nusB: a protein factor necessary for transcription antitermination in vitro by phage lambda N gene product.
nusB: a protein factor necessary for transcription antitermination in vitro by phage lambda N gene product.
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nusB：噬菌体 lambda N 基因产物在体外抗转录终止所必需的蛋白质因子。
DOI：
10.1073/pnas.81.20.6305
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发表时间：
1984
影响因子：
11.1
通讯作者：
Das,A
中科院分区：
文献类型：
--
作者：
Ghosh,B;Das,A
我们证明，大肠杆菌nusB基因的蛋白质产物是必需的体外转录抗终止噬菌体λ N基因产物。我们最近描述了一个方便的生化分析的N蛋白活性在S30偶联转录翻译系统，并证明了N的行动需要69-kDa的L因子（nusA），产品的E。colinusA基因。使用互补测定法恢复nusB突变体提取物中的N活性，我们纯化了nusB互补活性。这种活性是由于在E.大肠杆菌中含有多个拷贝的nusB基因。我们发现，nusA和nusB所需的N活性，以抑制ρ依赖以及ρ独立的终止。过量的nusA或N蛋白不能克服抗终止对nusB蛋白的需要，过量的nusB也不能克服抗终止对nusA的需要。我们的研究结果表明，由N形成的抗终止装置需要nusA和nusB蛋白等摩尔量。
We demonstrate that the protein product of the Escherichia coli nusB gene is essential for transcription antitermination in vitro by phage lambda N gene product. We recently have described a convenient biochemical assay for N protein activity in the S30-coupled transcription translation system and demonstrated that N action requires the 69-kDa L factor (nusA), the product of E. coli nusA gene. Using a complementation assay for the restoration of N activity specifically in the nusB mutant extract, we have purified the nusB complementing activity. This activity is due to a 15-kDa polypeptide that is overproduced in E. coli containing multiple copies of the nusB gene. We find that nusA and nusB are required for N activity to suppress a rho-dependent as well as a rho-independent terminator. The requirement for nusB protein in antitermination could not be overcome by an excess of nusA or N protein, nor could an excess of nusB overcome the requirements for nusA in antitermination. Our results suggest that the formation of an antitermination apparatus by N requires nusA and nusB proteins in equimolar amounts.