Editing of errors in selection of amino acids for protein synthesis.

Jakubowski, Hieronim; Goldman, E

doi:10.1128/mmbr.56.3.412-429.1992

Cited by 153 publications

(79 citation statements)

References 89 publications

(197 reference statements)

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“…This needs to be further investigated. Thus far, the only experimental finding regarding the ability of SerRS to correct errors is related to pretransfer editing, which seems to be negligible with any amino acid tested, including threonine [2]. Additionally, SerRS displays AMP-and pyrophospate-independent deacylation of cognate aminoacyl-tRNA in the presence of thiols, which mimics editing of homocysteine [15].…”

Section: Discussionmentioning

confidence: 99%

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tRNA‐dependent amino acid discrimination by yeast seryl‐tRNA synthetase

Gruić-Sovulj

Landeka

Söll

et al. 2002

European Journal of Biochemistry

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The ability of aminoacyl‐tRNA synthetases to distinguish between similar amino acids is crucial for accurate translation of the genetic code. Saccharomyces cerevisiae seryl‐tRNA synthetase (SerRS) employs tRNA‐dependent recognition of its cognate amino acid serine [Lenhard, B., Filipic, S., Landeka, I., Skrtic, I., Söll, D. & Weygand‐Durasevic, I. (1997) J. Biol. Chem.272, 1136–1141]. Here we show that dimeric SerRS enzyme complexed with one molecule of tRNASer is more specific and more efficient in catalyzing seryl‐adenylate formation than the apoenzyme alone. Sequence‐specific tRNA–protein interactions enhance discrimination of the amino acid substrate by yeast SerRS and diminish the misactivation of the structurally similar noncognate threonine. This may proceed via a tRNA‐induced conformational change in the enzyme's active site. The 3′‐terminal adenosine of tRNASer is not important in effecting the rearrangement of the serine binding site. Our results do not provide an indication for a readjustment of ATP binding in a tRNA‐assisted manner. The stoichiometric analyses of the complexes between the enzyme and tRNASer revealed that two cognate tRNA molecules can be bound to dimeric SerRS, however, with very different affinities.

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Section: Discussionmentioning

confidence: 99%

“…A higher mobility band, appearing in lanes with SerRS/ tRNA Ser ox ratios 1 : 1-1 : 3 (Fig. 6A, lanes 3-5) could be assigned to SerRS-(tRNA Ser ox ) 2 . Uncomplexed SerRS and tRNA Ser ox were used as mobility markers (Fig.…”

Section: Analysis Of the Complexes Between Serrs And Trna Sermentioning

confidence: 92%

tRNA‐dependent amino acid discrimination by yeast seryl‐tRNA synthetase

Gruić-Sovulj

Landeka

Söll

et al. 2002

European Journal of Biochemistry

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“…AaRSs employ several mechanisms of proofreading ( Fig. 1, reviewed in [4]). Misactivated amino acid can be eliminated before the transfer to the tRNA in a pre-transfer editing step.…”

Section: Introductionmentioning

confidence: 99%

Hydrolysis of non‐cognate aminoacyl‐adenylates by a class II aminoacyl‐tRNA synthetase lacking an editing domain

2007

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Aminoacyl-tRNA synthetases, a group of enzymes catalyzing aminoacyl-tRNA formation, may possess inherent editing activity to clear mistakes arising through the selection of non-cognate amino acid. It is generally assumed that both editing substrates, non-cognate aminoacyl-adenylate and misacylated tRNA, are hydrolyzed at the same editing domain, distant from the active site. Here, we present the first example of an aminoacyl-tRNA synthetase (seryl-tRNA synthetase) that naturally lacks an editing domain, but possesses a hydrolytic activity toward non-cognate aminoacyl-adenylates. Our data reveal that tRNA-independent pre-transfer editing may proceed within the enzyme active site without shuttling the non-cognate aminoacyl-adenylate intermediate to the remote editing site.

