Brosh R M, Karow J K, White E J, Shaw N D, Hickson I D, Bohr V A
Laboratory of Molecular Genetics, Box 1, National Institute on Aging, GRC, NIH, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA.
Nucleic Acids Res. 2000 Jun 15;28(12):2420-30. doi: 10.1093/nar/28.12.2420.
Maintenance of genomic integrity is vital to all organisms. A number of human genetic disorders, including Werner Syndrome, Bloom Syndrome and Rothmund-Thomson Syndrome, exhibit genomic instability with some phenotypic characteristics of premature aging and cancer predisposition. Presumably the aberrant cellular and clinical phenotypes in these disorders arise from defects in important DNA metabolic pathways such as replication, recombination or repair. These syndromes are all characterized by defects in a member of the RecQ family of DNA helicases. To obtain a better understanding of how these enzymes function in DNA metabolic pathways that directly influence chromosomal integrity, we have examined the effects of non-covalent DNA modifications on the catalytic activities of purified Werner (WRN) and Bloom (BLM) DNA helicases. A panel of DNA-binding ligands displaying unique properties for interacting with double helical DNA was tested for their effects on the unwinding activity of WRN and BLM helicases on a partial duplex DNA substrate. The levels of inhibition by a number of these compounds were distinct from previously reported values for viral, prokaryotic and eukaryotic helicases. The results demonstrate that BLM and WRN proteins exhibit similar sensitivity profiles to these DNA-binding ligands and are most potently inhibited by the structurally related minor groove binders distamycin A and netropsin (K(i) </=1 microM). The distinct inhibition of WRN and BLM helicases by the minor groove binders suggest that these helicases unwind double-stranded DNA by a related mechanism.
基因组完整性的维持对所有生物体都至关重要。包括沃纳综合征、布卢姆综合征和罗思蒙德 - 汤姆森综合征在内的一些人类遗传疾病表现出基因组不稳定性，并伴有一些早衰和癌症易感性的表型特征。据推测，这些疾病中异常的细胞和临床表型源于重要DNA代谢途径（如复制、重组或修复）的缺陷。这些综合征的共同特征是DNA解旋酶RecQ家族成员存在缺陷。为了更好地理解这些酶如何在直接影响染色体完整性的DNA代谢途径中发挥作用，我们研究了非共价DNA修饰对纯化的沃纳（WRN）和布卢姆（BLM）DNA解旋酶催化活性的影响。测试了一组对与双链DNA相互作用具有独特性质的DNA结合配体，以考察它们对WRN和BLM解旋酶在部分双链DNA底物上解旋活性的影响。其中一些化合物的抑制水平与先前报道的病毒、原核生物和真核生物解旋酶的值不同。结果表明，BLM和WRN蛋白对这些DNA结合配体表现出相似的敏感性，并且最有效地被结构相关的小沟结合剂偏端霉素A和纺锤菌素抑制（K(i)≤1 microM）。小沟结合剂对WRN和BLM解旋酶的独特抑制作用表明，这些解旋酶通过相关机制解开双链DNA。
