Onn Itay, Kapeller Irit, Abu-Elneel Kawther, Shlomai Joseph
Department of Parasitology, The Kuvin Center for the Study of Infectious and Tropical Diseases.
J Biol Chem. 2006 Dec 8;281(49):37468-76. doi: 10.1074/jbc.M606374200. Epub 2006 Oct 16.
Kinetoplast DNA, the mitochondrial DNA of trypanosomatids, is a remarkable DNA structure that contains, in the species Crithidia fasciculata, 5000 topologically linked duplex DNA minicircles. Their replication initiates at two conserved sequences, a dodecamer, known as the universal minicircle sequence (UMS), and a hexamer, which are located at the replication origins of the minicircle L and H strands, respectively. A UMS-binding protein (UMSBP) binds specifically the 12-mer UMS sequence and a 14-mer sequence that contains the conserved hexamer in their single-stranded DNA conformation. In vivo cross-linking analyses reveal the binding of UMSBP to kinetoplast DNA networks in the cell. Furthermore, UMSBP binds in vitro to native minicircle origin fragments, carrying the UMSBP recognition sequences. UMSBP binding at the replication origin induces conformational changes in the bound DNA through its folding, aggregation and condensation.
动质体DNA是锥虫的线粒体DNA，是一种非凡的DNA结构，在纤细短膜虫物种中包含5000个拓扑连接的双链DNA微环。它们的复制起始于两个保守序列，一个十二聚体，称为通用微环序列（UMS），和一个六聚体，分别位于微环L链和H链的复制起点。一种UMS结合蛋白（UMSBP）特异性结合12聚体UMS序列和一个14聚体序列，该序列在其单链DNA构象中包含保守的六聚体。体内交联分析揭示了UMSBP与细胞中动质体DNA网络的结合。此外，UMSBP在体外与携带UMSBP识别序列的天然微环起源片段结合。UMSBP在复制起点的结合通过其折叠、聚集和凝聚诱导结合DNA的构象变化。
