The OAR/aristaless domain of the homeodomain protein Cart1 has an attenuating role in vivo.
Aristaless-related genes encode a structurally defined group of homeoproteins that share a C-terminal stretch of amino acids known as the OAR- or aristaless domain. Many aristaless-related genes have been linked to major developmental functions, but the function of the aristaless domain itself is poorly understood. Expression and functional studies have shown that a subgroup of these genes, including Prx1, Prx2, Alx3, Alx4 and Cart1, is essential for correct morphogenesis of the limbs and cranium. We now demonstrate the function of the aristaless domain in vivo by ectopically expressing normal and mutated forms of Cart1 and Alx3. Ectopic expression of Cart1 in transgenic mice does not disturb development, whereas expression of a Cart1 form from which the aristaless domain has been deleted results in severe cranial and vertebral malformations. The Alx3 protein contains a divergent aristaless domain that appears not to be functional, as ectopic expression of Alx3 results in an altered phenotype irrespective of the presence of this aristaless domain. Linking the Cart1 aristaless domain to Alx3 extinguishes teratogenicity. We show that, at the molecular level, the most important consequence of deleting the aristaless domain is increased DNA binding to its palindromic target sequence. This demonstrates that the aristaless domain functions as an intra-molecular switch to contain the activity of the transcription factor that it is part of.
Brouwer
Antje
A
Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands.
ten Berge
Derk
D
Wiegerinck
Rob
R
Meijlink
Frits
F
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001842:Bone and Bones / Q000002:abnormalities; D019465:Craniofacial Abnormalities / Q000235:genetics; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D008969:Molecular Sequence Data; D009154:Mutation; D017434:Protein Structure, Tertiary / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D012782:Shoulder / Q000002:abnormalities; D014158:Transcription, Genetic
C489986:Alx1 protein, mouse; C113607:Alx3 protein, mouse; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; C079410:al protein, Drosophila; D004247:DNA