Hydrolytic action of aminoacyl-tRNA synthetases from baker's yeast. "Chemical proofreading" of Thr-tRNAVal by valyl-tRNA synthetase studied with modified tRNAVal and amino acid analogs

Biochemistry ◽  
1977 ◽  
Vol 16 (8) ◽  
pp. 1696-1702 ◽  
Author(s):  
Gabor L. Igloi ◽  
Friedrich Von der Haar ◽  
Friedrich Cramer
Keyword(s):  
Amino Acid ◽  
Trna Synthetase ◽  
Baker’S Yeast ◽  
Baker's Yeast ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases ◽  
Amino Acid Analogs

Structure of nondiscriminating glutamyl-tRNA synthetase fromThermotoga maritima

2010 ◽  
Vol 66 (7) ◽  
pp. 813-820 ◽  
Author(s):  
Takuhiro Ito ◽  
Noriko Kiyasu ◽  
Risa Matsunaga ◽  
Seizo Takahashi ◽  
Shigeyuki Yokoyama
Keyword(s):  
Crystal Structure ◽  
Amino Acid ◽  
Thermotoga Maritima ◽  
Trna Synthetase ◽  
Characteristic Structure ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases ◽  
Rossmann Fold

Aminoacyl-tRNA synthetases produce aminoacyl-tRNAs from the substrate tRNA and its cognate amino acid with the aid of ATP. Two types of glutamyl-tRNA synthetase (GluRS) have been discovered: discriminating GluRS (D-GluRS) and nondiscriminating GluRS (ND-GluRS). D-GluRS glutamylates tRNAGluonly, while ND-GluRS glutamylates both tRNAGluand tRNAGln. ND-GluRS produces the intermediate Glu-tRNAGln, which is converted to Gln-tRNAGlnby Glu-tRNAGlnamidotransferase. Two GluRS homologues fromThermotoga maritima, TM1875 and TM1351, have been biochemically characterized and it has been clarified that only TM1875 functions as an ND-GluRS. Furthermore, the crystal structure of theT. maritimaND-GluRS, TM1875, was determined in complex with a Glu-AMP analogue at 2.0 Å resolution. TheT. maritimaND-GluRS contains a characteristic structure in the connective-peptide domain, which is inserted into the catalytic Rossmann-fold domain. The glutamylation ability of tRNAGlnby ND-GluRS was measured in the presence of the bacterial Glu-tRNAGlnamidotransferase GatCAB. Interestingly, the glutamylation efficiency was not affected even in the presence of excess GatCAB. Therefore, GluRS avoids competition with GatCAB and glutamylates tRNAGln.

scholarly journals A novel pathway for the conversion of homocysteine to methionine in eukaryotes

1997 ◽  
Vol 328 (1) ◽  
pp. 165-170 ◽  
Author(s):  
M. Celia ANTONIO ◽  
C. Marta NUNES ◽  
Helga REFSUM ◽  
K. Abraham ABRAHAM
Keyword(s):  
Amino Acid ◽  
Crude Extract ◽  
Trna Synthetase ◽  
Synthetase Activity ◽  
Enzyme Complex ◽  
Homocysteine Thiolactone ◽  
Initiator Trna ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases ◽  
Reticulocyte Lysates

Activation of amino acid homocysteine was compared with that of methionine in rabbit crude liver extracts and purified multi-enzyme complex of aminoacyl-tRNA synthetases. Activation was studied by measuring the incorporation of radioactive amino acid into unlabelled trichloroacetic-acid insoluble materials in the absence of protein synthesis. Homocysteine synthetase activity was found in the crude extract and in the purified multi-enzyme complex of aminoacyl-tRNA synthetases. On a molar basis, the activation of methionine by the crude extract was five times higher than the activation of homocysteine. There was a partial loss of Hcy-tRNA synthetase activity in the purified multi-enzyme complex. Preliminary reconstitution experiments indicated a requirement for an additional factor for Hcy-tRNA synthetase activity. TLC of the amino acid released from tRNA charged with [14C]homocysteine, revealed radioactivity in homocysteine, methionine and homocysteine thiolactone, indicating a conversion of tRNA-attached homocysteine to methionine. Total tRNA was separated on a benzoylated cellulose column into a fraction enriched in initiator tRNA and a methionine-accepting, but initiator tRNA-deficient, fraction. Homocysteine-accepting activity was present only in the initiator tRNA-enriched fraction. Based on the above data we propose that homocysteine activation in reticulocyte lysates, reported previously, also occurs in liver. Activated homocysteine is attached to initiator tRNA and then converted to methionine by a methylating enzyme. In the absence of methylation, tRNA-attached homocysteine is hydrolysed to produce homocysteine thiolactone.

