Zengel J M, Lindahl L
Department of Biology, University of Rochester, NY 14627.
Biochimie. 1991 Jun;73(6):719-27. doi: 10.1016/0300-9084(91)90052-3.
Ribosomal protein L4 of Escherichia coli functions not only as a component of the ribosome but also as a regulatory factor inhibiting both transcription and translation of its own operon, the 11 gene S10 operon. L4-mediated transcription control results in premature termination of transcription within the 172 base S10 operon leader. This attenuation control can be reproduced in a purified transcription system containing RNA polymerase, but depends on the addition of transcription factor NusA. The NusA stimulation saturates at about 2-4 copies per RNA polymerase. The L4 effect plateaus at about 4 copies per RNA polymerase. The specific recognition sites on 23S rRNA and in the S10 leader for L4 binding are not yet known. However, we can demonstrate that a fragment of 23S rRNA containing the proximal 840 bases can eliminate in vitro L4-stimulated attenuation, and hence, contains the information sufficient for L4 binding to 23S rRNA.
大肠杆菌的核糖体蛋白L4不仅作为核糖体的一个组成部分发挥作用，还作为一种调节因子，抑制其自身操纵子（11基因的S10操纵子）的转录和翻译。L4介导的转录控制导致在172个碱基的S10操纵子前导区内转录提前终止。这种衰减控制可以在含有RNA聚合酶的纯化转录系统中重现，但依赖于转录因子NusA的添加。NusA的刺激在每个RNA聚合酶约2 - 4个拷贝时达到饱和。L4的效应在每个RNA聚合酶约4个拷贝时趋于平稳。L4结合在23S rRNA和S10前导区的特异性识别位点尚不清楚。然而，我们可以证明，包含近端840个碱基的23S rRNA片段可以消除体外L4刺激的衰减，因此，包含了L4与23S rRNA结合所需的足够信息。
