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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The relative genetic position of the following four mutations of ribosomal protein S5 has been determined: spc-13, a mutation to spectinomycin resistance; stri N421 and strid1023, mutations suppressing dependence on streptomycin and sup0-1, a mutation suppressing partially the temperature-sensitive phenotype of an alanyl-tRNA synthetase mutation. The transduction experiments performed indicate that the spc-13 site is located in the S5 cistron proximal to the strA locus, that sup0-1 maps proximal to the aroE gene and that the striN421 and strid1023 loci are located between these two mutational sites. Proteinchemical analysis of the amino acid replacement in protein S5 of strain N421 (carrying the striN421 allele) has shown that an arginine residue is replaced by leucine which results in the appearance of a trypsin intensitive bond between the tryptic peptides T2 and T16. The same alteration has been previously found by Itoh and Wittmann (1973) in the S5 protein of strain d1023. Determination of the alteration of ribosomal protein S5 of strain 0-1 (sup0-1 allele) revealed that the C-terminal tryptic peptide is altered. It differs from that of the wild-type protein by the lack of five amino acids and the appearance of a C-terminal glycine residue instead of a lysine residue. This change can be explained by the deletion of eleven nucleotides in the S5 cistron of strain 0-1. The recent determination of the primary structure of ribosomal protein S5 (Wittmann-Liebold and Greuer, 1975) allows the ordering of the S5 alterations employed: The order is spc-13-strid1023 (striN421)-sup0-1 with the spc-13 amino acid replacement being located at the NH2-terminal portion of the S5 sequence and the alteration of strain 0-1 at the COOH-terminal end. The proteinchemical results are therefore in full agreement with the genetic data and unambiguously allow the conclusion that the S5 cistron is transcribed counterclock-wise on the Escherichia coli chromosome.
Mol Gen Genet 1975 Dec 30
PMID:Genetic position and amino acid replacements of several mutations in ribosomal protein S5 from Escherichia coli. 12 73

Among temperature resistant revertants of a temperature sensitive E. Coli alanyl-tRNA synthetase mutant a strain was found which contains an alanyl-tRNA synthetase with an additional mutation in the structural gene of the enzyme. This mutant enzyme has a 9 or 38 fold decreased Km value for alanine compared to that of the thermolabile parental enzyme or to wild-type enzyme, respectively. The alaS gene maps just counterclockwise from recA on the E. coli map (94% cotransduction frequency). It appears that the enzyme's increased affinity for alanine is the mechanism of suppressing the temperature sensitive character of the cell. In addition, some cold-sensitive temperature resistant revertants were found, where the cold-sensitive character mapped near strA. Presumably they are due to changes in ribosomal proteins as characterized by Ruffler et al. (1974).
Mol Gen Genet 1977 Nov 14
PMID:Suppression of a defective alanyl-tRNA synthetase in Escherichia coli: a compensatory mutation to high alanine affinity. 34 Sep 3

Aminoacyl tRNA synthetases discriminate between tRNA species by a highly specific mechanism. Physical and chemical studies indicate that the synthetases bind along and around the inside of the three-dimensional L-shaped tRNA structure. Studies of mutant tRNAs that affect synthetase interaction tend to confirm this conclusion. However, in contrast to proteins that recognize a specific block of contiguous nucleotide units (e.g., repressors, restriction enzymes, etc.), synthetases appear to interact with spatially disperse elements of the structure. Available evidence suggests that tRNA binding clefts on various synthetases may be roughly similar, with specificity being achieved by the choice of amino acid residues in a few critical positions in the tRNA binding clefts. With this idea in mind, it should be possible to introduce amino acid substitutions into the binding clefts and thereby change tRNA recognition specificity. This has been attempted (by genetic manipulations) and a mutant alanine tRNA synthetase with altered tRNA recognition has been isolated. This enzyme can attach alanine to isoleucine specific tRNA. When presented with valine specific tRNA, a tRNA similar in some structural features to the isoleucine specific tRNA, or with the structurally quite different tyrosine specific tRNA, no significant aminoacylation occurs. Thus, a precise specificity alteration can occur through mutation; this result supports the idea of similarities in synthetase binding clefts, with specificity being achieved by the positioning of amino acids at critical positions in these clefts. Finally, further data have been obtained on the issue of possible transient covalent bond formation between synthetases and tRNAs, as a critical part of the interaction.
Mol Cell Biochem 1979 May 06
PMID:Recent results on how aminoacyl transfer RNA synthetases recognize specific transfer RNAs. 38 92

