Silico analysis of interaction between full-length SARS-CoV2 S protein with human Ace2 receptor: Modelling, docking, MD simulation

Recent developments in molecular modeling tools and applications related to pharmaceutical and biomedical research

In modern pharmaceutical and biomedical research, molecular modeling represents a useful tool to explore processes and their mechanistic bases at the molecular level. Integrating experimental and virtual analysis is a fruitful approach to study ligand-receptor interaction in chemical, biochemical and biological environments. In these fields, molecular docking and molecular dynamics are considered privileged techniques for modeling (bio)macromolecules and related complexes. This review aims to present the current landscape of molecular modeling in pharmaceutical and biomedical research by examining selected representative applications published in the last years and highlighting current topics and trends of this field. Thus, a systematic compilation of all published literature has not been attempted herein. After a brief overview of the main theoretical and computational tools used to investigate mechanisms at molecular level, recent applications of molecular modeling in drug discovery, ligand binding and for studying protein conformation and function will be discussed. Furthermore, specific sections will be devoted to the application of molecular modeling for unravelling enantioselective mechanisms underlying the enantioseparation of chiral compounds of pharmaceutical and biomedical interest as well as for studying new forms of noncovalent interactivity identified in biochemical and biological environments. The general aim of this review is to provide the reader with a modern overview of the topic, highlighting advancements and outlooks as well as drawbacks and pitfalls still affecting the applicability of theoretical and computational methods in the field of pharmaceutical and biomedical research.

Evolution of Sequence and Structure of SARS-CoV-2 Spike Protein: A Dynamic Perspective

Novel coronavirus (SARS-CoV-2) enters its host cell through a surface spike protein. The viral spike protein has undergone several modifications/mutations at the genomic level, through which it modulated its structure-function and passed through several variants of concern. Recent advances in high-resolution structure determination and multiscale imaging techniques, cost-effective next-generation sequencing, and development of new computational methods (including information theory, statistical methods, machine learning, and many other artificial intelligence-based techniques) have hugely contributed to the characterization of sequence, structure, function of spike proteins, and its different variants to understand viral pathogenesis, evolutions, and transmission. Laying on the foundation of the sequence-structure-function paradigm, this review summarizes not only the important findings on structure/function but also the structural dynamics of different spike components, highlighting the effects of mutations on them. As dynamic fluctuations of three-dimensional spike structure often provide important clues for functional modulation, quantifying time-dependent fluctuations of mutational events over spike structure and its genetic/amino acidic sequence helps identify alarming functional transitions having implications for enhanced fusogenicity and pathogenicity of the virus. Although these dynamic events are more difficult to capture than quantifying a static, average property, this review encompasses those challenging aspects of characterizing the evolutionary dynamics of spike sequence and structure and their implications for functions.

Artificial Lipid Biomembranes for Full-Length SARS-CoV-2 Receptor

The angiotensin-converting enzyme 2 (ACE2), as a functional receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is essential for assessing potential hosts and treatments. However, many studies are based on its truncated version but not full-length structure. Indeed, a single transmembrane (TM) helix presents in the full-length ACE2, influencing its interaction with SARS-CoV-2. Therefore, synthesis of the full-length ACE2 is an urgent requirement. Here, cell-free membrane protein synthesis systems (CFMPSs) are constructed for full-length membrane proteins. MscL is screened as a model among ten membrane proteins based on their expression and solubility. Next, CFMPSs are constructed and optimized based on natural vesicles, vesicles with four membrane proteins removed or two chaperonins added, and 37 types of nanodiscs. They all increase membrane protein solubility to over 50%. Finally, the full-length ACE2 of 21 species are successfully expressed with yields between 0.4 and 0.9 mg mL^-1 . The definite functional differences from the truncated version suggest that the TM region affects ACE2's structure and function. CFMPSs can be extended to more membrane proteins, paving the way for further applications.

In silico bioprospecting of antiviral compounds from marine fungi and mushroom for rapid development of nutraceuticals against SARS-CoV-2

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) affects human respiratory function that causes COVID-19 disease. COVID-19 has spread rapidly all over the world and became a pandemic within no time. Therefore, it is the need of hour to screen potential lead candidates from natural resources like edible mushrooms and marine fungi. These natural resources are very less explored till now and known to be the source for many medicinal compounds with several health benefits. These medicinal compounds can be easily exploited for the faster development of nutraceuticals for controlling SARS-CoV-2 infections. Our Insilico research suggests, bioactive compounds originating from mushroom and marine fungi shows strong potential to interact with ACE2 receptor or main protease of SARS-CoV-2, showing the inhibition activity towards the enzymatic protease. We performed a series of Insilico studies for the validation of our results, which includes Molecular docking, drug likeness property investigation by Swiss ADME tools, MD simulation, and thermodynamically stable free binding energy calculation. Overall, these results suggest that Ganodermadiol and Heliantriol F bioactive compounds originating from edible mushroom has strong potential to be developed as low-cost nutraceutical against SARS-CoV-2 viral infection. The drug candidate isolated from marine fungi and edible mushroom are highly unexplored for the development of potential alternative drug against SARS-CoV-2 virus with minimum side effects. Though our in silico studies of these compounds are showing a promising results against SARS-CoV-2 main protease and ACE2 receptor binding domain, the effectiveness of these bioactive compounds should be further validated by proper clinical trials.Communicated by Ramaswamy H. Sarma.

