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5agc

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== Publication Abstract from PubMed ==
== Publication Abstract from PubMed ==
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NAP-1 fold histone chaperones play an important role in escorting histones to and from sites of nucleosome assembly and disassembly. The two NAP-1 fold histone chaperones in budding yeast, Vps75 and Nap1, have previously been crystalized in a characteristic homodimeric conformation. In this study, a combination of small angle X-ray scattering, multi angle light scattering and pulsed electron-electron double resonance approaches were used to show that both Vps75 and Nap1 adopt ring-shaped tetrameric conformations in solution. This suggests that the formation of homotetramers is a common feature of NAP-1 fold histone chaperones. The tetramerisation of NAP-1 fold histone chaperones may act to shield acidic surfaces in the absence of histone cargo thus providing a 'self-chaperoning' type mechanism.
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Vps75 is a histone chaperone that has been historically characterized as homodimer by X-ray crystallography. In this study, we present a crystal structure containing two related tetrameric forms of Vps75 within the crystal lattice. We show Vps75 associates with histones in multiple oligomers. In the presence of equimolar H3-H4 and Vps75, the major species is a reconfigured Vps75 tetramer bound to a histone H3-H4 tetramer. However, in the presence of excess histones, a Vps75 dimer bound to a histone H3-H4 tetramer predominates. We show the Vps75-H3-H4 interaction is compatible with the histone chaperone Asf1 and deduce a structural model of the Vps75-Asf1-H3-H4 (VAH) co-chaperone complex using the Pulsed Electron-electron Double Resonance (PELDOR) technique and cross-linking MS/MS distance restraints. The model provides a molecular basis for the involvement of both Vps75 and Asf1 in Rtt109 catalysed histone H3 K9 acetylation. In the absence of Asf1 this model can be used to generate a complex consisting of a reconfigured Vps75 tetramer bound to a H3-H4 tetramer. This provides a structural explanation for many of the complexes detected biochemically and illustrates the ability of Vps75 to interact with dimeric or tetrameric H3-H4 using the same interaction surface.
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The histone chaperones Vps75 and Nap1 form ring-like, tetrameric structures in solution.,Bowman A, Hammond CM, Stirling A, Ward R, Shang W, El-Mkami H, Robinson DA, Svergun DI, Norman DG, Owen-Hughes T Nucleic Acids Res. 2014 May;42(9):6038-51. doi: 10.1093/nar/gku232. Epub 2014 Mar, 31. PMID:24688059<ref>PMID:24688059</ref>
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The histone chaperone Vps75 forms multiple oligomeric assemblies capable of mediating exchange between histone H3-H4 tetramers and Asf1-H3-H4 complexes.,Hammond CM, Sundaramoorthy R, Larance M, Lamond A, Stevens MA, El-Mkami H, Norman DG, Owen-Hughes T Nucleic Acids Res. 2016 Apr 1. pii: gkw209. PMID:27036862<ref>PMID:27036862</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

Revision as of 18:14, 10 May 2016

Crystallographic forms of the Vps75 tetramer

5agc, resolution 4.00Å

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