1s37
From Proteopedia
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Accomodation of Mispair-Aligned N3T-Ethyl-N3T DNA Interstrand Crosslink
Overview
The solution structure of the undecamer d(CGAAATTTTCG)(2), where T, represents a N(3)T-ethyl-N(3)T interstrand cross link, was elucidated, using molecular dynamics calculations restrained by NOE and dihedral data, obtained from NMR spectroscopy. The ethyl moiety is particularly, well-accommodated between the minor and major grooves. This is an, exceptional example of the plasticity along the axis defined by the stem, and a unique finding of an interstrand cross link occupying the area, associating minor and major grooves. The mismatch-aligned tethered bases, preserve good intrastrand stacking with flanking bases. Base-pair steps, adjacent to the lesion site are overwound. Accommodation of the lesion, also results in an increase in mispair staggering alignment modulated by, flexibility because of the tetrahedral geometry of the exocyclic ethyl, carbon atoms. This is mechanically coupled with a small measure of, concomitant propeller twisting without an increase in intrastrand, base-step distance. Both x displacement and sugar puckering are indicative, of canonical B DNA throughout the stem. We have thus established that the, lesion defined by mismatch-aligned minor groove N(3)T-ethyl-N(3)T, cross-linked thymine bases produces very localized distortions in a DNA, stem that may be difficult to recognize by repair mechanisms that are not, transcription- or replication-coupled. Thus, this synthetic DNA is a, valuable structural probe to study mechanisms of repair.
About this Structure
1S37 is a Protein complex structure of sequences from [1] with EHN as ligand. Full crystallographic information is available from OCA.
Reference
Accommodation of mispair aligned N3T-ethyl-N3T DNA interstrand cross link., da Silva MW, Wilds CJ, Noronha AM, Colvin OM, Miller PS, Gamcsik MP, Biochemistry. 2004 Oct 5;43(39):12549-54. PMID:15449944
Page seeded by OCA on Sat Nov 24 23:49:00 2007
