Effect of a thiobenzimidazolone derivative on DNA strand transfer catalyzed by HIV-1 reverse transcriptase

Vidhya Gopalakrishnan, Stephen Benkovic

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Thiobenzimidazolone (TIBO) derivatives are known inhibitors of the DNA polymerase activity of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT). The effect of a TIBO derivative ((+)-S-4,5,6,7- tetrahydro-9-chloro-5-methyl-6-(3-methyl-2-butenyl)-imidazol[4,5,1-jk]1,4- benzodiazapine-2-thione) on the DNA strand transfer reaction catalyzed by HIV-1 RT (which is a function of both the DNA polymerase and RNase H activities) was investigated by delineating the effect of the drug on the constitutive DNA polymerase and RNase H activities. Single nucleotide incorporation on template-primer 1 was used to study the DNA polymerase activity of HIV-1 RT while template-primer 2 was used to study the effect of TIBO on the RNase H activity (polymerase independent). The drug was found to decrease the amplitude of the presteady-state burst when preequilibrated with the enzyme-substrate complex besides decreasing the steady-state rate of single nucleotide incorporations. In the absence of preincubation, TIBO did not affect the burst amplitude but decreased the steady-state rate after the pre-transient phase. This suggested that binding of TIBO to RT was affected by the presence of template-primer and required dissociation of the enzyme from the template-primer for effective binding. The polymerase-independent RNase H activity was activated in the presence of TIBO. The effect of TIBO on the overall process of DNA strand transfer is a balance between its inhibition of the polymerase activity and its activation of the RNase H activity.

Original languageEnglish (US)
Pages (from-to)4110-4115
Number of pages6
JournalJournal of Biological Chemistry
Issue number6
Publication statusPublished - Feb 11 1994


All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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