Essential structural and functional determinants within the forkhead domain of FOXC1.
The forkhead domain (FHD)-containing developmental transcription factor FOXC1 is mutated in patients presenting with Axenfeld-Rieger malformations. In this paper, we report the introduction of positive, negative or neutral charged amino acids into critical positions within the forkhead domain of FOXC1 in an effort to better understand the essential structural and functional determinants within the FHD. We found that FOXC1 is intolerant of mutations at I87. Additionally, alterations of amino acids within alpha-helix 1 of the FOXC1 FHD affected both nuclear localization and transactivation. Amino acids within alpha-helix 3 were also found to be necessary for transactivation and can have roles in correct localization. Interestingly, changing amino acids within alpha-helix 3, particularly R127, resulted in altered DNA-binding specificity and granted FOXC1 the ability to bind to a novel DNA sequence. Given the limited topological variation of FHDs, due to the high conservation of residues, we anticipate that models of forkhead domain function derived from these data will be relevant to other members of the FOX family of transcription factors.
Department of Medical Genetics and Department of Ophthalmology, 832 Medical Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2H7.
R A
RA
Saleem
S
S
Banerjee-Basu
T C
TC
Murphy
A
A
Baxevanis
M A
MA
Walter
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000502:physiology; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D051858:Forkhead Transcription Factors; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
D000596:Amino Acids; D004268:DNA-Binding Proteins; C112743:FOXC1 protein, human; D051858:Forkhead Transcription Factors; D014157:Transcription Factors