RESUMEN

In animal embryos, the maternal-to-zygotic transition (MZT) hands developmental control from maternal to zygotic gene products. We show that the maternal proteome represents more than half of the protein-coding capacity of Drosophila melanogaster's genome, and that 2% of this proteome is rapidly degraded during the MZT. Cleared proteins include the post-transcriptional repressors Cup, Trailer hitch (TRAL), Maternal expression at 31B (ME31B), and Smaug (SMG). Although the ubiquitin-proteasome system is necessary for clearance of these repressors, distinct E3 ligase complexes target them: the C-terminal to Lis1 Homology (CTLH) complex targets Cup, TRAL, and ME31B for degradation early in the MZT and the Skp/Cullin/F-box-containing (SCF) complex targets SMG at the end of the MZT. Deleting the C-terminal 233 amino acids of SMG abrogates F-box protein interaction and confers immunity to degradation. Persistent SMG downregulates zygotic re-expression of mRNAs whose maternal contribution is degraded by SMG. Thus, clearance of SMG permits an orderly MZT.

Asunto(s)

Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Regulación del Desarrollo de la Expresión Génica , Proteínas Represoras/genética , Transcripción Genética , Cigoto/metabolismo , Animales , Regulación hacia Abajo/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriología , Embrión no Mamífero/metabolismo , Desarrollo Embrionario/genética , Femenino , Complejo de la Endopetidasa Proteasomal/metabolismo , Unión Proteica , Biosíntesis de Proteínas/genética , Subunidades de Proteína/metabolismo , Proteolisis , Proteoma/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Proteínas Represoras/metabolismo , Ribonucleoproteínas/metabolismo , Factores de Tiempo , Transcriptoma/genética , Ubiquitina/metabolismo