<scp>l</scp>‐Phenylalanyl‐tRNA Synthetase of <i>Escherichia coli</i> K‐10

Hanke, Till; Bartmann, Peter; Hennecke, Hauke; Kosakowski, Heinz M.; Jaenicke, Rainer; Holler, Eggehard; Böck, August

doi:10.1111/j.1432-1033.1974.tb03447.x

Cited by 68 publications

(38 citation statements)

References 16 publications

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“…This is also in agreement with functional subunit polypeptide chain fusions described by Toth and Schimmel (28). There is a much higher level of predicted amino acid identity in the amino-terminal sequence, again consistent with previous comparisons of other bacterial aminoacyl-tRNA synthetases (10,32,37). Interestingly, the predicted size of the protein encoded by glyQS varied little from that encoded by the combined ␣-␤ E. coli sequence (glyQ and glyS).…”

Section: Discussionsupporting

confidence: 73%

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The glycyl-tRNA synthetase of Chlamydia trachomatis

Wagar¹,

Giese²,

Yasin³

et al. 1995

J Bacteriol

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Aminoacyl-tRNA synthetases specifically charge tRNAs with their cognate amino acids. A prototype for the most complex aminoacyl-tRNA synthetases is the four-subunit glycyl-tRNA synthetase from Escherichia coli, encoded by two open reading frames. We examined the glycyl-tRNA synthetase gene from Chlamydia trachomatis, a genetically isolated bacterium, and identified only a single open reading frame for the chlamydial homolog (glyQS). This is the first report of a prokaryotic glycyl-tRNA synthetase encoded by a single gene.

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Section: Discussionsupporting

confidence: 73%

“…These findings suggest that a single polypeptide may have been the progenitor of the ␣2␤2 quaternary structure (28,34). Also, others have questioned whether the carboxyl-terminal amino acid sequence of aminoacyl-tRNA synthetases is necessary for enzymatic activity (10,29,32,34,37).…”

mentioning

confidence: 99%

The glycyl-tRNA synthetase of Chlamydia trachomatis

Wagar¹,

Giese²,

Yasin³

et al. 1995

J Bacteriol

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“…PheRS is one of three tRNA synthetases, all members of the class II family, that have been previously shown to exist as tetramers. PheRS and (in some organisms) glycyl-tRNA synthetase (GlyRS) possess a heterotetrameric (␣ 2 ␤ 2 ) quaternary organization (5,6). In contrast, alanyl-tRNA synthetase (AlaRS) from Escherichia coli is a homotetramer in solution (7).…”

mentioning

confidence: 99%

The Homotetrameric Phosphoseryl-tRNA Synthetase from Methanosarcina mazei Exhibits Half-of-the-sites Activity

Hauenstein

Hou

Perona

2008

Journal of Biological Chemistry

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Synthesis of cysteinyl-tRNACys in methanogenic archaea proceeds by a two-step pathway in which tRNA Cys is first aminoacylated with phosphoserine by phosphoseryl-tRNA synthetase (SepRS). Characterization of SepRS from the mesophile Methanosarcina mazei by gel filtration and nondenaturing mass spectrometry shows that the native enzyme exists as an ␣4 tetramer when expressed at high levels in Escherichia coli. However, active site titrations monitored by ATP/PP i burst kinetics, together with analysis of tRNA binding stoichiometry by fluorescence spectroscopy, show that the tetrameric enzyme binds two tRNAs and that only two of the four chemically equivalent subunits catalyze formation of phosphoseryl adenylate. Therefore, the phenomenon of half-of-the-sites activity, previously described for synthesis of 1 mol of tyrosyl adenylate by the dimeric class I tyrosyl-tRNA synthetase, operates as well in this homotetrameric class II tRNA synthetase. Analysis of cognate and noncognate reactions by ATP/PP i and aminoacylation kinetics strongly suggests that SepRS is able to discriminate against the noncognate amino acids glutamate, serine, and phosphothreonine without the need for a separate hydrolytic editing site. tRNA Cys binding to SepRS also enhances the capacity of the enzyme to discriminate among amino acids, indicating the existence of functional connectivity between the tRNA and amino acid binding sites of the enzyme.

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“…No isomerization step could be evidenced. The experiments were carried out under two conditions corresponding to those used by Merault et al ( 3 978, Eur. J. Biochem.…”

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confidence: 99%

“…The aminoacyl-tRNA synthetases present a great variety of oligomeric structures, ranging from small monomers such as the cysteine enzyme (M, 54000) [l] or the glutamic acid enzyme (M, 56000) [2] to large tetramers such as the phenylalanine enzymes (M, 260000) [3,4] or the alanine enzyme (A4, 380000) [S]. However most of them are either monomers showing sequence repetitions [6] or oligomers [7].…”

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confidence: 99%

Kinetic Anticooperativity in Pre‐Steady‐State Formation of Tryptophanyl Adenylate by Tryptophanyl‐tRNA Synthetase from Beef Pancreas

Mazat

Merle

Graves

et al. 1982

European Journal of Biochemistry

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The kinetics of formation of tryptophanyl adenylate by tryptophanyl-tRNA synthetase from beef pancreas has been followed by stopped-flow, using the quenching of fluorescence of the enzyme linked to the amino acid activation reaction. Both subunits of this LYZ enzyme catalyze the adenylate formation. At saturation with substrates the rate constant of the activation reaction is the same for both subunits. The same behaviour is observed for the pyrophosphorolysis reaction. Both subunits exhibit the same affinity for ATP-Mg in the forward reaction and the same affinity for magnesium pyrophosphate in the backward reaction. On the contrary the formation of tryptophanyl adenylate follows biphasic kinetics when tryptophan concentration is much below saturation. This is independent of ATP-Mg concentration and is the consequence of different affinities of the two subunits for tryptophan as already observed by Graves et al. (1979, Eur. J. Biochem. 96, 509-518) in equilibrium dialysis experiments. A monoadenylate-enzyme complex on one subunit has been prepared. This complex made possible the study of the formation of the second adenylate on the other subunit. The formation of this second adenylate followed first-order kinetics at all ATP-Mg and tryptophan concentrations. The tryptophan concentration dependence of the rate of formation of this second adenylate leads to a Michaelis constant close to the dissociation constant of the low affinity tryptophan site of the enzyme. No isomerization step could be evidenced. The experiments were carried out under two conditions corresponding to those used by Merault et al. ( 3 978, Eur. J. Biochem. 87, 541 -550) in the steady state of the tRNATrp aminoacylation reaction (10 mM total magnesium in 100 mM KCI and 1 mM free magnesium ions, both at pH 8.0, 25 "C). No great difference either in the mechanism or in the dissociation and rate constants was observed but an inhibitory effect of KCl. It is concluded that the enzyme is symmetrical as far as the ATP-Mg and the magnesium pyrophosphate sites are concerned and that the rate of the activation reaction reflects the anticooperative occupancy of the tryptophan sites carried by the two subunits.

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l‐Phenylalanyl‐tRNA Synthetase of Escherichia coli K‐10

Cited by 68 publications

References 16 publications

The glycyl-tRNA synthetase of Chlamydia trachomatis

The glycyl-tRNA synthetase of Chlamydia trachomatis

The Homotetrameric Phosphoseryl-tRNA Synthetase from Methanosarcina mazei Exhibits Half-of-the-sites Activity

Kinetic Anticooperativity in Pre‐Steady‐State Formation of Tryptophanyl Adenylate by Tryptophanyl‐tRNA Synthetase from Beef Pancreas

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