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Jeong Min CHUNG 한국생물공학회 2021 한국생물공학회 학술대회 Vol.2021 No.10
Some of the most essential and fundamental cellular functions are often carried out by dynamic multimolecular assemblies. Although our categorization of the number and assortment of protein interactions is increasing, we still lack knowledge about how collections of proteins are precisely assembled into macromolecular machines. Bacterial pathogens are a threat to global health and have evolved elaborate strategies to infect their hosts. Bacteria use specialized membrane spanning macromolecular machines, bacterial secretion systems, to transport virulence factors across bacterial and host membranes. Legionella pneumophila use a Type IV Secretion System (T4SS) to translocate as many as 300 effector proteins into human lung macrophages, resulting in the potentially fatal pneumonia Legionnaires’ disease. Helicobacter pylori and Bordetella pertussis also use T4SS to establish infections causing stomach cancer and whooping cough, respectively. In this study, we used cryo-electron microscopy (cryo-EM) as a structural approach for visualizing organization and function of dynamic molecular complexes. With the recent advances in cryo-EM, we have yielded a wealth of structural information about these complex macromolecular machines. Detailed structures of the machines used by bacteria to infect and hijack host cells will not only lead to mechanistic insights into pathogenesis, but also provide exciting possibilities for pharmacological intervention towards preventative therapies and/or treatment of human disease.
Tackling multiple bacterial diseases of Solanaceae with a handful of immune receptors
Ho Bang Kim,최지현,Cécile Segonzac 한국원예학회 2022 Horticulture, Environment, and Biotechnology Vol.63 No.2
Every year, despite the use of chemicals, signifi cant crop loss is caused by pathogenic microbes. Plant innate resistance to pathogens depends on two sets of genetically encoded immune receptors that sense invaders and trigger signaling cascades leading to reinforcement of physical barriers and production of various antimicrobial compounds. In the past 30 years, the molecular cloning and characterization of plant immune receptors have deepened our understanding of the plant immune system and more importantly, have provided means to improve crop protection against devastating pathogens. Here, we review the molecular characterization of selected immune receptors that can detect multiple species of bacterial pathogens through an expanded recognition range, or through the detection of conserved pathogen activities or host targets. These recent structural and molecular insights about the activation of immune receptors provide the necessary framework to design their concomitant deployment in crops, in order to lower selective pressure on pathogen populations and prevent evasion from recognition. Hence, these few immune receptors emerge as high potential genetic resources to provide durable and environmentally safe protection against important bacterial diseases of solanaceous crops.
Ji Eun Kang,Byeong Jun Jeon,Min Young Park,Beom Seok Kim 한국식물병리학회 2020 Plant Pathology Journal Vol.36 No.6
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.
정혜정(Hyejung Jung),김홍섭(Hong-Seop Kim),한길(Gil Han),박정욱(Jungwook Park),서영수(Young-Su Seo) 한국식물병리학회 2022 Plant Pathology Journal Vol.38 No.2
Pseudomonas amygdali is a hemibiotrophic phytopathogen that causes disease in woody and herbaceous plants. Complete genomes of four P. amygdali pathovars were comparatively analyzed to decipher the impact of genomic diversity on host colonization. The pan-genome indicated that 3,928 core genes are conserved among pathovars, while 504-1,009 are unique to specific pathovars. The unique genome contained many mobile elements and exhibited a functional distribution different from the core genome. Genes involved in O-antigen biosynthesis and antimicrobial peptide resistance were significantly enriched for adaptation to hostile environments. While the type III secretion system was distributed in the core genome, unique genomes revealed a different organization of secretion systems as follows: type I in pv. tabaci, type II in pv. japonicus, type IV in pv. morsprunorum, and type VI in pv. lachrymans. These findings provide genetic insight into the dynamic interactions of the bacteria with plant hosts.
The Role of Type III Secretion System 2 in Vibrio parahaemolyticus Pathogenicity
Hyeilin Ham,Kim Orth 한국미생물학회 2012 The journal of microbiology Vol.50 No.5
Vibrio parahaemolyticus, a Gram-negative marine bacterial pathogen, is emerging as a major cause of food-borne illnesses worldwide due to the consumption of raw seafood leading to diseases including gastroenteritis, wound infection, and septicemia. The bacteria utilize toxins and type III secretion system (T3SS) to trigger virulence. T3SS is a multi-subunit needle-like apparatus used to deliver bacterial proteins, termed effectors, into the host cytoplasm which then target various eukaryotic signaling pathways. V. parahaemolyticus carries two T3SSs in each of its two chromosomes, named T3SS1 and T3SS2, both of which play crucial yet distinct roles during infection: T3SS1 causes cytotoxicity whereas T3SS2 is mainly associated with enterotoxicity. Each T3SS secretes a unique set of effectors that contribute to virulence by acting on different host targets and serving different functions. Emerging studies on T3SS2 of V. parahaemolyticus, reveal its regulation,translocation, discovery, characterization of its effectors, and development of animal models to understand the enterotoxicity. This review on recent findings for T3SS2 of V. parahaemolyticus highlights a novel mechanism of invasion that appears to be conserved by other marine bacteria.
Novosphingobium sp. PP1Y as a novel source of outer membrane vesicles
Federica De Lise,Francesca Mensitieri,Giulia Rusciano,Fabrizio Dal Piaz,Giovanni Forte,Flaviana Di Lorenzo,Antonio Molinaro,Armando Zarrelli,Valeria Romanucci,Valeria Cafaro,Antonio Sasso,Amelia Filip 한국미생물학회 2019 The journal of microbiology Vol.57 No.6
Outer membrane vesicles (OMVs) are nanostructures of 20– 200 nm diameter deriving from the surface of several Gramnegative bacteria. OMVs are emerging as shuttles involved in several mechanisms of communication and environmental adaptation. In this work, OMVs were isolated and characterized from Novosphingobium sp. PP1Y, a Gram-negative non-pathogenic microorganism lacking LPS on the outer membrane surface and whose genome was sequenced and annotated. Scanning electron microscopy performed on samples obtained from a culture in minimal medium highlighted the presence of PP1Y cells embedded in an extracellular matrix rich in vesicular structures. OMVs were collected from the exhausted growth medium during the mid-exponential phase, and purified by ultracentrifugation on a sucrose gradient. Atomic force microscopy, dynamic light scattering and nanoparticle tracking analysis showed that purified PP1Y OMVs had a spherical morphology with a diameter of ca. 150 nm and were homogenous in size and shape. Moreover, proteomic and fatty acid analysis of purified OMVs revealed a specific biochemical “fingerprint”, suggesting interesting details concerning their biogenesis and physiological role. Moreover, these extracellular nanostructures do not appear to be cytotoxic on HaCaT cell line, thus paving the way to their future use as novel drug delivery systems.