Biomaterial Database

A transcriptional barrier in the regulatory region of the tryptophan operon of Escherichia coli: its role in the regulation of repressor-independent RNA synthesis. 1976

P H Pouwels, and H Pannekoek

A study was made of the influence of the growth rate of Escherichia coli bacteria on the transcription of the tryptophan (trp) operon, in various trp repressor negative strains. Selective measurement of the levels of RNA transcribed from the regulatory region (reg) of this operon and from the structural genes, respectively, has revealed that the increase of the rate of trpRNA synthesis with bacterial growth rate (Rose and Yanofsky, 1972) is due to a decrease of the frequency of termination of transcription at the transcriptional barrier in the regulatory region of the operon. In a mutant strain of E. coli with a deletion covering the promotor distal part of the regulatory region of the trp operon where the barrier is located, the rate of trpRNA synthesis is not affected by the growth rate. In suA- strains, in which Rho factor activity is reduced the bacterial growth rate does not affect the rate of synthesis of trpRNA. This result suggests that in wild type bacteria Rho factor contributes to the control of the transcription of the trp operon. In bacteria with a mutation rendering Tryptophanyl-tRNA synthetase (TRSase) inactive (trpS- strains) the rate of trpRNA synthesis is affected by the growth rate in the same way as in the isogenic wild type bacteria. This result indicates that TRSase plays no obligatory role in the control of trpRNA synthesis through a mechanism of termination and anti-termination of transcription, at least not in the studied strains, which carried a relA mutation.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009693	Nucleic Acid Hybridization	Widely used technique which exploits the ability of complementary sequences in single-stranded DNAs or RNAs to pair with each other to form a double helix. Hybridization can take place between two complimentary DNA sequences, between a single-stranded DNA and a complementary RNA, or between two RNA sequences. The technique is used to detect and isolate specific sequences, measure homology, or define other characteristics of one or both strands. (Kendrew, Encyclopedia of Molecular Biology, 1994, p503)	Genomic Hybridization,Acid Hybridization, Nucleic,Acid Hybridizations, Nucleic,Genomic Hybridizations,Hybridization, Genomic,Hybridization, Nucleic Acid,Hybridizations, Genomic,Hybridizations, Nucleic Acid,Nucleic Acid Hybridizations
D009876	Operon	In bacteria, a group of metabolically related genes, with a common promoter, whose transcription into a single polycistronic MESSENGER RNA is under the control of an OPERATOR REGION.	Operons
D002455	Cell Division	The fission of a CELL. It includes CYTOKINESIS, when the CYTOPLASM of a cell is divided, and CELL NUCLEUS DIVISION.	M Phase,Cell Division Phase,Cell Divisions,Division Phase, Cell,Division, Cell,Divisions, Cell,M Phases,Phase, Cell Division,Phase, M,Phases, M
D003090	Coliphages	Viruses whose host is Escherichia coli.	Escherichia coli Phages,Coliphage,Escherichia coli Phage,Phage, Escherichia coli,Phages, Escherichia coli
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D001667	Binding, Competitive	The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements.	Competitive Binding
D012329	RNA, Bacterial	Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis.	Bacterial RNA
D012367	RNA, Viral	Ribonucleic acid that makes up the genetic material of viruses.	Viral RNA
D013045	Species Specificity	The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.	Species Specificities,Specificities, Species,Specificity, Species