Dodecameric structure and ATPase activity of the human TIP48/TIP49 complex
Dodecameric structure and ATPase activity of the human TIP48/TIP49 complex
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DOI：
10.1016/j.jmb.2006.11.030
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发表时间：
2007-02-09
影响因子：
5.6
通讯作者：
Tsaneva, Irina R.
中科院分区：
文献类型：
--
作者：
Puri, Teena;Wendler, Petra;Tsaneva, Irina R.
TIP 48和TIP 49是两种高度保守的真核AAA（+）蛋白，具有重要的生物学功能，在与癌症密切相关的主要途径中起关键作用。它们一起被发现作为几个高度保守的染色质修饰复合物的组分。这两种蛋白质都显示出与细菌RuvB的序列同源性，但它们的生化作用的性质和机制仍然未知。将重组人TIP 48和TIP 49组装成稳定的高分子量等摩尔复合物，并在体外测试活性。TIP 48/TIP 49复合物的形成导致ATP酶活性的协同增加，但在单链、双链或四向连接DNA的存在下不刺激ATP水解，并且没有检测到DNA解旋酶或分支迁移活性。在TIP 48或TIP 49中具有催化缺陷的复合物没有ATP酶活性，这表明TIP 48/TIP 49复合物中的两种蛋白质都是ATP水解所需的。通过负染电子显微镜检查TIP 48/TIP 49复合物的结构。在20 A分辨率下的三维重建揭示了TIP 48/TIP 49复合物由两个堆叠的具有C6对称性的六聚体环组成。顶环和底环显示出实质性的结构差异。有趣的是，TIP 48在腺嘌呤核苷酸的存在下形成寡聚体，而TIP 49没有。结果指出了TIP 48和TIP 49之间的生物化学差异，这可以解释两个六聚体环之间的结构差异，并且可能对蛋白质单独执行的专门功能具有重要意义。(c)2006爱思唯尔有限公司保留所有权利。
TIP48 and TIP49 are two related and highly conserved eukaryotic AAA(+) proteins with an essential biological function and a critical role in major pathways that are closely linked to cancer. They are found together as components of several highly conserved chromatin-modifying complexes. Both proteins show sequence homology to bacterial RuvB but the nature and mechanism of their biochemical role remain unknown. Recombinant human TIP48 and TIP49 were assembled into a stable high molecular mass equimolar complex and tested for activity in vitro. TIP48/TIP49 complex formation resulted in synergistic increase in ATPase activity but ATP hydrolysis was not stimulated in the presence of single-stranded, double-stranded or four-way junction DNA and no DNA helicase or branch migration activity could be detected. Complexes with catalytic defects in either TIP48 or TIP49 had no ATPase activity showing that both proteins within the TIP48/TIP49 complex are required for ATP hydrolysis. The structure of the TIP48/TIP49 complex was examined by negative stain electron microscopy. Three-dimensional reconstruction at 20 A resolution revealed that the TIP48/TIP49 complex consisted of two stacked hexameric rings with C6 symmetry. The top and bottom rings showed substantial structural differences. Interestingly, TIP48 formed oligomers in the presence of adenine nucleotides, whilst TIP49 did not. The results point to biochemical differences between TIP48 and TIP49, which may explain the structural differences between the two hexameric rings and could be significant for specialised functions that the proteins perform individually. (c) 2006 Elsevier Ltd. All rights reserved.