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      The structure of a novel DNA duplex formed by human centromere d(TGGAA) repeats with possible implications for chromosome attachment during mitosis.

      1 , ,
      Journal of molecular biology
      Elsevier BV

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          Abstract

          The solution structure of the DNA duplex [GTGGAATGGAAC]2 containing a tandem repeat of the human centromere (TGGAA)n unit has been determined by two-dimensional nuclear magnetic resonance (2D-NMR), distance geometry (DG) and molecular dynamics/energy minimization (MD/EM) methods. This remarkably stable "self-complementary" antiparallel duplex contains a tandem repeated motif in which unpaired guanine residues from opposite strands intercalate and costack between sheared G.A pairs. Twelve independent refined structures were determined from the NMR data and found to converge to a single family of closely related structures with pair-wise r.m.s.d. values of 0.55 +/- 0.25 Angstrum. All sugar residues are in the normal C2'-endo conformation except for the unpaired guanosines, which are in the unusual C3'-endo conformation. The guanosine residues of the bracketing G.A pairs have high-antiglycosidic torsion angles and zeta backbone torsion angles close to the trans domain. The structure exhibits many unusual interstrand interactions, including base-sugar stacking, base-phosphate hydrogen bonding and cross-strand base stacking. The [GGA]2 unit contains a stack of four contiguous guanine residues, all of which have their hydrogen-bonding surface (N2H-N1H-O6-N7) exposed to solvent and available for interaction with other bases or ligands. This unexpected property may explain the unique morphology and function of the human centromere in mitosis.

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          Author and article information

          Journal
          J Mol Biol
          Journal of molecular biology
          Elsevier BV
          0022-2836
          0022-2836
          Dec 08 1995
          : 254
          : 4
          Affiliations
          [1 ] Chemistry Department University of Washington, Seattle 98195, USA.
          Article
          S0022-2836(85)70643-2
          10.1006/jmbi.1995.0643
          7500338
          7aceab06-518f-40ed-a322-1f2c5771c66b
          History

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