| Institution: | 1. Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan;2. WPI Nano Life Science Institute, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192, Japan;3. Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan;4. Graduate School of Integrated Sciences for Life, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima 739-8258, Japan;5. HPC- and AI-driven Drug Development Platform Division, Center for Computational Science, RIKEN, 1-7-22, Suehiro-cho, Tsurumi-ku, Yokohama 230-0045, Japan;6. Materials and Life Science Division, J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan |
| Abstract: | Nucleosome assembly protein 1 (NAP1) binds to histone H2A-H2B heterodimers, mediating their deposition on and eviction from the nucleosome. Human NAP1 (hNAP1) consists of a dimerization core domain and intrinsically disordered C-terminal acidic domain (CTAD), both of which are essential for H2A-H2B binding. Several structures of NAP1 proteins bound to H2A-H2B exhibit binding polymorphisms of the core domain, but the distinct structural roles of the core and CTAD domains remain elusive. Here, we have examined dynamic structures of the full-length hNAP1 dimer bound to one and two H2A-H2B heterodimers by integrative methods. Nuclear magnetic resonance (NMR) spectroscopy of full-length hNAP1 showed CTAD binding to H2A-H2B. Atomic force microscopy revealed that hNAP1 forms oligomers of tandem repeated dimers; therefore, we generated a stable dimeric hNAP1 mutant exhibiting the same H2A-H2B binding affinity as wild-type hNAP1. Size exclusion chromatography (SEC), multi-angle light scattering (MALS) and small angle X-ray scattering (SAXS), followed by modelling and molecular dynamics simulations, have been used to reveal the stepwise dynamic complex structures of hNAP1 binding to one and two H2A-H2B heterodimers. The first H2A-H2B dimer binds mainly to the core domain of hNAP1, while the second H2A-H2B binds dynamically to both CTADs. Based on our findings, we present a model of the eviction of H2A-H2B from nucleosomes by NAP1. |
