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.