Biomaterial Database

A single substitution in the motif 1 of Escherichia coli lysyl-tRNA synthetase induces cooperativity toward amino acid binding. 1995

S Commans, and S Blanquet, and P Plateau

Laboratoire de Biochimie, URA 240 CNRS, Ecole Polytechnique, Palaiseau, France.

The constitutive lysyl-tRNA synthetase (LysRS) of the Escherichia coli strain OEL134 differs from the wild-type enzyme by the single substitution of threonine 208 with methionine. In vitro study of the isotopic [32P]PPi-ATP exchange reaction catalyzed by purified T208M LysRS revealed specific features that are not observed with the wild-type LysRS: (i) The steady state of the reaction was reached after a approximately 1-min lag when the addition of the enzyme was used to initiate the reaction. This lag disappeared upon preincubation of the enzyme with lysine and ATP. (ii) The variation of the steady state rate as a function of the lysine concentration in the assay was sigmoidal (Hill coefficient of 1.65), suggesting cooperativity of lysine binding to this dimeric enzyme. The allosteric behavior of the mutant enzyme was further established by showing that, at low concentrations of lysine, low amounts of cadaverine stimulated T208M LysRS activity. T208A LysRS, in which threonine 208 had been changed into alanine by site-directed mutagenesis, displayed the same properties as T208M LysRS. Remarkably, Thr 208 makes part of the first signature motif of class II aminoacyl-tRNA synthetases, a motif likely to be involved in the dimerization of the enzyme subunits. Therefore, the behavior of the Thr 208 mutants of LysRS supports the idea that the dimerization of class II aminoacyl-tRNA synthetases is important for an efficient structuration of their active site.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D008239	Lysine	An essential amino acid. It is often added to animal feed.	Enisyl,L-Lysine,Lysine Acetate,Lysine Hydrochloride,Acetate, Lysine,L Lysine
D008250	Lysine-tRNA Ligase	An enzyme that activates lysine with its specific transfer RNA. EC 6.1.1.6.	Lysyl T RNA Synthetase,Lys-tRNA Ligase,Lysyl-tRNA Synthetase,Ligase, Lys-tRNA,Ligase, Lysine-tRNA,Lys tRNA Ligase,Lysine tRNA Ligase,Lysyl tRNA Synthetase,Synthetase, Lysyl-tRNA
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D010710	Phosphates	Inorganic salts of phosphoric acid.	Inorganic Phosphate,Phosphates, Inorganic,Inorganic Phosphates,Orthophosphate,Phosphate,Phosphate, Inorganic
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
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
D000255	Adenosine Triphosphate	An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.	ATP,Adenosine Triphosphate, Calcium Salt,Adenosine Triphosphate, Chromium Salt,Adenosine Triphosphate, Magnesium Salt,Adenosine Triphosphate, Manganese Salt,Adenylpyrophosphate,CaATP,CrATP,Manganese Adenosine Triphosphate,MgATP,MnATP,ATP-MgCl2,Adenosine Triphosphate, Chromium Ammonium Salt,Adenosine Triphosphate, Magnesium Chloride,Atriphos,Chromium Adenosine Triphosphate,Cr(H2O)4 ATP,Magnesium Adenosine Triphosphate,Striadyne,ATP MgCl2
D000494	Allosteric Regulation	The modification of the reactivity of ENZYMES by the binding of effectors to sites (ALLOSTERIC SITES) on the enzymes other than the substrate BINDING SITES.	Regulation, Allosteric,Allosteric Regulations,Regulations, Allosteric
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein