PT  - JOURNAL ARTICLE
AU  - Subhas Chandra Bera
AU  - Mona Seifert
AU  - Robert N. Kirchdoerfer
AU  - Pauline van Nies
AU  - Yibulayin Wubulikasimu
AU  - Salina Quack
AU  - Flávia S. Papini
AU  - Jamie J. Arnold
AU  - Bruno Canard
AU  - Craig E. Cameron
AU  - Martin Depken
AU  - David Dulin
TI  - The nucleotide addition cycle of the SARS-CoV-2 polymerase
AID  - 10.1101/2021.03.27.437309
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.03.27.437309
4099  - http://biorxiv.org/content/early/2021/03/27/2021.03.27.437309.short
4100  - http://biorxiv.org/content/early/2021/03/27/2021.03.27.437309.full
AB  - Coronaviruses have evolved elaborate multisubunit machines to replicate and transcribe their genomes. Central to these machines are the RNA-dependent RNA polymerase subunit (nsp12) and its intimately associated cofactors (nsp7 and nsp8). We have used a high-throughput magnetic-tweezers approach to develop a mechanochemical description of this core polymerase. The core polymerase exists in at least three catalytically distinct conformations, one being kinetically consistent with incorporation of incorrect nucleotides. We provide the first evidence that an RdRp uses a thermal ratchet instead of a power stroke to transition from the pre- to post-translocated state. Ultra-stable magnetic tweezers enables the direct observation of coronavirus polymerase deep and long-lived backtrack that are strongly stimulated by secondary structure in the template. The framework presented here elucidates one of the most important structure-dynamics-function relationships in human health today, and will form the grounds for understanding the regulation of this complex.Competing Interest StatementThe authors have declared no competing interest.