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PDBsum entry 1vtw
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References listed in PDB file
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Key reference
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Title
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At base pairs are less stable than gc base pairs in z-Dna: the crystal structure of d(m5cgtam5cg).
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Authors
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A.H.Wang,
T.Hakoshima,
G.Van der marel,
J.H.Van boom,
A.Rich.
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Ref.
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Cell, 1984,
37,
321-331.
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PubMed id
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Abstract
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Two hexanucleoside pentaphosphates , 5-methyl and 5-bromo cytosine derivatives
of d( CpGpTpApCpG ) have been synthesized, crystallized, and their
three-dimensional structure solved. They both form left-handed Z-DNA and the
methylated derivative has been refined to 1.2 A resolution. These are the first
crystal Z-DNA structures that contain AT base pairs. The overall form of the
molecule is very similar to that of the unmethylated or the fully methylated
(dC-dG)3 hexamer although there are slight changes in base stacking. However,
significant differences are found in the hydration of the helical groove. When
GC base pairs are present, the helical groove is systematically filled with two
water molecules per base pair hydrogen bonded to the bases. Both of these water
molecules are not seen in the electron density map in the segments of the helix
containing AT base pairs, probably because of solvent disorder. This could be
one of the features that makes AT base pairs form Z-DNA less readily than GC
base pairs.
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Headers
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