Removal of ribonucleotides by p53 protein incorporated during DNA synthesis by HIV-1 reverse transcriptase

Tzofit Akua, Galia Rahav, Yossi Saragani, Amnon Hizi, Mary Bakhanashvili

Research output: Contribution to journalArticlepeer-review

Abstract

Objective(s): HIV-1 reverse transcriptase frequently incorporates ribonucleotides into the proviral DNA in macrophages, but not in lymphocytes. The enzyme exerts an efficient ribonucleotide-terminated primer extension capacity. Furthermore, ribonucleotide-editing repair is attenuated in macrophages. Tumor suppressor p53 protein, displaying an intrinsic 30!50 exonuclease activity, was found to be involved in efficient proofreading of base-base mismatches produced during DNA synthesis. As the presence of proofreading activity is cardinal for the DNA synthesis accuracy, it was of interest to assess whether p53 can serve as a trans-acting proofreader for HIV-1 reverse transcriptase during ribonucleotide incorporation. Design: We investigated the potential involvement of cytoplasmic p53 in error correction during insertion of ribonucleotides into DNA by recombinant HIV-1 reverse transcriptase in a p53-proficient and deficient background. Methods: Primer extension reactions were carried out to elucidate the incorporation and removal of ribonucleotides. Results: The biochemical studies suggest that p53 is involved in a ribonucleotide damage-associated repair mechanism through its capacity to remove preformed 30-terminal ribonucleotides, to decrease ribonucleotide incorporation and to prevent the 30-ribo-terminated primer extension during ongoing DNA synthesis by HIV-1 reverse transcriptase. A positive correlation exists between the presence of endogenous p53 and decrease in stable incorporation of ribonucleotides into DNA with p53-harboring lysates of HCT116 cells. p53, by preferential removal of purine over pyrimidine ribonucleotides, may affect the ribonucleotide mutation spectra produced by HIV-1 reverse transcriptase. Conclusion: The data implies that p53 can excise incorrect sugar in addition to base mispairs, thereby expanding the role of p53 in the repair of nucleic acids replication errors.

Original languageEnglish
Pages (from-to)343-353
Number of pages11
JournalAIDS
Volume31
Issue number3
DOIs
StatePublished - 28 Jan 2017

Keywords

  • Exonuclease
  • HIV-1 reverse transcriptase
  • P53
  • Proofreading
  • Proviral DNA
  • Ribonucleotides

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