Isolation and characterization of target sequences of the chicken CdxA homeobox gene

• Published in: Nucleic acids research 1993-10, Vol.21 (21), p.4915-4922
• Main Authors: Margalit, Yael, Yarus, Sinai, Shapira, Eli, Gruenbaum, Yosef, Fainsod, Abraham
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Analytical, structural and metabolic biochemistry; Animals; Avian Proteins; Base Sequence; Binding and carrier proteins; Biological and medical sciences; Cells, Cultured; Chickens; DNA - metabolism; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; Genes, Homeobox; Homeodomain Proteins; Molecular Sequence Data; Protein Binding; Proteins; Sequence Homology, Amino Acid; Transcription, Genetic
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/21.21.4915

The DNA binding specificity of the chicken homeodomain protein CDXA was studied. Using a CDXAglutathione- S-tranferase fusion protein, DNA fragments containing the binding site for this protein were isolated. The sources of DNA were oligonucleotides with random sequence and chicken genomic DNA. The DNA fragments isolated were sequenced and tested in DNA bindin assays. Sequencing revealed that most DNA fragments are AT rich which is a common feature of homeodomain binding sites. B electrophoretic mobility shift assays it was shown that the different target sequences isolated bind to the CDXA protein with different affinities. The specific sequences bound by the CDXA protein in the genomic fragments isolated, were determined by DNase I footprinting. From the footprinted sequences, the CDXA consensus binding site was determined. The CDXA protein binds the consensus sequence A, A/T, T, A/T, A, T, A/G. The CAUDAL binding site in the ftz promoter is also included in this consensus sequence. When tested, some of the genomic target sequences were capable of enhancing the transcriptional activity of reporter plasmids when introduced into CDXA expressing cells. This study determined the DNA sequence specificity of the CDXA protein and it also shows that this protein can further activate transcription in cells in culture.