title: Structural insight into how the human helicase subunit MCM2 may act as a histone chaperone together with ASF1 at the replication fork.
abstract: MCM2 is a subunit of the replicative helicase machinery shown to interact with histones H3 and H4 during the replication process through its N-terminal domain. During replication, this interaction has been proposed to assist disassembly and assembly of nucleosomes on DNA. However, how this interaction participates in crosstalk with histone chaperones at the replication fork remains to be elucidated. Here, we solved the crystal structure of the ternary complex between the histone-binding domain of Mcm2 and the histones H3-H4 at 2.9 Å resolution. Histones H3 and H4 assemble as a tetramer in the crystal structure, but MCM2 interacts only with a single molecule of H3-H4. The latter interaction exploits binding surfaces that contact either DNA or H2B when H3-H4 dimers are incorporated in the nucleosome core particle. Upon binding of the ternary complex with the histone chaperone ASF1, the histone tetramer dissociates and both MCM2 and ASF1 interact simultaneously with the histones forming a 1:1:1:1 heteromeric complex. Thermodynamic analysis of the quaternary complex together with structural modeling support that ASF1 and MCM2 could form a chaperoning module for histones H3 and H4 protecting them from promiscuous interactions. This suggests an additional function for MCM2 outside its helicase function as a proper histone chaperone connected to the replication pathway.
authors.affiliation: CEA, iBiTec-S, SB2SM, Laboratoire de Biologie Structurale et Radiobiologie, France Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Batiment 144, Gif-sur-Yvette, F-91191, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Richet
authors.affiliation: CEA, iBiTec-S, SB2SM, Laboratoire de Biologie Structurale et Radiobiologie, France Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Batiment 144, Gif-sur-Yvette, F-91191, France.
authors.forename: Danni
authors.initials: D
authors.lastname: Liu
authors.affiliation: Synchrotron SOLEIL, F-91190, Gif-sur-Yvette, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Legrand
authors.affiliation: Laboratoire d'Enzymologie et de Biologie Structurale, CNRS UPR 3082, 1 avenue de la Terrasse, Gif-sur-Yvette, F-91190, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Velours
authors.affiliation: Institut Curie, Centre de Recherche, CNRS UMR 3664, Equipe Labellisée Ligue contre le Cancer, and Université Pierre et Marie Curie, Université Sorbonne PSL*, Paris, F-75248, France.
authors.forename: Armelle
authors.initials: A
authors.lastname: Corpet
authors.affiliation: CEA, iBiTec-S, SB2SM, Laboratoire de Biologie Structurale et Radiobiologie, France Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Batiment 144, Gif-sur-Yvette, F-91191, France.
authors.forename: Albane
authors.initials: A
authors.lastname: Gaubert
authors.affiliation: CEA, iBiTec-S, SB2SM, Laboratoire de Biologie Structurale et Radiobiologie, France Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Batiment 144, Gif-sur-Yvette, F-91191, France.
authors.forename: May
authors.initials: M
authors.lastname: Bakail
authors.affiliation: CEA, iBiTec-S, SB2SM, Laboratoire de Biologie Structurale et Radiobiologie, France Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Batiment 144, Gif-sur-Yvette, F-91191, France.
authors.forename: Gwenaelle
authors.initials: G
authors.lastname: Moal-Raisin
authors.affiliation: CEA, iBiTec-S, SB2SM, Laboratoire de Biologie Structurale et Radiobiologie, France Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Batiment 144, Gif-sur-Yvette, F-91191, France.
authors.forename: Raphael
authors.initials: R
authors.lastname: Guerois
authors.affiliation: CEA, iBiTec-S, SB2SM, Laboratoire de Biologie Structurale et Radiobiologie, France Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Batiment 144, Gif-sur-Yvette, F-91191, France.
authors.forename: Christel
authors.initials: C
authors.lastname: Compper
authors.affiliation: CEA, iBiTec-S, SB2SM, Laboratoire de Biologie Structurale et Radiobiologie, France Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Batiment 144, Gif-sur-Yvette, F-91191, France.
authors.forename: Arthur
authors.initials: A
authors.lastname: Besle
authors.affiliation: CEA, iBiTec-S, SB2SM, Laboratoire de Biologie Structurale et Radiobiologie, France Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Batiment 144, Gif-sur-Yvette, F-91191, France.
authors.forename: Berengère
authors.initials: B
authors.lastname: Guichard
authors.affiliation: Institut Curie, Centre de Recherche, CNRS UMR 3664, Equipe Labellisée Ligue contre le Cancer, and Université Pierre et Marie Curie, Université Sorbonne PSL*, Paris, F-75248, France.
authors.forename: Genevieve
authors.initials: G
authors.lastname: Almouzni
authors.affiliation: CEA, iBiTec-S, SB2SM, Laboratoire de Biologie Structurale et Radiobiologie, France Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Batiment 144, Gif-sur-Yvette, F-91191, France francoise.ochsenbein@cea.fr.
authors.forename: Françoise
authors.initials: F
authors.lastname: Ochsenbein
mesh_terms: D000818:Animals; D002151:Calorimetry; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002850:Chromatography, Gel; D004331:Drosophila melanogaster; D006657:Histones / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D064111:Minichromosome Maintenance Complex Component 2 / Q000737:chemistry / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D013816:Thermodynamics; D014961:X-Ray Diffraction
chemical_list: C491641:ASF1A protein, human; D018797:Cell Cycle Proteins; D006657:Histones; D018832:Molecular Chaperones; C084859:MCM2 protein, human; D064111:Minichromosome Maintenance Complex Component 2