Suto R K, Clarkson M J, Tremethick D J, Luger K
Department of Biochemistry Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870 USA.
Nat Struct Biol. 2000 Dec;7(12):1121-4. doi: 10.1038/81971.
Activation of transcription within chromatin has been correlated with the incorporation of the essential histone variant H2A.Z into nucleosomes. H2A.Z and other histone variants may establish structurally distinct chromosomal domains; however, the molecular mechanism by which they function is largely unknown. Here we report the 2.6 A crystal structure of a nucleosome core particle containing the histone variant H2A.Z. The overall structure is similar to that of the previously reported 2.8 A nucleosome structure containing major histone proteins. However, distinct localized changes result in the subtle destabilization of the interaction between the (H2A.Z-H2B) dimer and the (H3-H4)(2) tetramer. Moreover, H2A.Z nucleosomes have an altered surface that includes a metal ion. This altered surface may lead to changes in higher order structure, and/or could result in the association of specific nuclear proteins with H2A.Z. Finally, incorporation of H2A.Z and H2A within the same nucleosome is unlikely, due to significant changes in the interface between the two H2A.Z-H2B dimers.
染色质内转录的激活与必需的组蛋白变体H2A.Z掺入核小体有关。H2A.Z和其他组蛋白变体可能会建立结构不同的染色体结构域；然而，它们发挥功能的分子机制在很大程度上尚不清楚。在此，我们报道了包含组蛋白变体H2A.Z的核小体核心颗粒的2.6埃晶体结构。其整体结构与先前报道的包含主要组蛋白的2.8埃核小体结构相似。然而，明显的局部变化导致（H2A.Z - H2B）二聚体与（H3 - H4）2四聚体之间相互作用的细微不稳定。此外，H2A.Z核小体有一个包含金属离子的改变的表面。这个改变的表面可能导致更高层次结构的变化，和/或可能导致特定核蛋白与H2A.Z结合。最后，由于两个H2A.Z - H2B二聚体之间界面的显著变化，同一核小体内不太可能同时掺入H2A.Z和H2A。
