RESUMEN
A P element enhancer trap screen was conducted to identify genes involved in dorsal-ventral boundary formation in Drosophila. The son of Notch (son) gene was identified by the son(2205) enhancer trap insertion, which is a partial loss-of-function mutation. Based on son(2205) mutant phenotypes and genetic interactions with Notch and wingless mutations, we conclude that son participates in wing development, and functions in the Notch signaling pathway at the dorsal-ventral boundary in the wing. Notch signaling pathway components activate son enhancer trap expression in wing cells. son enhancer trap expression is regulated positively by wingless, and negatively by cut in boundary cells. Ectopic Son protein induces wingless and cut expression in wing discs. We hypothesize that there is positive feedback regulation of son by wingless, and negative regulation by cut at the dorsal-ventral boundary during wing development.
Asunto(s)
Drosophila melanogaster/crecimiento & desarrollo , Drosophila melanogaster/genética , Genes de Insecto , Alas de Animales/crecimiento & desarrollo , Animales , Animales Modificados Genéticamente , Secuencia de Bases , Tipificación del Cuerpo/genética , Cartilla de ADN/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/metabolismo , Elementos de Facilitación Genéticos , Femenino , Regulación del Desarrollo de la Expresión Génica , Proteínas de Homeodominio/genética , Proteínas de Homeodominio/metabolismo , Masculino , Modelos Biológicos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Receptores Notch/genética , Receptores Notch/metabolismo , Transducción de Señal , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Factores de Transcripción Winged-Helix/genética , Factores de Transcripción Winged-Helix/metabolismo , Proteína Wnt1RESUMEN
GTP cyclohydrolase I (E.C. 3.5.4.16) is a homodecameric protein that catalyzes the conversion of GTP to 7,8- dihydroneopterin triphosphate (H(2)NTP), the initial step in the biosynthesis of pteridines. It was proposed that the enzyme complex could be composed of a dimer of two pentamers, or a pentamer of tightly associated dimers; then the active site of the enzyme was located at the interface of three monomers (Nar et al. 1995a, b). Using mutant enzymes that were made by site-directed mutagenesis, we showed that a decamer of GTP cyclohydrolase I should be composed of a pentamer of five dimers, and that the active site is located between dimers, as analyzed by a series of size exclusion chromatography and the reconstitution experiment. We also show that the residues Lys 136, Arg139, and Glu152 are of particular importance for the oligomerization of the enzyme complex from five dimers to a decamer.