1r41
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(New page: 200px<br /><applet load="1r41" size="450" color="white" frame="true" align="right" spinBox="true" caption="1r41, resolution 1.9Å" /> '''Crystal structures of...)
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Revision as of 19:57, 24 November 2007
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Crystal structures of d(Gm5CGm5CGCGC) and d(GCGCGm5CGm5C): Effects of methylation on alternating DNA octamers
Overview
The crystal structures of two alternating octamers d(Gm(5)CGm(5)CGCGC) and, d(GCGCGm(5)CGm(5)C) have been determined at 1.7 and 1.9 A resolution with, R(work)/R(free) of 16.9/19.6% and 17.9/19.8%, respectively. The two, octamers crystallized in the same tetragonal space group P4(3)2(1)2, with, unit-cell parameters a = b = 43.0, c = 24.9 A and a = b = 43.1, c = 24.7, A, respectively. Both structures adopt the A-type double helix and the, abutting crystal packing. Despite the different positions of the, methylated cytosine in the sequence, the two octamers display essentially, the same conformation. The close similarity of the two structures, indicates that methylation at different positions in a DNA sequence does, not affect the helical conformation of the alternating DNA octamer., Investigation of other related crystal structures implies that methylation, of cytosine stabilizes the A-type conformation for alternating DNA, sequences beginning with a 5'-purine but is beneficial to the Z-type, conformation for alternating DNA sequences beginning with a 5'-pyrimidine.
About this Structure
1R41 is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Structures of d(Gm5)CGm5CGCGC) and d(GCGCGm5CGm5C): effects of methylation on alternating DNA octamers., Shi K, Pan B, Tippin D, Sundaralingam M, Acta Crystallogr D Biol Crystallogr. 2004 Jan;60(Pt 1):61-5. Epub 2003 Dec, 18. PMID:14684893
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