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The crystal structure of a single chain H2B-H2A histone chimera from Xenopus laevis
Structural highlights
FunctionH2B11_XENLA Core component of nucleosome. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling.H2A1_XENLA Core component of nucleosome. Nucleosomes wrap and compact DNA into chromatin, limiting DNA accessibility to the cellular machineries which require DNA as a template. Histones thereby play a central role in transcription regulation, DNA repair, DNA replication and chromosomal stability. DNA accessibility is regulated via a complex set of post-translational modifications of histones, also called histone code, and nucleosome remodeling. Publication Abstract from PubMedChromatin is the complex assembly of nucleic acids and proteins that makes up the physiological form of the eukaryotic genome. The nucleosome is the fundamental repeating unit of chromatin, and is composed of approximately 147 bp of DNA wrapped around a histone octamer formed by two copies of each core histone: H2A, H2B, H3 and H4. Prior to nucleosome assembly, and during histone eviction, histones are typically assembled into soluble H2A/H2B dimers and H3/H4 dimers and tetramers. A multitude of factors interact with soluble histone dimers and tetramers, including chaperones, importins, histone-modifying enzymes and chromatin-remodeling enzymes. It is still unclear how many of these proteins recognize soluble histones; therefore, there is a need for new structural tools to study non-nucleosomal histones. Here, a single-chain, tailless Xenopus H2A/H2B dimer was created by directly fusing the C-terminus of H2B to the N-terminus of H2A. It is shown that this construct (termed scH2BH2A) is readily expressed in bacteria and can be purified under non-denaturing conditions. A 1.31 A resolution crystal structure of scH2BH2A shows that it adopts a conformation that is nearly identical to that of nucleosomal H2A/H2B. This new tool is likely to facilitate future structural studies of many H2A/H2B-interacting proteins. Structure of a single-chain H2A/H2B dimer.,Warren C, Bonanno JB, Almo SC, Shechter D Acta Crystallogr F Struct Biol Commun. 2020 May 1;76(Pt 5):194-198. doi:, 10.1107/S2053230X20004604. Epub 2020 Apr 28. PMID:32356520[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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