The Werner Syndrome Protein Is Distinguished from the Bloom Syndrome Protein by Its Capacity to Tightly Bind Diverse DNA Structures
The Werner Syndrome Protein Is Distinguished from the Bloom Syndrome Protein by Its Capacity to Tightly Bind Diverse DNA Structures
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DOI：
10.1371/journal.pone.0030189
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发表时间：
2012-01-17
期刊：
影响因子：
3.7
通讯作者：
Fry, Michael
中科院分区：
文献类型：
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作者：
Kamath-Loeb, Ashwini;Loeb, Lawrence A.;Fry, Michael
沃纳综合征解旋酶-外切核酸酶（WRN）或其同系物布卢姆综合征解旋酶（BLM）的缺失导致不同的遗传性疾病。维尔纳综合征的特征是衰老和年龄相关疾病的过早发作，而布卢姆综合征涉及发育异常和多种恶性肿瘤的易感性增加。为了确定WRN和BLM之间可能导致其丢失结果不同的生化差异，我们比较了它们在体外解开和结合不同DNA结构的能力。全长重组WRN和BLM蛋白在Sf 9昆虫细胞中表达并纯化，以可比较的程度解绕，并且具有相似的K-m值，部分DNA双链体、张开臂DNA和G ′ 2双分子四链体DNA。然而，WRN解决气泡DNA类似的25倍，更有效地比BLM。这两种酶的区别主要在于它们结合DNA的能力不同。WRN结合部分双链体，气泡和张开臂DNA和G '2双分子和G4四分子四链体，解离常数为0.25至25 nM。相比之下，BLM仅与G4四链体DNA形成实质性复合物，而仅少量结合其他DNA结构。我们提出的可能性，除了它的酶活性WRN可以作为一个支架上的额外的DNA加工蛋白的DNA组装。
Loss of Werner syndrome helicase-exonuclease (WRN) or of its homolog Bloom syndrome helicase (BLM) results in different inherited disorders. Whereas Werner syndrome is characterized by premature onset of aging and age-associated diseases, Bloom syndrome involves developmental abnormalities and increased predisposition to diverse malignancies. To identify biochemical differences between WRN and BLM that might contribute to the dissimilar outcomes of their loss, we compared their abilities to unwind and bind in vitro diverse DNA structures. Full-length recombinant WRN and BLM proteins expressed in and purified from Sf9 insect cells unwound to comparable extents and with similar K-m values partial DNA duplex, splayed arm DNA and G'2 bimolecular quadruplex DNA. However, WRN resolved bubble DNA similar to 25-fold more efficiently than BLM. The two enzymes were mainly distinguished by their contrasting abilities to bind DNA. WRN bound partial duplexes, bubble and splayed arm DNA and G'2 bimolecular and G4 four-molecular quadruplexes with dissociation constants of 0.25 to 25 nM. By contrast, BLM formed substantial complexes with only G4 quadruplex DNA while binding only marginally other DNA structures. We raise the possibility that in addition to its enzymatic activities WRN may act as a scaffold for the assembly on DNA of additional DNA processing proteins.