• KSBB Journal
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• v.24 no.4
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• pp.393-396
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• 2009

New protein secretion system was developed using Type III Secretion System of Salmonella. N-terminal region of SlrP and SptP effector proteins were fused with TliA and EstA-P lipases by overlapping PCR. Lipase activity of Salmonella with SptP-TliA fusion system increased by 2.6 fold compare with wild type Salmonella strain. This result showed that lipase secretion via the T3SS would be a useful protein secretion machinery.

• The Plant Pathology Journal
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• v.36 no.6
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• pp.608-617
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• 2020

The type III secretion system (T3SS) is a key virulence determinant in the infection process of Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). Pathogen constructs a type III apparatus to translocate effector proteins into host cells, which have various roles in pathogenesis. 4-Hydroxybenozic acid and vanillic acid were identified from root extract of Sedum middendorffianum to have inhibitory effect on promoter activity of hrpA gene encoding the structural protein of the T3SS apparatus. The phenolic acids at 2.5 mM significantly suppressed the expression of hopP1, hrpA, and hrpL in the hrp/hrc gene cluster without growth retardation of Pst DC3000. Auto-agglutination of Pst DC3000 cells, which is induced by T3SS, was impaired by the treatment of 4-hydroxybenzoic acid and vanillic acid. Additionally, 2.5 mM of each two phenolic acids attenuated disease symptoms including chlorosis surrounding bacterial specks on tomato leaves. Our results suggest that 4-hydroxybenzoic acid and vanillic acid are potential anti-virulence agents suppressing T3SS of Pst DC3000 for the control of bacterial diseases.

• The Plant Pathology Journal
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• v.39 no.6
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• pp.584-591
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• 2023

Active plant immune response involving programmed cell death called the hypersensitive response (HR) is elicited by microbial effectors delivered through the type III secretion system (T3SS). The marine bacterium Hahella chejuensis contains two T3SSs that are similar to those of animal pathogens, but it was able to elicit HR-like cell death in the land plant Nicotiana benthamiana. The cell death was comparable with the transcriptional patterns of H. chejuensis T3SS-1 genes, was mediated by SGT1, a general regulator of plant resistance, and was suppressed by AvrPto1, a type III-secreted effector of a plant pathogen that inhibits HR. Thus, type III-secreted effectors of a marine bacterium are capable of inducing the nonhost HR in a land plant it has never encountered before. This suggests that plants may have evolved to cope with a potential threat posed by alien pathogen effectors. Our work documents an exceptional case of nonhost HR and provides an expanded perspective for studying plant nonhost resistance.

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.73.2-73.2
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• 2008

• The Plant Pathology Journal
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• v.38 no.1
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• pp.12-24
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• 2022

In this study, we conducted whole-genome sequencing with six species of Pectobacterium composed of seven strains, JR1.1, BP201601.1, JK2.1, HNP201719, MYP201603, PZ1, and HC, for the analysis of pathogenic factors associated with the genome of Pectobacterium. The genome sizes ranged from 4,724,337 bp to 5,208,618 bp, with the GC content ranging from 50.4% to 52.3%. The average nucleotide identity was 98% among the two Pectobacterium species and ranged from 88% to 96% among the remaining six species. A similar distribution was observed in the carbohydrate-active enzymes (CAZymes) class and extracellular plant cell wall degrading enzymes (PCWDEs). HC showed the highest number of enzymes in CAZymes and the lowest number in the extracellular PCWDEs. Six strains showed four subsets, and HC demonstrated three subsets, except hasDEF, in type I secretion system, while the type II secretion system of the seven strains was conserved. Components of human pathogens, such as Salmonella pathogenicity island 1 type type III secretion system (T3SS) and effectors, were identified in PZ1; T3SSa was not identified in HC. Two putative effectors, including hrpK, were identified in seven strains along with dspEF. We also identified 13 structural genes, six regulator genes, and five accessory genes in the type VI secretion system (T6SS) gene cluster of six Pectobacterium species, along with the loss of T6SS in PZ1. HC had two subsets, and JK2.1 had three subsets of T6SS. With the GxSxG motif, the phospholipase A gene did locate among tssID and duf4123 genes in the T6SSa cluster of all strains. Important domains were identified in the vgrG/paar islands, including duf4123, duf2235, vrr-nuc, and duf3396.

