Recognition and use of the unusual X-DNA as a primer-template by Klenow DNA polymerase enzyme

Biochem Biophys Res Commun. 1989 Jun 30;161(3):1204-12. doi: 10.1016/0006-291x(89)91370-3.


Based on CD spectra, 2-amino-2'-deoxyadenosine-containing synthetic alternating DNA, poly(amino2dA-dt) undergoes a conformational transition from a B-form to a non-Z zig-zag form of DNA, called X, even under conditions where enzymes can work. Kinetic parameters of the E. coli Klenow DNA polymerase enzyme-catalyzed copying of both the B- and X-forms of poly(amino2dA-dT) have been determined. Binding affinity of X-DNA to the enzyme proved to be even higher than that of the B-DNA; primer-chain extension of X-poly(amino2dA-dT) was however hindered as compared to its B-form. This differential utilization of X-DNA versus B-DNA by a DNA polymerase is an in vitro enzymatic evidence of an unusual DNA conformation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Circular Dichroism
  • DNA Polymerase I / metabolism*
  • DNA Replication
  • DNA*
  • Escherichia coli / enzymology
  • Kinetics
  • Nucleic Acid Conformation
  • Poly dA-dT
  • Polydeoxyribonucleotides
  • Templates, Genetic


  • Polydeoxyribonucleotides
  • poly(amino(2)dA-dT)
  • Poly dA-dT
  • DNA
  • DNA Polymerase I