Richardson John P
Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, IN 47405, USA.
Biochim Biophys Acta. 2002 Sep 13;1577(2):251-260. doi: 10.1016/s0167-4781(02)00456-6.
Transcription factor Rho is a ring-shaped, homohexameric protein that causes transcript termination through actions on nascent RNAs that are coupled to ATP hydrolysis. The Rho polypeptide has a distinct RNA-binding domain (RNA-BD) of known structure as well as an ATP-binding domain (ATP-BD) for which a structure has been proposed based on homology modeling. A model is proposed in which Rho first makes an interaction with a nascent RNA on a C-rich, primarily single-stranded rut region of the transcript as that region emerges from the exit site of RNA polymerase. A subsequent step involves a temporary release of one subunit of the hexamer to allow the 3' segment of the nascent transcript to enter the central channel of the Rho ring. Actions of the Rho structure in the channel on the 3' segment that are coupled to ATP hydrolysis pull the RNA from its contacts with the template and RNA polymerase, thus causing termination of its synthesis.
转录因子Rho是一种环状的同六聚体蛋白，它通过作用于与ATP水解偶联的新生RNA来导致转录终止。Rho多肽具有已知结构的独特RNA结合结构域（RNA-BD）以及基于同源建模提出了结构的ATP结合结构域（ATP-BD）。提出了一个模型，其中Rho首先与转录本富含C的、主要为单链的rut区域上的新生RNA相互作用，当该区域从RNA聚合酶的出口位点出现时。随后的步骤涉及六聚体的一个亚基的暂时释放，以允许新生转录本的3'段进入Rho环的中央通道。通道中Rho结构对3'段的作用与ATP水解偶联，将RNA从其与模板和RNA聚合酶的接触中拉出来，从而导致其合成终止。
