Tryptophanyl-tRNA synthetase (WRS) is a critical enzyme involved in protein synthesis, responsible for charging tRNA with the essential amino acid tryptophan. Recent studies have highlighted its novel role in stimulating innate immunity against bacterial and viral infections. However, the significance of WRS in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remains elusive. In this study, we aimed to investigate the complex interplay between WRS, inflammatory markers, Toll-like receptor-4 (TLR-4), and clinical outcomes in coronavirus disease 19 (COVID-19) patients. A case-control investigation comprised 127 COVID-19 patients, carefully classified as severe or moderate upon admission, and 112 healthy individuals as a comparative group. Blood samples were meticulously collected before treatment initiation, and WRS, interleukin-6 (IL-6), and C-reactive protein (CRP) concentrations were quantified using a well-established commercial ELISA kit. Peripheral blood mononuclear cells (PBMCs) were isolated from the blood samples, and RNA was extracted for cDNA synthesis. Semi-quantitative real-time polymerase chain reaction (PCR) was employed to assess the relative expression of TLR-4. COVID-19 patients exhibited elevated levels of WRS, IL-6, CRP, and TLR-4 expression compared to healthy individuals, with the severe group displaying significantly higher levels than the moderate group. Notably, severe patients demonstrated substantial fluctuations in CRP, IL-6, and WRS levels over time, a pattern not observed in their moderate counterparts. Although no significant distinctions were observed in the dynamic alterations of WRS, IL-6, CRP, and TLR-4 expression between deceased and surviving patients, a trend emerged indicating higher IL-6_1 levels in deceased patients and elevated lactate dehydrogenase (LDH) levels in severe patients who succumbed to the disease. This pioneering research highlights the dynamic alterations of WRS in COVID-19 patients, providing valuable insights into the correlation between WRS, inflammatory markers, and disease severity within this population. Understanding the role of WRS in SARS-CoV-2 infection may open new avenues for therapeutic interventions targeting innate immunity to combat COVID-19.

Over the past several years, structural studies have led to the unexpected discovery of iron-sulfur clusters in enzymes that are involved in DNA replication/repair and protein biosynthesis. Although these clusters are generally well-studied cofactors, their significance in the new contexts often remains elusive. One fascinating example is a tryptophanyl-tRNA synthetase from the thermophilic bacterium Thermotoga maritima, TmTrpRS, that has recently been structurally characterized. It represents an unprecedented connection among a primordial iron-sulfur cofactor, RNA and protein biosynthesis. Here, a possible role of the [Fe4S4] cluster in tRNA anticodon-loop recognition is investigated by means of density functional theory and comparison with the structure of a human tryptophanyl-tRNA synthetase/tRNA complex. It turns out that a cluster-coordinating cysteine residue, R224, and polar main chain atoms form a characteristic structural motif for recognizing a putative 5\' cytosine or 5\' 2-thiocytosine moiety in the anticodon loop of the tRNA molecule. This motif provides not only affinity but also specificity by creating a structural and energetical penalty for the binding of other bases, such as uracil.

BACKGROUND: Depression and inflammation have been suggested to be involved in the atherosclerotic processes, but empirical evidence is mixed. We tested the hypothesis that depressive symptoms are associated with atherosclerosis only when combined with other risk factors, such as inflammation indicated by indoleamine 2,3-dioxygenase (IDO) activation.
METHODS: Participants were 544 women and 442 men (aged 24-39 years) who participated in the Young Finns Study medical examinations in 2001 and 2007. At baseline (in 2001), IDO activity (tryptophan and kynurenine ratio) and other biological and behavioral risk factors were assessed and depressive symptoms were determined using a modified 21-item Beck Depression Inventory. Carotid atherosclerosis was measured on the basis of carotid intimamedia thickness (IMT) at baseline and again in 2007.
RESULTS: In women, IDO activity moderated the association between depressive symptoms and IMT (p=0.02), so that a longitudinal association between depressive symptoms and IMT was found only in combination with high IDO activity (B=0.21, p=0.009). This association was robust to adjustment for other risk factors except body mass index and lipids which largely removed the association.
CONCLUSIONS: The results of this study need to be confirmed using larger data sets and studies using clinical cut-off point for depression.
CONCLUSIONS: These data suggest that depressive symptoms are associated with preclinical y carotid atherosclerosis only if they are linked to inflammation, and that this association is present only in women. Underlying mechanisms are unknown but probably relate to adiposity.

