Biomaterial Database

Isomeric aminoacyl-tRNAs are both bound by elongation factor Tu. 1977

S M Hecht, and K H Tan, and A C Chinault, and P Arcari

Recent suggestions that elongation factor Tu (EF-Tu) is specific for 2'-O-aminoacyl-tRNA, as compared with the 3'-isomer, prompted us to assay [3H]aminoacyl-tRNAs from Escherichia coli terminating in 2'- or 3'-deoxyadenosine for binding to EF-Tu to determine the possible positional specificity of the factor. Binding of modified aminaocyl-tRNAs to EF-Tu-GTP was measured both as a function of the ability of EF-Tu-GTP to diminish the rate of chemical deacylation of [3H]aminoacyl-tRNAs and by gel filtration of the individual ternary complexes. Fifteen different tRNA isoacceptors were tested by the deacylation procedure, including three (tRNAAsp, tRNACys, and tRNATyr) for which isomeric modified aminoacyl-tRNAs were available. All of the modified aminoacyl-tRNAs were protected fromdeacylation, although generally to a lesser extent than the corresponding unmodified species. Six modified tRNA isoacceptors (including tRNATrp and tRNATyr, for which both modified aminoacyl-tRNAs were accessible by enzymatic aminoacylation) were used in gel filtration experiments to permit direct measurement of the individual aminoacyl-tRNA-EF-Tu-GTP complexes. These experiments were also done in the presence of equimolar amounts of the corresponding unmodified [14C]aminoacyl-tRNAs, and the relative affinities for a limiting amount of EF-Tu-GTP were measured. The results were completely consistent with those obtained by the deacylation procedure and indicated that EF-Tu can bind to both positional isomers of aminoacyl-tRNA with no obvious preference for either.

UI	MeSH Term	Description	Entries
D007536	Isomerism	The phenomenon whereby certain chemical compounds have structures that are different although the compounds possess the same elemental composition. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)	Isomerisms
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D010445	Peptide Elongation Factors	Protein factors uniquely required during the elongation phase of protein synthesis.	Elongation Factor,Elongation Factors, Peptide,Factor, Elongation,Factors, Peptide Elongation
D011485	Protein Binding	The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.	Plasma Protein Binding Capacity,Binding, Protein
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
D006150	Guanine Nucleotides		Guanine Nucleotide,Guanosine Phosphates,Nucleotide, Guanine,Nucleotides, Guanine,Phosphates, Guanosine
D000596	Amino Acids	Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.	Amino Acid,Acid, Amino,Acids, Amino
D012343	RNA, Transfer	The small RNA molecules, 73-80 nucleotides long, that function during translation (TRANSLATION, GENETIC) to align AMINO ACIDS at the RIBOSOMES in a sequence determined by the mRNA (RNA, MESSENGER). There are about 30 different transfer RNAs. Each recognizes a specific CODON set on the mRNA through its own ANTICODON and as aminoacyl tRNAs (RNA, TRANSFER, AMINO ACYL), each carries a specific amino acid to the ribosome to add to the elongating peptide chains.	Suppressor Transfer RNA,Transfer RNA,tRNA,RNA, Transfer, Suppressor,Transfer RNA, Suppressor,RNA, Suppressor Transfer
D013329	Structure-Activity Relationship	The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.	Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships