Synthesis and evaluation of adenosine containing 3-arylfuran-2(5 H )-ones as tyrosyl-tRNA synthetase inhibitors

The pathophyiological role of aminoacyl-tRNA synthetases in digestive system diseases

Aminoacyl-tRNA synthetases (ARSs) catalyze the ligation of amino acids to their cognate transfer RNAs and are indispensable enzymes for protein biosynthesis in all the cells. Previously, ARSs were considered simply as housekeeping enzymes, however, they are now known to be involved in a variety of physiological and pathological processes, such as tumorigenesis, angiogenesis, and immune response. In this review, we summarize the role of ARSs in the digestive system, including the esophagus, stomach, small intestine, colon, as well as the auxiliary organs such as the pancreas, liver, and the gallbladder. Furthermore, we specifically focus on the diagnostic and prognostic value of ARSs in cancers, aiming to provide new insights into the pathophysiological implications of ARSs in tumorigenesis.

Potent Inhibition of SARS-CoV-2 nsp14 N7-Methyltransferase by Sulfonamide-Based Bisubstrate Analogues

Enzymes involved in RNA capping of SARS-CoV-2 are essential for the stability of viral RNA, translation of mRNAs, and virus evasion from innate immunity, making them attractive targets for antiviral agents. In this work, we focused on the design and synthesis of nucleoside-derived inhibitors against the SARS-CoV-2 nsp14 (N7-guanine)-methyltransferase (N7-MTase) that catalyzes the transfer of the methyl group from the S-adenosyl-l-methionine (SAM) cofactor to the N7-guanosine cap. Seven compounds out of 39 SAM analogues showed remarkable double-digit nanomolar inhibitory activity against the N7-MTase nsp14. Molecular docking supported the structure-activity relationships of these inhibitors and a bisubstrate-based mechanism of action. The three most potent inhibitors significantly stabilized nsp14 (ΔTm ≈ 11 °C), and the best inhibitor demonstrated high selectivity for nsp14 over human RNA N7-MTase.

Two Forms of Tyrosyl-tRNA Synthetase from Pseudomonas aeruginosa: Characterization and Discovery of Inhibitory Compounds

Pseudomonas aeruginosa is a multidrug-resistant (MDR) pathogen and a causative agent of both nosocomial and community-acquired infections. The genes (tyrS and tyrZ) encoding both forms of P. aeruginosa tyrosyl-tRNA synthetase (TyrRS-S and TyrRS-Z) were cloned and the resulting proteins purified. TyrRS-S and TyrRS-Z were kinetically evaluated and the K_m values for interaction with Tyr, ATP, and tRNA^Tyr were 172, 204, and 1.5 μM and 29, 496, and 1.9 μM, respectively. The k_cat^obs values for interaction with Tyr, ATP, and tRNA^Tyr were calculated to be 3.8, 1.0, and 0.2 s^-1 and 3.1, 3.8, and 1.9 s^-1, respectively. Using scintillation proximity assay (SPA) technology, a druglike 2000-compound library was screened to identify inhibitors of the enzymes. Four compounds (BCD37H06, BCD38C11, BCD49D09, and BCD54B04) were identified with inhibitory activity against TyrRS-S. BCD38C11 also inhibited TyrRS-Z. The IC₅₀ values for BCD37H06, BCD38C11, BCD49D09, and BCD54B04 against TyrRS-S were 24, 71, 65, and 50 μM, respectively, while the IC₅₀ value for BCD38C11 against TyrRS-Z was 241 μM. Minimum inhibitory concentrations (MICs) were determined against a panel of clinically important pathogens. All four compounds were observed to inhibit the growth of cultures of both Gram-positive and Gram-negative bacteria organisms with a bacteriostatic mode of action. When tested against human cell cultures, none of the compounds were toxic at concentrations up to 400 μg/mL. In mechanism of inhibition studies, BCD38C11 and BCD49D09 selectively inhibited TyrRS activity by competing with ATP for binding. BCD37H06 and BCD54B04 inhibited TyrRS activity by a mechanism other than substrate competition.

A bisubstrate reagent orchestrating adenosine triphosphate and l-tyrosine and making tyrosyl adenylate: partial mimicking of tyrosyl-tRNA synthetase

We report the development of a bisubstrate reagent that, similar to tyrosyl t-RNA synthetase (TyrTS), provides a surface for ATP and l-Tyr to render a pseudo-intramolecular reaction forming 5'-tyrosyl adenylate (tyrAd). The presence of the reagent in solution with TyrTS marred the enzymatic reaction and, noticeably, tyrAd formed under the catalytic mode of the biomodel reagent was not picked up by TyrTS and hence was not transferred to tRNA. A potential application of this reagent, which doesn't allow the formation of tyrosyl tRNA, may lie in an emerging therapeutic targeting the translation machinery of cells without inhibiting the normal workings of enzymes.