Mechanism of DNA polymerase alpha inhibition by aphidicolin

Biochemistry. 1991 Sep 3;30(35):8590-7. doi: 10.1021/bi00099a014.


Synthetic oligonucleotides of defined sequence were used to examine the mechanism of calf thymus DNA polymerase alpha inhibition by aphidicolin. Aphidicolin competes with each of the four dNTPs for binding to a pol alpha-DNA binary complex and thus should not be viewed as a dCTP analogue. Kinetic evidence shows that inhibition proceeds through the formation of a pol alpha.DNA.aphidicolin ternary complex, while DNase I protection experiments provide direct physical evidence. When deoxyguanosine is the next base to be replicated, Ki = 0.2 microM. In contrast, the Ki is 10-fold higher when the other dNMPs are at this position. Formation of a pol alpha.DNA.aphidicolin ternary complex did not inhibit the primase activity of the pol alpha.primase complex. Neither the rate of primer synthesis nor the size distribution of primers 2-10 nucleotides long was changed. Elongation of the primase-synthesized primers by pol alpha was inhibited both by ternary complex formation using exogenously added DNA and by aphidicolin alone.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aphidicolin
  • Base Sequence
  • Binding, Competitive
  • DNA Polymerase II / antagonists & inhibitors*
  • DNA Polymerase II / chemistry
  • DNA Replication / drug effects
  • Diterpenes / chemistry
  • Diterpenes / pharmacology*
  • Kinetics
  • Molecular Sequence Data
  • Oligonucleotide Probes
  • Structure-Activity Relationship
  • Substrate Specificity
  • Templates, Genetic


  • Diterpenes
  • Oligonucleotide Probes
  • Aphidicolin
  • DNA Polymerase II