A new mechanism of post-transfer editing by aminoacyl-tRNA synthetases: catalysis of hydrolytic reaction by bacterial-type prolyl-tRNA synthetase.

Aminoacyl tRNA synthetases are enzymes that specifically attach amino acids to cognate tRNAs for use in the ribosomal stage of translation. For many aminoacyl tRNA synthetases, the required level of amino acid specificity is achieved either by specific hydrolysis of misactivated aminoacyl-adenylate intermediate (pre-transfer editing) or by hydrolysis of the mischarged aminoacyl-tRNA (post-transfer editing). To investigate the mechanism of post-transfer editing of alanine by prolyl-tRNA synthetase from the pathogenic bacteria Enterococcus faecalis, we used molecular modeling, molecular dynamic simulations, quantum mechanical (QM) calculations, site-directed mutagenesis of the enzyme, and tRNA modification.

Discovery of potent anti-tuberculosis agents targeting leucyl-tRNA synthetase.

Tuberculosis is a serious infectious disease caused by human pathogen bacteria Mycobacterium tuberculosis. Bacterial drug resistance is a very significant medical problem nowadays and development of novel antibiotics with different mechanisms of action is an important goal of modern medical science. Leucyl-tRNA synthetase (LeuRS) has been recently clinically validated as antimicrobial target.

[tRNA-dependent editing of errors by prolyl-tRNA synthetase from bacteria Enterococcus faecalis].

Maintenance of amino acid specificity by aminoacyl-tRNA synthetases, particularly prolyl-tRNA synthetase, requires for not only specific recognition of homologic amino acid, but also missynthesized products hydrolysis, known as editing. The speeding-up of the enzymatic hydrolysis of missynthesized alanyl adenylate by bacteria Enterococcus faecalis prolyl-tRNA synthetase in the presence of tRNAPro, and also importance for this function of 2'- and 3'-hydroxyle groups of tRNA 3'-terminal adenosine ribose is shown in the work. Furthermore, results are shown, that support the absence of editing (INS) domain role in alanyl adenylate hydrolysis.

Class I tyrosyl-tRNA synthetase has a class II mode of cognate tRNA recognition.

Bacterial tyrosyl-tRNA synthetases (TyrRS) possess a flexibly linked C-terminal domain of approximately 80 residues, which has hitherto been disordered in crystal structures of the enzyme. We have determined the structure of Thermus thermophilus TyrRS at 2.0 A resolution in a crystal form in which the C-terminal domain is ordered, and confirm that the fold is similar to part of the C-terminal domain of ribosomal protein S4.

Improved crystals of Thermus thermophilus prolyl-tRNA synthetase complexed with cognate tRNA obtained by crystallization from precipitate.

The complex between Thermus thermophilus prolyl-tRNA synthetase (ProRSTT) and its cognate tRNA has been crystallized using two different isoacceptors of tRNA(Pro). Similar bipyramidal crystals of the complexes of ProRSTT with the two different tRNA(Pro) isoacceptors grow within two weeks from 32% saturated ammonium sulfate solution. They belong to space group P4(3)2(1)2, with unit-cell parameters a = 143.

[Comparative study of the reactability of phosphoric acid residues in tRNA(Ser) and tRNA(Leu) from Thermus thermophilus].

The reactivity of phosphates in the Thermus thermophilus tRNA(Ser) (GCU) and tRNA(Leu) (CAG) was studied using the ethylnitrosourea modification. It was shown that phosphates of nucleotides 58-60 (T loop), 20-22 (D loop), and 48 (at the junction of the variable and T stems) were poorly modified in both tRNAs. The most pronounced differences in the reactivity were observed for phosphates at the junctions of the variable stem with T-stem (47q, 49) and anticodon stem (45).

[Comparative analysis of interaction sites of Thermus thermophilus and Escherichia coli tRNA(Tyr) with homologous aminoacyl-tRNA synthetases by means of chemical modification and nuclease hydrolysis].

A nucleotide sequence of tRNA(Tyr) from the extreme thermophile Thermus thermophilus HB-27 living at 75 degrees C was determined. It is 86 nt long and shares a 52% homology with tRNA(Tyr) from Escherichia coli. A comparative analysis of the interaction sites of tRNA(Tyr) from T.

[Primary structure of tRNALeuIAG from the mammary gland of the lactating cow].

The nucleotide sequence of the tRNALeuIAG from a lactating cow mammary gland was determined by ultramicrospectrophotometrical method and rapid gel sequencing procedure. The chain length of this tRNA is 85 nucleotides, 15 of them including 6 psi, are modified nucleotides. The primary structure of tRNALeuIAG is absolutely identical to major species of leucyl tRNAIAG from bovine liver and differs in 21 positions from cow mammary gland tRNALeuCAG.

[Functional properties of rat hemoglobin fractions].

The functional properties of total hemoglobin and some of its major fractions obtained by polyacrylamide gel disk-electrophoresis were studied. It was shown that p50 for intact hemoglobin is 1.18, that for fractions 2, 4-6-1.