Tandem 5'-GA:GA-3' mismatches account for the high stability of the fold-back structures formed by the centromeric Drosophila dodeca-satellite

J Mol Biol. 1998 Apr 10;277(4):757-62. doi: 10.1006/jmbi.1998.1646.

Abstract

The centromeric dodeca-satellite of Drosophila forms unusual DNA structures in which its purine-rich strand (GTACGGGACCGA)n folds into very stable intramolecular hairpins. These intramolecular hairpins contain groups of tandem 5'-GA:GA-3' mismatches that, as judged by gel electrophoresis analysis and UV-melting studies, have a determinant contribution to their stability. Duplexes of the dodeca-satellite purine-rich strand, carrying tandem 5'-GA:GA-3' mismatches, are as stable as equivalent fully Watson-Crick duplexes containing tandem 5'-TA:TA-3' Watson-Crick pairs in place of the non-Watson-Crick G.A pairs. On the other hand, duplexes carrying any of the other three possible tandem combinations of purine.purine mismatches, including G.A pairs on the opposite orientation 5'-AG:AG-3', are very unstable. The high stability of the dodeca-satellite hairplus suggests that the tandem G.A pairs are on the sheared configuration although they are found within the less favourable 5'-G-(G-A)-C-3' sequence context. Other centromeres DNA sequences, including the AAGAG satellite of Drosophila and the mammalian CENP-B box sequence, have the potential of forming intramolecular hairpins stabilised by similar purine.purine interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Composition
  • Base Sequence
  • Centromere / genetics
  • DNA, Satellite / chemistry*
  • DNA, Satellite / genetics*
  • DNA, Satellite / radiation effects
  • Drosophila / genetics*
  • Drug Stability
  • Nucleic Acid Conformation / radiation effects
  • Nucleic Acid Denaturation / radiation effects
  • Repetitive Sequences, Nucleic Acid
  • Ultraviolet Rays

Substances

  • DNA, Satellite