Guest Speaker – Julien Bethuné

On Thursday, 30.01.2020, 5.15 pm

Julien Bethuné (Heidelberg University Biochemistry Center), will give an SFB 902 lecture:

„Analysis of context-dependent protein complexes with next-generation proximity proteomics assays“.

Venue: TU Darmstadt, Campus Botanischer Garten, lecture hall: B101/52

Guests are welcome!

Abstract

Since its initial description in 2012, the proximity-dependent biotinylation technique BioID has established itself as a reliable alternative to the classical Affinity Purification-MS approach for the identification of protein-protein interactions. Recently we engineering split-BioID, a proteinfragments complementation assay that greatly enhances the resolution of BioID by allowing the analysis of context-dependent protein complexes. Applied to the miRNA silencing pathway, split-BioID let us identify the 4EHP-binding protein GIGYF2 as a novel miRISC-associated factor. The 4EHPGIGYF2 dimer has been proposed to be recruited by RNA-binding proteins to stimulate the repression of translation of their associated transcripts. In line with this model we found that the
miRISC component TNRC6 directly binds to GIGYF2 which in turns promotes miRNA-mediated translation repression. More recently we uncovered an additional mechanism of GIGYF2-mediated repression that is independent of 4EHP but rather relies on the CCR4-NOT deadenylation complex. This suggests that GIGYF2 is part of two distinct functional units that exert distinct modes of repression on their associated target mRNAs. To define the composition of these context-dependent GIGYF2 complexes, we have developed more versatile proximity labeling assays that rely on a smaller labeling enzyme with improved labeling kinetics and that can be used in a split assay format.

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