Study Of The Effects Of Juglone To Escherichia Coli Protein Expression

Juglone is separated from the hydroxyl naphthoquinone compounds extraction from walnut plants of the genus fresh root and stem bark, olive skin, because it has a variety of biological activities, including antitumor, antioxidant, antibacterial and insecticidal effect, but also has low toxicity, natural, no residue, not easy to produce drug resistance and other characteristics, and been widely concerned by researchers at home and abroad. If the walnut green husk and other plant waste can be used to a greater extent, it can not only save natural plant resources, but also reduce its pollution to the environment, even Juglone counts for various scientific research itself.Juglone has a certain inhibitory effect against bacteria, but its antibacterial mechanism is unclear. The results of previous studies showed a good effect of Juglone on the growth inhibition of Escherichia coli which is one of the most important and the largest number of bacteria in the intestinal tract of human and many animals, belonging to gram negative bacteria (G-), often used as a model organism in the study of structure or function. This aim of the study was to identify changes in the proteome of an original strain of Escherichia coli as compared with its strain treated with juglone and to analyze the differences using a proteomic approach in order to explore the inhibition mechanism of juglone on Escherichia coli exactly.This experiment treated Escherichia coli with 1/2MIC (minimal inhibitory concentration) of juglone and then breaked two groups of cells using the ultrasonic method to get their whole protein extraction. Then the technique of Lable-free mass spectrometry quantitative proteomics (LC-MS/MS) was used to identify differences of two isolates in protein expression. The differential proteins were subsequently analyzed via GO, Pathway and Network of bioinformatics processing according to protein function and metabolic pathway information to suggest the antibacterial mechanism of juglone.The results showed that the identified proteins (Ratio>2 or<0.5 and P<0.01) in the number of 2081 and 17020 peptides are found, in which 417 diffential proteins include 192 proteins down-regulated and 225 up-regulated. Through the GO analysis of differential protein on the base of three functional classification, the results showed that the biological process of proteins involves developmental process, cellular process, single-organism process, biological adhesion, metabolic process, localization, cellular component organization or biogenesis, signaling, behavior, response to stimulus, growth, locomotion, biological regulation and multi-organism process; the molecular function includes antioxidant activity, translation regulator activity, molecular function regulator, electron carrier activity, nucleic acid binding transcription factor activity, molecular transducer activity, binding, transporter activity, structural molecule activity, transcription factor activity(protein binding)and catalytic activity; the cell components involved include organelle, cell, extracellular region, macromolecular complex, nucleoid and membrane. Pathway KEGG database for annotation of proteins based on gene pathway proteins have a total of 107, calculates the significance level of these pathways through the inspection (P<0.05), screens 16 specific pathways, including Ribosome, Carbon metabolism, Glycine serine and threonine metabolism, Citrate cycle, Pyruvate metabolism, Tryptophan metabolism, Glyoxylate and dicarboxylate metabolism, Propanoate metabolism, Cysteine and methionine metabolism, Bacterial chemotaxis, and Metabolic pathways, Purine metabolism, Microbial metabolism in diverse environments, Cyanoamino acid metabolism, Biosynthesis of amino acids and RNA degradation. It can be seen from the identification results, effect of juglone on Escherichia coli involves almost all aspects of cell life activities. Through the analysis of functions and pathway of differentially expressed proteinand from the proteome level, we can detect that juglone on Escherichia coli inhibition mechanism is reflected in the life activities of protein synthesis, redox metabolism, transmembrane transport and stress response in E. coli, where the cellar response to DNA damage stimulation of the treatment group is relatively strong and DNA gyrase GyrA is possibly one of the targets.