Identifying promising druggable binding sites and their flexibility to target the receptor-binding domain of SARS-CoV-2 spike protein.

The spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is crucial for viral infection. The interaction of its receptor-binding domain (RBD) with the human angiotensin-converting enzyme 2 (ACE2) protein is required for the virus to enter the host cell. We identified RBD binding sites to block its function with inhibitors by combining the protein structural flexibility with machine learning analysis. Molecular dynamics simulations were performed on unbound or ACE2-bound RBD conformations. Pockets estimation, tracking and druggability prediction were performed on a large sample of simulated RBD conformations. Recurrent druggable binding sites and their key residues were identified by clustering pockets based on their residue similarity. This protocol successfully identified three druggable sites and their key residues, aiming to target with inhibitors for preventing ACE2 interaction. One site features key residues for direct ACE2 interaction, highlighted using energetic computations, but can be affected by several mutations of the variants of concern. Two highly druggable sites, located between the spike protein monomers interface are promising. One weakly impacted by only one Omicron mutation, could contribute to stabilizing the spike protein in its closed state. The other, currently not affected by mutations, could avoid the activation of the spike protein trimer.

The child as a medium. Breakdown and possible resurgence of children's agency in the era of pandemic.

This paper deals with the unpredictable outbreak of the pandemic, explaining its impact on the education system, and with structural flexibility as a way to face unpredictability, based on the generalisability and coordination of manifestations of agency. The pandemic has enhanced a narrative of the child as a medium of learning, which undermines children's agency. The example of the research project CHILD-UP (Children Hybrid Integration: Learning Dialogue as a way of Upgrading policies of Participation) is used to show how children's agency and structural flexibility in classroom interactions can be supported and analysed.

Continued Complexity of Mutations in Omicron Sublineages.

The latest SARS-CoV-2 variant of concern (VOC), Omicron (B.1.1.529), has diversified into more than 300 sublineages. With an expanding number of newly emerging sublineages, the mutation profile is also becoming complicated. There exist mutually exclusive and revertant mutations in different sublineages. Omicron sublineages share some common mutations with previous VOCs (Alpha, Beta, Gamma, and Delta), indicating an evolutionary relationship between these VOCs. A diverse mutation profile at the spike-antibody interface, flexibility of the regions harboring mutations, mutation types, and coexisting mutations suggest that SARS-CoV-2's evolution is far from over.

LL-37, a Multi-Faceted Amphipathic Peptide Involved in NETosis.

Innate immunity responds to infections and inflammatory stimuli through a carefully choreographed set of interactions between cells, stimuli and their specific receptors. Of particular importance are endogenous peptides, which assume roles as defensins or alarmins, growth factors or wound repair inducers. LL-37, a proteolytic fragment of cathelicidin, fulfills the roles of a defensin by inserting into the membranes of bacterial pathogens, functions as alarmin in stimulating chemotaxis of innate immune cells, and alters the structure and efficacy of various cytokines. Here, we draw attention to the direct effect of LL-37 on neutrophils and the release of extracellular traps (NETs), as NETs have been established as mediators of immune defense against pathogens but also as important contributors to chronic disease and tissue pathogenesis. We propose a specific structural basis for LL-37 function, in part by highlighting the structural flexibility of LL-37 and its ability to adapt to distinct microenvironments and interacting counterparts.

Molecular modeling identification of potential drug candidates from selected African plants against SARS-CoV-2 key druggable proteins.

Coronavirus disease 2019 (COVID-19) pandemic, caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is one of the major health threats the world has experienced. In order to stem the tide of the virus and its associated disease, rapid efforts have been dedicated to identifying credible anti-SARS-CoV-2 drugs. This study forms part of the continuing efforts to develop anti-SARS-CoV-2 molecules and employed a computational structure-activity relationship approach with emphasis on 99 plant secondary metabolites from eight selected African medicinal plants with proven therapeutic benefits against respiratory diseases focusing on the viral protein targets [Spike protein (Sgp), Main protease (Mpro), and RNA-dependent RNA polymerase (RdRp)]. The results of the molecular dynamics simulation of the best docked compounds presented as binding free energy revealed that three compounds each against the Sgp (VBS, COG and ABA), and Mpro (COR, QOR and ABG) had higher and better affinity for the proteins than the respective reference drugs, cefoperazone (CSP) and Nelfinavir (NEF), while four compounds (HDG, VBS, COR and KOR) had higher and favorable binding affinity towards RdRp than the reference standard, ramdesivir (RDS). Analysis of interaction with the receptor binding domain amino acid residues of Sgp showed that VBS had the highest number of interactions (17) relative to 14 and 13 for COG and ABA, respectively. For Mpro, COR showed interactions with catalytic dyad residues (His172 and Cys145). Compared to RDS, COR, HDG, VBS and KOR formed 19, 18, 17 and 12 H-bond and Van der Waal bonds, respectively, with RdRp. Furthermore, structural examination of the three proteins after binding to the lead compounds revealed that the compounds formed stable complexes. These observations suggest that the identified compounds might be beneficial in the fight against COVID-19 and are suggested for further in vitro and in vivo experimental validation.