Journal of Microbiology

Journal Article

ZntR positively regulates T6SS4 expression in Yersinia pseudotuberculosis: Tietao Wang , Keqi Chen , Fen Gao , Yiwen Kang , Muhammad Tausif Chaudhry , Zhuo Wang , Yao Wang , Xihui Shen; J. Microbiol. 2017;55(6):448-456. Published online March 10, 2017; DOI: https://doi.org/10.1007/s12275-017-6540-2

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Abstract: The type VI secretion system (T6SS) is a widespread and versatile protein secretion system found in most Gram- negative bacteria. Studies of T6SS have mainly focused on its role in virulence toward host cells and inter-bacterial inter-actions, but studies have also shown that T6SS4 in Yersinia pseudotuberculosis participates in the acquisition of zinc ions to alleviate the accumulation of hydroxyl radicals induced by multiple stressors. Here, by comparing the gene expression patterns of wild-type and zntR mutant Y. pseudotubercu-losis cells using RNA-seq analysis, T6SS4 and 17 other bio-logical processes were found to be regulated by ZntR. T6SS4 was positively regulated by ZntR in Y. pseudotuberculosis, and further investigation demonstrated that ZntR regulates T6SS4 by directly binding to its promoter region. T6SS4 ex-pression is regulated by zinc via ZntR, which maintains in-tracellular zinc homeostasis and controls the concentration of reactive oxygen species to prevent bacterial death under oxidative stress. This study provides new insights into the regulation of T6SS4 by a zinc-dependent transcriptional regu-lator, and it provides a foundation for further investigation of the mechanism of zinc transport by T6SS.

Research Support, Non-U.S. Gov'ts

Roles of RpoS in Yersinia pseudotuberculosis stress survival, motility, biofilm formation and type VI secretion system expression: Jingyuan Guan , Xiao Xiao , Shengjuan Xu , Fen Gao , Jianbo Wang , Tietao Wang , Yunhong Song , Junfeng Pan , Xihui Shen , Yao Wang; J. Microbiol. 2015;53(9):633-642. Published online August 27, 2015; DOI: https://doi.org/10.1007/s12275-015-0099-6

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47 Citations

Abstract: RpoS (σS), the stationary phase/stress σ factor, controls the expression of a large number of genes involved in cellular responses to a variety of stresses. However, the role of RpoS appears to differ in different bacteria. While RpoS is an important regulator of flagellum biosynthesis, it is associated with biofilm development in Edwardsiella tarda. Biofilms are dense communities formed by bacteria and are important for microbe survival under unfavorable conditions. The type VI secretion system (T6SS) discovered recently is reportedly associated with several phenotypes, ranging from biofilm formation to stress sensing. For example, Vibrio anguillarum T6SS was proposed to serve as a sensor for extracytoplasmic signals and modulates RpoS expression and stress response. In this study, we investigated the physiological roles of RpoS in Yersinia pseudotuberculosis, including bacterial survival under stress conditions, flagella formation, biofilm development and T6SS expression. We found that RpoS is important in resistance to multiple stressors–including H2O2, acid, osmotic and heat shock–in Y. pseudotuberculosis. In addition, our study showed that RpoS not only modulates the expression of T6SS but also regulates flagellum formation by positively controlling the flagellar master regulatory gene flhDC, and affects the formation of biofilm on Caenorhabditis elegans by regulating the synthesis of exopolysaccharides. Taken together, these results show that RpoS plays a central role in cell fitness under several adverse conditions in Y. pseudotuberculosis.

Nucleotide-Binding Oligomerization Domain 2 (Nod2) Is Dispensable for the Innate Immune Responses of Macrophages against Yersinia enterocolitica: Yu-Jin Jeong , Chang-Hwan Kim , Eun-Jung Song , Min-Jung Kang , Jee-Cheon Kim , Sang-Muk Oh , Kyung-Bok Lee , Jong-Hwan Park; J. Microbiol. 2012;50(3):489-495. Published online June 30, 2012; DOI: https://doi.org/10.1007/s12275-012-1534-6

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Abstract: Nucleotide-binding oligomerization domain 2 (Nod2) is a cytosolic sensor for muramyl dipeptide, a component of bacterial peptidoglycan. In this study, we have examined whether Nod2 mediates the immune response of macrophages against Yersinia enterocolitica. Bone-marrow-derived macrophages (BMDMs) were isolated from WT and Nod2-deficient mice and were infected with various strains of Y. enterocolitica. ELISA showed that the production of IL-6 and TNF-α in BMDMs infected with Y. enterocolitica was not affected by the Nod2 deficiency. iNOS mRNA expression was induced in both WT and Nod2-deficienct BMDMs in response to Y. enterocolitica, beginning 2 h after infection. Nitric oxide (NO) production by Y. enterocolitica did not differ between WT and Nod2-deficient BMDMs. Western blot analysis revealed that Y. enterocolitica induces activation of NF-κB, p38, and ERK MAPK through a Nod2-independent pathway. Neither LDH release by Y. enterocolitica nor the phagocytic activity of the macrophages was altered by Nod2 deficiency. An in vivo experiment showed that bacterial clearance ability and production of IL-6 and KC in serum were comparable in WT and Nod2-deficient mice infected with Y. enterocolitica. These findings suggest that Nod2 may not be critical for initiating the innate immune response of macrophages against Yersinia infection.

