Structure of the origin-binding domain of simian virus 40 large T antigen bound to DNA
Structure of the origin-binding domain of simian virus 40 large T antigen bound to DNA
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DOI：
10.1038/sj.emboj.7601452
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发表时间：
2006-12-13
期刊：
影响因子：
11.4
通讯作者：
Bochkarev, Alexey
中科院分区：
文献类型：
--
作者：
Bochkareva, Elena;Martynowski, Dariusz;Bochkarev, Alexey
大T抗原（T-ag）蛋白结合并激活猿猴病毒40（SV 40）中DNA复制起点（ori）的DNA复制。在这里，我们确定了载脂蛋白形式的T-ag起源结合结构域（OBD）的晶体结构，并结合到17 bp的回文序列（位点1和3）或23 bp的ori DNA回文序列，包括OBD的所有四个GAGGC结合位点。T-ag OBD显示通过包含Ser 147-Thr 155（A1环）、DNA结合螺旋和环的组合（His 203-Asn 210）和Asn 227的环与DNA相互作用。A1环沿着大沟来回移动，并占了与DNA的大部分序列决定性接触。出乎意料的是，在两种T-ag-DNA结构中，T-ag OBD独立地结合DNA，并且不进行直接的蛋白质-蛋白质接触。即使在其典型位点GAGGC存在下，T-ag OBD也被捕获结合到非共有位点ATGGC。我们的观察与已知的生物化学和结构特征的T-Ag-起源的相互作用一起提出了一个模型起源解旋。
The large T antigen (T-ag) protein binds to and activates DNA replication from the origin of DNA replication (ori) in simian virus 40 (SV40). Here, we determined the crystal structures of the T-ag origin-binding domain (OBD) in apo form, and bound to either a 17 bp palindrome (sites 1 and 3) or a 23 bp ori DNA palindrome comprising all four GAGGC binding sites for OBD. The T-ag OBDs were shown to interact with the DNA through a loop comprising Ser147-Thr155 (A1 loop), a combination of a DNA-binding helix and loop (His203-Asn210), and Asn227. The A1 loop traveled back-and-forth along the major groove and accounted for most of the sequence-determining contacts with the DNA. Unexpectedly, in both T-ag-DNA structures, the T-ag OBDs bound DNA independently and did not make direct protein-protein contacts. The T-ag OBD was also captured bound to a non-consensus site ATGGC even in the presence of its canonical site GAGGC. Our observations taken together with the known biochemical and structural features of the T-ag-origin interaction suggest a model for origin unwinding.