PMID:2839479
| Citation |
Swindle, J, Zylicz, M, Georgopoulos, C, Li, J and Greenblatt, J (1988) Purification and properties of the NusB protein of Escherichia coli. J. Biol. Chem. 263:10229-35 |
|---|---|
| Abstract |
Mutations in the nusB gene of Escherichia coli block transcriptional antitermination mediated by the N gene protein of bacteriophage lambda. We describe here two methods of overproducing the NusB protein in E. coli and a method of purifying NusB to apparent homogeneity on a large scale. Purified NusB directly stimulates transcriptional antitermination by the lambda N protein in vitro. It behaves as a monomer (Mr = 15,689) during gel permeation chromatography and gradient sedimentation. The number of NusB molecules in a wild type E. coli K12 cell ranges from about 3,000 to about 6,000 molecules/cell, depending on the growth medium, and is about 50-80% of the number of molecules of the core component of RNA polymerase in the cell. This implies that NusB has a major role in regulating chain elongation during the transcription of E. coli genes. Many E. coli strains with nusB mutations cannot grow at low temperature. However, a sup+ strain with the suppressible amber mutation nusBam115 can grow at 42 degrees C. Since such a strain does not produce NusB protein detectable by immunoprecipitation with anti-NusB, normal amounts of NusB are not essential for the survival of E. coli at 42 degrees C. |
| Links | |
| Keywords |
Bacterial Proteins/genetics; Bacterial Proteins/isolation & purification; Cloning, Molecular; Escherichia coli/genetics; Escherichia coli/metabolism; Genes; Genes, Bacterial; Mutation; Transcription, Genetic |
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