Date of this Version
Angeletti, M. K. & Zhang, L. 2020. Adaptations of Interferon Regulatory Factor 3 During Transition from Terrestrial to Aquatic Life. Undergraduate Honors Thesis. University of Nebraska-Lincoln
Interferon regulatory factor 3 (IRF3) and IRF7 are closely related IRF members and play a major role in the induction of interferons, which are a key component in vertebrate innate immunity. However, there is limited knowledge regarding the evolution and adaptation of these IRFs to the environment. Two unique motifs in IRF3 and 7 were identified. One motif, GASSL, is highly conserved throughout the evolution of IRF3 and 7 and located in the signal response domain. Another motif, DPHK, is in the DNA-binding domain. The ancestral protein of IRF3 and 7 seemed to possess the DPHK motif. In the ray-finned fish lineage, while the DPHK is maintained in IRF7, the motif in IRF3 is changed to NPHK with a D → N amino acid substitution. The D → N substitution is also found in amphibian IRF3 but not in amphibian IRF7. Terrestrial animals such as reptiles and mammals predominantly possess DPHK sequences in both IRF3 and 7. However, the D → N substitution in IRF3 DPHK is again found in cetaceans such as whales and dolphins as well as in marsupials. These observations suggest that the D → N substitutions in the IRF3 DPHK motif are likely to be associated with vertebrate adaptations to aquatic environments and other environmental changes.