The work described in this paper was done to see whether the partial suppression of temperature-sensitive aminoacyl-tRNA synthetase mutations by ribosomal mutations is restricted to the aminoacyl-tRNA synthetase mutation which was used for the selection of the suppressor strains or whether the ribosomal mutations can also suppress mutations of other aminoacyl-tRNA synthetases. It is shown that a mutation in ribosomal protein S5 which was selected for suppression of an alanyl-tRNA synthetase mutation (alaS-3) can also partially compensate the temperature-sensitivity of two valyl-tRNA synthetase mutants and of another alanyl-tRNA synthetase mutant. Furthermore, revertants of a temperature-sensitive valyl-tRNA synthetase mutant were isolated and screened for alterations in ribosomal proteins by electrophoretic and immunochemical methods. Alterations in at least two proteins, S8 and S20, were clearly observed among the mutants. The alteration in protein S8 renders the growth of this strain severely cold-sensitive. Presence of the mutation in protein S8 is strictly correlated with suppression of temperature-sensitivity. The S8 mutation maps between strA and spc on the Escherichia coli chromosome. Five suppressor strains have quantitatively or qualitatively altered ribosomal proteins S20. In one strain no S20 protein could be detected at all, employing different electrophoretic and immunological methods. All five suppressor mutations map in the thr-leu region of the E. coli chromosome, i.e. in an area where the alteration of protein S20 in two alaS suppressor strains has been localized previously.
Mol Gen Genet 1975 Dec 09
PMID:Alteration of ribosomal proteins in revertants of a valyl-tRNA synthetase mutant of Escherichia coli. 76 30

The biochemical basis of suppression of a temperature-sensitive alanyl-tRNA synthetase (alaS) mutation by mutational alterations of the ribosome has been investigated. Measurement of the polyU-dependent polyphenylalanine synthesis showed that ribosomes from the suppressor strains are less active than ribosomes from the unsuppressed aminoacyl-tRNA synthetase mutant. In this system no increased translational ambiguity could be detected for the suppressor ribosomes. This fact and also the findings that the ram-1 mutation is not able to suppress the aminoacyl-tRNA synthetase mutation and that presence of the suppressor allele is not accompanied by a measureably improved alanyl-tRNA synthetase activity argue against the possibility that suppression might be due to increased translational misreading rates of the alanyl-tRNA synthetase mRNA. It has been further found that partial suppression of temperature sensitive growth of the alaS mutation can be achieved by independent ribosomal mutations leading to reduced growth rates because of a mutation to antibiotic resistance. Addition of low concentrations of a variety of antibiotics acting at the ribosomal level can also partially revert the temperature-sensitive phenotype of the alaS mutant. Although the possibility cannot be excluded that suppression is due to the stabilisation or activation of the mutant enzyme by some indirect effect of the suppressor ribosomal mutations, the following working hypothesis is favoured at the moment: It is assumed that limitation of the aminoacyl-tRNA synthetase activity in a certain range of the restrictive temperature causes growth inhibition by the premature termination of polypeptide synthesis at the ribosome or by the unbalanced synthesis of the individual cellular proteins under this condition. The mechanism of suppression by ribosomal mutations is proposed to consist of the release of this growth inhibition by the reduction of the rate of polypeptide synthesis, which would keep amino acid incorporation from exceeding the slow charging of tRNA and thus exhausting the pool of charged tRNA. In the suppressor strains, therefore, growth at the semi-restrictive temperature is no longer limited by the aminoacylation of tRNA but by the translational process at the mutated ribosome. This influence of the ribosomal mutation on the speed of translation could be directly or indirectly coupled with an effect on translational fidelity resulting in the prevention of the binding of uncharged or non-cognate charged tRNA or in the tighter binding of peptidyl-tRNA when cognate aminoacyl-tRNA is limiting.
Mol Gen Genet 1976 Nov 24
PMID:Suppression of temperature-sensitive aminoacyl-tRNA synthetase mutations by ribosomal mutations: a possible mechanism. 79 71

