Conformations of the alternating (C‐T)n sequence under neutral and low pH

FEBS Letters

Jaishree, T.N.¹  Wang, Andrew H.-J.¹ 

[1] Biophysics Division and Department of Cell and Structural Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

关键词: Unusual DNA conformation;    Modified DNA base;    Nuclear Overhauser effect;   

DOI  :  10.1016/0014-5793(94)80261-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The structures of the (C-T)_n sequence at two different pHs have been analyzed by 500 MHz 2D-NMR using a modified DNA decamer d(CT[m⁵C]TCU[m⁵C]UCT) as a model system. The chemical modifications serve to perturb the monotonous C-T repeat, and consequently to yield a better chemical shift dispersion. The results reinforce our earlier suggestion that there are three major pH-depedent confonnational species: two antiparallel-stranded (APS) duplexes at pH 7 and pH 3, and a different structure near pH 5. Structural refinement of the decamer duplexes at pH = 7.5 and pH = 2.9 using 2D-NOE data suggests that the C : T or C⁺ : T base pairs are continuously stacked. Exchangeable proton NMR spectra at pH 7.5 and pH 2.9 are consistent with C : T or C⁺ : T base pairing schemes in which a water molecule bridges the two bases.

【 授权许可】

Unknown