A type <scp>VI</scp> secretion system regulated by <scp>OmpR</scp> in <scp>Y</scp>ersinia pseudotuberculosis functions to maintain intracellular <scp>pH</scp> homeostasis

Zhang, Weipeng; Wang, Yao; Song, Yunhong; Wang, Tietao; Xu, Shengjuan; Peng, Zhong; Lin, Xiaojun; Zhang, Lei; Shen, Xihui

doi:10.1111/1462-2920.12005

Cited by 95 publications

(127 citation statements)

References 62 publications

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“…The T6SS-4 cluster is important for Y. pseudotuberculosis survival under acidic conditions, high osmolarity, and exposure to the detergents, such as deoxycholate, that impair outer membrane integrity. Consistent with this, T6SS-4 is known to be regulated by RpoS and might function as a part of the general stress response (31)(32)(33). Hence, the observed upregulation in the TatC-deficient strain at 26°C could be a response to alterations in the outer membrane integrity (see also below) and the consequent upregulation of one or more stress response genes involved in the maintenance and repair of this structure.…”

Section: Resultssupporting

confidence: 53%

Transcriptomic and Phenotypic Analysis Reveals New Functions for the Tat Pathway in Yersinia pseudotuberculosis

et al. 2016

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The twin-arginine translocation (Tat) system mediates the secretion of folded proteins that are identified via an N-terminal signal peptide in bacteria, plants, and archaea. Tat systems are associated with virulence in many bacterial pathogens, and our previous studies revealed that Tat-deficient Yersinia pseudotuberculosis was severely attenuated for virulence. Aiming to identify Tat-dependent pathways and phenotypes of relevance for in vivo infection, we analyzed the global transcriptome of parental and ⌬tatC mutant strains of Y. pseudotuberculosis during exponential and stationary growth at 26°C and 37°C. The most significant changes in the transcriptome of the ⌬tatC mutant were seen at 26°C during stationary-phase growth, and these included the altered expression of genes related to virulence, stress responses, and metabolism. Subsequent phenotypic analysis based on these transcriptome changes revealed several novel Tat-dependent phenotypes, including decreased YadA expression, impaired growth under iron-limited and high-copper conditions, as well as acidic pH and SDS. Several functionally related Tat substrates were also verified to contribute to these phenotypes. Interestingly, the phenotypic defects observed in the Tat-deficient strain were generally more pronounced than those in mutants lacking the Tat substrate predicted to contribute to that specific function. Altogether, this provides new insight into the impact of Tat deficiency on in vivo fitness and survival/replication of Y. pseudotuberculosis during infection. IMPORTANCEIn addition to its established role in mediating the secretion of housekeeping enzymes, the Tat system has been recognized as being involved in infection. In some clinically relevant bacteria, such as Pseudomonas spp., several key virulence determinants can readily be identified among the Tat substrates. In enteropathogens, such as Yersinia spp., there are no obvious virulence determinants among the Tat substrates. Tat mutants show no growth defect in vitro but are highly attenuated in in vivo. This makes Tat an attractive target for the development of novel antimicrobials. Therefore, it is important to establish the causes of the attenuation. Here, we show that the attenuation is likely due to synergistic effects of different Tat-dependent phenotypes that each contributes to lowered in vivo fitness. Bacteria have evolved several specialized secretion systems for protein export as part of their successful strategies to colonize niches where they encounter various environmental conditions. Gram-negative bacteria possess different mechanisms to transport/export proteins, including virulence-related factors from the cytoplasm across the inner membrane and/or the outer membrane, either in a single step or acting together with other secretion systems (1). Two pathways, the secretory (Sec) and the twin-arginine translocation (Tat) pathways, are involved in the translocation of proteins from the cytoplasm to the periplasm. In Gramnegative bacteria, they can cooperate with other s...

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Section: Resultssupporting

confidence: 53%

Transcriptomic and Phenotypic Analysis Reveals New Functions for the Tat Pathway in Yersinia pseudotuberculosis

et al. 2016

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“…The 900-bp upstream PCR product and 862-bp downstream PCR product of nrdH were amplified using primer pairs DNrdH-F1/DNrdH-R1 and DNrdH-F2/DNrdH-R2, respectively. In the next step, the upstream and downstream PCR fragments were fused together with primer pairs DNrdH-F1/DNrdH-R2 by overlap PCR (30), and the resulting DNA fragments were digested with BamHI/SalI and inserted into similarly digested suicide plasmid pK18mobsacB to create pK18mobsacB-⌬nrdH. The plasmid pK18mobsacB-⌬prx used to construct the prx mutant was constructed similarly by using primers DPrx-F1/DPrx-R1 and DPrx-F2/DPrx-R2.…”

Section: Methodsmentioning

confidence: 99%

“…The plasmid pK18mobsacB-⌬prx used to construct the prx mutant was constructed similarly by using primers DPrx-F1/DPrx-R1 and DPrx-F2/DPrx-R2. Site-directed mutagenesis was carried out by overlap PCR (30) to mutate the active-site cysteine residue at position 11 of NrdH into a serine residue (NrdH::SXXC). In brief, the mutant nrdH::SXXC DNA segment was amplified by two rounds of PCR.…”

