An exonuclease-resistant chain-terminating nucleotide analogue targeting the SARS-CoV-2 replicase complex.
Nucleic Acids Res
; 52(3): 1325-1340, 2024 Feb 09.
Article
en En
| MEDLINE
| ID: mdl-38096103
ABSTRACT
Nucleotide analogues (NA) are currently employed for treatment of several viral diseases, including COVID-19. NA prodrugs are intracellularly activated to the 5'-triphosphate form. They are incorporated into the viral RNA by the viral polymerase (SARS-CoV-2 nsp12), terminating or corrupting RNA synthesis. For Coronaviruses, natural resistance to NAs is provided by a viral 3'-to-5' exonuclease heterodimer nsp14/nsp10, which can remove terminal analogues. Here, we show that the replacement of the α-phosphate of Bemnifosbuvir 5'-triphosphate form (AT-9010) by an α-thiophosphate renders it resistant to excision. The resulting α-thiotriphosphate, AT-9052, exists as two epimers (RP/SP). Through co-crystallization and activity assays, we show that the Sp isomer is preferentially used as a substrate by nucleotide diphosphate kinase (NDPK), and by SARS-CoV-2 nsp12, where its incorporation causes immediate chain-termination. The same -Sp isomer, once incorporated by nsp12, is also totally resistant to the excision by nsp10/nsp14 complex. However, unlike AT-9010, AT-9052-RP/SP no longer inhibits the N-terminal nucleotidylation domain of nsp12. We conclude that AT-9052-Sp exhibits a unique mechanism of action against SARS-CoV-2. Moreover, the thio modification provides a general approach to rescue existing NAs whose activity is hampered by coronavirus proofreading capacity.
Texto completo:
1
Banco de datos:
MEDLINE
Asunto principal:
Antivirales
/
Polifosfatos
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SARS-CoV-2
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COVID-19
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Tratamiento Farmacológico de COVID-19
Límite:
Humans
Idioma:
En
Año:
2024
Tipo del documento:
Article