184d
From Proteopedia
(New page: 200px<br /><applet load="184d" size="450" color="white" frame="true" align="right" spinBox="true" caption="184d, resolution 1.800Å" /> '''SELF-ASSOCIATION OF...) |
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| - | [[Image:184d.gif|left|200px]]<br /><applet load="184d" size=" | + | [[Image:184d.gif|left|200px]]<br /><applet load="184d" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="184d, resolution 1.800Å" /> | caption="184d, resolution 1.800Å" /> | ||
'''SELF-ASSOCIATION OF A DNA LOOP CREATES A QUADRUPLEX: CRYSTAL STRUCTURE OF D(GCATGCT) AT 1.8 ANGSTROMS RESOLUTION'''<br /> | '''SELF-ASSOCIATION OF A DNA LOOP CREATES A QUADRUPLEX: CRYSTAL STRUCTURE OF D(GCATGCT) AT 1.8 ANGSTROMS RESOLUTION'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: The flexibility of DNA enables it to adopt three | + | BACKGROUND: The flexibility of DNA enables it to adopt three interconvertible types of duplex termed the A-, B- and Z-forms. It can also produce hairpin loops, triplex structures and guanine-rich quadruplex structures. Conformational flexibility assists in the tight packaging of DNA, for example in chromosomes. This is important given the large quantity of genetic information that must be packaged efficiently. Moreover, the ability of DNA to specifically self-associate or interact with complementary sequences is fundamental to many biological processes. Structural studies provide information about DNA conformation and DNA-DNA interactions and suggest features that might be relevant to how the molecule performs its biological role. RESULTS: We have characterized the structure of a synthetic heptanucleotide that folds into a novel loop structure. The loop is stabilized by association with a cation, by intra-strand hydrogen bonds between guanine and cytosine that are distinct from the normal Watson-Crick hydrogen bonds, and by van der Waals interactions. Two loops associate through the formation of four G.C pairs that exhibit pronounced base-stacking interactions. The formation of a symmetric A.A base pair further stabilizes loop dimerization. Stacking of the A.A pair on a symmetry-related A.A pairing assists the formation of a four-stranded assembly. A T.T pairing is also observed between symmetry-related loops. CONCLUSIONS: This analysis provides a rare example of an experimentally determined non-duplex DNA structure. It provides conformational detail relevant to the tight packaging or folding of a DNA strand and illustrates how a cation might modulate phosphate-phosphate repulsion in a tightly packed structure. The observation of base quartets involving G.C base pairs suggests a further structure to be considered in DNA-DNA interactions. The structure also provides detailed geometries for A.A and T.T base pairs. |
==About this Structure== | ==About this Structure== | ||
| - | 184D is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ] with MG as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http:// | + | 184D is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ] with <scene name='pdbligand=MG:'>MG</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=184D OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Protein complex]] | [[Category: Protein complex]] | ||
[[Category: Brown, T.]] | [[Category: Brown, T.]] | ||
| - | [[Category: Cruse, W | + | [[Category: Cruse, W B.T.]] |
| - | [[Category: Estaintot, B | + | [[Category: Estaintot, B Langlois D.]] |
| - | [[Category: Harrop, S | + | [[Category: Harrop, S J.]] |
| - | [[Category: Helliwell, J | + | [[Category: Helliwell, J R.]] |
| - | [[Category: Hunter, W | + | [[Category: Hunter, W N.]] |
[[Category: Kennard, O.]] | [[Category: Kennard, O.]] | ||
| - | [[Category: Leonard, G | + | [[Category: Leonard, G A.]] |
| - | [[Category: Peterson, M | + | [[Category: Peterson, M R.]] |
[[Category: Zhang, S.]] | [[Category: Zhang, S.]] | ||
[[Category: MG]] | [[Category: MG]] | ||
| Line 28: | Line 28: | ||
[[Category: u-dna]] | [[Category: u-dna]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:39:02 2008'' |
Revision as of 09:39, 21 February 2008
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SELF-ASSOCIATION OF A DNA LOOP CREATES A QUADRUPLEX: CRYSTAL STRUCTURE OF D(GCATGCT) AT 1.8 ANGSTROMS RESOLUTION
Overview
BACKGROUND: The flexibility of DNA enables it to adopt three interconvertible types of duplex termed the A-, B- and Z-forms. It can also produce hairpin loops, triplex structures and guanine-rich quadruplex structures. Conformational flexibility assists in the tight packaging of DNA, for example in chromosomes. This is important given the large quantity of genetic information that must be packaged efficiently. Moreover, the ability of DNA to specifically self-associate or interact with complementary sequences is fundamental to many biological processes. Structural studies provide information about DNA conformation and DNA-DNA interactions and suggest features that might be relevant to how the molecule performs its biological role. RESULTS: We have characterized the structure of a synthetic heptanucleotide that folds into a novel loop structure. The loop is stabilized by association with a cation, by intra-strand hydrogen bonds between guanine and cytosine that are distinct from the normal Watson-Crick hydrogen bonds, and by van der Waals interactions. Two loops associate through the formation of four G.C pairs that exhibit pronounced base-stacking interactions. The formation of a symmetric A.A base pair further stabilizes loop dimerization. Stacking of the A.A pair on a symmetry-related A.A pairing assists the formation of a four-stranded assembly. A T.T pairing is also observed between symmetry-related loops. CONCLUSIONS: This analysis provides a rare example of an experimentally determined non-duplex DNA structure. It provides conformational detail relevant to the tight packaging or folding of a DNA strand and illustrates how a cation might modulate phosphate-phosphate repulsion in a tightly packed structure. The observation of base quartets involving G.C base pairs suggests a further structure to be considered in DNA-DNA interactions. The structure also provides detailed geometries for A.A and T.T base pairs.
About this Structure
184D is a Protein complex structure of sequences from [1] with as ligand. Full crystallographic information is available from OCA.
Reference
Self-association of a DNA loop creates a quadruplex: crystal structure of d(GCATGCT) at 1.8 A resolution., Leonard GA, Zhang S, Peterson MR, Harrop SJ, Helliwell JR, Cruse WB, d'Estaintot BL, Kennard O, Brown T, Hunter WN, Structure. 1995 Apr 15;3(4):335-40. PMID:7613864
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