• Korean Journal of Microbiology
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• v.50 no.4
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• pp.281-284
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• 2014

Immune defense responses against Pseudomonas aeruginosa infection play an important role in maintaining homeostasis in the human body. Previously, we reported that expression of the bradykinin receptor (BR) is induced in response to P. aeruginosa infection. However, the factors responsible for the induction was uncertain. Here, we found that the type III secretion system (T3SS) is responsible for the induction of BR expression, and nucleoside diphosphate kinase (Ndk), as a novel T3SS effector, mediates the upregulation. The Ndk-mediated expression of BR was not induced by fliC mutant treatment, indicating the involvement of flagellin, one of the well-known pathogen-associated molecular patterns (PAMPs). Taken together, this study demonstrated that Ndk cooperates with flagella in the development of defense responses against P. aeruginosa infection.

• Journal of Microbiology and Biotechnology
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• v.21 no.7
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• pp.679-685
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• 2011

Xanthomonas oryzae pv. oryzae (Xoo) produces a putative effector, XoAvrBs2. We expressed XoAvrBs2 homologously in Xoo with a TAP-tag at the C-terminus to enable quantitative analysis of protein expression and secretion. Addition of rice leaf extracts from both Xoo-sensitive and Xoo-resistant rice cultivars to the Xoo cells induced expression of the XoAvrBs2 gene at the transcriptional and translational levels, and also stimulated a remarkable amount of XoAvrBs2 secretion into the medium. In a T3SS-defective Xoo mutant strain, secretion of the TAPtagged XoAvrBs2 was blocked. Thus, we elucidated the transcriptional and translational expressions of the XoAvrBs2 gene in Xoo was induced in vitro by the interaction with rice and the induced secretion of XoAvrBs2 was T3SSdependent. It is the first report to measure the homologous expression and secretion of XoAvrBs2 in vitro by rice leaf extract. Our system for the quantitative analysis of effector protein expression and secretion could be generally used for the study of host-pathogen interactions.

• Biomedical Science Letters
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• v.24 no.1
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• pp.1-8
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• 2018

${\mu}MT$ knockout mice are genetically deficient in the transmembrane domain of mu chain of the immunoglobulin M (IgM) heavy chain, resulting in the absence of mature B cells. ${\mu}MT$ knockout mice is an in vivo model system used to clarify the role of B cells in various diseases. Enteropathogenic Escherichia coli (EPEC) induces acute and chronic diarrheal disease, especially in children of developing countries. The formation of attaching and effacing (A/E) lesion is a prominent pathogenic factor in the intestinal epithelium of EPEC infection. The A/E lesion is modulated by genes located on the pathogenic island locus of enterocyte effacement (LEE) which encode a type III secretion system (T3SS) and A/E lesion-related effector proteins. Citrobacter rodentium is a murine pathogen utilized in studying the pathogenic mechanisms of EPEC in human infections. Citrobacter rodentium produce A/E lesion to attach to intestinal epithelium, thus providing a murine model pathogen to study EPEC. Several studies have investigated the pathogenesis of Citrobacter rodentium in the ${\mu}MT$ knockout mice. In this review, we introduce the ${\mu}MT$ murine model in the context of C. rodentium pathogenesis and describe in detail the role of B cells and antibodies in this disease.

• IMMUNE NETWORK
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• v.12 no.6
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• pp.284-290
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• 2012

Innate immune cells sense and respond to the cytoplasmic infection of bacterial pathogens through NLRP3, NLRC4 or AIM2 inflammasome depending on the unique molecular pattern of invading pathogens. The infection of flagellin- or type III secretion system (T3SS)-containing Gram-negative bacteria such as Salmonella enterica serovar Typhimurium (S. typhimurium) or Pseudomonas aeruginosa (P. aeruginosa) triggers NLRC4-dependent caspase-1 activation leading to the secretion of proinflammatory cytokines such as interleukin-1-beta (IL-$1{\beta}$) and IL-18. Previous studies have shown that apoptosis-associated speck-like protein containing a CARD (ASC) is also required for Salmonella-induced caspase-1 activation, but it is still unclear how ASC contributes to the activation of NLRC4 inflammasome in response to S. typhimurium infection. In this study, we demonstrate that S. typhimurium triggers the formation of ASC oligomer in a potassium depletion-independent manner as determined by in vitro crosslinking and in situ fluorescence imaging. Remarkably, inhibition of potassium efflux failed to block Salmonella-promoted caspase-1 activation and macrophage cell death. These results collectively suggest that ASC is substantially oligomerized to facilitate the activation of caspase-1 in response to S. typhimurium infection. Contrary to NLRP3 inflammasome, intracellular potassium depletion is not critical for NLRC4 inflammasome signaling by S. typhimurium.