The Histone Chaperone Vps75 Forms Multiple Oligomeric Assemblies Capable of Mediating Exchange between Histone H3-H4 Tetramers and Asf1-H3-H4 Complexes.
Hammond, C.M., Sundaramoorthy, R., Larance, M., Lamond, A., Stevens, M.A., El-Mkami, H., Norman, D.G., Owen-Hughes, T.(2016) Nucleic Acids Res 44: 6157
- PubMed: 27036862 
- DOI: https://doi.org/10.1093/nar/gkw209
- Primary Citation of Related Structures:  
5AGC - PubMed Abstract: 
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.
Organizational Affiliation: 
Centre for Gene Regulation and Expression, School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.