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Chu F.-L.,Shandong University | Wen H.-L.,Shandong University | Zhang W.-Q.,U.S. Center for Disease Control and Prevention | Lin B.,U.S. Center for Disease Control and Prevention | And 6 more authors.

Objectives: To determine the effects of heptad repeat regions (HRs) and N-linked carbohydrate sites of the Newcastle disease virus hemagglutinin- neuraminidase (HN) protein on fusion of HN and fusion (F) proteins and HN-F interaction. Methods: We mutated six 'a' residues in the HRs and four asparagines in N-linked carbohydrate sites to alanine in the HN protein. A vaccinia-T7 RNA polymerase expression system was used to express HN cDNAs in BHK-21 cells to determine the HN functions. Deglycosylation was treated with PGNase F digestion. The formation of HN-F protein complexes was determined by the coimmunoprecipitation assay. Results: Each HR-mutated protein interfered with fusion and the HN-F interaction. The G4-mutated protein not only impaired fusion and HN-F interaction but also decreased activities in cell fusion promotion, hemadsorption and neuraminidase. Conclusions: It is assumed that two different mechanisms for mutations in these two regions are responsible for the decreased fusion promotion activity and the reduced ability of interaction with F protein. Mutations in the HRs impair fusion and HN-F interaction by altering the transmission of a signal from the globular domain to the F-specific region in the stalk, but the G4 mutation modulates fusion and HN-F interaction by the misfolding of some important structures. Copyright © 2012 S. Karger AG, Basel. Source

Liu S.,Key Laboratory for Experimental Teratology | Sun Y.,Key Laboratory for Experimental Teratology | Li W.,Key Laboratory for Experimental Teratology | Yu H.,Key Laboratory for Experimental Teratology | And 6 more authors.
FEMS Microbiology Letters

Eradication of Helicobacter pylori with traditional therapy often fails in clinical treatment. As a result, a novel efficacious therapeutic agent is strongly needed. Allitridi, a proprietary garlic derivative, has been successfully used to treat both systemic fungal and bacterial infections in China. Our previous study has shown a dose-dependent inhibitory effect of allitridi on H. pylori growth. However, the antibacterial mode of action of allitridi is still unclear. Proteomic analysis was used to study the global protein alterations induced by allitridi. A total of 21 protein spots were identified to be differentially expressed. Our results indicated that the bacteriostatic mechanism of allitridi in H. pylori can be attributed to its multitarget inhibitory effects in energy metabolism and biosynthesis including amino acid biosynthesis, protein synthesis, mRNA synthesis and fatty acid biosynthesis. Allitridi can also disturb the expression of antioxidant proteins and decrease the production of virulence factors. Western blot analysis showed that allitridi at subinhibitory concentrations can potently suppress the production of CagA and VacA. Our investigations on the antibacterial mode of action of allitridi provide an insight into the potential use of allitridi as a therapeutic agent against H. pylori infection. © 2009 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved. Source

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