tetano
Editor, Senior Moderator
Cell Rep
. 2022 Dec 23;111901.
doi: 10.1016/j.celrep.2022.111901. Online ahead of print.
Direct observation of backtracking by influenza A and B polymerases upon consecutive incorporation of the nucleoside analog T1106
Tomas Kouba[SUP] 1 [/SUP], Anna Dubankova[SUP] 1 [/SUP], Petra Drncova[SUP] 1 [/SUP], Elisa Donati[SUP] 2 [/SUP], Pietro Vidossich[SUP] 2 [/SUP], Valentina Speranzini[SUP] 1 [/SUP], Alex Pflug[SUP] 1 [/SUP], Johanna Huchting[SUP] 3 [/SUP], Chris Meier[SUP] 3 [/SUP], Marco De Vivo[SUP] 2 [/SUP], Stephen Cusack[SUP] 4 [/SUP]
Affiliations
Abstract
The antiviral pseudo-base T705 and its de-fluoro analog T1106 mimic adenine or guanine and can be competitively incorporated into nascent RNA by viral RNA-dependent RNA polymerases. Although dispersed, single pseudo-base incorporation is mutagenic, consecutive incorporation causes polymerase stalling and chain termination. Using a template encoding single and then consecutive T1106 incorporation four nucleotides later, we obtained a cryogenic electron microscopy structure of stalled influenza A/H7N9 polymerase. This shows that the entire product-template duplex backtracks by 5 nt, bringing the singly incorporated T1106 to the +1 position, where it forms an unexpected T1106:U wobble base pair. Similar structures show that influenza B polymerase also backtracks after consecutive T1106 incorporation, regardless of whether prior single incorporation has occurred. These results give insight into the unusual mechanism of chain termination by pyrazinecarboxamide base analogs. Consecutive incorporation destabilizes the proximal end of the product-template duplex, promoting irreversible backtracking to a more energetically favorable overall configuration.
Keywords: CP: Molecular biology; RNA-dependent RNA polymerase; T1106; T705; antiviral drug; backtracking; cap-dependent transcription; influenza virus; molecular dynamics; nucleoside analog; single-particle cryogenic electron microscopy.
. 2022 Dec 23;111901.
doi: 10.1016/j.celrep.2022.111901. Online ahead of print.
Direct observation of backtracking by influenza A and B polymerases upon consecutive incorporation of the nucleoside analog T1106
Tomas Kouba[SUP] 1 [/SUP], Anna Dubankova[SUP] 1 [/SUP], Petra Drncova[SUP] 1 [/SUP], Elisa Donati[SUP] 2 [/SUP], Pietro Vidossich[SUP] 2 [/SUP], Valentina Speranzini[SUP] 1 [/SUP], Alex Pflug[SUP] 1 [/SUP], Johanna Huchting[SUP] 3 [/SUP], Chris Meier[SUP] 3 [/SUP], Marco De Vivo[SUP] 2 [/SUP], Stephen Cusack[SUP] 4 [/SUP]
Affiliations
- PMID: 36596301
- DOI: 10.1016/j.celrep.2022.111901
Abstract
The antiviral pseudo-base T705 and its de-fluoro analog T1106 mimic adenine or guanine and can be competitively incorporated into nascent RNA by viral RNA-dependent RNA polymerases. Although dispersed, single pseudo-base incorporation is mutagenic, consecutive incorporation causes polymerase stalling and chain termination. Using a template encoding single and then consecutive T1106 incorporation four nucleotides later, we obtained a cryogenic electron microscopy structure of stalled influenza A/H7N9 polymerase. This shows that the entire product-template duplex backtracks by 5 nt, bringing the singly incorporated T1106 to the +1 position, where it forms an unexpected T1106:U wobble base pair. Similar structures show that influenza B polymerase also backtracks after consecutive T1106 incorporation, regardless of whether prior single incorporation has occurred. These results give insight into the unusual mechanism of chain termination by pyrazinecarboxamide base analogs. Consecutive incorporation destabilizes the proximal end of the product-template duplex, promoting irreversible backtracking to a more energetically favorable overall configuration.
Keywords: CP: Molecular biology; RNA-dependent RNA polymerase; T1106; T705; antiviral drug; backtracking; cap-dependent transcription; influenza virus; molecular dynamics; nucleoside analog; single-particle cryogenic electron microscopy.