文章基本信息

标题：Transcriptional arrest of yeast RNA polymerase II by Escherichia coli rho protein in vitro
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作者：S Y Wu ; T Platt
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1993
卷号：90
期号：14
页码：6606-6610
DOI：10.1073/pnas.90.14.6606
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A promoter-independent assay utilizing poly(dC)-tailed DNA templates has revealed that Saccharomyces cerevisiae whole-cell extracts can be proficient for transcription by the endogenous yeast RNA polymerase II as well as for correct 3'-end RNA processing. Our attempts to examine the fate of polymerase II itself were inconclusive, because only trace transcription products corresponded to the expected size of terminated RNA species. Transcription in our processing-proficient extract was thus insufficient to cause termination. To test our system with a known, albeit heterologous, signal, we examined a dC-tailed template carrying the E. coli rho-dependent termination signal trp t' in the yeast extract. Transcripts from this template were not susceptible to processing, but addition of rho protein resulted in two distinct truncated transcripts that could not be chased by excess unlabeled nucleotides. These RNA species thus represented stably paused or terminated polymerase II products, and their absence when a mutated unresponsive trp t' template was used affirmed that they were due to the effects of rho. E. coli RNA polymerase added to a yeast extract pretreated with alpha-amanitin was also halted by rho at these same two sites. A mutated rho protein, while only partly defective with E. coli polymerase, failed to provoke arrest when transcription was carried out by RNA polymerase II. Thus, functional rho and its cognate site, trp t', appear necessary and sufficient to elicit the production of truncated transcripts by RNA polymerase II in a yeast whole-cell extract. The ability of rho to halt the eukaryotic enzyme strengthens the likelihood that a rho-like helicase may be involved in RNA polymerase II transcription termination.