A comparative study on the localization of cytosolic Trp-tRNA synthetase (TrpRS), aminoacyl-tRNA synthetases associated in a multienzyme complex (Glu-tRNA synthetase (GluRS), and Arg-tRNA synthetase (ArgRS)) and polypeptides p37 and p43 from the multienzyme complex was carried out on ultrathin sections of cultured rabbit cells RK-1 by means of immunogold technique. It is shown that GluRS, ArgRS, and polypeptide p43 have approximately the same distribution in the cell as TrpRS. The data obtained evidences in favour of a multienzyme structure of most (or, may be all) aminoacyl-tRNA synthetases in intact cells. A statistical analysis of enzyme distribution in different cell organelles showed nonrandom, compartmentalized distribution of studied synthetases in the mammalian cell. Aminoacyl-tRNA synthetases were found in the cell nucleus in the vicinity of interchromatin granules and in the regions of diffused chromatin. This fact points to a role which these proteins may play in active chromatin functions (transcription, processing, transfer of gene products, etc.) and needs special attention. Detection of ArgRS and GluRS in the nucleus allows one to suggest that either multienzyme synthetase complexes are present not only in the cytoplasm, but also in the nucleus, or these enzymes can dissociate from the complex and pass to the nucleus as individual proteins.

By means of small angle X-ray scattering, an aggregation of beef pancreas Trp-tRNA synthetase (EC 6.1.1.2) was observed at physiological temperatures. A Trp-tRNA synthetase preparation which is homogeneous after PAGE in beta-ME-SDS was found to be heterogeneous in particle sizes even at low (4-8 degrees C) temperature. At heating up to 30-45 degrees C, the oligomer sizes increased as well as its proportion depending on the incubation time and temperature; very large aggregates were observed 10 times exceeding the sizes of initial particles. Cooling to 20 degrees C caused no disaggregation due to disulphide bond formation between associated subunits of Trp-tRNA synthetase. A hypothesis is proposed that the aggregation of bovine Trp-tRNA synthetase evaluated in vitro and not observed earlier with any aminoacyl-tRNA synthetases of unicellular organisms might serve as one of the mechanisms of its compartmentation in pancreas.

The immunochemical approach used extensively in medicine and in some fields of biology has not yet been systematically applied to enzymology, in particular, to the study of a large, functionally significant group of enzymes, such as aminoacyl-tRNA synthetases (EC 6.1.1). The present investigation was aimed at the analysis of applicability of polyclonal and monoclonal antibodies against bovine tryptophanyl-tRNA synthetase in the study of functional properties of this enzyme as well as of its distribution inside the cell and among organs and tissues of various animals. The general conclusions one may draw from these data are as follows. i) Tryptophanyl-tRNA synthetase of eukaryotes, eubacteria and archaebacteria share one common structural element (antigenic determinant) that is not essential for the catalytic activity. The evolutionary conservative nature of this element suggests that the enzyme may implement functions other than catalysis of tryptophanyl-tRNA formation. ii) Tryptophanyl-tRNA synthetase shows an anomalous distribution among mammalian organs: its content is far greater in the exocrine part of the ruminant animal pancreas in comparison with their other organs (liver) or with other mammalian orders. This finding suggests that the enzyme or its fragments may play a role in the digestive function of ruminant animals. iii) Tryptophanyl-tRNA synthetase was found in considerable quantities in diffuse chromatin of mammalian cell nuclei. This fact indicates that the enzyme may participate in such processes in the nucleus as transcription, processing, transport, etc. It may thus be concluded that tryptophanyl-tRNA synthetase of higher organisms, besides catalyzing the formation of aminoacyl-tRNAs can exert some other, yet unknown, noncanonical functions.

Equilibrium dialysis and gel filtration studies show that tryptophanyl-tRNA synthetase from beef pancreas binds two molecules of L-tryptophan per dimer in an anticooperative way. The binding of tryptophan ellicits a series of spectroscopic changes in the protein as seen by absorbance, fluorescence and circular dichroism. The molar absorption change of the protein-tryptophan system upon formation of the complex is delta epsilon292 = 10 400 +/- 1000 M(-1) cm(-1) per dimer. Taking an initial symmetrical dimeric protein the two dissociation constants for tryptophan at pH 8, 25 degrees C are respectively K1 = 2.0 +/- 0.5 muM and K2 = 10 +/- 4 muM. They are respectively K1 = 1 +/- 0.25 muM and K2 = 20 +/- 8 muM if one considers a sequenced binding of the two tryptophan molecules. The dichroic band at 290 nm of the free protein disappears when tryptophan is bound. All observed changes are characteristic of tryptophan perturbation and none of tyrosine perturbation. They all exceed the effect that can be expected from the change in environment of the bound tryptophan molecules and modifications of the tertiary structure of the protein have to be taken into account to explain the observed spectroscopic data.