Section: Methodsmentioning

confidence: 99%

“…Expression in C. glutamicum was induced by the addition of 0.5 mM isopropyl ␤-D-1-thiogalactopyranoside (IPTG) into cultures. The lacZ fusion reporter vector pK18mobsacB-P nrdH ::lacZ was made by fusion of the nrdH promoter to the lacZY reporter gene by overlap PCR (30). In the first round of PCR, the 1,000-bp NrdH promoter DNA fragment and the lacZY DNA fragment were amplified with the primer pair PnrdH-F/PnrdH-R and lacZY-F/lacZY-R, respectively.…”

Section: Methodsmentioning

confidence: 99%

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NrdH Redoxin Enhances Resistance to Multiple Oxidative Stresses by Acting as a Peroxidase Cofactor in Corynebacterium glutamicum

Zhang

Zhong

et al. 2014

Appl Environ Microbiol

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bNrdH redoxins are small protein disulfide oxidoreductases behaving like thioredoxins but sharing a high amino acid sequence similarity to glutaredoxins. Although NrdH redoxins are supposed to be another candidate in the antioxidant system, their physiological roles in oxidative stress remain unclear. In this study, we confirmed that the Corynebacterium glutamicum NrdH redoxin catalytically reduces the disulfides in the class Ib ribonucleotide reductases (RNR), insulin and 5,5=-dithiobis-(2-nitrobenzoic acid) (DTNB), by exclusively receiving electrons from thioredoxin reductase. Overexpression of NrdH increased the resistance of C. glutamicum to multiple oxidative stresses by reducing ROS accumulation. Accordingly, elevated expression of the nrdH gene was observed when the C. glutamicum wild-type strain was exposed to oxidative stress conditions. It was discovered that the NrdH-mediated resistance to oxidative stresses was largely dependent on the presence of the thiol peroxidase Prx, as the increased resistance to oxidative stresses mediated by overexpression of NrdH was largely abrogated in the prx mutant. Furthermore, we showed that NrdH facilitated the hydroperoxide reduction activity of Prx by directly targeting and serving as its electron donor. Thus, we present evidence that the NrdH redoxin can protect against the damaging effects of reactive oxygen species (ROS) induced by various exogenous oxidative stresses by acting as a peroxidase cofactor.

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“…Acid survival assays. Acid survival assays were performed according to Zhang et al (2013) with a minor modification as follows: The overnight cultures of C. glutamicum strains in LB were appropriately diluted into LB or mineral salts medium (pH 4.0), and incubated at 30∞C for 1 h. After acid stress, the cultures were serially diluted and plated onto LB agar plates, and colonies were counted after 24 h growth at 30∞C. The percentage survival was calculated as follows: [(C.F.U.…”

Section: Methodsmentioning

confidence: 99%

Mycothiol protects Corynebacterium glutamicum against acid stress via maintaining intracellular pH homeostasis, scavenging ROS, and S-mycothiolating MetE

Liu

Yang

Yin

et al. 2016

J. Gen. Appl. Microbiol.

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Mycothiol (MSH) plays a major role in protect-ing cells against oxidative stress and detoxification from a broad range of exogenous toxic agents. In the present study, we reveal that intracellular MSH contributes significantly to the adaptation to acidic conditions in the model organism Corynebacterium glutamicum. We present evidence that MSH confers C. glutamicum with the ability to adapt to acidic conditions by maintaining pH i homeostasis, scavenging reactive oxygen species (ROS), and protecting methionine synthesis by the S-mycothiolation modification of methionine synthase (MetE). The role of MSH in acid adaptation was further confirmed by improving the acid tolerance of C. glutamicum by overexpressing the key MSH synthesis gene mshA. Hence, our work provides insights into a previously unknown, but important, aspect of the C. glutamicum cellular response to acid stress. The results reported here may help to understand acid tolerance mechanisms in acid sensitive bacteria and may open a new avenue for improving acid resistance in industry strains for the production of bio-based chemicals from renewable biomass.

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A type VI secretion system regulated by OmpR in Yersinia pseudotuberculosis functions to maintain intracellular pH homeostasis

Cited by 95 publications

References 62 publications

Transcriptomic and Phenotypic Analysis Reveals New Functions for the Tat Pathway in Yersinia pseudotuberculosis

Transcriptomic and Phenotypic Analysis Reveals New Functions for the Tat Pathway in Yersinia pseudotuberculosis

NrdH Redoxin Enhances Resistance to Multiple Oxidative Stresses by Acting as a Peroxidase Cofactor in Corynebacterium glutamicum

Mycothiol protects <i>Corynebacterium glutamicum</i> against acid stress via maintaining intracellular pH homeostasis, scavenging ROS, and <i>S</i>-mycothiolating MetE

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