| Bacterial infection serious threat to human health, the emergence of antibiotic let’s have the power and capacity ability to overcome of the bacteria-Antibiotics have been used as effective compounds to treat infections for a long time. At the same time, however, more and more pathogens evaluate antibiotic tolerance. Quorum sensing (QS) is the regulation of gene expression in response to concentration of bacteria to regulate the behaviors of bacteria community. Quorum sensing regulation produces some phenomenons, such as virulence factors, antibiotics, the light emitting, biofilm, and so on. Different kinds of signaling molecules mediated different QS systems, to prevent the accumulation of signaling molecules or recognition and combine with receptors can inhibit the QS regulation of virulence gene expression. Therefore, quorum-sensing inhibitors (QSI) are expected to become the effective weapon to control the pathogen infection and drug resistance. It is hoped that according to research the QS phenomenon to clarify the relationship of bacterial resistance and pathogenicity, and eventually find a new kind of antibiotics which not lead to bacteria produce drug resistance and eliminate pathogenic, to resolve the current the growing problem of bacterial resistance.First, in this paper, simulation the three-dimensional space of Pseudomonas aeruginosa quorum sensing receptor protein RhlR by computer software, establish a method of virtual screening quorum sensing inhibitors by molecular docking. We got 10 species quorum sensing inhibitors by molecular docking in the herbal small molecule database, then select the chlorogenic acid and andrographis lactone do activity verification, and showed good inhibitory effect of violacein produce.Edible fungi is safe, as well as long-term coexistence and struggle with the bacteria, so we have reason to believe that exist bacterial quorum sensing inhibitory factor in the edible fungi. Based on this, we use 75% methanol extract inhibit factor from a dozen edible fungi powder, utilize the report bacterium C. violaceum CV026 plate assay and inhibit pigment produced experiments, ultimately we got four effective crude extracts. Studied cell migration inhibition of the clinical common pathogenic bacteria Pseudomonas aeruginosa PA01 and Serratia marcescens MG1 by the four kinds of edible fungi crude extracts, the results show that they have different levels to inhibit bacteria migration.In order to study the active substance do damage the structure of the receptor protein or compete receptor protein loci with signal molecules, choose pseudomonas aeruginosa RhlR receptor protein as the research object, constructing RhlR gene expression host bacteria, induced produce a lot of receptor proteins, with interact with quorum sensing inhibitors discovered receptor proteins was not damaged, suggest that the active substances could be signaling molecules competitive inhibitor.Utilize multiple chromatographic techniques combined with quorum sensing AHL reporter strain, after samples dissolved, fumbled TLC separation conditions, column chromatography and active tracking, HPLC, separate and purifying the 4 kinds of edible fungi crude extract, eventually won the pure samples, structure analysis is underway.This study via virtual screening by molecular docking, screening edible fungus, genetic engineering strains and inhibiting factor separation and purification, received 10 small molecule inhibitors and 4 kinds of edible fungi crude extract, and preliminary study the quorum-sensing inhibition effect mechanism, may all belong to the competitive inhibitors. Different from the traditional antibiotics mechanism of to kill bacteria, bacteria QSI by interfering with bacterial quorum sensing system blocking the expression of virulence genes to achieve the purpose of anti-infective, does not affect the growth of bacteria, in theory, would not develop resistance. In the treatment of bacterial infections, plant disease and industrial production and other fields have broadly application prospects. |
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