DNA Structure: A‐, B‐ and Z‐DNA Helix Families


There are three major families of DNA helices: A‐DNA, B‐DNA and Z‐DNA. The helical structure of DNA is variable and depends on the sequence as well as the environment.

Keywords: DNA structure; A‐DNA; B‐DNA; Z‐DNA; DNA helix; left‐handed DNA

Figure 1.

Different views of the DNA helix. (a) The structure of B‐DNA as proposed by Watson and Crick in 1953, based on fibre diffraction studies. Modified from Sinden et al. (1998). (b) A‐, B‐ and Z‐DNA, as seen from the side of the helix (above), and looking down the helix axis (below). The structures were drawn from the crystal structures, using the Cn3D programme, available from the NCBI home page.

Figure 2.

Chemical structure of DNA. (a) The chemical structure of the nucleotide adenosine triphosphate (ATP). (b) The phosphodiester backbone for the sequence d(ACGT). Modified from Sinden et al. (1998).

Figure 3.

Properties of DNA bases. (a) The base pairs for guanine–cytosine (G•C) and adenine–thymine (A•T). (b) Twist angle for the A•A dinucleotide, and propeller twist for an A•T base pair. Modified from Sinden et al. (1998).


Further Reading

Calladine CR and Drew HR (1997) Understanding DNA, 2nd edn. San Diego, CA: Academic Press.

Centre of Biological Sequence Analysis (2001) http://www.cbs.dtu.dk/dave/DNAbooks.html [A list of more than 100 books about DNA.]

Centre for Biological Sequence Analysis (2001) http://www.cbs.dtu.dk/services/GenomeAtlas/A_DNA.html

Frank‐Kamenetskii MD (1993) Unraveling DNA. Cambridge, UK: VCH Publishers (UK) Ltd.

Gagna CE, Kuo H and Lambert WC (1999) Terminal differentiation and left‐handed Z‐DNA: a review. Cell Biology International 23: 1–5.

Herbert A and Rich A (1999) Left‐handed Z‐DNA: structure and function. Genetica 106: 37–47.

Malinia L, Fernandez LG, Huynh‐Dinh T and Subirana JA (1999) Structure of the d(CGCCCGCGGGCG) dodecamer: a kinked A‐DNA molecule showing some B‐DNA features. Journal of Molecular Biology 285: 1679–1690.

National Center for Biotechnology Information (2001) http://www.ncbi.nlm.gov:80/entrez/query.fcgi?db=Structure [type in A‐DNA, for example, for a list of A‐DNA crystal structures].

Ng H, Kopka ML and Dickerson RE (2000) The structure of a stable intermediate in the A‐DNA helix transition. Proceedings of the National Academy of Sciences of the USA 97: 2035–2039.

Saenger W (1984) Principles of Nucleic Acid Structure. New York: Springer.

Sinden RR (1994) DNA Structure and Function. San Diego: Academic Press.

Sinden RR, Pearson CE, Potaman VN and Ussery DW (1998) DNA: structure and function. Advances in Genome Biology 5A: 1–141.

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Ussery, David W(May 2002) DNA Structure: A‐, B‐ and Z‐DNA Helix Families. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0003122]