Long repeated stretches of d(CCG) and tri-nucleotide are crucial mutations that cause hereditary forms of mental retardation (fragile X-syndrome). Moreover, the alternating (CG) di-nucleotide is one of the candidates for Z-DNA conformation. Solution NMR structure of d(CCGCGG)(2) has been solved and is discussed. The determined NMR solution structure is a distorted highly bent B-DNA conformation with increased flexibility in both terminal residues. This conformation differs significantly from the Z-DNA tetramer structure reported for the same hexamer in the crystal state at similar ionic strength by Malinina and co-workers. Crystal structure of d(CCGCGG)(2) at high salt concentration includes a central alternating tetramer in Z-DNA conformation, while the initial cytosine swings out and forms a Watson-Crick base-pair with the terminal guanine of a symmetry-related molecule. In solution, NMR data for sugar ring puckering combined with restrained molecular dynamics simulations starting from a Z-DNA form show that terminal furanose residues could adopt the conformation required for aromatic bases swinging out. Therefore, tetramer formation could be considered possible once the hexanucleotide had previously adopted the Z-DNA form. This work gives some insight into correlations between anomalous crystal structures and their accessibility in the solution state.
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==About this Structure==
==About this Structure==
Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1N1K OCA].
Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1N1K OCA].
==Reference==
==Reference==
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[[Category: Nmr]]
[[Category: Nmr]]
[[Category: Recombination-like]]
[[Category: Recombination-like]]
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Revision as of 04:17, 28 July 2008
This article has been automatically seeded. Changes to this page should pertain to the PDB entry only and not to the protein or biomolecule in general.
Full experimental information is available from OCA.
ReferenceReference
NMR study of hexanucleotide d(CCGCGG)2 containing two triplet repeats of fragile X syndrome., Monleon D, Esteve V, Celda B, Biochem Biophys Res Commun. 2003 Mar 28;303(1):81-90. PMID:12646170
