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International Journal of Molecular... Nov 2019The prominent antibacterial and quorum sensing (QS) inhibition activity of aromatic plants can be used as a novel intervention strategy for attenuating bacterial...
The prominent antibacterial and quorum sensing (QS) inhibition activity of aromatic plants can be used as a novel intervention strategy for attenuating bacterial pathogenicity. In the present work, a total of 29 chemical components were identified in the essential oil (EO) of leaves by gas chromatography-mass spectrometry (GC-MS). The principal component was methyleugenol, followed by methyl trans-cinnamate, with relative contents of 90.46% and 4.25%, respectively. Meanwhile, the antibacterial activity and the QS inhibitory activity of EO were first evaluated here. Antibacterial activity assay and MIC detection against seven pathogens ( Onc5, ATCC25933, spp., ATCC25922, MG1, PAO1 and ATCC31532) demonstrated that ATCC25933 and MG1 had the higher sensitivity to EO, while PAO1 displayed the strongest resistance to EO. An anti-QS (anti-quorum sensing) assay revealed that at sub-minimal inhibitory concentrations (sub-MICs), EO strongly interfered with the phenotype, including violacein production, biofilm biomass, and swarming motility, as well as -hexanoyl-L-homoserine lactone (C6-HSL) production (i.e., a signaling molecule in ATCC31532) of . Detection of C6-HSL indicated that EO was capable of not only inhibiting C6-HSL production in , but also degrading the C6-HSL. Importantly, changes of exogenous C6-HSL production in CV026 revealed a possible interaction between EO and a regulatory protein (cviR). Additionally, quantitative real-time polymerase chain reaction (RT-qPCR) analysis demonstrated that the expression of QS-related genes (, , , , , , , and ) was significantly suppressed. Conclusively, these results indicated that EO can act as a potential antibacterial agent and QS inhibitor (QSI) against pathogens, preventing and controlling bacterial contamination.
Topics: Anti-Bacterial Agents; Bacteria; Biofilms; Gas Chromatography-Mass Spectrometry; Melaleuca; Microbial Sensitivity Tests; Oils, Volatile; Phenotype; Plant Extracts; Plant Leaves; Quorum Sensing
PubMed: 31739398
DOI: 10.3390/ijms20225696 -
Environmental Microbiology Aug 2019Dickeya dadantii is a plant pathogen that causes soft rot disease on vegetable and potato crops. To successfully cause infection, this pathogen needs to coordinately...
Dickeya dadantii is a plant pathogen that causes soft rot disease on vegetable and potato crops. To successfully cause infection, this pathogen needs to coordinately modulate the expression of genes encoding several virulence determinants, including plant cell wall degrading enzymes (PCWDEs), type III secretion system (T3SS) and flagellar motility. Here, we uncover a novel feed-forward signalling circuit for controlling virulence. Global RNA chaperone Hfq interacts with an Hfq-dependent sRNA ArcZ and represses the translation of pecT, encoding a LysR-type transcriptional regulator. We demonstrate that the ability of ArcZ to be processed to a 50 nt 3'- end fragment is essential for its regulation of pecT. PecT down-regulates PCWDE and the T3SS by repressing the expression of a global post-transcriptional regulator- (RsmA-) associated sRNA encoding gene rsmB. In addition, we show that the protein levels of two cyclic di-GMP (c-di-GMP) diguanylate cyclases (DGCs), GcpA and GcpL, are repressed by Hfq. Further studies show that both DGCs are essential for the Hfq-mediated post-transcriptional regulation on RsmB. Overall, our report provides new insights into the interplays between ubiquitous signalling transduction systems that were most studied independently and sheds light on multitiered regulatory mechanisms for a precise disease regulation in bacteria.
Topics: Bacterial Proteins; Cell Wall; Cyclic GMP; Enterobacteriaceae; Gene Expression Regulation, Bacterial; Plant Diseases; RNA, Bacterial; RNA, Small Untranslated; RNA-Binding Proteins; Signal Transduction; Type III Secretion Systems; Virulence; Virulence Factors
PubMed: 30895662
DOI: 10.1111/1462-2920.14603 -
ACS Chemical Biology Oct 2019Quaternary distance restraints are essential to define the three-dimensional structures of protein assemblies. These distances often fall within a range of 10-18 Å,...
Quaternary distance restraints are essential to define the three-dimensional structures of protein assemblies. These distances often fall within a range of 10-18 Å, which challenges the high and low measurement limits of conventional nuclear magnetic resonance (NMR) and double electron-electron resonance electron spin resonance spectroscopies. Here, we report the use of F paramagnetic relaxation enhancement (PRE) NMR in combination with F/paramagnetic labeling to equivalent sites in different subunits of a protein complex in micelles to determine intersubunit distances. The feasibility of this strategy was evaluated on a pentameric ligand-gated ion channel, for which we found excellent agreement of the F PRE NMR results with previous structural information. The study suggests that F PRE NMR is a viable tool in extracting distance restraints to define quaternary structures.
Topics: Animals; Bacterial Proteins; Dickeya; Fluorine; Gammaproteobacteria; Ion Channels; Mice; Nuclear Magnetic Resonance, Biomolecular; Protein Structure, Quaternary; Protein Subunits
PubMed: 31525026
DOI: 10.1021/acschembio.9b00692