'''Solution structure of reduced interstrand cross-link arising from S-alpha-methyl-gamma-OH-1,N2-propano-2'-deoxyguanosine in the 5'-CpG-3' DNA sequence'''
===Solution structure of reduced interstrand cross-link arising from S-alpha-methyl-gamma-OH-1,N2-propano-2'-deoxyguanosine in the 5'-CpG-3' DNA sequence===
==Overview==
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The solution structures of 5'-Cp-N2-dG-3'-R-(alpha)-CH3-propyl-5'-Cp-N2-dG-3' and 5'-Cp-N2-dG-3'-S-(alpha)-CH3-propyl-5'-Cp-N2-dG-3' interstrand DNA cross-links in the 5'-CpG-3' sequence were determined by NMR spectroscopy. These were utilized as chemically stable surrogates for the corresponding carbinolamine interstrand cross-links arising from the crotonaldehyde- and acetaldehyde-derived R- and S-alpha-CH3-gamma-OH-1,N2-propanodeoxyguanosine adducts. The results provide an explanation for the observation that interstrand cross-link formation in the 5'-CpG-3' sequence by the R- and S-alpha-CH3-gamma-OH-1,N2-propanodeoxyguanosine adducts is dependent upon stereochemistry, favoring the R-alpha-CH3-gamma-OH-1,N2-propanodeoxyguanosine adduct [Kozekov, I. D., Nechev, L. V., Moseley, M. S., Harris, C. M., Rizzo, C. J., Stone, M. P., and Harris, T. M. (2003) J. Am. Chem. Soc. 125, 50-61]. Molecular dynamics calculations, restrained by NOE-based distances and empirical restraints, revealed that both the 5'-Cp-N2-dG-3'-R-(alpha)-CH3-propyl-5'-Cp-N2-dG-3' and 5'-Cp-N2-dG-3'-S-(alpha)-CH3-propyl-5'-Cp-N2-dG-3' cross-links were located in the minor groove and retained Watson-Crick hydrogen bonds at the tandem cross-linked C.G base pairs. However, for the 5'-Cp-N2-dG-3'-R-(alpha)-CH3-propyl-5'-Cp-N2-dG-3' cross-link, the (alpha)-CH3 group was positioned in the center of the minor groove, whereas for the 5'-Cp-N2-dG-3'-S-(alpha)-CH3-propyl-5'-Cp-N2-dG-3' cross-link, the (alpha)-CH3 group was positioned in the 3' direction, showing steric interference with the DNA helix. The 5'-Cp-N2-dG-3'-S-(alpha)-CH3-propyl-5'-Cp-N2-dG-3' cross-link exhibited a lower thermal stability as evidenced by NMR spectroscopy as a function of temperature. The two cross-links also exhibited apparent differences in the conformation of the interstrand three-carbon cross-link, which may also contribute to the lower apparent thermodynamic stability of the 5'-Cp-N2-dG-3'-S-(alpha)-CH3-propyl-5'-Cp-N2-dG-3' cross-link.
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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=2HMR OCA].
Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HMR OCA].
==Reference==
==Reference==
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[[Category: Stone, M P.]]
[[Category: Stone, M P.]]
[[Category: Crotonaldehyde interstrand dna cross-link]]
[[Category: Crotonaldehyde interstrand dna cross-link]]
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Revision as of 12:25, 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.
Reference
Stereochemistry modulates the stability of reduced interstrand cross-links arising from R- and S-alpha-CH3-gamma-OH-1,N2-propano-2'-deoxyguanosine in the 5'-CpG-3' DNA sequence., Cho YJ, Kozekov ID, Harris TM, Rizzo CJ, Stone MP, Biochemistry. 2007 Mar 13;46(10):2608-21. Epub 2007 Feb 17. PMID:17305317
