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275d

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{{STRUCTURE_275d| PDB=275d | SCENE= }}
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'''ALTERNATING AND NON-ALTERNATING DG-DC HEXANUCLEOTIDES CRYSTALLIZE AS CANONICAL A-DNA'''
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===ALTERNATING AND NON-ALTERNATING DG-DC HEXANUCLEOTIDES CRYSTALLIZE AS CANONICAL A-DNA===
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==Overview==
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We have solved the single-crystal X-ray structures of two different hexanucleotides: the alternating sequence d(Gm5CGm5CGC), and the non-alternating sequence d(Gm5CCGGC). Both of these hexamers crystallize readily as A-DNA in the orthorhombic space group C222(1). Although hexanucleotides have been previously crystallized as Z-DNA, and in one case as B-DNA, this is the first time hexanucleotides have been crystallized as A-DNA. Both hexamers adopt a typical A-conformation, which is surprisingly more similar to the structure of A-DNA fibers than to other A-DNA single crystals. The structure of d(Gm5CGm5CGC) was solved to a resolution of 2.1 A (R-factor = 19.6%). This structure has all of the features characteristic of canonical A-DNA, including it's helical repeat (11.2 bp/turn), helical rise (2.6 A/bp), base-pair displacement (-4.7 A), base inclination angle (16.9 degrees), and sugar puckers that are predominantly 3'-endo. The lower resolution, non-alternating structure has similar overall average values for these parameters. We observed several sequence-dependent correlations in these parameters, especially in the d(CG) base step. These steps have lower twist and rise values, coupled with high roll angles as compared to d(GC) steps. The molecular interactions involved in crystal packing and the detailed structure of the bound water in the crystals, however, are similar to those of longer 8 and 10 bp A-DNA crystal structures. Although the structural effect of cytosine methylation on A-DNA appears to be minimal, this modification significantly affects the ability of these sequences to crystallize as A-DNA. In conclusion, we present the A-DNA forming class of hexanucleotides, a new crystallographic system for studying DNA structure at near atomic resolution.
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{{ABSTRACT_PUBMED_7602589}}
==About this Structure==
==About this Structure==
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 18:24:58 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 15:29:37 2008''

Revision as of 12:29, 29 July 2008

Image:275d.png

Template:STRUCTURE 275d

ALTERNATING AND NON-ALTERNATING DG-DC HEXANUCLEOTIDES CRYSTALLIZE AS CANONICAL A-DNA

Template:ABSTRACT PUBMED 7602589

About this Structure

Full crystallographic information is available from OCA.

Reference

Alternating and non-alternating dG-dC hexanucleotides crystallize as canonical A-DNA., Mooers BH, Schroth GP, Baxter WW, Ho PS, J Mol Biol. 1995 Jun 16;249(4):772-84. PMID:7602589

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