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. Author manuscript; available in PMC: 2026 May 22.
Published before final editing as: Cell Rep. 2026 Apr 16;45(4):117273. doi: 10.1016/j.celrep.2026.117273

Figure 2. Nsp13 helicase forms a specific complex with the SARS-CoV-2 core RTC, and nsp13.2 supports the elongating polymerase by translocating on the non-template strand.

Figure 2.

(A–C) On the left, schematics describing the measurements performed with nsp13 helicase and either poliovirus RdRp (A) or SARS-CoV-2 core RTC (B and C), elongating on either a dsRNA (A and B) or ssRNA (C) template, with either a wild-type nsp13 helicase (A and C) or an ATPase-dead K288A nsp13-helicase mutant (B). The corresponding elongation activity traces are shown on the right, i.e., without (gray) or with (black) nsp13 helicase at the indicated concentration. 20 pN was applied to the RNA during the measurements on a dsRNA template (A and B), while 25 pN was applied during the measurements on an ssRNA template (C).

(D) Schematic representation of resuming the observations. The core RTC elongates slowly through duplex RNA. Once associated with the two helicases, nsp13.2 binds to the non-template RNA and utilizes ATP hydrolysis to translocate 5′ to 3′ and enable fast RTC elongation.

See also Figures S3A–S3D.