In Silico Prediction of New Mutations That Can Improve the Binding Abilities Between 2019-nCoV Coronavirus and Human ACE2.

The Coronavirus Disease 2019 (COVID-19) has become an international public health emergency, posing a serious threat to human health and safety around the world. The 2019-nCoV coronavirus spike protein was confirmed to be highly susceptible to various mutations, which can trigger apparent changes of virus transmission capacity and the pathogenic mechanism. In this article, the binding interface was obtained by analyzing the interaction modes between 2019-nCoV coronavirus and the human ACE2. Based on the "SIFT server" and the "bubble" identification mechanism, 9 amino acid sites were selected as potential mutation-sites from the 2019-nCoV-S1-ACE2 binding interface. Subsequently, a total number of 171 mutant systems for 9 mutation-sites were optimized for binding-pattern comparsion analysis, and 14 mutations that may improve the binding capacity of 2019-nCoV-S1 to ACE2 were selected. The Molecular Dynamic Simulations were conducted to calculate the binding free energies of all the 14 mutant systems. Finally, we found that most of the 14 mutations on the 2019-nCoV-S1 protein could enhance the binding ability between 2019-nCoV coronavirus and human ACE2. Among which, the binding capacities for G446R, Y449R and F486Y mutations could be increased by 20 percent, and that for S494R mutant increased even by 38.98 percent. We hope this research could provide significant help for the future epidemic detection, drug and vaccine development.

Key residues influencing binding affinities of 2019-nCoV with ACE2 in different species.

The Novel Coronavirus Disease 2019 (COVID-19) has become an international public health emergency, which poses the most serious threat to the human health around the world. Accumulating evidences have shown that the new coronavirus could not only infect human beings, but also can infect other species which might result in the cross-species infections. In this research, 1056 ACE2 protein sequences are collected from the NCBI database, and 173 species with >60% sequence identity compared with that of human beings are selected for further analysis. We find 14 polar residues forming the binding interface of ACE2/2019-nCoV-Spike complex play an important role in maintaining protein-protein stability. Among them, 8 polar residues at the same positions with that of human ACE2 are highly conserved, which ensure its basic binding affinity with the novel coronavirus. 5 of other 6 unconserved polar residues (positions at human ACE2: Q24, D30, K31, H34 and E35) are proved to have an effect on the binding patterns among species. We select 21 species keeping close contacts with human beings, construct their ACE2 three-dimensional structures by Homology Modeling method and calculate the binding free energies of their ACE2/2019-nCoV-Spike complexes. We find the ACE2 from all the 21 species possess the capabilities to bind with the novel coronavirus. Compared with the human beings, 8 species (cow, deer, cynomys, chimpanzee, monkey, sheep, dolphin and whale) present almost the same binding abilities, and 3 species (bat, pig and dog) show significant improvements in binding affinities. We hope this research could provide significant help for the future epidemic detection, drug and vaccine development and even the global eco-system protections.

Amphoteric natural starch-coated polymer nanoparticles with excellent protein corona-free and targeting properties.

The protein corona on nano drug carriers is an important well-known biological issue that often induces biological incompatibility and screens the targeting molecules on the surfaces of carriers, thus causing a loss of targeting specificity. Although polyethylene glycol (PEG) and zwitterionic polymers have been widely used as anti-fouling materials, there still remain critical challenges for their use as protein-corona agents for drug delivery and targeting. Here, we have designed novel amphoteric natural starch-stabilized core-shell colloidal nanoparticles with more efficient protein corona-free properties, under long term circulation, at different protein concentrations and in different protein charge environments, compared to typical anti-fouling materials such as PEG and zwitterionic polymers. More importantly, the starch-coated polymer nanoparticles can be further functionalized by antibodies to achieve additional excellent targeting and cell internalization capabilities for their use in photodynamic therapy. Our findings demonstrate a novel protein-free or anti-fouling natural material that is very promising for use as highly efficient nano drug carriers and marine coatings.

L51P, a novel mutation in the PAS domain of hERG channel, confers long QT syndrome by impairing channel activation.

The human ether-à-go-go-related gene (hERG) potassium channel mediates the repolarization of ventricular action potentials. Mutations in the KCNH2 cause long QT syndrome (LQTS) and are associated with cardiac arrhythmias and sudden death. Here, we functionally analyzed a mutation of hERG potassium channel (p.L51P), gaining novel insights into clinical genotype-phenotype relationships. Potassium currents were recorded by whole-cell patch clamping in HEK293 cells transiently transfected with wild-type and/or mutant hERG potassium channel. Immunofluorescence assay and confocal imaging were undertaken to study the effects of L51P mutation on channel trafficking. The models of the protein structure of hERG and its mutations are predicted by Amber16 software. Molecular dynamics (MD) of individual protein were performed with Particle Mesh Ewald (PME). The production of MD simulations of hERG-WT and hERG-Mut at constant pressure and temperature were carried out with SHAKE. L51 was a conservative amino acid, located in the Per-Arnt-Sim (PAS) domain of the amino terminus. L51P caused loss of function via impairing channel activation. L51P was predicted to destroy hydrophobic structure in the PAS domain, thus causing the failure of channel opening. In summary, the present study identifies L51P as a novel mutation of hERG potassium channel. L51P mutation mechanistically impairs channel activation, reducing channel functionality.