Chemical Incorporation of Chain-Terminating Nucleoside Analogs as 3'-Blocking DNA Damage and Their Removal by Human ERCC1-XPF Endonuclease.

Junpei Yamamoto,Shigenori Iwai,Chiaki Takahata,Isao Kuraoka,Kouji Hirota

doi:10.3390/molecules21060766

Junpei Yamamoto, Shigenori Iwai + Show 3 more

Open Access

https://doi.org/10.3390/molecules21060766

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Abstract

Nucleoside/nucleotide analogs that lack the 3′-hydroxy group are widely utilized for HIV therapy. These chain-terminating nucleoside analogs (CTNAs) block DNA synthesis after their incorporation into growing DNA, leading to the antiviral effects. However, they are also considered to be DNA damaging agents, and tyrosyl-DNA phosphodiesterase 1, a DNA repair enzyme, is reportedly able to remove such CTNA-modifications of DNA. Here, we have synthesized phosphoramidite building blocks of representative CTNAs, such as acyclovir, abacavir, carbovir, and lamivudine, and oligonucleotides with the 3′-CTNAs were successfully synthesized on solid supports. Using the chemically synthesized oligonucleotides, we investigated the excision of the 3′-CTNAs in DNA by the human excision repair cross complementing protein 1-xeroderma pigmentosum group F (ERCC1-XPF) endonuclease, which is one of the main components of the nucleotide excision repair pathway. A biochemical analysis demonstrated that the ERCC1-XPF endonuclease cleaved 2–7 nt upstream from the 3′-blocking CTNAs, and that DNA synthesis by the Klenow fragment was resumed after the removal of the CTNAs, suggesting that ERCC1-XPF participates in the repair of the CTNA-induced DNA damage.

Highlights

Nucleoside/nucleotide analogs lacking their 31 -hydroxyl group, such as 31 -azidothymidine (AZT), function as efficient antiviral drugs
FDA in in 1998, 1998, and the cyclopropylmethylamino group is reportedly hydrolyzed by cellular deaminases to form its active structure, carbovir (CBV) [12]
We successfully synthesized the 31 -chain-terminating nucleoside analogs (CTNAs) oligonucleotides on a solid support, and used them to investigate the repair of the CTNA-induced DNA damage by ERCC1-XPF endonuclease

Summary

Introduction

Nucleoside/nucleotide analogs lacking their 31 -hydroxyl group, such as 31 -azidothymidine (AZT), function as efficient antiviral drugs. Their common therapeutic target is DNA synthesis by DNA polymerases or reverse transcriptases (RTs) [1]. They are first metabolized into the corresponding. The drug triphosphates either inhibit the correct binding of the intact nucleotides to polymerases/RTs or are incorporated into the growing viral DNA. The chain elongation in reverse transcription and DNA replication is halted once the drug triphosphates have been incorporated (Figure 1A), due to the inability to form the 51 –31 phosphodiester bonds during. These chain-terminating nucleoside analogs (CTNAs) are widely utilized for HIV therapy [2]

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Conclusion