The role of zinc in 5?,5?-diadenosine tetraphosphate production by aminoacyl-transfer RNA synthetases

Blanquet, Sylvain; Plateau, Pierre; Brevet, Annie

doi:10.1007/bf00230583

Cited by 75 publications

(46 citation statements)

References 32 publications

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“…This rate constant is larger than that of AppppA synthesis for all of the aminoacyl-tRNA synthetases tested in the absence of zinc [5]. It is comparable to the rate of AppppA synthesis at low zinc ion concentrations for the phenylalanine and the lysine enzymes, which are the most active reported producers of AppppA [5]. Thus, the rate constant of tryptophanamide formation is not negligible, and the actual rate in the cell is more likely to be limited by the concentration of free ammonia and by competition with the regular aminoacylation reaction.…”

Section: Scheme 2 Discussionmentioning

confidence: 84%

“…The successive reactions catalyzed by tryptophanyl-tRNA synthetase from Escherichia coli Since the original observation by Weiss et al [l] that an aminoacyl-tRNA synthetase is able to catalyze a reaction other than the regular tRNA aminoacylation, several side reactions have been described, the most important of which being the synthesis of AppppA [4] and its modulation by zinc ions [5,221. All of these reactions result from the presence of aminoacyl-adenylate, an intermediate which has been shown to be formed by all synthetases, even when it has not actually been isolated [23,24].…”

Section: Scheme 2 Discussionmentioning

confidence: 99%

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Tryptophanamide formation by Escherichia coli tryptophanyl‐tRNA synthetase

Andrews

Trezeguet

Merle

et al. 1985

European Journal of Biochemistry

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When tryptophanyl-tRNA synthetase from Escherichia coli is allowed to react with L-tryptophan and ATPMg in the presence of inorganic pyrophosphatase, the fluorescence change of the reaction mixture reveals three or four sequential processes, depending on the buffer used. Quenched-flow and stopped-flow experiments show that the first two processes, which occur in the 0.001 -1.0-s time scale, can be correlated to the formation of two moles of tryptophanyl-adenylate per mole of dimeric enzyme. These two processes are reversible by adding PPi, as seen in the fluorimeter. The third process leads to a reaction product that can no longer reform ATP after addition of PPi and that represents tryptophanyl-ATP ester, as demonstrated by thin-layer chromatography. This compound has been previously shown to be formed by tryptophanyl-tRNA synthetase from E. coli [K. H. Muench (1969) Biochemistry 8, 4872-48791. Its formation is accompanied by a fluorescence decrease which reaches a minimum in about 30 min. The nature of the fourth process depends on the reaction conditions employed. In sodium bicarbonate or potassium phosphate buffer, the fourth process corresponds to the non-enzymatic hydrolysis of tryptophanyl-ATP ester. This spontaneous hydrolysis competes with formation of the ester and limits its concentration. Eventually, the progressive exhaustion of ATP brings the fluorescence intensity of the reaction mixture back to its initial value. In contrast, in ammonium bicarbonate buffer the previous third process is no longer visible, as evidenced by the absence of a fluorescence decrease beyond the fast initial quenching linked to the formation of tryptophanyl-adenylate. Instead, a fluorescence increase is observed. However, unlike the fourth process seen in sodium bicarbonate buffer, the fluorescence increase in ammonium bicarbonate is much larger than the initial fluorescence decrease linked to adenylate formation, the final fluorescence greatly surpassing the starting fluorescence signal. The reaction product of this process is tryptophanamide, as evidenced by highperformance liquid chromatography. Tryptophanamide formation is faster than that of tryptophanyl-ATP ester and is enzyme-catalyzed with a K , of 1 mM for ammonia and a rate constant of 5.7 min-' at pH 8.3,25"C. The affinity of tryptophanamide for the protein is too weak to allow the formation of a significant concentration of enzyme-product complex. Tryptophanamide is therefore released in the reaction medium and its concentration reaches that of the limiting substrate.The aminoacylation of tRNA proceeds via the production of a high-energy intermediate formed between the carboxyl group of the amino acid and the phosphate group of AMP, derived from ATP by the release of pyrophosphate. The resulting mixed anhydride bond between the amino acid and AMP provides both species with a high chemical transfer potential, which can lead to several reactions deviating from the regular charging of tRNA. Depending on the synthetase studied, reactions of varying specificity and ...

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Section: Scheme 2 Discussionmentioning

confidence: 84%

Section: Scheme 2 Discussionmentioning

confidence: 99%

Tryptophanamide formation by Escherichia coli tryptophanyl‐tRNA synthetase

Andrews

Trezeguet

Merle

et al. 1985

European Journal of Biochemistry

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“…Although most ARSs belong to either one of the two classes, both forms exist in KRS (11,12). Second, it can synthesize diadenosine polyphosphates in addition to its aminoacylation activity (13,14). This activity was recently shown to play a role in transcription control through microphthalmia transcription factor (15).…”

mentioning

confidence: 99%

Human lysyl-tRNA synthetase is secreted to trigger proinflammatory response

Park

Kim

Min

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

158

144

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Although aminoacyl-tRNA synthetases (ARSs) are essential for protein synthesis, they also function as regulators and signaling molecules in diverse biological processes. Here, we screened 11 different human ARSs to identify the enzyme that is secreted as a signaling molecule. Among them, we found that lysyl-tRNA synthetase (KRS) was secreted from intact human cells, and its secretion was induced by TNF-␣. The secreted KRS bound to macrophages and peripheral blood mononuclear cells to enhance the TNF-␣ production and their migration. The mitogen-activated protein kinases, extracellular signal-regulated kinase and p38 mitogen-activated protein kinase, and G␣i were determined to be involved in the signal transduction triggered by KRS. All of these activities demonstrate that human KRS may work as a previously uncharacterized signaling molecule, inducing immune response through the activation of monocyte͞macrophages.aminoacyl-tRNA synthetase ͉ cytokine ͉ TNF-␣ ͉ immune response ͉ cell migration

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“…ARSs also catalyze a secondary reaction in which the aminoacyl-AMP reaction intermediate reacts with ATP to produce diadenosine tetraphosphate (Ap 4 A) (27,28). Protein kinase C-dependent phosphorylation of ARSs increases Ap 4 A synthesis by several fold (29) without affecting the aminoacylation reaction.…”

mentioning

confidence: 99%