Fig. 6. Zoom on essential RNA-LACV-L contacts during transcription.

a 5′-cap interaction with LACV-L_{CItag_H34K} in the transcription cleavage conformation. The endonuclease (ENDO) active site residues are colored in red. The capped primer is colored in cyan and the dotted line stands for the potential cleavage path. The position of the prime-and-realign loop (PR loop) and the cap-binding domain (CBD) are shown respectively in purple and orange. On the right panel, residues implicated in the 5′-capped stabilization are displayed. b Capped primer path from the CBD active site to the RdRp active site during transcription initiation. On the right panel, residues that are proximal to the capped primer are indicated. POP corresponds to the pyrophosphate product. c In vitro transcription activity of LACV-L_{CItag_H34K}, LACV-L_{CItag_H34K_M989A} (M989A), LACV-L_{CItag_H34K-I990A} (I990A), LACV-L_{CItag_H34K_S991A} (S991A) with 5′-1-17BPm, cap14AG, 3′-vRNA1-25 and four NTPs. Transcription products are labeled. MW37 and MW lanes are equivalent to Fig. 4a description. Source data are provided as a Source Data file. This experiment was repeated independently 2 times with similar results. d Interaction between the capped RNA product and LACV-L_{CItag_H34K} in transcription elongation state. Residues stabilizing it are indicated. Flexible nucleotides are represented as a dotted line.