Biomaterial Database

Isoleucine and valine metabolism of Escherichia coli. XVI. Pattern of multivalent repression in strain K-12. 1968

S B Dwyer, and H E Umbarger

The levels of the five enzymes required for isoleucine and valine synthesis were examined under several growth conditions in strain K-12 of Escherichia coli and mutants derived from it. In strains with wild type repressibility, the same pattern of derepression was found on limiting isoleucine as is found to be constitutive in strain Tir-8, which has an altered isoleucine-activating enzyme. Homoserine dehydrogenase, which is essential for the biosynthesis of threonine and is normally derepressed on limiting isoleucine or threonine, is also derepressed in strain Tir-8. Threonine deaminase and homoserine dehydrogenase were partially repressed in strain Tir-8 by very high levels of isoleucine, but were not further derepressed over levels in minimal medium by limiting isoleucine.

UI	MeSH Term	Description	Entries
D007532	Isoleucine	An essential branched-chain aliphatic amino acid found in many proteins. It is an isomer of LEUCINE. It is important in hemoglobin synthesis and regulation of blood sugar and energy levels.	Alloisoleucine,Isoleucine, L-Isomer,L-Isoleucine,Isoleucine, L Isomer,L-Isomer Isoleucine
D008025	Ligases	A class of enzymes that catalyze the formation of a bond between two substrate molecules, coupled with the hydrolysis of a pyrophosphate bond in ATP or a similar energy donor. (Dorland, 28th ed) EC 6.	Ligase,Synthetases,Synthetase
D008967	Molecular Biology	A discipline concerned with studying biological phenomena in terms of the chemical and physical interactions of molecules.	Biochemical Genetics,Biology, Molecular,Genetics, Biochemical,Genetics, Molecular,Molecular Genetics,Biochemical Genetic,Genetic, Biochemical,Genetic, Molecular,Molecular Genetic
D010088	Oxidoreductases	The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)	Dehydrogenases,Oxidases,Oxidoreductase,Reductases,Dehydrogenase,Oxidase,Reductase
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
D006836	Hydro-Lyases	Enzymes that catalyze the breakage of a carbon-oxygen bond leading to unsaturated products via the removal of water. EC 4.2.1.	Dehydratase,Dehydratases,Hydrase,Hydrases,Hydro Lyase,Hydro-Lyase,Hydro Lyases,Lyase, Hydro,Lyases, Hydro
D000637	Transaminases	A subclass of enzymes of the transferase class that catalyze the transfer of an amino group from a donor (generally an amino acid) to an acceptor (generally a 2-keto acid). Most of these enzymes are pyridoxyl phosphate proteins. (Dorland, 28th ed) EC 2.6.1.	Aminotransferase,Aminotransferases,Transaminase
D013912	Threonine	An essential amino acid occurring naturally in the L-form, which is the active form. It is found in eggs, milk, gelatin, and other proteins.	L-Threonine,L Threonine
D014633	Valine	A branched-chain essential amino acid that has stimulant activity. It promotes muscle growth and tissue repair. It is a precursor in the penicillin biosynthetic pathway.	L-Valine,L Valine