287d

<table><tr><td colspan='2'>[[287d]] is a 2 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=287D OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=287D FirstGlance]. <br>

</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=287d FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=287d OCA], [http://pdbe.org/287d PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=287d RCSB], [http://www.ebi.ac.uk/pdbsum/287d PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=287d ProSAT]</span></td></tr>

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== Publication Abstract from PubMed ==

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.

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<ref>PMID:9126841</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 287d" style="background-color:#fffaf0;"></div>

== References ==

<references/>

[[Category: Eisenstein, M]]

[[Category: Shakked, Z]]

[[Category: Shatzky-Schwartz, M]]

[[Category: Double helix]]