Dynamic evolution of the major transcription factor DNA binding domain, and protein-protein interaction families during the evolution of the avian lineage

Transcription factors are characterized by their domain architecture, including DNA binding and protein-protein interaction domain combinations, which regulate their binding specificity, as well as their ability to effect a change on gene expression of their downstream targets. Transcription factors are central to organismal development, thus they potentially are instrumental in producing phenotypic diversity. Transcription factor abundance was estimated via 49 major DNA binding domain families, as well as 34 protein-protein interaction domain families, in 48 bird genomes, which were then compared with 6 available reptile genomes, in an effort to assess the degree to which these domains are potentially connected to increased phenotypic diversity in the avian lineage. We hypothesized that there would be increased abundance in multiple transcription factor domain families, as well as domains associated with protein-protein interactions, that would correlate with the increased phenotypic diversity found in birds; instead, this data shows a general loss/contraction of major domain families, with the largest losses in domain families associated with multiple developmental (feather, body-plan, immune) and metabolic processes. Ultimately, the results of this analyses represent a general characterization of domain family composition in birds, thus the specific domain composition of TF families should be probed further, especially those with the largest reductions seen in this study.