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Li Y, Sun W, Wang Q, Yu Y, Wan Y, Zhou K, Guo R, Han X, Chen Z, Fang W, Jiang W. The GntR-like transcriptional regulator HutC involved in motility, biofilm-forming ability, and virulence in Vibrio parahaemolyticus. Microb Pathog 2022; 167:105546. [DOI: 10.1016/j.micpath.2022.105546] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 06/12/2021] [Accepted: 04/15/2022] [Indexed: 12/19/2022]
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Zhou X, Liu B, Liu Y, Shi C, Fratamico PM, Zhang L, Wang D, Zhang J, Cui Y, Xu P, Shi X. Two homologous Salmonella serogroup C1-specific genes are required for flagellar motility and cell invasion. BMC Genomics 2021; 22:507. [PMID: 34225670 PMCID: PMC8259012 DOI: 10.1186/s12864-021-07759-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/26/2021] [Indexed: 11/16/2022] Open
Abstract
Background Salmonella is a major bacterial pathogen associated with a large number of outbreaks of foodborne diseases. Many highly virulent serovars that cause human illness belong to Salmonella serogroup C1, and Salmonella ser. Choleraesuis is a prominent cause of invasive infections in Asia. Comparative genomic analysis in our previous study showed that two homologous genes, SC0368 and SC0595 in Salmonella ser. Choleraesuis were unique to serogroup C1. In this study, two single-deletion mutants (Δ0368 and Δ0595) and one double-deletion mutant (Δ0368Δ0595) were constructed based on the genome. All these mutants and the wild-type strain were subjected to RNA-Seq analysis to reveal functional relationships of the two serogroup C1-specific genes. Results Data from RNA-Seq indicated that deletion of SC0368 resulted in defects in motility through repression of σ28 in flagellar regulation Class 3. Consistent with RNA-Seq data, results from transmission electron microcopy (TEM) showed that flagella were not present in △0368 and △0368△0595 mutants resulting in both swimming and swarming defects. Interestingly, the growth rates of two non-motile mutants △0368 and △0368△0595 were significantly greater than the wild-type, which may be associated with up-regulation of genes encoding cytochromes, enhancing bacterial proliferation. Moreover, the △0595 mutant was significantly more invasive in Caco-2 cells as shown by bacterial enumeration assays, and the expression of lipopolysaccharide (LPS) core synthesis-related genes (rfaB, rfaI, rfaQ, rfaY, rfaK, rfaZ) was down-regulated only in the △0368△0595 mutant. In addition, this study also speculated that these two genes might be contributing to serotype conversion for Salmonella C1 serogroup based on their apparent roles in biosynthesis of LPS and the flagella. Conclusion A combination of biological and transcriptomic (RNA-Seq) analyses has shown that the SC0368 and SC0595 genes are involved in biosynthesis of flagella and complete LPS, as well as in bacterial growth and virulence. Such information will aid to revealing the role of these specific genes in bacterial physiology and evolution within the serogroup C1. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07759-z.
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Affiliation(s)
- Xiujuan Zhou
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture & Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Bin Liu
- College of Food Science and Engineering, Northwest Agriculture and Forestry University, Yangling, 712100, Shaanxi, China
| | - Yanhong Liu
- Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA, 19038, USA
| | - Chunlei Shi
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture & Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Pina M Fratamico
- Molecular Characterization of Foodborne Pathogens Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA, 19038, USA
| | - Lida Zhang
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture & Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Dapeng Wang
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture & Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jianhua Zhang
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture & Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yan Cui
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture & Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Ping Xu
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture & Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xianming Shi
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture & Biology, and State Key Lab of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240, China.
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Taw MN, Lee HI, Lee SH, Chang WS. Characterization of MocR, a GntR-like transcriptional regulator, in Bradyrhizobium japonicum: its impact on motility, biofilm formation, and soybean nodulation. J Microbiol 2015; 53:518-25. [PMID: 26224454 DOI: 10.1007/s12275-015-5313-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 07/15/2015] [Accepted: 07/20/2015] [Indexed: 10/23/2022]
Abstract
Bradyrhizobium japonicum is a Gram-negative soil bacterium that can fix nitrogen into ammonia by developing a symbiotic relationship with the soybean plant. MocR proteins make up a subfamily of GntR superfamily, one of the most widely distributed and prolific groups of the helix-turn-helix transcription factors. In this study, we constructed a mutant strain for mocR (blr6977) to investigate its role in cellular processes and symbiosis in B. japonicum. Although growth rate and morphology of the mutant were indistinguishable from those of the wild type, the mutant showed significant differences in motility and attachment (i.e., biofilm formation) from the wild type. The mutant displayed a decrease in biofilm formation, but was more motile than the wild type. The inactivation of mocR did not affect the number of nodules on soybean roots, but caused delayed nodulation. Delayed nodulation intrigued us to study competitiveness of the mutant infecting soybeans. The mutant was less competitive than the wild type, indicating that delayed nodulation might be due to competitiveness. Gene expressions of other MocR subfamily members were also compared between the wild type and mutant strains. None of the mocR-like genes examined in this study were differentially expressed between both strains.
