C-2 Thiophenyl Tryptophan Trimers Inhibit Cellular Entry of SARS-CoV-2 through Interaction with the Viral Spike (S) Protein

26 páginas, 6 figuras, 2 tablas.Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19, by infecting cells via the interaction of its spike protein (S) with the primary cell receptor angiotensin-converting enzyme (ACE2). To search for inhibitors of this key step in viral infection, we screened an in-house library of multivalent tryptophan derivatives. Using VSV-S pseudoparticles, we identified compound 2 as a potent entry inhibitor lacking cellular toxicity. Chemical optimization of 2 rendered compounds 63 and 65, which also potently inhibited genuine SARS-CoV-2 cell entry. Thermofluor and microscale thermophoresis studies revealed their binding to S and to its isolated receptor binding domain (RBD), interfering with the interaction with ACE2. High-resolution cryoelectron microscopy structure of S, free or bound to 2, shed light on cell entry inhibition mechanisms by these compounds. Overall, this work identifies and characterizes a new class of SARS-CoV-2 entry inhibitors with clear potential for preventing and/or fighting COVID-19.Funding for this project was provided by grants from the European Commission NextGenerationEU fund (EU 2020/2094), through CSIC’s Global Health Platform (PTI Salud Global), Crue-CSIC-Santander Fondo Supera Covid-19, and CSIC grant (CSIC-COV19-082) to R.G., M.-J-P.-P., V.R., J.B., A.M., and J.-L.L. and CIBERER, Instituto de Salud Carlos III (COV20/00437) to V.R., J.B., A.M., and J.-L.L. In addition, this work was funded by grant (Covid_19-SCI) from the Generalitat Valenciana y Conselleria de Innovación, Universidades, Ciencia y Sociedad digital to R.G., and by grants PID2020-120322RB-C21 and PID2020-116880GB-I00 from the Agencia Estatal de Investigación of the Spanish Government to V.R. and J.-L.L., respectively.Peer reviewe

The altered expression of Microrna408 influences the arabidopsis response to iron deficiency

MicroRNAs contribute to the adaptation of plants to varying environmental conditions by affecting systemic mineral nutrient homeostasis. Copper and iron deficiencies antagonistically control the expression of Arabidopsis thaliana microRNA408 (miR408), which post-transcriptionally regulates laccase-like multicopper oxidase family members LAC3, LAC12, and LAC13. In this work, we used miR408 T-DNA insertion mutants (408-KO1 and 408-KO2) and a previously characterized transgenic line overexpressing miR408 (35S:408-14) to explore how miR408 influences copper- and iron-dependent metabolism. We observed that the altered expression of miR408 diminished plant performance and the activation of the iron-regulated genes under iron-deficient conditions. Consistently with the low expression of the miR408-target laccases, we showed that the vascular bundle lignification of the 35S:408-14 plants diminished. The decrease in the phenoloxidase and ferroxidase activities exhibited by wild-type plants under iron deficiency did not occur in the 408-KO1 plants, probably due to the higher expression of laccases. Finally, we observed that the hydrogen peroxide levels under iron starvation were altered in both the 408-KO1 and 35S:408-14 lines. Taken together, these results suggest that Arabidopsis plants with modified miR408 levels undergo multiple deregulations under iron-deficient conditions.This work was supported by grant BIO2017-87828-C2-1-P from the Spanish Ministry of Economy, Industry and Competitiveness, and by FEDER funds from the European Union. ÀC-S and AP-G were recipients of predoctoral FPI and post-doctoral Juan de la Cierva Formación contracts, respectively, from the Spanish Ministry of Economy, Industry and Competitiveness.Peer Reviewe