Structure of nucleosome core particles containing uH2A (A24).

We have purified uH2A (A24) and reconstituted it, in place of H2A, into high molecular weight nucleohistone containing the core histones and DNA. uH2A-containing core particles were then prepared by nuclease digestion and studies on these particles were carried out. We show that two uH2A molecules can be accommodated within a core particle. We also show that the presence of two uH2A molecules in a core particle does not alter significantly either the pattern or the rate of DNase I digestion as compared to both reconstituted and native core particles. Finally, we show that HMG proteins 14 and 17 can bind to uH2A-containing core particles. We conclude that uH2A has little influence on structure at the level of individual nucleosomes.