Review

REVIEW] Recent Findings about the Yersinia enterocolitica Phage Shock Protein Response: Saori Yamaguchi , Andrew J. Darwin; J. Microbiol. 2012;50(1):1-7. Published online February 27, 2012; DOI: https://doi.org/10.1007/s12275-012-1578-7

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Abstract: The phage shock protein (Psp) system is a conserved extracytoplasmic stress response in bacteria that is essential for virulence of the human pathogen Yersinia enterocolitica. This article summarizes some recent findings about Y. enterocolitica Psp system function. Increased psp gene expression requires the transcription factor PspF, but under non-inducing conditions PspF is inhibited by an interaction with another protein, PspA, in the cytoplasm. A Psp-inducing stimulus causes PspA to relocate to the cytoplasmic membrane, freeing PspF to induce psp gene expression. This PspA relocation requires the integral cytoplasmic membrane proteins, PspB and PspC, which might sense an inducing trigger and sequester PspA by direct interaction. The subsequent induction of psp gene expression increases the PspA concentration, which also allows it to contact the membrane directly, perhaps for its physiological function. Mutational analysis of the PspB and PspC proteins has revealed that they both positively and negatively regulate psp gene expression and has also identified PspC domains associated with each function. We also compare the contrasting physiological roles of the Psp system in the virulence of Y. enterocolitica and Salmonella enterica sv. Typhimurium (S. Typhimurium). In S. Typhimurium, PspA maintains the proton motive force, which provides the energy needed to drive ion importers required for survival within macrophages. In contrast, in the extracellular pathogen Y. enterocolitica, PspB and PspC, but not PspA, are the Psp components needed for virulence. PspBC protect Y. enterocolitica from damage caused by the secretin component of its type 3 secretion system, an essential virulence factor.

Research Support, Non-U.S. Gov'ts

DNA Microarray-Based Global Transcriptional Profiling of Yersinia pestis in Multicellularity: Jingfu Qiu , Zhaobiao Guo , Haihong Liu , Dongsheng Zhou , Yanping Han , Ruifu Yang; J. Microbiol. 2008;46(5):557-563. Published online October 31, 2008; DOI: https://doi.org/10.1007/s12275-008-0140-0

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Abstract: Yersinia pestis, the causative agent of plague, has a feature of forming multicellular aggregates at liquid-air interface around the wall of glass tube. In this study, we employed the whole-genome DNA microarray of Y. pestis to investigate the global transcriptional profile in multicellularity compared with that in its planktonic growth. A total of 177 genes were differentially expressed in Y. pestis during early stage of multicellular formation; Seventy genes of them were up-regulated while 107 down-regulated. In addition to a large number of genes encoding unknown functions, most of the induced genes encode cell envelope and transport/binding proteins. The up-regulation of amino acid biosynthesis, the differentially altered genes that are involved in virulence, and the cold shock protein genes were for the first time reported to be associated with the multicellular formation. Our results revealed the global gene expression of Y. pestis were changed in the formation of multicellularity, providing insights into the molecular mechanism of multicellular behaviour, which need investigating further.

Novel Pathogenetic Mechanism in a Clinical Isolate of Yersinia enterocolitica KU14: Yoshinori Sato , Kenichi Kaneko , Takeshi Sasahara , Matsuhisa Inoue; J. Microbiol. 2006;44(1):98-105.; DOI: https://doi.org/2330 [pii]

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Abstract: Yersinia enterocolitica induces a broad range of gastrointestinal syndromes, including acute enteritis. We previously reported that the clinical isolate, Y. enterocolitica KU14, which lacks pYV, was still capable of causing clinical infection. The present study demonstrated that KU14 did not trigger the death of macrophages in vitro, unlike WA-314 (ATCC51871, which harbors the pYV virulence plasmid). However, the intracellular growth of KU14 in the macrophages was greater than that of WA-C (ATCC51872, a non-plasmid harboring the derivative pYV plasmid). Treatment with a cholesterol-binding drug (β-cyclodextrin) that affected lipid rafts resulted in a dramatic reduction in the intracellular growth of KU14. These data clearly indicate that the enhanced intracellular growth of KU14 is related to lipid raft-mediated infection.

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