Structure and expression during development of Drosophila melanogaster gene for DNA polymerase α
Structure and expression during development of Drosophila melanogaster gene for DNA polymerase α
复制标题
DOI：
10.1093/nar/19.18.4991
复制
发表时间：
1991-09
影响因子：
14.9
通讯作者：
F. Hirose;M. Yamaguchi;Y. Nishida;M. Masutani;H. Miyazawa;F. Hanaoka;A. Matsukage
中科院分区：
文献类型：
--
作者：
F. Hirose;M. Yamaguchi;Y. Nishida;M. Masutani;H. Miyazawa;F. Hanaoka;A. Matsukage
摘要 克隆了果蝇基因和 cDNA，涵盖了 DNA 聚合酶 α 的整个开放阅读框，并测定了它们的核苷酸序列。该基因由 6 个外显子组成，由 5 个短内含子分隔。主要转录起始位点位于起始密码子上游 85 bp 处。开放阅读框的核苷酸序列揭示了1,505个氨基酸残基的多肽，分子量为170,796。该多肽的氨基酸序列与人DNA聚合酶α的催化亚基的氨基酸序列有37％的同源性。该序列包含六个区域，其顺序和氨基酸序列在许多其他病毒和真核DNA聚合酶中高度保守。我们在第 639 位和第 758 位之间的区域发现了 7 个氨基酸残基，与大肠杆菌 DNA 聚合酶 I 相关的 3'----5' 核酸外切酶活性位点所必需的氨基酸残基相同。因此，核酸外切酶活性可能与果蝇DNA聚合酶α有关。 DNA聚合酶α mRNA的水平在未受精卵和早期胚胎中较高，在成年雌性果蝇和二龄幼虫中相对较高，而在其他发育阶段的身体中较低。这一表达特征与增殖细胞核抗原（DNA聚合酶δ的辅助蛋白）相似，似乎与各个发育阶段增殖细胞的比例相吻合。由于DNA聚合酶α的mRNA在培养的果蝇Kc细胞中的半衰期为15分钟，DNA聚合酶α基因的表达可能在转录步骤受到严格调控。
Abstract The Drosophila melanogaster gene and cDNA which span the entire open reading frame for DNA polymerase alpha, were cloned, and their nucleotide sequences were determined. The gene consists of 6 exons separated by 5 short introns. The major transcription initiation site was localized 85 bp upstream from the initiation codon. The nucleotide sequence of the open reading frame revealed a polypeptide of 1,505 amino acid residues with a molecular weight of 170,796. The amino acid sequence of the polypeptide was 37% homologous with that of the catalytic subunit of human DNA polymerase alpha. This sequence contains six regions, the orders and amino acid sequences of which are highly conserved among a number of other viral and eukaryotic DNA polymerases. We found 7 amino acid residues in the region between the 639th and 758th positions, identical to those essential for the active site of Escherichia coli DNA polymerase I-associated 3'----5' exonuclease. Thus, the exonuclease activity may be associated with Drosophila DNA polymerase alpha. Levels of the DNA polymerase alpha mRNA were high in unfertilized eggs and early embryos, relatively high in adult female flies and second-instar larva, and low in bodies at other stages of development. This feature of the expression is similar to that of the proliferating cell nuclear antigen (an auxiliary protein of DNA polymerase delta) and seems to coincide with the proportions of proliferating cells in various developmental stages. As the half life of the mRNA for DNA polymerase alpha in cultured Drosophila Kc cells was 15 min, expression of the DNA polymerase alpha gene is probably strictly regulated at the step of transcription.