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Affiliation(s)
- May Nyan Taw
- Department of Biology, University of Texas at Arlington, Arlington, Texas, 76019, USA
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Directed construction and analysis of a Sinorhizobium meliloti pSymA deletion mutant library. Appl Environ Microbiol 2013; 79:2081-7. [PMID: 23335760 DOI: 10.1128/aem.02974-12] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Resources from the Sinorhizobium meliloti Rm1021 open reading frame (ORF) plasmid libraries were used in a medium-throughput method to construct a set of 50 overlapping deletion mutants covering all of the Rm1021 pSymA megaplasmid except the replicon region. Each resulting pSymA derivative carried a defined deletion of approximately 25 ORFs. Various phenotypes, including cytochrome c respiration activity, the ability of the mutants to grow on various carbon and nitrogen sources, and the symbiotic effectiveness of the mutants with alfalfa, were analyzed. This approach allowed us to systematically evaluate the potential impact of regions of Rm1021 pSymA for their free-living and symbiotic phenotypes.
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Liu B, Zhang L, Zhu X, Shi C, Chen J, Liu W, He X, Shi X. PCR identification of Salmonella serogroups based on specific targets obtained by comparative genomics. Int J Food Microbiol 2011; 144:511-8. [DOI: 10.1016/j.ijfoodmicro.2010.11.010] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 11/01/2010] [Accepted: 11/07/2010] [Indexed: 11/28/2022]
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Chen AM, Wang YB, Jie S, Yu AY, Luo L, Yu GQ, Zhu JB, Wang YZ. Identification of a TRAP transporter for malonate transport and its expression regulated by GtrA from Sinorhizobium meliloti. Res Microbiol 2010; 161:556-64. [PMID: 20594941 DOI: 10.1016/j.resmic.2010.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 05/05/2010] [Accepted: 05/06/2010] [Indexed: 10/19/2022]
Abstract
Sinorhizobium meliloti can live as a saprophyte in soil or as a nitrogen-fixing symbiont inside the root nodule cells of alfalfa and related legumes by utilizing different organic compounds as its carbon source. Here we have identified the matPQMAB operon in S. meliloti 1021. Within this operon, matP, matQ and the M region of the fused gene matMA encode an extracytoplasmic solute receptor, a small transmembrane protein and a large transmembrane protein, consisting of three components of the tripartite ATP-independent periplasmic (TRAP) transporter for malonate transport. The A region of the fused gene matMA and matB encode malonate-metabolizing enzymes, malonyl-CoA decarboxylase and malonyl-CoA synthetase. The null mutant of each matPQMAB gene is unable to grow on M9 minimal medium containing malonate as the sole carbon source. However, these mutants can induce the formation of efficient nitrogen-fixing root nodules on alfalfa. The matPQMAB operon is expressed in free-living bacterial cells and symbiotic bacterial cells from infection threads and root nodules. The GntR family transcriptional regulator, GtrA, specifically binds the promoter of the matPQMAB operon, positively regulating its expression. Moreover, the matPQMAB can be transcriptionally induced by malonate. These results suggested that a C(3)-dicarboxylic acid TRAP transporter is responsible for malonate transport in S. meliloti.
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Affiliation(s)
- Ai-Min Chen
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
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Abstract
The ExpR/Sin quorum-sensing system of the gram-negative soil bacterium Sinorhizobium meliloti plays an important role in the establishment of symbiosis with its host plant Medicago sativa. A mutant unable to produce autoinducer signal molecules (sinI) is deficient in its ability to invade the host, but paradoxically, a strain lacking the quorum-sensing transcriptional regulator ExpR is as efficient as the wild type. We compared the whole-genome expression profile of the wild-type strain with strains missing one of the quorum-sensing regulatory components to identify genes controlled by the ExpR/Sin system throughout the different phases of the bacterial growth cycle, as well as in planta. Our analyses revealed that ExpR is a highly versatile regulator with a unique ability to show different regulatory capabilities in the presence or absence of an autoinducer. In addition, this study provided us with insight into the plant invasion defect displayed by the autoinducer mutant. We also discovered that the ExpR/Sin quorum-sensing system is repressed after plant invasion. Therefore, quorum sensing plays a crucial role in the regulation of many cell functions that ensures the successful invasion of the host and is inactivated once symbiosis is established.
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