The maternal-to-zygotic transition (MZT) is a conserved step in animal development, where control is passed from the maternal to the zygotic genome. Although the MZT is typically considered from its impact on the transcriptome, we previously found that three maternally deposited Drosophila RNA binding proteins (ME31B, Trailer Hitch [TRAL], and Cup) are also cleared during the MZT by unknown mechanisms. Here, we show that these proteins are degraded by the ubiquitin-proteasome system. Marie Kondo, an E2 conjugating enzyme, and the E3 CTLH ligase are required for the destruction of ME31B, TRAL, and Cup. Structure modeling of the Drosophila CTLH complex suggests that substrate recognition is different than orthologous complexes. Despite occurring hours earlier, egg activation mediates clearance of these proteins through the Pan Gu kinase, which stimulates translation of Kondo mRNA. Clearance of the maternal protein dowry thus appears to be a coordinated, but as-yet underappreciated, aspect of the MZT.
Sequencing data have been deposited in GEO under accession code GSE140436. All data generated during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 2 and 4.
Me31B interaction with Kondo in stage 14 oocytesNCBI Gene Expression Omnibus, GSE140436.
mRNA Poly(A)-tail Changes Specified by Deadenylation Broadly Reshape Translation in Drosophila Oocytes and Early EmbryosNCBI Gene Expression Omnibus, GSE83616.
ME31B/DDX6 globally represses maternal mRNAs by two distinct mechanisms during the Drosophila maternal-to-zygotic transitionNCBI Gene Expression Omnibus, GSE98106.
- Olivia S Rissland
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Michael B Eisen, University of California, Berkeley, United States
© 2020, Zavortink et al.
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