A Defect in the Twin-Arginine Translocation Pathway Decreases the Tolerance of Xanthomonas campestris pv. campestris to Phenazines

Phenazine-1-carboxylic acid (PCA), a member of phenazines secreted by microorganisms, inhibits the growth of many bacteria and fungi. Xanthomonas campestris pv. campestris is the causal agent of black rot, the most important disease of cruciferous crops worldwide, and is more tolerant to PCA than other Xanthomonas species. Previous studies reported that reactive oxygen species (ROS) scavenging ability is involved in regulating the PCA tolerance of Xanthomonas species. Additionally, the cytochrome c maturation (CCM) system has been found to play a more important role in tolerance to phenazines than the ROS scavenging system. In this study, a highly PCA-sensitive insertion mutant of X. campestris pv. campestris, X-5, was identified and studied. The insertion site of X-5 was found to be in tatB gene (XC_4183), which encodes a subunit of the twin-arginine translocation (TAT) complex. Disruption of the three genes of TAT pathway resulted in decreased biological fitness and reduced tolerance to phenazines in comparison with the wild-type strain 8004. These results imply that the tolerance mechanism of the TAT pathway to phenazines is related to the CCM system, but not due to the ROS scavenging system. Furthermore, respiration-related characteristic tests and peptide analysis suggested that disruption of the TAT complex causes a defect in the cytochrome bc1 complex, which may be involved in the tolerance to phenazines. In summary, this study sheds new light on the critical role of the TAT pathway in influencing the fitness and phenazines tolerance of Xanthomonas species.

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The critical role of cytochrome c maturation (CCM) system in the tolerance of Xanthomonas campestris pv. campestris to phenazines

Pesticide Biochemistry and Physiology ◽

10.1016/j.pestbp.2019.02.003 ◽

2019 ◽

Vol 156 ◽

pp. 63-71 ◽

Cited By ~ 2

Author(s):

Jian Wu ◽

Xiayan Pan ◽

Shu Xu ◽

Yabing Duan ◽

Jianying Luo ◽

...

Keyword(s):

Cytochrome C ◽

Xanthomonas Campestris ◽

Critical Role ◽

Cytochrome C Maturation ◽

Xanthomonas Campestris Pv Campestris

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The Twin-Arginine Translocation System Is Important for Stress Resistance and Virulence of Brucella melitensis

Infection and Immunity ◽

10.1128/iai.00389-20 ◽

2020 ◽

Vol 88 (11) ◽

Author(s):

Xin Yan ◽

Sen Hu ◽

Yan Yang ◽

Da Xu ◽

Huoming Li ◽

...

Keyword(s):

Ex Vivo ◽

Brucella Melitensis ◽

Cell Envelope ◽

Critical Role ◽

Sodium Dodecyl ◽

Methionine Sulfoxide Reductase ◽

Content Type ◽

Twin Arginine Translocation ◽

Tat Pathway

ABSTRACT Brucella, the causative agent of brucellosis, is a stealthy intracellular pathogen that is highly pathogenic to a range of mammals, including humans. The twin-arginine translocation (Tat) pathway transports folded proteins across the cytoplasmic membrane and has been implicated in virulence in many bacterial pathogens. However, the roles of the Tat system and related substrates in Brucella remain unclear. We report here that disruption of Tat increases the sensitivity of Brucella melitensis M28 to the membrane stressor sodium dodecyl sulfate (SDS), indicating cell envelope defects, as well as to EDTA. In addition, mutating Tat renders M28 bacteria more sensitive to oxidative stress caused by H2O2. Further, loss of Tat significantly attenuates B. melitensis infection in murine macrophages ex vivo. Using a mouse model for persistent infection, we demonstrate that Tat is required for full virulence of B. melitensis M28. Genome-wide in silico prediction combined with an in vivo amidase reporter assay indicates that at least 23 proteins are authentic Tat substrates, and they are functionally categorized into solute-binding proteins, oxidoreductases, cell envelope biosynthesis enzymes, and others. A comprehensive deletion study revealed that 6 substrates contribute significantly to Brucella virulence, including an l,d-transpeptidase, an ABC transporter solute-binding protein, and a methionine sulfoxide reductase. Collectively, our work establishes that the Tat pathway plays a critical role in Brucella virulence.

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Gibberellin 20-Oxidase Gene OsGA20ox3 Regulates Plant Stature and Disease Development in Rice

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-05-12-0138-r ◽

2013 ◽

Vol 26 (2) ◽

pp. 227-239 ◽

Cited By ~ 61

Author(s):

Xue Qin ◽

Jun Hua Liu ◽

Wen Sheng Zhao ◽

Xu Jun Chen ◽

Ze Jian Guo ◽

...

Keyword(s):

Transgenic Plants ◽

Critical Role ◽

Insertion Site ◽

Insertion Mutant ◽

Wild Type Plant ◽

Wild Type ◽

Oxidase Gene ◽

Dna Insertion ◽

Flanking Sequences ◽

Plant Stature

Gibberellin (GA) 20-oxidase (GA20ox) catalyses consecutive steps of oxidation in the late part of the GA biosynthetic pathway. A T-DNA insertion mutant (17S-14) in rice, with an elongated phenotype, was isolated. Analysis of the flanking sequences of the T-DNA insertion site revealed that an incomplete T-DNA integration resulted in enhanced constitutively expression of downstream OsGA20ox3 in the mutant. The accumulation of bioactive GA1 and GA4 were increased in the mutant in comparison with the wild-type plant. Transgenic plants overexpressing OsGA20ox3 showed phenotypes similar to those of the 17S-14 mutant, and the RNA interference (RNAi) lines that had decreased OsGA20ox3 expression exhibited a semidwarf phenotype. Expression of OsGA20ox3 was detected in the leaves and roots of young seedlings, immature panicles, anthers, and pollens, based on β-glucuronidase (GUS) activity staining in transgenic plants expressing the OsGA20ox3 promoter fused to the GUS gene. The OsGA20ox3 RNAi lines showed enhanced resistance against rice pathogens Magnaporthe oryzae (causing rice blast) and Xanthomonas oryzae pv. oryzae (causing bacterial blight) and increased expression of defense-related genes. Conversely, OsGA20ox3-overexpressing plants were more susceptible to these pathogens comparing with the wild-type plants. The susceptibility of wild-type plants to X. oryzae pv. oryzae was increased by exogenous application of GA3 and decreased by S-3307 treatment. Together, the results provide direct evidence for a critical role of OsGA20ox3 in regulating not only plant stature but also disease resistance in rice.

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