Precise Temporal Regulation of Post-transcriptional Repressors Is Required for an Orderly Drosophila Maternal-to-Zygotic Transition. Author Wen Cao, Sarah Kabelitz, Meera Gupta, Eyan Yeung, Sichun Lin, Christiane Rammelt, Christian Ihling, Filip Pekovic, Timothy Low, Najeeb Siddiqui, Matthew Cheng, Stephane Angers, Craig Smibert, Martin Wühr, Elmar Wahle, Howard Lipshitz Publication Year 2020 Type Journal Article Abstract 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. Keywords Repressor Proteins, Animals, Drosophila Proteins, Protein Biosynthesis, Transcription, Genetic, RNA, Messenger, Protein Binding, Time Factors, Down-Regulation, Female, Drosophila melanogaster, Embryonic Development, Gene Expression Regulation, Developmental, Proteome, Embryo, Nonmammalian, Zygote, Ribonucleoproteins, Protein Subunits, Transcriptome, Proteolysis, Ubiquitin, Proteasome Endopeptidase Complex Journal Cell Rep Volume 31 Issue 12 Pages 107783 Date Published 2020 Jun 23 ISSN Number 2211-1247 DOI 10.1016/j.celrep.2020.107783 Alternate Journal Cell Rep PMCID PMC7372737 PMID 32579915 PubMedPubMed CentralGoogle ScholarBibTeXEndNote X3 XML