1i9k

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(New page: 200px<br /><applet load="1i9k" size="450" color="white" frame="true" align="right" spinBox="true" caption="1i9k" /> '''THE RNA I-MOTIF'''<br /> ==Overview== Oligo...)
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[[Image:1i9k.gif|left|200px]]<br /><applet load="1i9k" size="350" color="white" frame="true" align="right" spinBox="true"
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'''THE RNA I-MOTIF'''<br />
'''THE RNA I-MOTIF'''<br />
==Overview==
==Overview==
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Oligodeoxynucleotides with stretches of cytidine residues associate into a, four-stranded structure, the i-motif, in which two head-to-tail, intercalated, parallel-stranded duplexes are held together by, hemiprotonated C.C+ pairs. We have investigated the possibility of forming, an i-motif structure with C-rich ribonucleic acids. The four C-rich RNAs, studied, r(UC5), r(C5), r(C5U) and r(UC3), associate into multiple, intercalated structures at acidic pH. r(UC5) forms two i-motif structures, that differ by their intercalation topologies. We report on a structural, study of the main form and we analyze the small conformational differences, found by comparison with the DNA i-motif. The stacking topology of the, main structure avoids one of the six 2'-OH/2'-OH repulsive contacts, expected in a fully intercalated structure. The C3'-endo pucker of the RNA, sugars and the orientation of the intercalated C.C+ pairs result in a, modest widening of the narrow grooves at the steps where the hydroxyl, groups are in close contact. The free energy of the RNA i-motif, on, average -4 kJ mol(-1) per C.C+ pair, is half of the value found in DNA, i-motif structures.
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Oligodeoxynucleotides with stretches of cytidine residues associate into a four-stranded structure, the i-motif, in which two head-to-tail, intercalated, parallel-stranded duplexes are held together by hemiprotonated C.C+ pairs. We have investigated the possibility of forming an i-motif structure with C-rich ribonucleic acids. The four C-rich RNAs studied, r(UC5), r(C5), r(C5U) and r(UC3), associate into multiple intercalated structures at acidic pH. r(UC5) forms two i-motif structures that differ by their intercalation topologies. We report on a structural study of the main form and we analyze the small conformational differences found by comparison with the DNA i-motif. The stacking topology of the main structure avoids one of the six 2'-OH/2'-OH repulsive contacts expected in a fully intercalated structure. The C3'-endo pucker of the RNA sugars and the orientation of the intercalated C.C+ pairs result in a modest widening of the narrow grooves at the steps where the hydroxyl groups are in close contact. The free energy of the RNA i-motif, on average -4 kJ mol(-1) per C.C+ pair, is half of the value found in DNA i-motif structures.
==About this Structure==
==About this Structure==
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1I9K 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://ispc.weizmann.ac.il/oca-bin/ocashort?id=1I9K OCA].
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1I9K 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=1I9K OCA].
==Reference==
==Reference==
The RNA i-motif., Snoussi K, Nonin-Lecomte S, Leroy JL, J Mol Biol. 2001 May 25;309(1):139-53. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11491284 11491284]
The RNA i-motif., Snoussi K, Nonin-Lecomte S, Leroy JL, J Mol Biol. 2001 May 25;309(1):139-53. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11491284 11491284]
[[Category: Protein complex]]
[[Category: Protein complex]]
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[[Category: Lerou, J.L.]]
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[[Category: Lerou, J L.]]
[[Category: Nonin-Lecomte, S.]]
[[Category: Nonin-Lecomte, S.]]
[[Category: Snoussi, K.]]
[[Category: Snoussi, K.]]
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[[Category: rna]]
[[Category: rna]]
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''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Sun Nov 25 03:49:34 2007''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:09:26 2008''

Revision as of 11:09, 21 February 2008

Image:1i9k.gif

1i9k

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THE RNA I-MOTIF

Overview

Oligodeoxynucleotides with stretches of cytidine residues associate into a four-stranded structure, the i-motif, in which two head-to-tail, intercalated, parallel-stranded duplexes are held together by hemiprotonated C.C+ pairs. We have investigated the possibility of forming an i-motif structure with C-rich ribonucleic acids. The four C-rich RNAs studied, r(UC5), r(C5), r(C5U) and r(UC3), associate into multiple intercalated structures at acidic pH. r(UC5) forms two i-motif structures that differ by their intercalation topologies. We report on a structural study of the main form and we analyze the small conformational differences found by comparison with the DNA i-motif. The stacking topology of the main structure avoids one of the six 2'-OH/2'-OH repulsive contacts expected in a fully intercalated structure. The C3'-endo pucker of the RNA sugars and the orientation of the intercalated C.C+ pairs result in a modest widening of the narrow grooves at the steps where the hydroxyl groups are in close contact. The free energy of the RNA i-motif, on average -4 kJ mol(-1) per C.C+ pair, is half of the value found in DNA i-motif structures.

About this Structure

1I9K is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.

Reference

The RNA i-motif., Snoussi K, Nonin-Lecomte S, Leroy JL, J Mol Biol. 2001 May 25;309(1):139-53. PMID:11491284

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