A HUMAN NUCLEAR URACIL DNA GLYCOSYLASE IS THE 37-KDA SUBUNIT OF GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE
A HUMAN NUCLEAR URACIL DNA GLYCOSYLASE IS THE 37-KDA SUBUNIT OF GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE
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DOI：
10.1073/pnas.88.19.8460
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发表时间：
1991-10-01
影响因子：
11.1
通讯作者：
SIROVER, MA
中科院分区：
文献类型：
--
作者：
MEYERSIEGLER, K;MAURO, DJ;SIROVER, MA
我们已经分离并鉴定了一个质粒（pChug 20.1），该质粒含有从正常人胎盘中分离的核尿嘧啶DNA糖基化酶（UDG）基因的cDNA。 该cDNA指导了表现出UDG活性的融合蛋白（M（r）66，000）的合成。 酶活性对含尿嘧啶的多核苷酸底物具有特异性，并被糖基化酶抗体或β-半乳糖苷酶抗体抑制。 序列分析表明，一个开放阅读框架，编码335个氨基酸的蛋白质，计算的M（r）36，050和pI 8.7，对应于纯化的人胎盘UDG的M（r）37，000和pI 8.1。 该cDNA与单纯疱疹病毒、大肠杆菌和酵母的UDG之间没有同源性，也没有与推定的人线粒体UDG cDNA或第二个人核UDG cDNA的同源性。 令人惊讶的是，搜索GenBank数据库显示，UDG的cDNA与人甘油醛-3-磷酸脱氢酶的37-kDa亚基完全同源。 人红细胞甘油醛-3-磷酸脱氢酶以其四聚体形式商业获得。 一个37-kDa的亚基被分离出来，并显示具有UDG活性相当于所看到的纯化的人胎盘UDG。 这种37-kDa的蛋白质的多重功能，在这里和以前的报告表明，它拥有一系列的活动，这取决于它的寡聚状态。 因此，这种多功能蛋白质基因中的突变可能会导致布卢姆综合征的多种细胞表型。
We have isolated and characterized a plasmid (pChug 20.1) that contains the cDNA of a nuclear uracil DNA glycosylase (UDG) gene isolated from normal human placenta. This cDNA directed the synthesis of a fusion protein (M(r) 66,000) that exhibited UDG activity. The enzymatic activity was specific for a uracil-containing polynucleotide substrate and was inhibited by a glycosylase antibody or a beta-galactosidase antibody. Sequence analysis demonstrated an open reading frame that encoded a protein of 335 amino acids of calculated M(r) 36,050 and pI 8.7, corresponding to the M(r) 37,000 and pI 8.1 of purified human placental UDG. No homology was seen between this cDNA and the UDG of herpes simplex virus, Escherichia coli, and yeast; nor was there homology with the putative human mitochondrial UDG cDNA or with a second human nuclear UDG cDNA. Surprisingly, a search of the GenBank data base revealed that the cDNA of UDG was completely homologous with the 37-kDa subunit of human glyceraldehyde-3-phosphate dehydrogenase. Human erythrocyte glyceraldehyde-3-phosphate dehydrogenase was obtained commercially in its tetrameric form. A 37-kDa subunit was isolated from it and shown to possess UDG activity equivalent to that seen for the purified human placental UDG. The multiple function of this 37-kDa protein as here and previously reported indicate that it possesses a series of activities, depending on its oligomeric state. Accordingly, mutations(s) in the gene of this multifunctional protein may conceivably result in the diverse cellular phenotypes of Bloom syndrome.