ABSTRACT
Influenza A virus (H1N1) seriously affects the health of human and disrupts the development of global economic. The antimicrobial peptide urumin specifically binds to the conserved stem of the hemagglutinin (HA) protein of H1N1 virus, but its binding site and the mechanism of action are not clear. In this study, we investigated the possible binding sites and key amino acids for the interaction of urumin with HA protein by molecular docking and enzyme-linked immunosorbent assay (ELISA) experiments, suggesting that HA residues His32 (HA1), Asp19 (HA2), and Trp21 (HA2) are the key residues for the interaction of HA with urumin. Urumin's Arg4, Asn9, and Cys16 were associated with HA protein residues Asp19 (HA2), Trp21 (HA2), His32 (HA1), and Asn53 (HA2) form hydrogen bonding interactions, and Trp12 forms an aromatic π-stacking interaction with His32 (HA1) of HA, these interactions maintain the binding of urumin to HA protein. Wild-type HA and its alanine mutant [alanine substitutions His32 (HA1), Asp19 (HA2), and Trp21 (HA2)] were expressed in 293T cells. ELISA experiments showed that the affinity ability of urumin with HA wild-type was significantly higher than that of HA alanine mutant, suggesting that His32 (HA1), Asp19 (HA2), and Trp21 (HA2) may be the key residues for HA to interact with urumin. This study provides a theoretical and experimental basis for further modification and application of urumin.
ABSTRACT
Attenuated Salmonella VNP20009 specifically colonizes and proliferates within tumor tissues and inhibits tumor growth. It has been used as drug delivery vehicle or in combination with other therapies (such as chemotherapy), which shows a good application potential in tumor therapy. In this paper, study was conducted to determine the physiological changes of growth curve and formation of bacterial biofilm of VNP20009 under various environmental stresses, such as temperature, pH, and H2O2. The results showed that VNP20009 could grow normally under the conditions of 42 ℃, pH 6.5, and 1 mmol·L-1 H2O2. Furthermore, the weak acid environment was beneficial to the biofilm formation of VNP20009. This study provides a basis for in-depth study of the survival mechanism and application of attenuated Salmonella.
ABSTRACT
OBJECITVE: To explore the mechanism of Chinese herb Tripterygium wilfordii Hook f. in treatment with psoriasis, the virtual screening method was used to predict the potential protein targets of triptolide, one of the main effective compounds in Tripterygium.