Biomaterial Database

Proteolysis of the bifunctional methionine-repressible aspartokinase II-homoserine dehydrogenase II of Escherichia coli K12. Production of an active homoserine dehydrogenase fragment. 1977

A Dautry-Varsat, and G N Cohen

The dimeric bifunctional enzyme aspartokinase II-homoserine dehydrogenase II (Mr = 2 X 88,000) of Escherichia coli K12 can be cleaved into two nonoverlapping fragments by limited proteolysis with subtilisin. These two fragments can be separated under nondenaturing conditions as dimeric species, which indicates that each fragment has retained some of the association areas involved in the conformation of the native protein. The smaller fragment (Mr = 2 X 24,000) is devoid of aspartokinase and homoserine dehydrogenase activity. The larger fragment (Mr = 2 X 37,000) is endowed with full homoserine dehydrogenase activity. These results show that the polypeptide chains of the native enzyme are organized in two different domains, that both domains participate in building up the native dimeric structure, and that one of these domains only is responsible for homoserine dehydrogenase activity. A model of aspartokinase II-homoserine dehydrogenase II is proposed, which accounts for the present results.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008715	Methionine	A sulfur-containing essential L-amino acid that is important in many body functions.	L-Methionine,Liquimeth,Methionine, L-Isomer,Pedameth,L-Isomer Methionine,Methionine, L Isomer
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D009097	Multienzyme Complexes	Systems of enzymes which function sequentially by catalyzing consecutive reactions linked by common metabolic intermediates. They may involve simply a transfer of water molecules or hydrogen atoms and may be associated with large supramolecular structures such as MITOCHONDRIA or RIBOSOMES.	Complexes, Multienzyme
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
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
D000429	Alcohol Oxidoreductases	A subclass of enzymes which includes all dehydrogenases acting on primary and secondary alcohols as well as hemiacetals. They are further classified according to the acceptor which can be NAD+ or NADP+ (subclass 1.1.1), cytochrome (1.1.2), oxygen (1.1.3), quinone (1.1.5), or another acceptor (1.1.99).	Carbonyl Reductase,Ketone Reductase,Carbonyl Reductases,Ketone Reductases,Oxidoreductases, Alcohol,Reductase, Carbonyl,Reductase, Ketone,Reductases, Carbonyl,Reductases, Ketone
D001222	Aspartate Kinase	An enzyme that catalyzes the formation of beta-aspartyl phosphate from aspartic acid and ATP. Threonine serves as an allosteric regulator of this enzyme to control the biosynthetic pathway from aspartic acid to threonine. EC 2.7.2.4.	Aspartokinase,Aspartate Kinase I,Aspartate Kinase II,Aspartate Kinase III,Aspartyl Kinase,Kinase I, Aspartate,Kinase II, Aspartate,Kinase III, Aspartate,Kinase, Aspartate,Kinase, Aspartyl
D001225	Aspartokinase Homoserine Dehydrogenase	A bifunctional protein consisting of aspartokinase, and homoserine dehydrogenase activities. It is found primarily in BACTERIA and in PLANTS.	Aspartokinase I Homoserine Dehydrogenase I,Aspartokinase II Homoserine Dehydrogenase II,Bifunctional Aspartokinase-Homoserine Dehydrogenase,Bifunctional Aspartokinase-Homoserine Dehydrogenase 1,Bifunctional Aspartokinase-Homoserine Dehydrogenase 2,Aspartokinase-Homoserine Dehydrogenase, Bifunctional,Bifunctional Aspartokinase Homoserine Dehydrogenase,Bifunctional Aspartokinase Homoserine Dehydrogenase 1,Bifunctional Aspartokinase Homoserine Dehydrogenase 2,Dehydrogenase, Aspartokinase Homoserine,Dehydrogenase, Bifunctional Aspartokinase-Homoserine,Homoserine Dehydrogenase, Aspartokinase