Standard Article

DNA Structures of Biological Relevance, Studies of Unusual Sequences

Nucleic Acids Structure and Mapping

  1. Yuh-Hwa Wang

Published Online: 15 SEP 2006

DOI: 10.1002/9780470027318.a1409

Encyclopedia of Analytical Chemistry

Encyclopedia of Analytical Chemistry

How to Cite

Wang, Y.-H. 2006. DNA Structures of Biological Relevance, Studies of Unusual Sequences. Encyclopedia of Analytical Chemistry. .

Author Information

  1. University of Medicine and Dentistry of New Jersey, Piscataway, USA

Publication History

  1. Published Online: 15 SEP 2006


DNA molecules with unusual structures can have significant consequences in many DNA metabolic processes. This article summarizes structural studies of DNA molecules containing bulged and mismatched bases and trinucleotide repeating DNAs. Extra base bulges and mismatches in double-stranded DNA can arise from replication errors or imperfect recombination. If these lesions escape the repair system, they would subsequently cause mutagenesis. Using a combination of gel electrophoresis, electron microscopy (EM), chemical modification, and probing with RecA protein, the structure of bulged and mismatched DNAs was examined and factors such as base composition and flanking base sequence have been shown to influence the overall structure of these molecules.

Expansion of trinucleotide repeats is a major cause of several inherited neurodegenerative diseases. Described here are findings that show, by in vitro nucleosome assembly assay, that the expanded CTG triplet sequences derived from myotonic dystrophy (DM) patients form the most stable naturally occurring nucleosomes that are known. In contrast, long tracts of repeating CCG triplets (expanded in fragile X syndrome (FraX) patients) resist nucleosome assembly. This information could provide critical clues about how these unusual DNAs cause harmful biological effects in living cells.