A randomly generated mutation in Escherichia coli alanine tRNA synthetase compensates for a mutation in its cognate tRNA. The enzyme's mutation occurs next to a Cys-X2-Cys-X6-His-X2-His metal-binding motif that is distinct from the zinc finger motif found in some DNA-binding proteins. Instead, the synthetase's metal binding domain resembles the Cys-X2-Cys-X4-His-X4-Cys metal-binding domain of the gag gene product of retroviruses. For Ala-tRNA synthetase, the metal bound at the Cys-His motif is important specifically for the tRNA-dependent step of catalysis, and the enzyme-tRNA interaction is dependent on the geometry of metal co-ordination to the enzyme. These data, and the demonstrated sensitivity of RNA packaging to mutations in the metal-binding domain of the gag gene product of retroviruses, suggest that an aminoacyl-tRNA synthetase and retroviruses have adopted a related metal-binding motif for RNA recognition.
Mol Microbiol 1992 May
PMID:A metal-binding motif implicated in RNA recognition by an aminoacyl-tRNA synthetase and by a retroviral gene product. 137 18

Single crystals of an amino-terminal fragment of Escherichia coli alanine tRNA synthetase have been prepared by the vapor diffusion method. The fragment extends to amino acid residue 368 and catalyzes the synthesis of alanyl adenylate. The crystals grow in the presence of alanine as rhombic plates in space group P2(1)2(1)2(1) and with unit cell dimensions of a = 67.9 A, b = 98.5 A and c = 123.6 A (1 A = 0.1 nm). They diffract to better than 3 A resolution.
J Mol Biol 1988 Sep 20
PMID:Crystallization of a small fragment of an aminoacyl tRNA synthetase. 305 89

Aminoacyl tRNA synthetases, by means of a back reaction, are able to synthesize certain 5', 5"'-P1, P4-bisnucleoside tetraphosphates of biological importance, such as Ap4A. Here it is shown that HisRS and TrpRS (Bacillus stearothermophilus) and AlaRS (E. coli) also synthesize the hybrid compounds Ap4G, Ap4C, and Ap4U. GlnRS (E. coli) is unable to synthesize any of the above compounds. AlaRS synthesizes Ap4U very poorly, and Ap4C and Ap4G almost as effectively as Ap4A. HisRS and TrpRS synthesize Ap4G, Ap4U and Ap3U quite effectively, and Ap4C very poorly. The fact that hybrid bisnucleoside tetraphosphates can be made by the same enzymes, and at rates comparable to Ap4A, suggests that these compounds may also occur in vivo.
Mol Cell Biochem 1987 May
PMID:Synthesis of hybrid bisnucleoside 5',5"'-P1,P4-tetraphosphates by aminoacyl-tRNA synthetases. 330 44

Autoantibodies to aminoacyl-tRNA synthetases are common in myositis. Sera of one particular class, the PL-12 specificity, contain separate antibodies reacting with alanyl-tRNA synthetase and tRNA(Ala). We show here that the anti-RNA antibodies recognize at least six distinguishable human tRNA(Ala) species, grouped in two sequence families. We have elucidated the complete nucleotide sequence of two tRNA(Ala) species from HeLa cells that are closely related to silkworm moth tRNA(Ala), as well as the partial sequence of a third species. All three contain the anticodon IGC. No tRNAs with pyrimidine in the "wobble" position were found in the immunoprecipitate, and such species may fail to interact with the antibody.
Mol Biol Med 1987 Feb
PMID:Two human tRNA(Ala) families are recognized by autoantibodies in polymyositis sera. 361 74

Alanine and phenylalanine tRNA sequences were amplified by PCR from Arabidopsis thaliana nuclear DNA using degenerate oligonucleotides which introduced specific mutations into the acceptor stem. The aminoacylation of T7 RNA polymerase transcripts of these sequences was investigated in vitro using partially purified bean alanyl- or phenylalanyl-tRNA synthetase. In parallel, the in vivo activity of amber suppressor derivatives of these tRNAs was investigated in transient expression assays in tobacco protoplasts using a beta-glucuronidase (GUS) reporter gene containing a premature amber stop codon. The results show that mutation of the G3:U70 base pair to G3:C70 blocks aminoacylation of plant alanine tRNA, whilst conversion of the G3:C70 pair normally found in plant tRNA(Phe) to G3:U70 enables the mutated tRNA(Phe) to be a good substrate for alanyl-tRNA synthetase and impairs its aminoacylation with phenylalanine. In addition, the amber suppressor derivative of wild-type tRNA(Phe) showed very little suppressor activity in vivo, and was poorly aminoacylated with phenylalanine in vitro, suggesting that the anticodon is a major identity determinant for tRNA(Phe) in plant cells.
Plant Mol Biol 1994 Dec
PMID:Characterization of some major identity elements in plant alanine and phenylalanine transfer RNAs. 753 29


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