Intramitochondrial localization of universal minicircle sequence-binding protein, a trypanosomatid protein that binds kinetoplast minicircle replication origins.
Intramitochondrial localization of universal minicircle sequence-binding protein, a trypanosomatid protein that binds kinetoplast minicircle replication origins.
复制标题
通用微量圆序列结合蛋白的室内定位，这是一种结合动力学小块复制起源的锥虫蛋白。
DOI：
10.1083/jcb.153.4.725
复制
发表时间：
2001-05-14
影响因子：
7.8
通讯作者：
Shlomai, J
中科院分区：
文献类型：
--
作者：
Abu-Elneel, K;Robinson, D R;Drew, M E;Englund, P T;Shlomai, J
运动体DNA(KDNA)是束锥虫的线粒体DNA，是一种独特的结构，包含5000个DNA小环，在拓扑上连接成一个巨大的网络结构。在活体内，网络被浓缩成圆盘状结构。微环的复制始于独特的起始点，它由通用微环序列(UMS)结合蛋白(UMSBP)结合，UMSBP是一种序列特异性DNA结合蛋白。这种蛋白质由核基因编码，定位于细胞的单个线粒体内。使用免疫荧光，我们发现UMSBP仅定位于kDNA盘面附近离细胞鞭毛最近的两个相邻位置。这个位置不同于圆盘周长的两个对足位置，该位置由DNA聚合酶β、拓扑异构酶II和结构特异的核酸内切酶占据。虽然我们发现在整个细胞周期中，UMSBP的mRNA和蛋白水平保持恒定，UMSBP的合成速度也保持恒定，但免疫荧光显示UMSBP在动质粒中的定位并不是静态的。UMSBP和其他kDNA复制酶在线粒体内的定位大大澄清了我们对kDNA复制过程的理解。
Kinetoplast DNA (kDNA), the mitochondrial DNA of the trypanosomatid Crithidia fasciculata, is a unique structure containing 5,000 DNA minicircles topologically linked into a massive network. In vivo, the network is condensed into a disk-shaped structure. Replication of minicircles initiates at unique origins that are bound by universal minicircle sequence (UMS)-binding protein (UMSBP), a sequence-specific DNA-binding protein. This protein, encoded by a nuclear gene, localizes within the cell's single mitochondrion. Using immunofluorescence, we found that UMSBP localizes exclusively to two neighboring sites adjacent to the face of the kDNA disk nearest the cell's flagellum. This site is distinct from the two antipodal positions at the perimeter of the disk that is occupied by DNA polymerase β, topoisomerase II, and a structure-specific endonuclease. Although we found constant steady-state levels of UMSBP mRNA and protein and a constant rate of UMSBP synthesis throughout the cell cycle, immunofluorescence indicated that UMSBP localization within the kinetoplast is not static. The intramitochondrial localization of UMSBP and other kDNA replication enzymes significantly clarifies our understanding of the process of kDNA replication.