title: Evolutionary and functional analysis of the tailless enhancer in Musca domestica and Drosophila melanogaster.
abstract: To further understand the evolutionary dynamics of the regulatory interactions underlying development, we expand on our previous analysis of hunchback and compare the structure and function of the tailless enhancer between Musca domestica and Drosophila melanogaster. Our analysis shows that although the expression patterns and functional protein domains of tll are conserved between Musca and Drosophila, the enhancer sequences are unalignable. Upon closer investigation, we find that these highly diverged enhancer sequences encode the same regulatory information necessary for Bicoid, Dorsal, and the terminal system to drive tll expression. The binding sites for these transcription factors differ in the sequence, number, spacing, and position between the Drosophila and Musca tll enhancers, and we were unable to establish homology between binding sites from each species. This implies that the Musca and Drosophila Bcd-binding sites have evolved de novo in the 100 million years since these species diverged. However, in transgenic Drosophila embryos the Musca tll enhancer is able to drive the same expression pattern as endogenous Drosophila tll. Therefore, during the rapid evolution of enhancer sequences individual binding sites are continually lost and gained, but the transcriptional output is maintained by compensatory mutations in cis and in trans.
authors.affiliation: Department of Genetics, University of Leicester, Leicester LE1 7RH, UK.
authors.forename: Naomi S
authors.initials: NS
authors.lastname: Wratten
authors.forename: Alistair P
authors.initials: AP
authors.lastname: McGregor
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Shaw
authors.forename: Gabriel A
authors.initials: GA
authors.lastname: Dover
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D019143:Evolution, Molecular; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000235:genetics; D006793:Houseflies / Q000196:embryology / Q000235:genetics*; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015534:Trans-Activators / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D019476:Insect Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; C074090:TLL protein, Drosophila; D015534:Trans-Activators; C056478:bcd protein, Drosophila