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. 2014 Nov 5;9(11):e112378. doi: 10.1371/journal.pone.0112378

Figure 6. Structural association among lower vertebrate IFN ancestors and mammalian Type I IFN subtypes.

Figure 6

Consensus sequences (IFN-con) were generated using multiple alignment programs of MUSCLE [44] and Jalview [43] and manually curated to represent most conservative residues among the aligned IFN peptides. The 3-D structures were modeled based on the structures of closely related homologs in structure databases using ESyPred3D [42]. Generally, all type I IFN peptides have a typical structure containing 5 α-helices; however, the high-antiviral subtypes such as most mammalian IFN-α and -β have higher α-helice density (upper panel above the arrow implying evolution) compared with IFN-ε, -ω and –δ/τ subtypes (bottom panel) that contain more coil/loop structures connected to small α-helices, which generally show lower antiviral but higher developmental regulation. Therefore, structural manipulation preferentially promotes antiviral functions. Species abbreviations: Dr, Danio rerio; Gg, Gallus gallus; Ss, Sus scrofa; Pan, multiple mammalian species.