[Cloning of threonine operon genes in Escherichia coli cells]. 1980

Iu I Kozlov, and L P Kochetova, and V A Livshits, and S V Mashko, and V N Moshentseva

A set of hybrid plasmids carrying Escherichia coli threonine genes was obtained and cloned. The plasmid pBR322 was used as a vehicle. The genetic and restriction analyses showed that genes thrA and thrB were placed between SalGI and EcoRI sites on the 2.6 megadaltons DNA region. The transcription of threonine operon genes inserted in the hybrid plasmids is under the control of its own promoter. The copy number of hybrid plasmids was reverse proportional to their molecular weight and did not depend on the replicon number. Amplification of genes of threonine operon by hybrid plasmids led to 20-25-fold increase of homoserine dehydrogenase activity, encoded by thrA gene. The expression of this gene, incorporated in hybrid plasmids, was repressed by the addition of threonine and isoleucine in the culture medium.

UI MeSH Term Description Entries
D008970 Molecular Weight The sum of the weight of all the atoms in a molecule. Molecular Weights,Weight, Molecular,Weights, Molecular
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
D010957 Plasmids Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS. Episomes,Episome,Plasmid
D012093 Replicon Any DNA sequence capable of independent replication or a molecule that possesses a REPLICATION ORIGIN and which is therefore potentially capable of being replicated in a suitable cell. (Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed) Replication Unit,Replication Units,Replicons,Unit, Replication,Units, Replication
D003001 Cloning, Molecular The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells. Molecular Cloning
D004794 Enzyme Repression The interference in synthesis of an enzyme due to the elevated level of an effector substance, usually a metabolite, whose presence would cause depression of the gene responsible for enzyme synthesis. Repression, Enzyme
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
D005784 Gene Amplification A selective increase in the number of copies of a gene coding for a specific protein without a proportional increase in other genes. It occurs naturally via the excision of a copy of the repeating sequence from the chromosome and its extrachromosomal replication in a plasmid, or via the production of an RNA transcript of the entire repeating sequence of ribosomal RNA followed by the reverse transcription of the molecule to produce an additional copy of the original DNA sequence. Laboratory techniques have been introduced for inducing disproportional replication by unequal crossing over, uptake of DNA from lysed cells, or generation of extrachromosomal sequences from rolling circle replication. Amplification, Gene
D006715 Homoserine Dehydrogenase An enzyme that catalyzes the reduction of aspartic beta-semialdehyde to homoserine, which is the branch point in biosynthesis of methionine, lysine, threonine and leucine from aspartic acid. EC 1.1.1.3. Dehydrogenase, Homoserine
D006824 Hybridization, Genetic The genetic process of crossbreeding between genetically dissimilar parents to produce a hybrid. Crossbreeding,Hybridization, Intraspecies,Crossbreedings,Genetic Hybridization,Genetic Hybridizations,Hybridizations, Genetic,Hybridizations, Intraspecies,Intraspecies Hybridization,Intraspecies Hybridizations

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