The fidelity of misinsertion and mispair extension throughout DNA synthesis exhibited by mutants of the reverse transcriptase of human immunodeficiency virus type 2 resistant to nucleoside analogs

Ran Taube, Orna Avidan, Amnon Hizi

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The AIDS-causing retroviruses, human immunodeficiency virus types 1 and type 2 (HTV-1 and HIV-2, respectively) undergo extensive genetic variations, which effect their pathogenesis and resistance to drug therapy. It was postulated that this genetic hypervariability results from high rates of viral replication in conjugation with a relatively low fidelity of DNA synthesis [typical to the reverse transcriptases (RT) of these retroviruses]. As part of studying structure/function relationship in HIV RT, mutational analyses were conducted to identify amino acid residues which are involved in affecting the fidelity of DNA synthesis. The formation of 3'-mispaired DNA due to nucleotide misinsertions, and the subsequent elongation of this mismatched DNA were shown to be major determinants in affecting those substitutions during DNA synthesis (exhibited in vitro by HIV RT). It was interesting to find a correlation between sensitivity to nucleoside analogs (due to the ability to incorporate or reject an incoming analog) and the fidelity of DNA synthesis (which depends on the capacity to incorporate and extend a wrong nucleotide). Such a connection has already been found for several drug-resistant mutants of HIV-1 RT, with an increased fidelity of DNA synthesis relative to the wild-type RT. In the present study we have examined the fidelity of DNA synthesis using the same parameters of misinsertion and mispair extension for five novel drug-resistant mutants of HTV-2 RT; i.e. the single mutants [Val74]RT, [Gly89]RT and [Tyr215]RT and the double mutants [Val74,Tyr215]RT and [Gly89, Tyr215]RT. This comparative study suggests that unlike the Val74 mutant of HIV-1 RT, which was shown earlier to display a substantially enhanced fidelity, the comparable mutant of HIV-2 RT has fidelity similar to that of the wild-type RT. Depending on the assay employed and the DNA sequences extended, most other mutants of HIV-2 RT display moderate effects on the enzyme, leading to mild increases in fidelity of DNA synthesis. This implies a more complex and less distinctive correlation between drug-resistance, misinsertion and mispair extension in HIV-2 RT in contrast to HTV-1 RT, providing evidence for potential biochemical differences between these two related RT.

Original languageEnglish
Pages (from-to)106-114
Number of pages9
JournalEuropean Journal of Biochemistry
Volume250
Issue number1
DOIs
StatePublished - 1 Jan 1997
Externally publishedYes

Keywords

  • DNA synthesis
  • Drug-resistant mutant
  • Fidelity
  • Human immunodeficiency virus 2
  • Reverse transcriptase

ASJC Scopus subject areas

  • Biochemistry

Fingerprint

Dive into the research topics of 'The fidelity of misinsertion and mispair extension throughout DNA synthesis exhibited by mutants of the reverse transcriptase of human immunodeficiency virus type 2 resistant to nucleoside analogs'. Together they form a unique fingerprint.

Cite this