Willis A E, Weksberg R, Tomlinson S, Lindahl T
Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Hertfordshire, United Kingdom.
Proc Natl Acad Sci U S A. 1987 Nov;84(22):8016-20. doi: 10.1073/pnas.84.22.8016.
Cell lines derived from seven patients with Bloom syndrome all contain a DNA ligase I with unusual properties. Six lines were shown to have a reduced level of this enzyme activity and the residual enzyme was anomalously heat-labile. The seventh line contained a dimeric rather than monomeric form of ligase I. Several cell lines representative of other inherited human syndromes have apparently normal DNA ligases. The data indicate that Bloom syndrome is due to a defect in the structure of DNA ligase I caused by a "leaky" point mutation occurring at one of at least two alternative sites.
源自七名布卢姆综合征患者的细胞系均含有具有异常特性的DNA连接酶I。六个细胞系显示该酶活性水平降低,且残余酶对热异常敏感。第七个细胞系含有二聚体形式而非单体形式的连接酶I。代表其他遗传性人类综合征的几个细胞系的DNA连接酶显然正常。数据表明,布卢姆综合征是由至少两个替代位点之一发生的“渗漏”点突变导致的DNA连接酶I结构缺陷所致。