title: Reprogrammable recognition codes in bicoid homeodomain-DNA interaction.
abstract: We describe experiments to determine how the homeodomain of the Drosophila morphogenetic protein Bicoid recognizes different types of DNA sequences found in natural enhancers. Our chemical footprint analyses reveal that the Bicoid homeodomain makes both shared and distinct contacts with a consensus site A1 (TAATCC) and a nonconsensus site X1 (TAAGCT). In particular, the guanine of X1 at position 4 (TAAGCT) is protected by Bicoid homeodomain. We provide further evidence suggesting that the unique arginine at position 54 (Arg 54) of the Bicoid homeodomain enables the protein to recognize X1 by specifically interacting with this position 4 guanine. We also describe experiments to analyze the contribution of artificially introduced Arg 54 to DNA recognition by other Bicoid-related homeodomains, including that from the human disease protein Pitx2. Our experiments demonstrate that the role of Arg 54 varies depending on the exact homeodomain framework and DNA sequences. Together, our results suggest that Bicoid and its related homeodomains utilize distinct recognition codes to interact with different DNA sequences, underscoring the need to study DNA recognition by Bicoid-class homeodomains in an individualized manner.
authors.affiliation: Division of Developmental Biology, Children's Hospital Research Foundation, Cincinnati, Ohio 45229, USA.
authors.forename: V
authors.initials: V
authors.lastname: Dave
authors.forename: C
authors.initials: C
authors.lastname: Zhao
authors.forename: F
authors.initials: F
authors.lastname: Yang
authors.forename: C S
authors.initials: CS
authors.lastname: Tung
authors.forename: J
authors.initials: J
authors.lastname: Ma
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001120:Arginine / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D016384:Consensus Sequence / Q000235:genetics; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster; D004742:Enhancer Elements, Genetic / Q000235:genetics; D006147:Guanine / Q000378:metabolism; D018398:Homeodomain Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D051761:Paired Box Transcription Factors; D011485:Protein Binding; D011994:Recombinant Proteins; D016415:Sequence Alignment; D013379:Substrate Specificity; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism; D000097577:Homeobox Protein PITX2
chemical_list: D001120:Arginine; D004247:DNA; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006147:Guanine; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D051761:Paired Box Transcription Factors; D011994:Recombinant Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D000097577:Homeobox Protein PITX2; C056478:bcd protein, Drosophila; C101485:homeobox protein PITX1; C433629:homeobox protein PITX3