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Crystal structure of human SPT16 Mid-AID/H3-H4 tetramer FACT Histone complex
Structural highlights
FunctionSP16H_HUMAN Component of the FACT complex, a general chromatin factor that acts to reorganize nucleosomes. The FACT complex is involved in multiple processes that require DNA as a template such as mRNA elongation, DNA replication and DNA repair. During transcription elongation the FACT complex acts as a histone chaperone that both destabilizes and restores nucleosomal structure. It facilitates the passage of RNA polymerase II and transcription by promoting the dissociation of one histone H2A-H2B dimer from the nucleosome, then subsequently promotes the reestablishment of the nucleosome following the passage of RNA polymerase II. The FACT complex is probably also involved in phosphorylation of 'Ser-392' of p53/TP53 via its association with CK2 (casein kinase II).[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedFacilitates chromatin transcription (FACT) plays essential roles in chromatin remodeling during DNA transcription, replication, and repair. Our structural and biochemical studies of human FACT-histone interactions present precise views of nucleosome reorganization, conducted by the FACT-SPT16 (suppressor of Ty 16) Mid domain and its adjacent acidic AID segment. AID accesses the H2B N-terminal basic region exposed by partial unwrapping of the nucleosomal DNA, thereby triggering the invasion of FACT into the nucleosome. The crystal structure of the Mid domain complexed with an H3-H4 tetramer exhibits two separate contact sites; the Mid domain forms a novel intermolecular beta structure with H4. At the other site, the Mid-H2A steric collision on the H2A-docking surface of the H3-H4 tetramer within the nucleosome induces H2A-H2B displacement. This integrated mechanism results in disrupting the H3 alphaN helix, which is essential for retaining the nucleosomal DNA ends, and hence facilitates DNA stripping from histone. Integrated molecular mechanism directing nucleosome reorganization by human FACT.,Tsunaka Y, Fujiwara Y, Oyama T, Hirose S, Morikawa K Genes Dev. 2016 Mar 15;30(6):673-86. doi: 10.1101/gad.274183.115. Epub 2016 Mar, 10. PMID:26966247[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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