of a half-turn, left-handed RNA helix (CGCGCG)2 determined in 6 M NaClO4. This is the first nucleic acid motif determined at such high salt. Sequential assignments of non-exchangeable proton resonances of the Z-form were based on the hitherto unreported NOE connectivity path [H6(n)-H5'/H5(n)-H8(n+1)-H1'(n+1)-H6(n+2)] found for left-handed helices. Z-RNA structure shows several conformational features significantly different from Z-DNA. Intra-strand but no inter-strand base stacking was observed for both CpG and GpC steps. Helical twist angles for CpG steps have small positive values (4-7 degrees), whereas GpC steps have large negative values (-61 degrees). In the full-turn model of Z-RNA (12.4 bp per turn), base pairs are much closer to the helix axis than in Z-DNA, thus both the very deep, narrow minor groove with buried cytidine 2'-OH groups, and the major groove are well defined. The 2'-OH group of cytidines plays a crucial role in the Z-RNA structure and its formation; 2'-O-methylation of cytidine, but not of guanosine residues prohibits A to Z helicity reversal.
About this Structure
1T4X is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
High salt solution structure of a left-handed RNA double helix., Popenda M, Milecki J, Adamiak RW, Nucleic Acids Res. 2004 Aug 3;32(13):4044-54. Print 2004. PMID:15292450
Page seeded by OCA on Thu Feb 21 15:09:55 2008
