Mitochondrial DNA ligase in Crithidia fasciculata.
Mitochondrial DNA ligase in Crithidia fasciculata.
复制标题
DOI：
10.1073/pnas.0305705101
复制
发表时间：
2004-03
影响因子：
11.1
通讯作者：
K. Sinha;J. C. Hines;N. Downey;D. Ray
中科院分区：
文献类型：
--
作者：
K. Sinha;J. C. Hines;N. Downey;D. Ray
动质体 DNA (kDNA) 是锥虫中线粒体 DNA 的形式，由数千个互锁的环状 DNA 组成，组织成致密的盘状结构。 II 型 DNA 拓扑异构酶、DNA 聚合酶 β 和结构特异性核酸内切酶已与新生 DNA 小环一起定位到 kDNA 盘侧翼的反足位点。我们在锥虫 Crithidia fasciculata 中克隆了编码线粒体 DNA 连接酶的基因 (LIG k)，并且我们表明，连接酶的表位标记形式与其他复制蛋白在反足位点以及 kDNA 盘的两个面共定位。 DNA LIG k 在与 ATP 反应中变成腺苷酸化，并且通过与焦磷酸盐或带切口的 DNA 一起孵育去除腺苷酸部分。连接酶与β聚合酶发生物理相互作用，并被认为参与新合成的小环中间隙的修复。在酵母和哺乳动物中，单个基因编码核和线粒体形式的 DNA 连接酶。 LIG K 蛋白序列与其他真核生物中的线粒体 DNA 连接酶相似性较低，并且与 C. fasciculata 核 DNA 连接酶 (LIG I) 不同。
Kinetoplast DNA (kDNA), the form of mitochondrial DNA in trypanosomatids, consists of thousands of interlocked circular DNAs organized into a compact disk structure. A type II DNA topoisomerase, a DNA polymerase beta, and a structure-specific endonuclease have been localized to antipodal sites flanking the kDNA disk along with nascent DNA minicircles. We have cloned a gene (LIG k) encoding a mitochondrial DNA ligase in the trypanosomatid Crithidia fasciculata, and we show that an epitope-tagged form of the ligase colocalizes with the other replication proteins at the antipodal sites and also at the two faces of the kDNA disk. DNA LIG k becomes adenylated in reactions with ATP, and the adenylate moiety is removed by incubation with pyrophosphate or nicked DNA. The ligase interacts physically with the beta polymerase and is proposed to be involved in the repair of gaps in the newly synthesized minicircles. In yeast and mammals, a single gene encodes both nuclear and mitochondrial forms of DNA ligase. The LIG K protein sequence has low similarity to mitochondrial DNA ligases in other eukaryotes and is distinct from the C. fasciculata nuclear DNA ligase (LIG I).