Structural basis of histone H2A–H2B recognition by the essential chaperone FACT

• Published in: Nature (London) 2013-07, Vol.499 (7456), p.111-114
• Main Authors: Hondele, Maria, Stuwe, Tobias, Hassler, Markus, Halbach, Felix, Bowman, Andrew, Zhang, Elisa T., Nijmeijer, Bianca, Kotthoff, Christiane, Rybin, Vladimir, Amlacher, Stefan, Hurt, Ed, Ladurner, Andreas G.
• Format: Article
• Language: English
• Subjects: 631/337/100/1701; 631/45/535/1266; Amino Acid Motifs; Binding sites; Chaetomium; Chaetomium - chemistry; Conserved Sequence; Crystallography, X-Ray; Deoxyribonucleic acid; DNA; DNA - chemistry; DNA - metabolism; DNA Replication; Fungal Proteins - chemistry; Fungal Proteins - metabolism; Genetic transcription; Histones; Histones - chemistry; Histones - metabolism; Humanities and Social Sciences; Hydrophobic and Hydrophilic Interactions; letter; Models, Molecular; Molecular chaperones; Molecular Chaperones - chemistry; Molecular Chaperones - metabolism; multidisciplinary; Mutation; Nucleosomes - chemistry; Nucleosomes - metabolism; Protein Binding; Protein Multimerization; Protein Structure, Secondary; Protein Structure, Tertiary; Proteins; Science; Structure; Substrate Specificity
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature12242

The crystal structure of the FACT histone chaperone domain Spt16M in complex with the H2A–H2B heterodimer is solved; Spt16M makes several interactions with histones and seems to block the interaction of H2B with DNA, which could explain how FACT destabilizes nucleosomes to promote transcription. Structure of a histone chaperone The histone chaperone FACT recognizes histones H2A and H2B and has important roles during transcription, replication and DNA repair. Andreas Ladurner and colleagues describe the crystal structure of the complex between FACT's Spt16M chaperone domain and the H2A–H2B dimer, as well as the structure of the heterodimerization domain of FACT. Spt16M makes multiple interactions with histones and seems to block the interaction of H2B with DNA, which could explain how FACT destabilizes nucleosomes. Facilitates chromatin transcription (FACT) is a conserved histone chaperone that reorganizes nucleosomes and ensures chromatin integrity during DNA transcription, replication and repair 1 , 2 , 3 , 4 , 5 , 6 . Key to the broad functions of FACT is its recognition of histones H2A–H2B (ref. 2 ). However, the structural basis for how histones H2A–H2B are recognized and how this integrates with the other functions of FACT, including the recognition of histones H3–H4 and other nuclear factors, is unknown. Here we reveal the crystal structure of the evolutionarily conserved FACT chaperone domain Spt16M from Chaetomium thermophilum , in complex with the H2A–H2B heterodimer. A novel ‘U-turn’ motif scaffolded onto a Rtt106-like module 7 , 8 , 9 , 10 embraces the α1 helix of H2B. Biochemical and in vivo assays validate the structure and dissect the contribution of histone tails and H3–H4 towards Spt16M binding. Furthermore, we report the structure of the FACT heterodimerization domain that connects FACT to replicative polymerases. Our results show that Spt16M makes several interactions with histones, which we suggest allow the module to invade the nucleosome gradually and block the strongest interaction of H2B with DNA. FACT would thus enhance ‘nucleosome breathing’ by re-organizing the first 30 base pairs of nucleosomal histone–DNA contacts. Our snapshot of the engagement of the chaperone with H2A–H2B and the structures of all globular FACT domains enable the high-resolution analysis of the vital chaperoning functions of FACT, shedding light on how the complex promotes the activity of enzymes that require nucleosome reorganization.