Design of modular autoproteolytic gene switches responsive to anti-coronavirus drug candidates

The main (Mpro) and papain-like (PLpro) proteases encoded by SARS-CoV-2 are essential to process viral polyproteins into functional units, thus representing key targets for anti-viral drug development. There is a need for an efficient inhibitor screening system that can identify drug candidates in a cellular context. Here we describe modular, tunable autoproteolytic gene switches (TAGS) relying on synthetic transcription factors that self-inactivate, unless in the presence of coronavirus protease inhibitors, consequently activating transgene expression. TAGS rapidly report the impact of drug candidates on Mpro and PLpro activities with a high signal-to-noise response and a sensitivity matching concentration ranges inhibiting viral replication. The modularity of the TAGS enabled the study of other Coronaviridae proteases, characterization of mutations and multiplexing of gene switches in human cells. Mice implanted with Mpro or PLpro TAGS-engineered cells enabled analysis of the activity and bioavailability of protease inhibitors in vivo in a virus-free setting.

Kinetic Characterization and Inhibitor Screening of Pyruvate Kinase I From Babesia microti

The apicomplexan Babesia microti is a main pathogenic parasite causing human babesiosis, which is one of the most widely distributed tick-borne diseases in humans. Pyruvate kinase (PYK) plays a central metabolic regulatory role in most living organisms and catalyzes the essentially irreversible step in glycolysis that converts phosphoenolpyruvate (PEP) to pyruvate. Hence, PYK is recognized as an attractive therapeutic target in cancer and human pathogens such as apicomplexans. In this study, we cloned, expressed, and purified B. microti PYK I (BmPYKI). Western blotting illustrated that anti-rBmPYKI antibody could specifically recognize the native BmPYKI protein in the lysate of B. microti with a 54-kDa band, which is consistent with the predicted size. In addition, the enzymatic activity of the purified recombinant PYKI (rPYKI) was tested under a range of pH values. The results showed that the maximum catalytic activity could be achieved at pH 7.0. The saturation curves for substrates demonstrated that the Km value for PEP was 0.655 ± 0.117 mM and that for ADP was 0.388 ± 0.087 mM. We further investigated the effect of 13 compounds on rBmPYKI. Kinetic analysis indicated that six inhibitors (tannic acid, shikonin, apigenin, PKM2 inhibitor, rosiglitazone, and pioglitazone) could significantly inhibit the catalytic activity of PYKI, among which tannic acid is the most efficient inhibitor with an IC50 value 0.49 μM. Besides, four inhibitors (tannic acid, apigenin, shikonin, and PKM2 inhibitor) could significantly decrease the growth of in vitro-cultured B. microti with IC50 values of 0.77, 2.10, 1.73, and 1.15 μM. Overall, the present study provides a theoretical basis for the design and development of new anti-Babesia drugs.

Synergy between Experimental and Theoretical Investigations Reveals the Anti‑Corrosion Efficiency of Imine-Chalcones

The inhibitory action of three imine-chalcones on carbon steel corrosion in HCl was investigated by theoretical and experimental methods. Quantum descriptors were calculated at the conductor-like polarizable continuum model (CPCM)-Becke-3 Parameter-Lee-Yang-Parr (B3LYP)‑D3/def2-TZVPP level allowing the prediction of efficiency inhibition ranking. Electrochemical techniques and mass loss experiments were employed to determine inhibition efficiencies and related experimental parameters. Scanning electron microscopy was employed for metal surface analysis. The N-[(1Z,2E)-1,3-diphenylprop-2-in-1-ylidene]-1-phenethylamine (IM‑F) was pointed out as the most efficient inhibitor in this group, with 96% of corrosion inhibition. Moreover, theoretical results obtained from periodic calculations for the adsorption on the Fe(110) surface corroborated the highest efficacy of IM‑F.

Design of Carboxylated Single-Walled Carbon Nanotube as High-Efficient Inhibitor against Aβ40 Fibrillation based on HyBER Mechanism

Misfolding and subsequent self-assembly of amyloid-β protein (Aβ) is very important for the occurrence of Alzheimer's disease (AD). Thus, inhibition of Aβ aggregation is currently an effective method to alleviate...