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Elife. 2018 Feb 26;7. pii: e33150. doi: 10.7554/eLife.33150.

Identification of PNG kinase substrates uncovers interactions with the translational repressor TRAL in the oocyte-to-embryo transition.

Author information

1
Whitehead Institute, Cambridge, United States.
2
Department of Pharmacology, Yale School of Medicine, New Haven, United States.
3
Department of Biology, Massachusetts Institute of Technology, Cambridge, United States.

Abstract

The Drosophila Pan Gu (PNG) kinase complex regulates hundreds of maternal mRNAs that become translationally repressed or activated as the oocyte transitions to an embryo. In a previous paper (Hara et al., 2017), we demonstrated PNG activity is under tight developmental control and restricted to this transition. Here, examination of PNG specificity showed it to be a Thr-kinase yet lacking a clear phosphorylation site consensus sequence. An unbiased biochemical screen for PNG substrates identified the conserved translational repressor Trailer Hitch (TRAL). Phosphomimetic mutation of the PNG phospho-sites in TRAL reduced its ability to inhibit translation in vitro. In vivo, mutation of tral dominantly suppressed png mutants and restored Cyclin B protein levels. The repressor Pumilio (PUM) has the same relationship with PNG, and we also show that PUM is a PNG substrate. Furthermore, PNG can phosphorylate BICC and ME31B, repressors that bind TRAL in cytoplasmic RNPs. Therefore, PNG likely promotes translation at the oocyte-to-embryo transition by phosphorylating and inactivating translational repressors.

KEYWORDS:

BICC; D. melanogaster; Drosophila; ME31B; Pumilio; cytoplasmic RNPs; developmental biology; maternal mRNA; stem cells

PMID:
29480805
PMCID:
PMC5826265
DOI:
10.7554/eLife.33150
[Indexed for MEDLINE]
Free PMC Article

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