Biomaterial Database

Mutants of the elongation factor EF-Tu, a new class of nonsense suppressors. 1985

E Vijgenboom, and T Vink, and B Kraal, and L Bosch

Read-through of nonsense codons has been studied in wild-type Escherichia coli cells and in cells harbouring mutant species of the elongation factor EF-Tu. The two phenomena differ essentially. Readthrough of UGA in wild-type cells is reduced by inactivation of tufB but is restored to the original level by introducing into the cell plasmid-borne EF-Tu. This shows that the natural UGA leakiness is dependent on the intracellular concentration of EF-Tu. Strains of E. coli harbouring mutant species of the elongation factor EF-Tu suppress the nonsense codons UAG, UAA and UGA. Suppression shows a codon context dependence. It requires the combined action of two different EF-Tu species: EF-TuAR(Ala 375----Thr) and EF-TuBo(Gly 222----Asp). Cells harbouring EF-TuAR(Ala 375----Thr) and wild-type EF-TuB, or wild-type EF-TuA and EF-TuBo(Gly 222----Asp) do not display suppressor activity. These data demonstrate that mutated tuf genes form an additional class of nonsense suppressors. The requirement for two different mutant EF-Tu species raises the question whether translation of sense codons also occurs by the combined action of two EF-Tu molecules on the ribosome.

UI	MeSH Term	Description	Entries
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D010444	Peptide Elongation Factor Tu	A protein found in bacteria and eukaryotic mitochondria which delivers aminoacyl-tRNA's to the A site of the ribosome. The aminoacyl-tRNA is first bound to a complex of elongation factor Tu containing a molecule of bound GTP. The resulting complex is then bound to the 70S initiation complex. Simultaneously the GTP is hydrolyzed and a Tu-GDP complex is released from the 70S ribosome. The Tu-GTP complex is regenerated from the Tu-GDP complex by the Ts elongation factor and GTP.	Elongation Factor Tu,EF-Tu,Eucaryotic Elongation Factor Tu,Protein Synthesis Elongation Factor Tu,eEF-Tu,EF Tu,Factor Tu, Elongation,eEF Tu
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
D003062	Codon	A set of three nucleotides in a protein coding sequence that specifies individual amino acids or a termination signal (CODON, TERMINATOR). Most codons are universal, but some organisms do not produce the transfer RNAs (RNA, TRANSFER) complementary to all codons. These codons are referred to as unassigned codons (CODONS, NONSENSE).	Codon, Sense,Sense Codon,Codons,Codons, Sense,Sense Codons
D005144	F Factor	A plasmid whose presence in the cell, either extrachromosomal or integrated into the BACTERIAL CHROMOSOME, determines the "sex" of the bacterium, host chromosome mobilization, transfer via conjugation (CONJUGATION, GENETIC) of genetic material, and the formation of SEX PILI.	Resistance Transfer Factor,Sex Factor F,Sex Factor, Bacterial,Bacterial Sex Factor,Bacterial Sex Factors,F Plasmid,F Plasmids,Factor, Bacterial Sex,Factors, Bacterial Sex,Fertility Factor, Bacterial,Sex Factors, Bacterial,Bacterial Fertility Factor,Bacterial Fertility Factors,F Factors,Factor F, Sex,Factor Fs, Sex,Factor, Bacterial Fertility,Factor, F,Factor, Resistance Transfer,Factors, Bacterial Fertility,Factors, F,Factors, Resistance Transfer,Fertility Factors, Bacterial,Fs, Sex Factor,Plasmid, F,Plasmids, F,Resistance Transfer Factors,Sex Factor Fs,Transfer Factor, Resistance,Transfer Factors, Resistance
D005798	Genes, Bacterial	The functional hereditary units of BACTERIA.	Bacterial Gene,Bacterial Genes,Gene, Bacterial
D005838	Genotype	The genetic constitution of the individual, comprising the ALLELES present at each GENETIC LOCUS.	Genogroup,Genogroups,Genotypes
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D001616	beta-Galactosidase	A group of enzymes that catalyzes the hydrolysis of terminal, non-reducing beta-D-galactose residues in beta-galactosides. Deficiency of beta-Galactosidase A1 may cause GANGLIOSIDOSIS, GM1.	Lactases,Dairyaid,Lactaid,Lactogest,Lactrase,beta-D-Galactosidase,beta-Galactosidase A1,beta-Galactosidase A2,beta-Galactosidase A3,beta-Galactosidases,lac Z Protein,Protein, lac Z,beta D Galactosidase,beta Galactosidase,beta Galactosidase A1,beta Galactosidase A2,beta Galactosidase A3,beta Galactosidases
D013045	Species Specificity	The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.	Species Specificities,Specificities, Species,Specificity, Species