McBryant Steven J, Park Young-Jun, Abernathy Stephanie M, Laybourn Paul J, Nyborg Jennifer K, Luger Karolin
Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870, USA.
J Biol Chem. 2003 Nov 7;278(45):44574-83. doi: 10.1074/jbc.M305636200. Epub 2003 Aug 19.
The yeast nucleosome assembly protein 1 (yNAP1) participates in many diverse activities, such as the assembly of newly synthesized DNA into chromatin and the rearrangement of nucleosomes during transcriptional activation. yNAP1 does not require ATP hydrolysis to perform these functions and is a valuable tool for in vitro chromatin assembly. Using recombinant histone complexes, we show that yNAP1 has a preference for binding the (H3-H4)2 tetramer over the (H2A-H2B) dimer. We find that the loss of the histone tails abrogates this preference for H3 and H4, and we demonstrate a direct interaction between yNAP1 and the amino-terminal tails of H3 and H4. yNAP1 binds to one histone fold domain, thus specifying the stoichiometry of the complexes formed with the histone dimer and tetramer. Finally, we provide evidence that the acidic carboxyl-terminal region of yNAP1, although dispensable for nucleosome assembly in vitro, contributes to binding via structure-independent electrostatic interactions. Our results are consistent with recent mechanistic investigations of NAP1 and expand our understanding of the histone chaperone family of assembly factors.
酵母核小体组装蛋白1（yNAP1）参与多种不同的活动，如将新合成的DNA组装成染色质以及在转录激活过程中核小体的重排。yNAP1执行这些功能不需要ATP水解，是体外染色质组装的一种有价值的工具。使用重组组蛋白复合物，我们发现yNAP1相比于（H2A-H2B）二聚体更倾向于结合（H3-H4）2四聚体。我们发现组蛋白尾部的缺失消除了对H3和H4的这种偏好，并且我们证明了yNAP1与H3和H4的氨基末端尾部之间存在直接相互作用。yNAP1结合一个组蛋白折叠域，从而确定了与组蛋白二聚体和四聚体形成的复合物的化学计量。最后，我们提供证据表明yNAP1的酸性羧基末端区域虽然在体外核小体组装中是可有可无的，但通过不依赖结构的静电相互作用有助于结合。我们的结果与最近对NAP1的机制研究一致，并扩展了我们对组装因子的组蛋白伴侣家族的理解。
