HP1 binding to native chromatin in vitro is determined by the hinge region and not by the chromodomain
HP1 binding to native chromatin in vitro is determined by the hinge region and not by the chromodomain
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DOI：
10.1093/emboj/cdg306
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发表时间：
2003-06-16
期刊：
影响因子：
11.4
通讯作者：
Pennings, S
中科院分区：
文献类型：
--
作者：
Meehan, RR;Kao, CF;Pennings, S
我们已经分离出完整的编码序列的两个非洲爪蟾异染色质蛋白1亚型，对应于HP1 α和HP1 γ。xHP1alpha的序列与其哺乳动物同源物显示出相当大的差异，而xHP1gamma是高度保守的。在功能上，xHP1alpha的行为与人HP1alpha相同。我们观察到两种HP1变体在结合天然可溶性染色质方面的意想不到的差异，这似乎与它们在体内的不同核分布相关。一个令人惊讶的发现是，在预形成的染色质中未检测到HP1染色体结构域与组蛋白H3在甲基化赖氨酸9处的特征性相互作用，这是由于其不可接近性。相反，我们本地化一个强大的染色质结合活性之间的chromodomain和chromoshadow域的xHP1alpha，但不是xHP1gamma的短铰链区。这种新的染色质结合活性具有非特异性的DNA结合成分，除了连接体组蛋白依赖性偏好改变的染色质结构与可能的异染色质组织。
We have isolated the complete coding sequences for two Xenopus laevis isoforms of heterochromatin protein 1, corresponding to HP1alpha and HP1gamma. The sequence of xHP1alpha shows considerable divergence from its mammalian homologues, whereas xHP1gamma is highly conserved. Functionally, xHP1alpha behaves identically to human HP1alpha. We observe unexpected differences between the two HP1 variants in binding native soluble chromatin, which seem to correlate with their distinct nuclear distributions in vivo. A surprising finding is that the characteristic interaction of HP1 chromodomains with histone H3 at methylated lysine 9 is not detected in preformed chromatin due to its inaccessibility. Instead, we localize a strong chromatin-binding activity to the short hinge region between the chromodomain and the chromoshadow domain of xHP1alpha but not xHP1gamma. This novel chromatin-binding activity has a non-specific DNA-binding component in addition to a linker histone-dependent preference for an altered chromatin structure with a likely heterochromatin organization.