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Subject of the thesis

Physical interaction between epigenetic regulators involved in antagonistic histone H3 modifications

Published on 7 February 2019

Chromatin dynamics plays a major role in regulating genome usage for developmental outputs in higher eukaryotes. This involves a balance between the activities of two histone-modifying complexes: the Polycomb group (PcG, repressive) and trithorax group (TrxG, activating). However how PcG and trxG antagonise each other remains largely unclear. We previously showed that the ULT1 protein, which regulates stem cell fate in plants, physically connects with these two complexes. ULT1 activates the expression of many developmental genes in a manner antagonistic to the PcG CURLY LEAF (CLF) factor. CLF is the enzyme homologous to the human Ezh2 that methylates Histone 3 on lysine 27 (H3K27me3 repressive mark). The PhD project will decipher the molecular mechanism through which ULT1 counteracts CLF function and induces gene transcription. To this aim, the student will work at the molecular, atomic, cellular and in planta scales. He/she will use recombinant proteins and plant tissues to characterise (i) ULT1-CLF physical interaction domains and (ii) ULT1 effect on CLF activity. He/she will study (iii) the activating function of ULT1 through its interaction with a reader of the H3K4me3 active mark that is deposited by TrxG. The obtained results will represent a considerable breakthrough in epigenetics, by decrypting the original opposing mechanism between two key chromatin complexes, for which no direct interaction was ever identified in any living organism to date.

Miscellaneous information
• Recommended Master level training.
• A background in molecular biology and biochemistry is recommended. Interest in protein purification and interaction assays will be appreciated. Knowledge in plant biology is not a pre-requisite.
• Date requested for the start of the thesis: September 01, 2017
• Contact person:
Christel Carles (Thesis supervisor)
Université Joseph Fourier
Laboratoire Physiologie Cellulaire & Végétale
17 avenue des Martyrs
38054 Grenoble Cedex 9

More information on the team's web page.

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