Molecular evolution of the GATA family of transcription factors: Conservation within the DNA-binding domain

The GATA-binding transcription factors comprise a protein family whose memb ers contain either one or two highly conserved zinc finger DNA-binding doma ins. Members of this group have been identified in organisms ranging from c ellular slime mold to vertebrates, including plants, fungi, nematodes, inse cts, and echinoderms. While much work has been done describing the expressi on patterns, functional aspects, and target genes for many of these protein s, an evolutionary analysis of the entire family has been lacking. Herein w e show that,only the C-terminal zinc finger (Cf) and basic domain, which to gether constitute the GATA-binding domain, are conserved throughout this pr otein family. Phylogenetic analyses of amino acid sequences demonstrate dis tinct evolutionary pathways. Analysis of GATA factors isolated from vertebr ates suggests that the six distinct vertebrate GATAs are descended from a c ommon ancestral sequence, while those isolated from nonvertebrates (with th e exception of the fungal AREA orthologues and Arabidopsis paralogues) appe ar to be related only within the DNA-binding domain and otherwise provide l ittle insight into their evolutionary history. These results suggest multip le modes of evolution, including gene duplication and modular evolution of GATA factors based upon inclusion of a class IV zinc finger motif. As such, GATA transcription factors represent a group of proteins related solely by their homologous DNA-binding domains. Further analysis of this domain exam ines the degree of conservation at each amino acid site using the Boltzmann entropy measure, thereby identifying residues critical to preservation of structure and function, Finally, we construct a predictive motif that can a ccurately identify potential GATA proteins.