Solution structure of the DNA binding domain of the human forkhead transcription factor AFX (FOXO4).
AFX is a human forkhead transcription factor. Based on results from studies of the orthologous transcription factor DAF-16 in Caenorhabditis elegans, it was suggested that some of the metabolic defects in both type I and type II diabetes may be due to unregulated activity of AFX. In the present study, we report the high-resolution NMR solution structure of the DNA binding domain of AFX. It is the first structure of the DNA binding domain from a small subfamily of forkhead transcription factors (i.e., AFX, FKHR, FKHRL1, FKHRL1P1, and FKHRP1). Despite rather low sequence identity for a protein within the forkhead family, the structure is remarkably similar to those of the DNA binding domains of HNF3-gamma and FREAC-11, and to a lesser extent the DNA binding domain of Genesis which displays a slightly altered orientation of the DNA recognition helix. The high degree of structural similarity between the DNA binding domains of different forkhead transcription factors implies that the repositioning of helix 3, observed for Genesis, cannot be a general feature for modulation of the DNA binding specificity. Other mechanisms that could influence the DNA binding specificity are discussed.
Weigelt
J
J
Department of Structural Chemistry, Biovitrum Division, Pharmacia, S-112 87 Stockholm, Sweden. Johan.Weigelt@biovitrum.com
Climent
I
I
Dahlman-Wright
K
K
Wikström
M
M
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D051858:Forkhead Transcription Factors; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D051381:Rats; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012996:Solutions; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C108803:FOXO4 protein, human; D051858:Forkhead Transcription Factors; D012996:Solutions; D014157:Transcription Factors; D004247:DNA