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：1990
卷号：87
期号：7
页码：2675-2679
DOI：10.1073/pnas.87.7.2675
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The 11-gene S10 ribosomal protein operon of Escherichia coli is under the autogenous control of L4, the product of the third gene of the operon. Ribosomal protein L4 inhibits both transcription and translation of the operon. Our in vivo studies indicated that L4 regulates transcription by causing premature termination within the untranslated S10 operon leader. We have now used an in vitro transcription system to study the effect of purified L4 on expression of the S10 operon. We find that the cell-free system reproduces the in vivo observations. Namely, in the absence of L4, most of the RNA polymerases read through the termination site in the S10 attenuator; the addition of L4 results in increased termination at this site. However, RNA polymerase does not terminate at the S10 attenuator, with or without L4, unless an additional factor, protein NusA, is added to the transcription reaction. These results suggest that the attenuator in the S10 operon is a NusA-dependent terminator whose efficiency is regulated by ribosomal protein L4.
