UvrAB复合物中存在两个UvrB亚基可确保对两条DNA链中的损伤进行检测。
The presence of two UvrB subunits in the UvrAB complex ensures damage detection in both DNA strands.
作者信息
Verhoeven Esther E A, Wyman Claire, Moolenaar Geri F, Goosen Nora
机构信息
Laboratory of Molecular Genetics, Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, Einsteinweg 55, 2300 RA Leiden, The Netherlands.
出版信息
EMBO J. 2002 Aug 1;21(15):4196-205. doi: 10.1093/emboj/cdf396.
It is generally accepted that the damage recognition complex of nucleotide excision repair in Escherichia coli consists of two UvrA and one UvrB molecule, and that in the preincision complex UvrB binds to the damage as a monomer. Using scanning force microscopy, we show here that the damage recognition complex consists of two UvrA and two UvrB subunits, with the DNA wrapped around one of the UvrB monomers. Upon binding the damage and release of the UvrA subunits, UvrB remains a dimer in the preincision complex. After association with the UvrC protein, one of the UvrB monomers is released. We propose a model in which the presence of two UvrB subunits ensures damage recognition in both DNA strands. Upon binding of the UvrA(2)B(2) complex to a putative damaged site, the DNA wraps around one of the UvrB monomers, which will subsequently probe one of the DNA strands for the presence of a lesion. When no damage is found, the DNA will wrap around the second UvrB subunit, which will check the other strand for aberrations.
人们普遍认为，大肠杆菌核苷酸切除修复的损伤识别复合体由两个UvrA分子和一个UvrB分子组成，并且在切割前复合体中，UvrB以单体形式与损伤部位结合。利用扫描力显微镜，我们在此表明损伤识别复合体由两个UvrA亚基和两个UvrB亚基组成，DNA缠绕在其中一个UvrB单体上。在结合损伤部位并释放UvrA亚基后，UvrB在切割前复合体中仍为二聚体。与UvrC蛋白结合后，其中一个UvrB单体被释放。我们提出了一个模型，其中两个UvrB亚基的存在确保了对两条DNA链上损伤的识别。当UvrA(2)B(2)复合体与假定的损伤位点结合时，DNA缠绕在其中一个UvrB单体上，该单体随后会探测其中一条DNA链是否存在损伤。如果未发现损伤，DNA将缠绕在第二个UvrB亚基上，该亚基会检查另一条链是否有异常。
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