An Induced Pocket for the Binding of Potent Fusion Inhibitor CL-385319 with H5N1 Influenza Virus Hemagglutinin

<div><p>The influenza glycoprotein hemagglutinin (HA) plays crucial roles in the early stage of virus infection, including receptor binding and membrane fusion. Therefore, HA is a potential target for developing anti-influenza drugs. Recently, we characterized a novel inhibitor of highly pathogenic H5N1 influenza virus, CL-385319, which specifically inhibits HA-mediated viral entry. Studies presented here identified the critical binding residues for CL-385319, which clustered in the stem region of the HA trimer by site-directed mutagenesis. Extensive computational simulations, including molecular docking, molecular dynamics simulations, molecular mechanics generalized Born surface area (MM_GBSA) calculations, charge density and Laplacian calculations, have been carried out to uncover the detailed molecular mechanism that underlies the binding of CL-385319 to H5N1 influenza virus HA. It was found that the recognition and binding of CL-385319 to HA proceeds by a process of “induced fit” whereby the binding pocket is formed during their interaction. Occupation of this pocket by CL-385319 stabilizes the neutral pH structure of hemagglutinin, thus inhibiting the conformational rearrangements required for membrane fusion. This “induced fit” pocket may be a target for structure-based design of more potent influenza fusion inhibitors.</p></div

Hydrogen bonds formed between CL-385319 and residues in binding pocket.

<p>Hydrogen bonds formed between CL-385319 and residues in binding pocket.</p

The expression of HA on the surface of wild-type and mutant pseudoviruses, as determined by Western blotting.

<p>The expression of HA on the surface of wild-type and mutant pseudoviruses, as determined by Western blotting.</p

Self-Attention and Convolution Fusion Network for Land Cover Change Detection over a New Data Set in Wenzhou, China

With the process of increasing urbanization, there is great significance in obtaining urban change information by applying land cover change detection techniques. However, these existing methods still struggle to achieve convincing performances and are insufficient for practical applications. In this paper, we constructed a new data set, named Wenzhou data set, aiming to detect the land cover changes of Wenzhou City and thus update the urban expanding geographic data. Based on this data set, we provide a new self-attention and convolution fusion network (SCFNet) for the land cover change detection of the Wenzhou data set. The SCFNet is composed of three modules, including backbone (local–global pyramid feature extractor in SLGPNet), self-attention and convolution fusion module (SCFM), and residual refinement module (RRM). The SCFM combines the self-attention mechanism with convolutional layers to acquire a better feature representation. Furthermore, RRM exploits dilated convolutions with different dilation rates to refine more accurate and complete predictions over changed areas. In addition, to explore the performance of existing computational intelligence techniques in application scenarios, we selected six classical and advanced deep learning-based methods for systematic testing and comparison. The extensive experiments on the Wenzhou and Guangzhou data sets demonstrated that our SCFNet obviously outperforms other existing methods. On the Wenzhou data set, the precision, recall and F1-score of our SCFNet are all better than 85%

The lowest energy conformation of CL-385319-hemagglutinin complex.

<p>The lowest energy conformation of CL-385319-hemagglutinin complex.</p

Dynamic stability from molecular docking simulation.

<p>A) The root-mean square deviation (RMSD) values with respect to the initial structures. B) The total energy (ETOT), potential energy (EPTOT),temperature (TEMP) and kinetic energy (EKTOT) fluctuations of the complex with the ligand binding versus simulation time.</p

Charge Density (<b>ρ</b>_b) and Its Laplacian (<b>∇</b>²<b>ρ</b>_b) at BCPs between Substrate and Main Residues at B3LYP/6-31+G (d,p) Level of Theory (a.u.).

<p>Charge Density (<b>ρ</b>_b) and Its Laplacian (<b>∇</b>²<b>ρ</b>_b) at BCPs between Substrate and Main Residues at B3LYP/6-31+G (d,p) Level of Theory (a.u.).</p

Site-directed mutagenesis analysis.

<p>A) The infectivities of mutant H5N1 pseudoviruses in MDCK cells. Wild-type pseudovirus was used as the positive control, while Env^- pseudovirus and cells-only (mock) were used as the negative control. B) Inhibitory activity of CL-385319 against the infection of the mutant H5N1 pseudoviruses. The samples were tested in triplicate, and the data were presented in mean ± SD. This experiment was repeated twice with similar results.</p

The initial structure of CL-385319-hemagglutinin complex.

<p>The initial structure of CL-385319-hemagglutinin complex.</p