Title: "Plant Mobile Domain proteins regulate gene expression"

Speaker: Dr. Guillaume Moissiard, LGDP UMR5096 CNRS/UPVD

Abstract: 
In Eukaryotes, Polycomb group proteins repress genes through the deposition of trimethylation of lysine 27 on histone H3. Although the mechanisms involved in Polycomb recruitment are rather understood, it remains unclear how certain genes with apparent silencing-attracting features escape this process. The Arabidopsis plant mobile domain (PMD)-containing proteins MAINTENANCE OF MERISTEMS (MAIN), MAIN-LIKE 1 (MAIL1) and MAIL2 secure the expression of numerous actively transcribed genes by opposing Polycomb silencing. Mutations in MAIN, MAIL1 or MAIL2 result in ectopic H3K27me3 deposition, often associated with transcriptional repression. MAIN and MAIL1, which physically interact together, and MAIL2 target distinct sets of genes, and associate with chromatin at specific DNA sequence motifs. The integrity of these DNA motifs is essential for promoting gene expression and antagonizing H3K27me3 deposition. Thus, these results unveil a system opposing Polycomb silencing that involves PMD protein–DNA motif modules to ensure the proper development of Arabidopsis.