Die Funktion von TTF-I bei der Transkriptions-Termination in Chromatin und in der Organisation der Chomatinstruktur der rDNA Terminatoren

利用DNA作为模板的生物过程必须与将其包装到染色质中进行斗争，染色质是由核小体和非组蛋白蛋白质组成的复杂阵列，它们将DNA压缩成松散定义的更高阶结构。所有的过程，如转录和复制，都必须与染色质打交道，染色质是必不可少的额外调节层。染色质结构在转录起始中的重要性已经得到了充分的证实。一个具体的例子是我深入研究的小鼠rDNA基因。TTF-I(转录终止因子I)在染色质环境中激活核糖体基因。此外，TTF-I还终止延长的RNA聚合酶I并释放rRNA。关于染色质的转录终止，我们一无所知。我最初的实验显示了体内rDNA终止区的特殊染色质结构。实验还表明，多个结合位点能够协同TTF-I与rDNA终止子结合，并在体外允许染色质上的特异性转录终止。在这个项目中，我打算研究TTF-I在体外对rDNA终止子染色质结构的影响以及对转录终止的影响。

Biological processes utilizing DNA as a template must contend with its packaging into chromatin, a complex array of nucleosomes and non-histone proteins which compact DNA into a loosely defined higher order structure. All processes like transcription and replication have to deal with chromatin, an essential additional layer of regulation. The importance of chromatin structure in transcription initiation is well established. A specific example is the murine rDNA gene which I studied intensively. TTF-I (Transcription Termination Factor I) activates the ribosomal gene in a chromatin context. Moreover, TTF-I also terminates the elongating RNA polymerase I and releases the rRNA. Nothing is known about transcription termination in chromatin. My initial experiments show a specific chromatin structure of the rDNA terminator region in vivo. The experiments showed as well, that multiple binding sites enable cooperative TTF-I binding to the rDNA terminator and allow specific transcription termination on chromatin in vitro. In this project I propose to study the influence of TTF-I on the rDNA terminator chromatin structure in vitro and implications for transcription termination.