Flanking AT-rich tracts cause a structural distortion in Z-DNA in plasmids.

Abstract : The effect of neighboring AT-rich sequences on the right-handed B to left-handed Z transition was investigated in plasmids. The supercoil stabilized Z-DNA structure in (CG) tracts 36 and 40 base pairs (bp) in length revealed an unexpected conformational aberration at defined C residues proximal to one end (colL) when the inserts were bilaterally flanked by an 80% AT-rich segment (90 bp on one side and 331 bp on the other). The presence of the perturbed Z-conformation required (CG) stretches longer than 32 bp and bilateral flanking by the AT-rich tracts, since plasmids with the (CG) tracts unilaterally flanked had an orthodox Z-structure. The thermodynamics of the negative super-coil-induced transitions were influenced only slightly by the neighboring AT-rich regions. Hence, the nature of Z-conformations in plasmids is markedly influenced by intrinsic structural features of the (Pur-Pyr) tract and by seemingly modest changes in the properties of neighboring sequences over a distance of several helical turns.
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Submitted on : Monday, May 13, 2019 - 11:48:43 AM
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  • HAL Id : hal-02127194, version 1
  • PUBMED : 2211626


R Rajagopalan, A. Rachid Rahmouni, R Wells. Flanking AT-rich tracts cause a structural distortion in Z-DNA in plasmids.. Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology, 1990, 265 (28), pp.17294-9. ⟨hal-02127194⟩



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