Figure 2

Multiple sequence alignment of the TV-Pol domain. Secondary structure is shown above the alignment helices shown as cylinders and strands as arrows (See additional file 1 [Additional file 1] for details on alignment and secondary structure prediction methods). The 80% consensus shown below the alignment was derived using the following classes of amino acids: the aliphatic (l: LIV, yellow shading); hydrophobic (h: ACFILMVWY, yellow shading); small (s: ACDGNPSTV, green); tiny (u: GAS, green); big (b:KMILEWRYFQ); polar (p: CDEHKNQRST, blue); charged (c: DEHKR, pink); basic (+: HKR, pink). Strongly conserved amino acids are shaded red. Sequences are denoted by their gene name followed by species abbreviation and GenBank Identifier separated by underscores. In addition to the TV-Pols some of the key superfamily A polymerases and T7-like RNA polymerases detected with significant e-values are also shown in the alignment. The species abbreviations are: Amac: Alteromonas macleodii; Apro: alpha proteobacterium; BPMa-LMM01: Microcystis phage Ma-LMM01; BPT7: Enterobacteria phage T7; BPvirophage: Sputnik virophage; Bmel: Brucella melitensis; Bsui: Brucella suis; Chut: Cytophaga hutchinsonii; Dole: Desulfococcus oleovorans; Ecol: Escherichia coli; Fbac: Flavobacteriales bacterium; Gbem: Geobacter bemidjiensis; Gobs: Gemmata obscuriglobus; Gpro: gamma proteobacterium; Gste: Geobacillus stearothermophilus; Lves: Loktanella vestfoldensis; Mgam: marine gamma proteobacterium HTCC2143; Mmet: marine metagenome; Mnod: Methylobacterium nodulans; Mpop: Methylobacterium populi; Noli: Nephroselmis olivacea; Oind: Oceanibulbus indolifex; Pden: Paracoccus denitrificans; Pdok: Polaribacter dokdonensis; Ptor: Psychroflexus torquis; Rbac: Rhodobacterales bacterium; Rbal: Rhodopirellula baltica; Rnub: Roseovarius nubinhibens; Rpal: Rhodopseudomonas palustris; Rsp.: Reinekea sp.; Rsp.: Roseobacter sp.; Saur: Staphylococcus aureus; Shae: Staphylococcus haemolyticus; Ssp.: Sulfitobacter sp.; Taqu: Thermus aquaticus; Tsp.: Thauera sp.; Vsp.: Vibrio sp.