Identification of a Nidovirales Orf1a N7-guanine cap Methyltransferase signature-sequence as a genetic marker of large genome Tobaniviridae

François Ferron; Humberto Julio Debat; Etienne Decroly; Bruno Canard

The conserved Nidovirales C-terminus RdRp core was used to build phylogenetic trees based on MAFFT v7.427 multiple sequence alignment with BLOSUM62 scoring matrix and G-INSi iterative refinement method. The alignments were used as input for maximum likelihood trees generated with the FasTtree v2.1.5 software (best-fit model = JTT-Jones-Taylor-Thorton with single rate of evolution for each site = CAT). Local support values were computed using the Shimodaira-Hasegawa test (SH) with 1,000 replicates. Structural alignment of reference or retrieved Mtases were done using EXPRESSO [26] and proofed with Chimera [27] . N7-Mtases reference motifs were inferred and defined based on visual inspection and analysis of the structures. The subsequent motifs were used as orthogonal validation and not used for the search.