Stolzenburg F, Gerwig R, Dinkl E, Grummt F
Institut für Biochemie, Julius-Maximilians-Universität Würzburg, Germany.
Chromosoma. 1994 Jun;103(3):209-14. doi: 10.1007/BF00368014.
MuNTS2, a 423 bp sequence isolated from the non-transcribed spacer of murine rDNA stimulates the amplification of cis-linked plasmid DNA in mouse cells under selective conditions. Here we demonstrate that a 180 bp subdomain of muNTS2 is highly homologous (approximately 70%) to three domains of the first well-characterized origin of replication of mammalian chromosomes, i.e. the origin of bidirectional replication (OBR) of the dihydrofolate reductase (DHFR) locus in Chinese hamster ovary (CHO) cells. When subcloned, the 180 bp homology region of muNTS2 was revealed to be essential for the amplification promoting activity of muNTS2. Fragments of the initiation zone of DNA replication from the DHFR locus of hamster cells containing the domains of homology to the mouse muNTS2 element proved also to promote DNA amplification. Thus, the screening system for amplification promoting elements turned out to detect an origin of bidirectional replication.
MuNTS2是从鼠rDNA的非转录间隔区分离出的一段423 bp序列，在选择性条件下可刺激小鼠细胞中顺式连接的质粒DNA的扩增。在此我们证明，muNTS2的一个180 bp亚结构域与哺乳动物染色体第一个被充分表征的复制起点的三个结构域高度同源（约70%），即中国仓鼠卵巢（CHO）细胞中二氢叶酸还原酶（DHFR）基因座的双向复制起点（OBR）。当进行亚克隆时，muNTS2的180 bp同源区域被证明对muNTS2的扩增促进活性至关重要。来自仓鼠细胞DHFR基因座的DNA复制起始区的片段，包含与小鼠muNTS2元件同源的结构域，也被证明可促进DNA扩增。因此，扩增促进元件的筛选系统最终检测到了一个双向复制起点。
