RAD25 (SSL2), the yeast homolog of the human xeroderma pigmentosum group B DNA repair gene, is essential for viability.
RAD25 (SSL2), the yeast homolog of the human xeroderma pigmentosum group B DNA repair gene, is essential for viability.
复制标题
RAD25 (SSL2) 是人类着色性干皮病 B 组 DNA 修复基因的酵母同源物，对于活力至关重要。
DOI：
10.1073/pnas.89.23.11416
复制
发表时间：
1992
影响因子：
11.1
通讯作者：
Prakash,L
中科院分区：
文献类型：
--
作者：
Park,E;Guzder,SN;Koken,MH;Jaspers-Dekker,I;Weeda,G;Hoeijmakers,JH;Prakash,S;Prakash,L
着色性干皮病 (XP) 患者对紫外线 (UV) 极其敏感，并且由于核苷酸切除修复缺陷而导致皮肤癌的发生率很高。该疾病具有遗传异质性，已鉴定出七个互补组 A-G。人类切除修复基因 ERCC1、XPDC/ERCC2 和 XPAC 的同源物已在酿酒酵母中被鉴定。由于已知的酵母基因中不存在人类XPBC/ERCC3的同源物，我们利用XPBC cDNA作为杂交探针克隆了酵母同源物。酵母同源物 RAD25 (SSL2) 编码 843 个氨基酸的蛋白质 (M(r) 95,356)。 RAD25 (SSL2) 和 XPBC 编码的蛋白质具有 55% 的相同性和 72% 的保守氨基酸残基，并且这两种蛋白质在包含保守的 DNA 解旋酶序列基序方面彼此相似。密码子 799 处的无义突变删除了 RAD25 (SSL2) 中 45 个 C 端氨基酸残基，赋予了紫外线敏感性。该突变与切除修复组中的基因表现出上位性，而当它与其他 DNA 修复途径中的基因突变结合时，紫外线敏感性会出现协同增加，表明 RAD25 (SSL2) 在切除修复中起作用，但在其他修复途径中不起作用。我们还表明 RAD25 (SSL2) 是一个必需基因。保守的 Walker A 型核苷酸结合基序中的 Lys392 残基突变为精氨酸是致命的，这表明假定的 RAD25 (SSL2) ATP 酶/DNA 解旋酶活性在活力中发挥着重要作用。
Xeroderma pigmentosum (XP) patients are extremely sensitive to ultraviolet (UV) light and suffer from a high incidence of skin cancers, due to a defect in nucleotide excision repair. The disease is genetically heterogeneous, and seven complementation groups, A-G, have been identified. Homologs of human excision repair genes ERCC1, XPDC/ERCC2, and XPAC have been identified in the yeast Saccharomyces cerevisiae. Since no homolog of human XPBC/ERCC3 existed among the known yeast genes, we cloned the yeast homolog by using XPBC cDNA as a hybridization probe. The yeast homolog, RAD25 (SSL2), encodes a protein of 843 amino acids (M(r) 95,356). The RAD25 (SSL2)- and XPBC-encoded proteins share 55% identical and 72% conserved amino acid residues, and the two proteins resemble one another in containing the conserved DNA helicase sequence motifs. A nonsense mutation at codon 799 that deletes the 45 C-terminal amino acid residues in RAD25 (SSL2) confers UV sensitivity. This mutation shows epistasis with genes in the excision repair group, whereas a synergistic increase in UV sensitivity occurs when it is combined with mutations in genes in other DNA repair pathways, indicating that RAD25 (SSL2) functions in excision repair but not in other repair pathways. We also show that RAD25 (SSL2) is an essential gene. A mutation of the Lys392 residue to arginine in the conserved Walker type A nucleotide-binding motif is lethal, suggesting an essential role of the putative RAD25 (SSL2) ATPase/DNA helicase activity in viability.