非洲爪蟾NO38核心蛋白（一种核仁中的组蛋白伴侣）的结构与功能
The structure and function of Xenopus NO38-core, a histone chaperone in the nucleolus.
作者信息
Namboodiri V M Haridasan, Akey Ildikó V, Schmidt-Zachmann Marion S, Head James F, Akey Christopher W
机构信息
Department of Physiology and Biophysics, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118, USA.
出版信息
Structure. 2004 Dec;12(12):2149-60. doi: 10.1016/j.str.2004.09.017.
Xenopus NO38 is an abundant nucleolar chaperone and a member of the nucleoplasmin (Np) family. Here, we report high-resolution crystal structures of the N-terminal domain of NO38, as a pentamer and a decamer. As expected, NO38 shares the Np family fold. In addition, NO38- and Np-core pentamers each use highly conserved residues and numerous waters to form their respective decamers. Further studies show that NO38 and Np each bind equal amounts of the four core histones. However, NO38 prefers the (H3-H4)(2) tetramer, while Np probably prefers H2A-H2B dimers. We also show that NO38 and Np will each bind noncognate histones when the preferred partner is absent. We suggest that these chaperones must form decamers in order to bind histones and differentiate between histone tetramers and dimers. When taken together, these data imply that NO38 may function as a histone chaperone in the nucleolus.
非洲爪蟾NO38是一种丰富的核仁伴侣蛋白，属于核质蛋白（Np）家族成员。在此，我们报道了NO38 N端结构域作为五聚体和十聚体的高分辨率晶体结构。正如预期的那样，NO38具有Np家族的折叠结构。此外，NO38和Np核心五聚体各自利用高度保守的残基和大量水分子形成各自的十聚体。进一步研究表明，NO38和Np与等量的四种核心组蛋白结合。然而，NO38更倾向于（H3-H4）（2）四聚体，而Np可能更倾向于H2A-H2B二聚体。我们还表明，当缺乏首选伴侣时，NO38和Np都会结合非同源组蛋白。我们认为，这些伴侣蛋白必须形成十聚体才能结合组蛋白，并区分组蛋白四聚体和二聚体。综合来看，这些数据表明NO38可能在核仁中作为组蛋白伴侣发挥作用。
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