scholarly journals Oxidation of cellular amino acid pools leads to cytotoxic mistranslation of the genetic code

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Tammy J Bullwinkle ◽  
Noah M Reynolds ◽  
Medha Raina ◽  
Adil Moghal ◽  
Eleftheria Matsa ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Genetic Code ◽  
Trna Synthetase ◽  
Control Mechanisms ◽  
Cellular Toxicity ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases ◽  
The Cost

Aminoacyl-tRNA synthetases use a variety of mechanisms to ensure fidelity of the genetic code and ultimately select the correct amino acids to be used in protein synthesis. The physiological necessity of these quality control mechanisms in different environments remains unclear, as the cost vs benefit of accurate protein synthesis is difficult to predict. We show that in Escherichia coli, a non-coded amino acid produced through oxidative damage is a significant threat to the accuracy of protein synthesis and must be cleared by phenylalanine-tRNA synthetase in order to prevent cellular toxicity caused by mis-synthesized proteins. These findings demonstrate how stress can lead to the accumulation of non-canonical amino acids that must be excluded from the proteome in order to maintain cellular viability.

scholarly journals Aminoacyl tRNA Synthetases as Malarial Drug Targets: A Comparative Bioinformatics Study

2018 ◽  
Author(s):  
Dorothy Wavinya Nyamai ◽  
Özlem Tastan Bishop
Keyword(s):  
Amino Acid ◽  
Drug Targets ◽  
Motif Discovery ◽  
Protein Translation ◽  
Trna Synthetase ◽  
Potential Drug ◽  
Multiple Sequence ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases ◽  
Potential Drug Targets

AbstractTreatment of parasitic diseases has been challenging due to the development of drug resistance by parasites, and thus there is need to identify new class of drugs and drug targets. Protein translation is important for survival of plasmodium and the pathway is present in all the life cycle stages of the plasmodium parasite. Aminoacyl tRNA synthetases are primary enzymes in protein translation as they catalyse the first reaction where an amino acid is added to the cognate tRNA. Currently, there is limited research on comparative studies of aminoacyl tRNA synthetases as potential drug targets. The aim of this study is to understand differences between plasmodium and human aminoacyl tRNA synthetases through bioinformatics analysis. Plasmodium falciparum, P. fragile, P. vivax, P. ovale, P. knowlesi, P. bergei, P. malariae and human aminoacyl tRNA synthetase sequences were retrieved from UniProt database and grouped into 20 families based on amino acid specificity. Despite functional and structural conservation, multiple sequence analysis, motif discovery, pairwise sequence identity calculations and molecular phylogenetic analysis showed striking differences between parasite and human proteins. Prediction of alternate binding sites revealed potential druggable sites in PfArgRS, PfMetRS and PfProRS at regions that were weakly conserved when compared to the human homologues. These differences provide a basis for further exploration of plasmodium aminoacyl tRNA synthetases as potential drug targets.

Aminoacyl-tRNA synthetases from baker's yeast: Reacting site of enzymatic aminoacylation is not uniform for all tRNAs

FEBS Letters ◽  
1975 ◽  
Vol 56 (2) ◽  
pp. 212-214 ◽  
Author(s):  
F. Cramer ◽  
H. Faulhammer ◽  
F. Von Der Haar ◽  
M. Sprinzl ◽  
H. Sternbach
Keyword(s):  
Baker’S Yeast ◽  
Baker's Yeast ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases

scholarly journals Bacterial Aspartyl-tRNA Synthetase Has Glutamyl-tRNA Synthetase Activity

Genes ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 262 ◽  
Author(s):  
Udumbara M. Rathnayake ◽  
Tamara L. Hendrickson
Keyword(s):  
Amino Acid ◽  
Genetic Code ◽  
Trna Synthetase ◽  
Synthetase Activity ◽  
Messenger Rnas ◽  
Indirect Pathway ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases