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“…The origin of the low residual activity of the two H296Q mutants of L. bulgaricus enzyme is difficult to interpret. It cannot simply reflect translational misreading [21] since the residual activity is insensitive to diethylpyrocarbonate ( Fig. 1 A).…”

Section: Discussionmentioning

confidence: 99%

“…promoter [l]. The purified enzyme, like L. casei D-2-hydroxy-4-methylvalerate dehydrogenase [21], was shown to be active on a wide variety of 2-oxoacid substrates except those having a branched a-carbon [I]. Both enzymes belong to the recently established family of NAD-dependent D-2-hydroxyacid dehydrogenases [ 1, 3 -61.…”

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confidence: 99%

D‐2‐Hydroxy‐4‐Methylvalerate Dehydrogenase from Lactobacillus Delbrueckii Subsp. Bulgaricus— II. Mutagenic analysis of catalytically important residues

Bernard

Johnsen

Gelpí

et al. 1997

European Journal of Biochemistry

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Five residues involved in catalysis and coenzyme binding have been identified in ~-2-hydroxy-4-methylvalerate dehydrogenase from Lactobacillus delbrueckii subsp. bulgaricus by using biochemical and genetical methods. Enzyme inactivation with diethylpyrocarbonate indicated that a single histidine residue was involved in catalysis. Since H296 is the only conserved histidine in the whole family of NAD-dependent D-2-hydroxyacid dehydrogenases, we constructed the H296Q and H296S mutants and showed that their catalytic efficiencies were reduced 105-fold compared with the wild-type enzyme. This low residual activity was shown to be insensitive to diethylpyrocarbonate. Taken together these data demonstrate that H296 is responsible for proton exchange in the redox reaction. Two acidic residues (D259 and E264) were candidates for maintaining H296 in the protonated state and their roles were examined by mutagenesis. The D259N and E264Q mutant enzymes both showed similar and large reductions in their k,,,lK,,, ratios (200-800-fold, depending on pH), indicating that either D259 or E264 (or both) could partner H296. The conserved R235 residue was a candidate for binding the a-carboxyl group of the substrate and it was changed to lysine. The R235K mutant showed a 104-fold reduced k,,,lK,,, due to both an increased K,,, and a reduced k,,, for 2-0x0-4-methylvalerate. Thus R235 plays a role in binding the substrate carboxylate similar to R171 in the L-lactate dehydrogenases. Finally, we constructed the H205Q mutant to test the role of this partially conserved histidine residue (in 10/13 enzymes of the family). This mutant enzyme displayed a 7.7-fold increased k,,, and a doubled catalytic efficiency at pH 5, was as sensitive to diethylpyrocarbonate as the wild-type but showed a sevenfold increased K, for NADH and a 100-fold increase in Kd for NADH together with 10-30-fold lower substrate inhibition. The transient kinetic behaviour of the H205Q mutant is as predicted from our previous study on the enzymatic mechanism of D-2-hydroxy-4-methylvalerate dehydrogenase which showed that coenzyme binding is highly pH dependent and indicated that release of the oxidised coenzyme is a significant component of the rate-limiting processes in catalysis at pH 6.5. promoter [l]. The purified enzyme, like L. casei D-2-hydroxy-4-methylvalerate dehydrogenase [21], was shown to be active on a wide variety of 2-oxoacid substrates except those having a branched a-carbon [I]. Both enzymes belong to the recently established family of NAD-dependent D-2-hydroxyacid dehydrogenases [ 1, 3 -61. Keywords: D-2-hydroxy-4-methylvalerate dehydrogenaseThe work described here was intended to identify the essential residues of D-2-hydroxy-4-methylvalerate dehydrogenase and their respective roles in catalysis. We wished to test the premise that the catalytic mechanism of D-2-hydroxy-4-methylvalerate dehydrogenase is similar to the acidlbase catalysis operating in the better studied L-lactate: NAD' oxidoreductases. During reduction of pyruvate into L-lactate, His195 ac...

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Editing of errors in selection of amino acids for protein synthesis.

Cited by 153 publications

References 89 publications

tRNA‐dependent amino acid discrimination by yeast seryl‐tRNA synthetase

tRNA‐dependent amino acid discrimination by yeast seryl‐tRNA synthetase

Hydrolysis of non‐cognate aminoacyl‐adenylates by a class II aminoacyl‐tRNA synthetase lacking an editing domain

D‐2‐Hydroxy‐4‐Methylvalerate Dehydrogenase from Lactobacillus Delbrueckii Subsp. Bulgaricus— II. Mutagenic analysis of catalytically important residues

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