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297d

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{{STRUCTURE_297d| PDB=297d | SCENE= }}
{{STRUCTURE_297d| PDB=297d | SCENE= }}
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'''X-RAY AND SOLUTION STUDIES OF DNA OLIGOMERS AND IMPLICATIONS FOR THE STRUCTURAL BASIS OF A-TRACT-DEPENDENT CURVATURE'''
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===X-RAY AND SOLUTION STUDIES OF DNA OLIGOMERS AND IMPLICATIONS FOR THE STRUCTURAL BASIS OF A-TRACT-DEPENDENT CURVATURE===
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==Overview==
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DNA containing short periodic stretches of adenine residues (known as A-tracts), which are aligned with the helical repeat, exhibit a pronounced macroscopic curvature. This property is thought to arise from the cumulative effects of a distinctive structure of the A-tract. It has also been observed by gel electrophoresis that macroscopic curvature is largely retained when inosine bases are introduced singly into A-tracts but decreases abruptly for pure I-tracts. The structural basis of this effect is unknown. Here we describe X-ray and gel electrophoretic analyses of several oligomers incorporating adenine or inosine bases or both. We find that macroscopic curvature is correlated with a distinctive base-stacking geometry characterized by propeller twisting of the base-pairs. Regions of alternating adenine and inosine bases display large propeller twisting comparable to that of pure A-tracts, whereas the values observed for pure I-tracts are significantly smaller. We also observe in the crystal structures that propeller twist leads to close cross-strand contacts between amino groups from adenine and cytosine bases, indicating an attractive NH-N interaction, which is analogous to the NH-O interaction proposed for A-tracts. This interaction also occurs between adenine bases across an A-T step and may explain in part the different behavior of A-T versus T-A steps in the context of A-tract-induced curvature. We also note that hydration patterns may contribute to propeller-twisted conformation. Based on the present data and other structural and biophysical studies, we propose that DNA macroscopic curvature is related to the structural invariance of A-tract and A-tract-like regions conferred by high propeller twist, cross-strand interactions and characteristic hydration. The implications of these findings to the mechanism of DNA bending are discussed.
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(as it appears on PubMed at http://www.pubmed.gov), where 9126841 is the PubMed ID number.
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{{ABSTRACT_PUBMED_9126841}}
==About this Structure==
==About this Structure==
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[[Category: Double helix]]
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[[Category: Modified]]
[[Category: Modified]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 18:26:15 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 07:08:15 2008''

Revision as of 04:08, 28 July 2008

Image:297d.png

Template:STRUCTURE 297d

X-RAY AND SOLUTION STUDIES OF DNA OLIGOMERS AND IMPLICATIONS FOR THE STRUCTURAL BASIS OF A-TRACT-DEPENDENT CURVATURE

Template:ABSTRACT PUBMED 9126841

About this Structure

Full crystallographic information is available from OCA.

Reference

X-ray and solution studies of DNA oligomers and implications for the structural basis of A-tract-dependent curvature., Shatzky-Schwartz M, Arbuckle ND, Eisenstein M, Rabinovich D, Bareket-Samish A, Haran TE, Luisi BF, Shakked Z, J Mol Biol. 1997 Apr 4;267(3):595-623. PMID:9126841

Page seeded by OCA on Mon Jul 28 07:08:15 2008

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