Characterization of Molecular Chaperone GroEL as a Potential Virulence Factor in <i>Cronobacter sakazakii</i>
The molecular chaperone GroEL of <i>C. sakazakii</i>, a highly conserved protein encoded by the gene <i>grol</i>, has the basic function of responding to heat shock, thus enhancing the bacterium’s adaptation to dry and high-temperature environments, which poses a threat to fo...
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MDPI AG
2023-09-01
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| Series: | Foods |
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| Online Access: | https://www.mdpi.com/2304-8158/12/18/3404 |
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| author | Dongdong Zhu Yufei Fan Xiaoyi Wang Ping Li Yaping Huang Jingbo Jiao Chumin Zhao Yue Li Shuo Wang Xinjun Du |
| author_facet | Dongdong Zhu Yufei Fan Xiaoyi Wang Ping Li Yaping Huang Jingbo Jiao Chumin Zhao Yue Li Shuo Wang Xinjun Du |
| author_sort | Dongdong Zhu |
| collection | DOAJ |
| description | The molecular chaperone GroEL of <i>C. sakazakii</i>, a highly conserved protein encoded by the gene <i>grol</i>, has the basic function of responding to heat shock, thus enhancing the bacterium’s adaptation to dry and high-temperature environments, which poses a threat to food safety and human health. Our previous study demonstrated that GroEL was found in the bacterial membrane fraction and caused a strong immune response in <i>C. sakazakii</i>. In this study, we tried to elucidate the subcellular location and virulent effects of GroEL. In live <i>C. sakazakii</i> cells, GroEL existed in both the soluble and insoluble fractions. To study the secretory mechanism of GroEL protein, a non-reduced Western immunoblot was used to analyze the form of the protein, and the result showed that the exported GroEL protein was mainly in monomeric form. The exported GroEL could also be located on bacterial surface. To further research the virulent effect of <i>C. sakazakii</i> GroEL, an indirect immunofluorescence assay was used to detect the adhesion of recombinant GroEL protein to HCT-8 cells. The results indicated that the recombinant GroEL protein could adhere to HCT-8 cells in a short period of time. The recombinant GroEL protein could activate the NF-κB signaling pathway to release more pro-inflammatory cytokines (TNF-α, IL-6 and IL-8), downregulating the expression of tight-junction proteins (claudin-1, occluding, ZO-1 and ZO-2), which collectively resulted in dose-dependent virulent effects on host cells. Inhibition of the <i>grol</i> gene expression resulted in a significant decrease in bacterial adhesion to and invasion of HCT-8 cells. Moreover, the deficient GroEL also caused slow growth, decreased biofilm formation, defective motility and abnormal filamentation of the bacteria. In brief, <i>C. sakazakii</i> GroEL was an important virulence factor. This protein was not only crucial for the physiological activity of <i>C. sakazakii</i> but could also be secreted to enhance the bacterium’s adhesion and invasion capabilities. |
| first_indexed | 2024-03-10T22:45:04Z |
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| language | English |
| last_indexed | 2024-03-10T22:45:04Z |
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| spelling | doaj.art-1e2d7d547d7f4fba8d7e269206efadd92023-11-19T10:42:38ZengMDPI AGFoods2304-81582023-09-011218340410.3390/foods12183404Characterization of Molecular Chaperone GroEL as a Potential Virulence Factor in <i>Cronobacter sakazakii</i>Dongdong Zhu0Yufei Fan1Xiaoyi Wang2Ping Li3Yaping Huang4Jingbo Jiao5Chumin Zhao6Yue Li7Shuo Wang8Xinjun Du9State Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, ChinaState Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, ChinaState Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, ChinaState Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, ChinaState Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, ChinaState Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, ChinaState Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, ChinaState Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, ChinaState Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, ChinaState Key Laboratory of Food Nutrition and Safety, College of Food Science and Engineering, Tianjin University of Science and Technology, Tianjin 300457, ChinaThe molecular chaperone GroEL of <i>C. sakazakii</i>, a highly conserved protein encoded by the gene <i>grol</i>, has the basic function of responding to heat shock, thus enhancing the bacterium’s adaptation to dry and high-temperature environments, which poses a threat to food safety and human health. Our previous study demonstrated that GroEL was found in the bacterial membrane fraction and caused a strong immune response in <i>C. sakazakii</i>. In this study, we tried to elucidate the subcellular location and virulent effects of GroEL. In live <i>C. sakazakii</i> cells, GroEL existed in both the soluble and insoluble fractions. To study the secretory mechanism of GroEL protein, a non-reduced Western immunoblot was used to analyze the form of the protein, and the result showed that the exported GroEL protein was mainly in monomeric form. The exported GroEL could also be located on bacterial surface. To further research the virulent effect of <i>C. sakazakii</i> GroEL, an indirect immunofluorescence assay was used to detect the adhesion of recombinant GroEL protein to HCT-8 cells. The results indicated that the recombinant GroEL protein could adhere to HCT-8 cells in a short period of time. The recombinant GroEL protein could activate the NF-κB signaling pathway to release more pro-inflammatory cytokines (TNF-α, IL-6 and IL-8), downregulating the expression of tight-junction proteins (claudin-1, occluding, ZO-1 and ZO-2), which collectively resulted in dose-dependent virulent effects on host cells. Inhibition of the <i>grol</i> gene expression resulted in a significant decrease in bacterial adhesion to and invasion of HCT-8 cells. Moreover, the deficient GroEL also caused slow growth, decreased biofilm formation, defective motility and abnormal filamentation of the bacteria. In brief, <i>C. sakazakii</i> GroEL was an important virulence factor. This protein was not only crucial for the physiological activity of <i>C. sakazakii</i> but could also be secreted to enhance the bacterium’s adhesion and invasion capabilities.https://www.mdpi.com/2304-8158/12/18/3404<i>Cronobacter sakazakii</i>GroELexportvirulent effects |
| spellingShingle | Dongdong Zhu Yufei Fan Xiaoyi Wang Ping Li Yaping Huang Jingbo Jiao Chumin Zhao Yue Li Shuo Wang Xinjun Du Characterization of Molecular Chaperone GroEL as a Potential Virulence Factor in <i>Cronobacter sakazakii</i> Foods <i>Cronobacter sakazakii</i> GroEL export virulent effects |
| title | Characterization of Molecular Chaperone GroEL as a Potential Virulence Factor in <i>Cronobacter sakazakii</i> |
| title_full | Characterization of Molecular Chaperone GroEL as a Potential Virulence Factor in <i>Cronobacter sakazakii</i> |
| title_fullStr | Characterization of Molecular Chaperone GroEL as a Potential Virulence Factor in <i>Cronobacter sakazakii</i> |
| title_full_unstemmed | Characterization of Molecular Chaperone GroEL as a Potential Virulence Factor in <i>Cronobacter sakazakii</i> |
| title_short | Characterization of Molecular Chaperone GroEL as a Potential Virulence Factor in <i>Cronobacter sakazakii</i> |
| title_sort | characterization of molecular chaperone groel as a potential virulence factor in i cronobacter sakazakii i |
| topic | <i>Cronobacter sakazakii</i> GroEL export virulent effects |
| url | https://www.mdpi.com/2304-8158/12/18/3404 |
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