Understanding the Structure, Multimerization, Subcellular Localization and mC Selectivity of a Genomic Mutator and Anti-HIV Factor APOBEC3H.
Understanding the Structure, Multimerization, Subcellular Localization and mC Selectivity of a Genomic Mutator and Anti-HIV Factor APOBEC3H.
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DOI：
10.1038/s41598-018-21955-0
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发表时间：
2018-02-28
影响因子：
4.6
通讯作者：
Chen XS
中科院分区：
文献类型：
--
作者：
Ito F;Yang H;Xiao X;Li SX;Wolfe A;Zirkle B;Arutiunian V;Chen XS
APOBEC 3 H（A3 H）是DNA胞嘧啶脱氨酶的APOBEC 3亚家族的成员，其对于先天性免疫防御是重要的，并且已经涉及癌症生物发生。为了了解A3 H生化功能的结构基础，我们确定了人A3 H的高分辨率结构，并进行了广泛的生化分析。2.49 nm的晶体结构揭示了一个独特的长C-末端螺旋6（h6），一个典型的五链β-折叠核心的断裂β5链，以及一个围绕Zn活性中心的长环1。环7残基W115的突变破坏了RNA介导的A3 H二聚化，产生仍然具有核酸结合和脱氨酶活性的无RNA单体形式。在HEK 293 T细胞中表达的A3 H显示RNA依赖性HMW复合物形成和RNA酶A依赖性脱氨酶活性。A3 H具有围绕Zn活性中心的高度带正电荷的表面，并且该带电表面内的多个带正电荷的残基在RNA介导的HMW形成和脱氨酶抑制中起重要作用。此外，这些带正电荷的残基影响A3 H在细胞核和胞质溶胶之间的亚细胞定位。最后，我们已经确定了多个残基的环1和7，有助于整体脱氨酶活性和甲基胞嘧啶的选择性。
APOBEC3H (A3H) is a member of the APOBEC3 subfamily of DNA cytosine deaminases that are important for innate immune defense and have been implicated in cancer biogenesis. To understand the structural basis for A3H biochemical function, we determined a high-resolution structure of human A3H and performed extensive biochemical analysis. The 2.49 Å crystal structure reveals a uniquely long C-terminal helix 6 (h6), a disrupted β5 strand of the canonical five-stranded β-sheet core, and a long loop 1 around the Zn-active center. Mutation of a loop 7 residue, W115, disrupted the RNA-mediated dimerization of A3H yielding an RNA-free monomeric form that still possessed nucleic acid binding and deaminase activity. A3H expressed in HEK293T cells showed RNA dependent HMW complex formation and RNase A-dependent deaminase activity. A3H has a highly positively charged surface surrounding the Zn-active center, and multiple positively charged residues within this charged surface play an important role in the RNA-mediated HMW formation and deaminase inhibition. Furthermore, these positively charged residues affect subcellular localization of A3H between the nucleus and cytosol. Finally, we have identified multiple residues of loop 1 and 7 that contribute to the overall deaminase activity and the methylcytosine selectivity.
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影响因子：
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通讯作者：
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