SARS-CoV-2: Molecular Structure, Pathogenesis, Potential Therapeutic Targets, and Immune Response of the Infected Subject

Background

The pathogenic mechanisms and immune response of COVID-19 are far from clear. Through a documentary review of literature, the authors describe virological and molecular aspects of SARS-CoV-2, the intimate mechanisms of cell infection, and potential therapeutic targets. They also analyze the characteristics of immune response of the infected subject.

Objectives

Objectives of this study are to describe the state of knowledge on virological data, molecular and physiopathogenic mechanisms of SARS-CoV-2, with a view to a better understanding of the therapeutic targets, as well as the immune response of the infected subject. Methodology. This documentary review is a compilation of several meta-analyses, consistent with the methodology described in the PRISMA statement on literature data on SARS-CoV-2, published between March 22 and August 14, 2020 (Moher et al.). The search engines used for the selection of articles were as follows: PubMed, Google Scholar, Global Health, and WHO reports. Papers of interest were those addressing virological and molecular data on SARS-CoV-2, therapeutic aspects of COVID-19, and immunity of the infected subject. Of the 617 eligible papers, 417 could be retained after removing the duplicates. Ultimately, only 50 articles were retained for final evaluation. The data collected allowed the development of a two-armed model around the physiopathological aspects and potential therapeutic targets, as well as aspects of host immunity, respectively. The model was then compared to data from the HIV literature.

Conclusion

Reported data could contribute to a better understanding of molecular mechanisms of cellular infection by SARS-CoV-2 as well as to a more easy explanation of the action of pharmacological agents used for the treatment, while elucidating intimate mechanisms of the immunity of infected subject.

Screening of potential spike glycoprotein / ACE2 dual antagonists against COVID-19 in silico molecular docking

The novel coronavirus disease has spread rapidly and caused sustained pressure on economic and medical resources to many countries. Vaccines and effective drugs are needed to fight against the epidemic. Traditional Chinese Medicine (TCM) plays an important and effective role in the treatment of COVID-19. Therefore, the active components of TCM are potential structural basis for the discovery of antiviral drugs. Through screening by molecular docking, Oleanolic acid, Tryptanthrin, Chrysophanol and Rhein were found to have better spike protein and ACE2 inhibitory activity, which could block the invasion and recognition of SARS-CoV-2 at the same time, should be investigated as antiviral candidates.

Identification of Hotspot Residues in Binding of SARS-CoV-2 Spike and Human ACE2 Proteins

Coronaviruses are a large family of viruses that can cause respiratory infections with varying severity from common cold to severe diseases such as novel coronavirus disease (COVID-19). COVID-19 has been declared as a global pandemic by the World Health Organization on March 11, 2020 and with the development of vaccines it slowed down as of this date. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) uses its spike glycoprotein (Sgp) to bind human angiotensin-converting enzyme 2 (hACE2) receptor, and mediates membrane fusion and virus entry. The recognition of Sgp to human ACE2 and its high affinity for it has been of great importance since this provides the first step in viral entry to human cells. Therefore, it is crucial to identify key residues (hotspots) in this process. In this study, computational alanine scanning has been performed for Sgp and hACE2. The residues identified with significance in binding and other residues in close proximity were studied further through molecular mechanics-based protein binding free energy change prediction methods. Moreover, the interfacial residues in both proteins were investigated for their cooperative binding. Additionally, folding free energy changes upon mutation to Ala were calculated to assess their effect on stability of Sgp and hACE2. Our results taken together with findings from previous studies revealed the residues that are most significant and are relatively significant in binding of Sgp to human ACE2 protein.

Unravelling the molecular interactions between the SARS-CoV-2 RBD spike protein and various specific monoclonal antibodies

Vaccination against SARS-CoV-2 just started in most of the countries. However, the development of specific vaccines against SARS-CoV-2 is not the only approach to control the virus and monoclonal antibodies (mAbs) start to merit special attention as a therapeutic option to treat COVID-19 disease. Here, the main conformations and interactions between the receptor-binding domain (RBD) of spike glycoprotein of SARS-CoV-2 (S protein) with two mAbs (CR3022 and S309) and the ACE2 cell receptor are studied as the main representatives of three different epitopes on the RBD of S protein. The combined approach of 1 μs accelerated molecular dynamics (aMD) and ab-initio hybrid molecular dynamics is used to identify the most predominant interactions under physiological conditions. Results allow to determine the main receptor-binding mapping, hydrogen bonding network and salt bridges in the most populated antigen-antibody interface conformations. The deep knowledge on the protein-protein interactions involving mAbs and ACE2 receptor with the spike glycoprotein of SARS-CoV-2 increases background knowledge to speed up the development of new vaccines and therapeutic drugs.

Arbidol targeting influenza virus A Hemagglutinin; A comparative study

Influenza (flu) is a serious global health threat. The Hemagglutinin (HA) protein binds the flu virus to the sialic acids at the surface of the host cells' membrane which allows the endocytosis of the virus. Therefore, potential inhibitors can attach to the active site of HA and block the virus life-cycle. In this study, the antiviral drug arbidol (ARB) and 16 HA-subtypes were docked and analyzed to represent different approaches in predicting the conformation of protein-ligand, protein-protein, and protein-glycan complex and its binding energy. Our findings show that ARB interacts with all HA subtypes, and H7 possesses the best affinity. The next influenza pandemic could be caused by H4, H5, H6, and H14 subtypes, which prompts further studies in investigating the interaction between these particular HA subtypes and other antiviral drugs to obtain higher efficacy.