Plateforme de protéines recombinantes


Année de publication : 2016

Catharina von Nicolai, Åsa Ehlén, Charlotte Martin, Xiaodong Zhang, Aura Carreira (2016 Sep 15)

A second DNA binding site in human BRCA2 promotes homologous recombination.

Nature communications : 12813 : DOI : 10.1038/ncomms12813 En savoir plus

BRCA2 tumour-suppressor protein is well known for its role in DNA repair by homologous recombination (HR); assisting the loading of RAD51 recombinase at DNA double-strand breaks. This function is executed by the C-terminal DNA binding domain (CTD) which binds single-stranded (ss)DNA, and the BRC repeats, which bind RAD51 and modulate its assembly onto ssDNA. Paradoxically, analysis of cells resistant to DNA damaging agents missing the CTD restore HR proficiency, suggesting another domain may take over its function. Here, we identify a region in the N terminus of BRCA2 that exhibits DNA binding activity (NTD) and provide evidence for NTD promoting RAD51-mediated HR. A missense variant detected in breast cancer patients located in the NTD impairs HR stimulation on dsDNA/ssDNA junction containing substrates. These findings shed light on the function of the N terminus of BRCA2 and have implications for the evaluation of breast cancer variants.

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Année de publication : 2015

Serena Sanulli, Neil Justin, Aurélie Teissandier, Katia Ancelin, Manuela Portoso, Matthieu Caron, Audrey Michaud, Berangère Lombard, Simao T da Rocha, John Offer, Damarys Loew, Nicolas Servant, Michel Wassef, Fabienne Burlina, Steve J Gamblin, Edith Heard, Raphaël Margueron (2015 Mar 5)

Jarid2 Methylation via the PRC2 Complex Regulates H3K27me3 Deposition during Cell Differentiation.

Molecular cell : 769-83 : DOI : 10.1016/j.molcel.2014.12.020 En savoir plus

Polycomb Group (PcG) proteins maintain transcriptional repression throughout development, mostly by regulating chromatin structure. Polycomb Repressive Complex 2 (PRC2), a component of the Polycomb machinery, is responsible for the methylation of histone H3 lysine 27 (H3K27me2/3). Jarid2 was previously identified as a cofactor of PRC2, regulating PRC2 targeting to chromatin and its enzymatic activity. Deletion of Jarid2 leads to impaired orchestration of gene expression during cell lineage commitment. Here, we reveal an unexpected crosstalk between Jarid2 and PRC2, with Jarid2 being methylated by PRC2. This modification is recognized by the Eed core component of PRC2 and triggers an allosteric activation of PRC2’s enzymatic activity. We show that Jarid2 methylation is important to promote PRC2 activity at a locus devoid of H3K27me3 and for the correct deposition of this mark during cell differentiation. Our results uncover a regulation loop where Jarid2 methylation fine-tunes PRC2 activity depending on the chromatin context.


Année de publication : 2014

Laura Picas, Julien Viaud, Kristine Schauer, Stefano Vanni, Karim Hnia, Vincent Fraisier, Aurélien Roux, Patricia Bassereau, Frédérique Gaits-Iacovoni, Bernard Payrastre, Jocelyn Laporte, Jean-Baptiste Manneville, Bruno Goud (2014 Dec 9)

BIN1/​M-Amphiphysin2 induces clustering of phosphoinositides to recruit its downstream partner dynamin

Nature Communications5 : DOI : 10.1038/ncomms6647 En savoir plus

Phosphoinositides play a central role in many physiological processes by assisting the recruitment of proteins to membranes through specific phosphoinositide-binding motifs. How this recruitment is coordinated in space and time is not well understood. Here we show that ​BIN1/​M-Amphiphysin2, a protein involved in T-tubule biogenesis in muscle cells and frequently mutated in centronuclear myopathies, clusters PtdIns(4,5)P2 to recruit its downstream partner dynamin. By using several mutants associated with centronuclear myopathies, we find that the N-BAR and the SH3 domains of ​BIN1 control the kinetics and the accumulation of dynamin on membranes, respectively. We show that phosphoinositide clustering is a mechanism shared by other proteins that interact with PtdIns(4,5)P2, but do not contain a BAR domain. Our numerical simulations point out that clustering is a diffusion-driven process in which phosphoinositide molecules are not sequestered. We propose that this mechanism plays a key role in the recruitment of downstream phosphoinositide-binding proteins.

Abdeslam Et Taouil, Emilie Brun, Patricia Duchambon, Yves Blouquit, Manon Gilles, Emmanuel Maisonhaute, Cécile Sicard-Roselli (2014 Oct 14)

How protein structure affects redox reactivity: example of Human centrin 2.

Physical chemistry chemical physics : PCCP : 16 : 24493-24498 : DOI : 10.1039/c4cp03536d En savoir plus

Electron transfer inside proteins plays a central role in their reactivity and biological functions. Herein, we developed a combined approach by gamma radiolysis and electrochemistry which allowed a deep insight into the reactivity of Human centrin 2, a protein very sensitive to oxidative stress and involved in several key biological processes. This protein bears a single terminal tyrosine and was observed to be extremely sensitive to ionizing radiation sources, leading to a tyrosine dimer. By cyclic voltammetry in the 100-1000 V s(-1) range, its redox potential and dimerization rate could be evaluated. Accordingly, reaction in solution with a redox mediator revealed an efficient catalysis. Finally, protein denaturation by a progressive increase in temperature was proportional to a decrease of dimerization radiolytic yield. Our results thus demonstrated that the protein structure plays a major role in oxidation sensitivity. This leads to meaningful results to understand protein redox reactivity.