The aminoacyl-tRNA synthetases (aaRSs) are well established as the translators of the genetic code, because their products, the aminoacyl-tRNAs, read codons to translate messenger RNAs into proteins. Consequently, deleterious errors by the aaRSs can be transferred into the proteome via misacylated tRNAs. Nevertheless, many microorganisms use an indirect pathway to produce Asn-tRNAAsn via Asp-tRNAAsn. This intermediate is produced by a non-discriminating aspartyl-tRNA synthetase (ND-AspRS) that has retained its ability to also generate Asp-tRNAAsp. Here we report the discovery that ND-AspRS and its discriminating counterpart, AspRS, are also capable of specifically producing Glu-tRNAGlu, without producing misacylated tRNAs like Glu-tRNAAsn, Glu-tRNAAsp, or Asp-tRNAGlu, thus maintaining the fidelity of the genetic code. Consequently, bacterial AspRSs have glutamyl-tRNA synthetase-like activity that does not contaminate the proteome via amino acid misincorporation.

scholarly journals Human histidyl-tRNA synthetase: recognition of amino acid signature regions in class 2a aminoacyl-tRNA synthetases

1992 ◽  
Vol 20 (5) ◽  
pp. 1075-1081 ◽  
Author(s):  
Nina Raben ◽  
Frank Borriello ◽  
Jay Amin ◽  
Randy Horwitz ◽  
David Fraser ◽  
...  
Keyword(s):  
Amino Acid ◽  
Trna Synthetase ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases ◽  
Amino Acid Signature

scholarly journals Relaxed Substrate Specificity Leads to Extensive tRNA Mischarging by Streptococcus pneumoniae Class I and Class II Aminoacyl-tRNA Synthetases

mBio ◽  
2014 ◽  
Vol 5 (5) ◽  
Author(s):  
Jennifer Shepherd ◽  
Michael Ibba
Keyword(s):  
Quality Control ◽  
Cell Wall ◽  
Protein Synthesis ◽  
Streptococcus Pneumoniae ◽  
Amino Acid ◽  
Substrate Specificity ◽  
Trna Synthetase ◽  
Content Type ◽  
Trna Synthetases ◽  
Aminoacyl Trna Synthetases

ABSTRACTAminoacyl-tRNA synthetases provide the first step in protein synthesis quality control by discriminating cognate from noncognate amino acid and tRNA substrates. While substrate specificity is enhanced in many instances bycis-andtrans-editing pathways, it has been revealed that in organisms such asStreptococcus pneumoniaesome aminoacyl-tRNA synthetases display significant tRNA mischarging activity. To investigate the extent of tRNA mischarging in this pathogen, the aminoacylation profiles of class I isoleucyl-tRNA synthetase (IleRS) and class II lysyl-tRNA synthetase (LysRS) were determined. Pneumococcal IleRS mischarged tRNAIlewith both Val, as demonstrated in other bacteria, and Leu in a tRNA sequence-dependent manner. IleRS substrate specificity was achieved in an editing-independent manner, indicating that tRNA mischarging would only be significant under growth conditions where Ile is depleted. Pneumococcal LysRS was found to misaminoacylate tRNALyswith Ala and to a lesser extent Thr and Ser, with mischarging efficiency modulated by the presence of an unusual U4:G69 wobble pair in the acceptor stems of both pneumococcal tRNALysisoacceptors. Addition of thetrans-editing factor MurM, which also functions in peptidoglycan synthesis, reduced Ala-tRNALysproduction by LysRS, providing evidence for cross talk between the protein synthesis and cell wall biogenesis pathways. Mischarging of tRNALysby AlaRS was also observed, and this would provide additional potential MurM substrates. More broadly, the extensive mischarging activities now described for a number ofStreptococcus pneumoniaeaminoacyl-tRNA synthetases suggest that adaptive misaminoacylation may contribute significantly to the viability of this pathogen during amino acid starvation.IMPORTANCEStreptococcus pneumoniaeis a common causative agent of several debilitating and potentially life-threatening infections, such as pneumonia, meningitis, and infectious endocarditis. Such infections are increasingly difficult to treat due to widespread development of penicillin resistance. High-level penicillin resistance is known to depend in part upon MurM, a protein involved in both aminoacyl-tRNA-dependent synthesis of indirect amino acid cross-linkages within cell wall peptidoglycan and in translation quality control. The involvement of MurM in both protein synthesis and antibiotic resistance identify it as a potential target for the development of new and potent antibiotics for pneumococcal infections. The goals of this work were to identify and characterizeS. pneumoniaepathways that can synthesize mischarged tRNAs and to relate these activities to expected changes in protein and peptidoglycan biosynthesis during antibiotic and nutritional stress.

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