Fig. 4.

Transcription activities of PB2 mutants in a minireplicon system. (A and B) Effects of mutations of m⁷GTP stacking residues in FluA (A) and FluB (B) PB2 on transcription activity. (C and D) Effects of mutations in residues involved in hydrogen bonds with the guanine residue of m⁷GTP in FluA (C) and FluB (D) PB2 on transcription activity. (E) Effect of mutations in Gln325 with an Asp mutation at position 363 in FluB PB2 on transcription activity. The firefly luciferase activity was normalized to Renilla luciferase activity. The results are averages and standard deviations (SD) from four independent experiments.