Structures of importin-α bound to the wild-type and an internal deletion mutant of the bipartite nuclear localization signal of HIF-1α
Structures of importin-α bound to the wild-type and an internal deletion mutant of the bipartite nuclear localization signal of HIF-1α
复制标题
与 HIF-1α 野生型和二分核定位信号的内部缺失突变体结合的 importin-α 的结构
DOI：
10.1016/j.bbrc.2023.02.036
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发表时间：
2023
影响因子：
3.1
通讯作者：
Miyawaki Kazuya
中科院分区：
文献类型：
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作者：
Matsuura Yoshiyuki;Miyawaki Kazuya
缺氧诱导因子1 （Hypoxia-inducible factor 1, HIF-1）是一种异二聚体转录因子，在氧稳态中起着重要的调节作用。HIF-1的活性部分受其α亚基（HIF-1α）在细胞核和细胞质之间穿梭的细胞内动态运输的调节。研究表明，HIF-1α的核定位需要一个经典核定位信号（NLS）的变体，而NLS中氨基酸残基（724-751残基）的内部缺失几乎消除了核定位。本文报道了与野生型HIF-1α NLS结合的核输入接头importin-α1在1.8 Å分辨率和与HIF-1α NLS的Δ724-751突变体结合的importin-α1在1.9 Å分辨率下的x射线晶体结构。在野生型结构中，HIF-1α NLS中的两个基本簇在两个位点（主要位点和次要位点）上与输入蛋白α1发生广泛的相互作用。在突变体结构中，NLS残基仍与输入蛋白-α1的主位点广泛相互作用，但未观察到与次要位点的相互作用。结构数据和结合自由能的计算分析表明，小位点相互作用的缺失抑制了HIF-1α的核积累。
Hypoxia-inducible factor 1 (HIF-1) is a heterodimeric transcription factor that plays an important role as a master regulator of oxygen homeostasis. The activity of HIF-1 is regulated in part by dynamic intracellular trafficking of its α subunit (HIF-1α) that can shuttle between the nucleus and cytoplasm. It has been shown that nuclear localization of HIF-1α requires a variant of classic nuclear localization signal (NLS) and that an internal deletion of the amino acid residues (residues 724–751) in the NLS almost abolish the nuclear localization. Here we report the X-ray crystal structure of the nuclear import adaptor importin-α1 bound to the wild-type HIF-1α NLS at 1.8 Å resolution and of importin-α1 bound to the Δ724-751 mutant of the HIF-1α NLS at 1.9 Å resolution. In the wild-type structure, two basic clusters in the HIF-1α NLS made extensive interactions with importin-α1 on two sites (the major site and the minor site). In the mutant structure, the NLS residues still interacted extensively with the major site on importin-α1, but the interactions with the minor site were not observed. The structural data, together with computational analyses of binding free energies, indicate that the loss of the minor-site interactions inhibit nuclear accumulation of HIF-1α.