329d
From Proteopedia
(New page: 200px<br /><applet load="329d" size="350" color="white" frame="true" align="right" spinBox="true" caption="329d, resolution 2.700Å" /> '''EFFECT OF CYTOSINE ...) |
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==Overview== | ==Overview== | ||
| - | Although DNA methylation is a fundamental mechanism for repressing genetic | + | Although DNA methylation is a fundamental mechanism for repressing genetic activity, the influence of methyl groups on DNA conformation is found to be small. In this study, the role of cytosine methylation is analysed in the context of DNA condensation by examining its influence on DNA-DNA recognition processes. Previously CpG sites were found to act as sequence determinants for the close and specific self-fit of B-DNA helices into cross-overs. In the present study, the crystal structure of the B-DNA dodecamer d(ACCGCCGGCGCC) methylated at its central CpG sequence shows that the methyl groups do not interfere with DNA self-fitting. In contrast, the two methyl groups form a clamp, which traps the incoming phosphate in the groove-backbone interaction. This geometry allows the formation of two new C-H...O hydrogen bonds between the methyl groups and the anionic oxygen atoms of the phosphate, which may further stabilize the interaction. This finding relates cytosine methylation to the formation of higher-order DNA structures and could provide new insights for understanding the mode of action of DNA methylation in genetic inactivation. |
==About this Structure== | ==About this Structure== | ||
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[[Category: double helix]] | [[Category: double helix]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:02:02 2008'' |
Revision as of 17:02, 21 February 2008
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EFFECT OF CYTOSINE METHYLATION ON DNA-DNA RECOGNITION AT CPG STEPS
Overview
Although DNA methylation is a fundamental mechanism for repressing genetic activity, the influence of methyl groups on DNA conformation is found to be small. In this study, the role of cytosine methylation is analysed in the context of DNA condensation by examining its influence on DNA-DNA recognition processes. Previously CpG sites were found to act as sequence determinants for the close and specific self-fit of B-DNA helices into cross-overs. In the present study, the crystal structure of the B-DNA dodecamer d(ACCGCCGGCGCC) methylated at its central CpG sequence shows that the methyl groups do not interfere with DNA self-fitting. In contrast, the two methyl groups form a clamp, which traps the incoming phosphate in the groove-backbone interaction. This geometry allows the formation of two new C-H...O hydrogen bonds between the methyl groups and the anionic oxygen atoms of the phosphate, which may further stabilize the interaction. This finding relates cytosine methylation to the formation of higher-order DNA structures and could provide new insights for understanding the mode of action of DNA methylation in genetic inactivation.
About this Structure
329D is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Effect of cytosine methylation on DNA-DNA recognition at CpG steps., Mayer-Jung C, Moras D, Timsit Y, J Mol Biol. 1997 Jul 18;270(3):328-35. PMID:9237900
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