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Zeng J, Yang Q, Ran Y, Guo Y, Jiao P, Qiao D, Cao Y, Xu H. Novel extracellular lipase gene Lip1728 influences nutrient-dependent performance bacterial quorum sensing of Burkholderia pyrrocinia WZ10-3. Int J Biol Macromol 2024; 278:134299. [PMID: 39097047 DOI: 10.1016/j.ijbiomac.2024.134299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 07/19/2024] [Accepted: 07/28/2024] [Indexed: 08/05/2024]
Abstract
Quorum sensing (QS) is a cellular communication mechanism in which bacteria secrete and recognize signaling molecules to regulate group behavior. Lipases provide energy for bacterial cell growth but it is unknown whether they influence nutrient-dependent QS by hydrolyzing substrate. A high-yield lipase-producing strain, Burkholderia pyrrocinia WZ10-3, was previously identified in our laboratory, but the composition of its crude enzymes was not elucidated. Here, we identified a key extracellular lipase, Lip1728, in WZ10-3, which accounts for 99 % of the extracellular lipase activity. Lip1728 prefers to hydrolyze triglycerides at sn-1,3 positions, with pNP-C16 being its optimal substrate. Lip1728 exhibited activity at pH 5.0-10.0 and regardless of the presence of metal ions. It had strong resistance to sodium dodecyl sulfate and short-chain alcohols and was activated by phenylmethanesulfonylfluoride (PMSF). Lip1728 knockout significantly affected lipid metabolism and biofilm formation in the presence of olive oil. Finally, oleic acid, a hydrolysate of Lip1728, influenced the production of the signal molecule N-acyl homoserine lactone (AHL) and biofilm formation by downregulating the AHL synthetase gene pyrI. In conclusion, Lip1728, as a key extracellular lipase in B. pyrrocinia WZ10-3, exhibits superior properties that make it suitable for biodiesel production and plays a crucial role in QS.
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Affiliation(s)
- Jie Zeng
- Microbiology and Metabolic Engineering of Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu 610065, PR China
| | - Qingzhuoma Yang
- Microbiology and Metabolic Engineering of Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu 610065, PR China
| | - Yulu Ran
- Microbiology and Metabolic Engineering of Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu 610065, PR China
| | - Yihan Guo
- Microbiology and Metabolic Engineering of Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu 610065, PR China
| | - Pengrui Jiao
- Microbiology and Metabolic Engineering of Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu 610065, PR China
| | - Dairong Qiao
- Microbiology and Metabolic Engineering of Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu 610065, PR China
| | - Yi Cao
- Microbiology and Metabolic Engineering of Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu 610065, PR China.
| | - Hui Xu
- Microbiology and Metabolic Engineering of Key Laboratory of Sichuan Province, College of Life Sciences, Sichuan University, Chengdu 610065, PR China.
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Krekhno Z, Woodward SE, Serapio-Palacios A, Peña-Díaz J, Moon KM, Foster LJ, Finlay BB. Citrobacter rodentium possesses a functional type II secretion system necessary for successful host infection. Gut Microbes 2024; 16:2308049. [PMID: 38299318 PMCID: PMC10841016 DOI: 10.1080/19490976.2024.2308049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 01/17/2024] [Indexed: 02/02/2024] Open
Abstract
Infectious diarrheal diseases are the third leading cause of mortality in young children, many of which are driven by Gram-negative bacterial pathogens. To establish successful host infections these pathogens employ a plethora of virulence factors necessary to compete with the resident microbiota, and evade and subvert the host defenses. The type II secretion system (T2SS) is one such conserved molecular machine that allows for the delivery of effector proteins into the extracellular milieu. To explore the role of the T2SS during natural host infection, we used Citrobacter rodentium, a murine enteric pathogen, as a model of human intestinal disease caused by pathogenic Escherichia coli such as Enteropathogenic and Enterohemorrhagic E. coli (EPEC and EHEC). In this study, we determined that the C. rodentium genome encodes one T2SS and 22 potential T2SS-secreted protein effectors, as predicted via sequence homology. We demonstrated that this system was functional in vitro, identifying a role in intestinal mucin degradation allowing for its utilization as a carbon source, and promoting C. rodentium attachment to a mucus-producing colon cell line. During host infection, loss of the T2SS or associated effectors led to a significant colonization defect and lack of systemic spread. In mice susceptible to lethal infection, T2SS-deficient C. rodentium was strongly attenuated, resulting in reduced morbidity and mortality in infected hosts. Together these data highlight the important role of the T2SS and its effector repertoire during C. rodentium pathogenesis, aiding in successful host mucosal colonization.
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Affiliation(s)
- Z Krekhno
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - SE Woodward
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - A Serapio-Palacios
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - J Peña-Díaz
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - KM Moon
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
| | - LJ Foster
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - BB Finlay
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, Canada
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
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3
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Jung H, Kim HS, Han G, Park J, Seo YS. Comparative Analyses of Four Complete Genomes in Pseudomonas amygdali Revealed Differential Adaptation to Hostile Environments and Secretion Systems. THE PLANT PATHOLOGY JOURNAL 2022; 38:167-174. [PMID: 35385921 PMCID: PMC9343901 DOI: 10.5423/ppj.nt.11.2021.0175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 03/03/2022] [Accepted: 03/10/2022] [Indexed: 06/14/2023]
Abstract
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.
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Affiliation(s)
- Hyejung Jung
- Department of Integrated Biological Science, Pusan National University, Busan 46241, Korea
| | - Hong-Seop Kim
- Korea Seed & Variety Service, Pyeongchang 25343, Korea
| | - Gil Han
- Department of Integrated Biological Science, Pusan National University, Busan 46241, Korea
| | - Jungwook Park
- Department of Integrated Biological Science, Pusan National University, Busan 46241, Korea
- Environmental Microbiology Research Team, Nakdonggang National Institute of Biological Resources (NNIBR), Sangju 37242, Korea
| | - Young-Su Seo
- Department of Integrated Biological Science, Pusan National University, Busan 46241, Korea
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4
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Goo E, Hwang I. Essential roles of Lon protease in the morpho-physiological traits of the rice pathogen Burkholderia glumae. PLoS One 2021; 16:e0257257. [PMID: 34525127 PMCID: PMC8443046 DOI: 10.1371/journal.pone.0257257] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 08/26/2021] [Indexed: 11/18/2022] Open
Abstract
The highly conserved ATP-dependent Lon protease plays important roles in diverse biological processes. The lon gene is usually nonessential for viability; however, lon mutants of several bacterial species, although viable, exhibit cellular defects. Here, we show that a lack of Lon protease causes pleiotropic effects in the rice pathogen Burkholderia glumae. The null mutation of lon produced three colony types, big (BLONB), normal (BLONN), and small (BLONS), in Luria–Bertani (LB) medium. Colonies of the BLONB and BLONN types were re-segregated upon subculture, while those of the BLONS type were too small to manipulate. The BLONN type was chosen for further studies, as only this type was fully genetically complemented. BLONN-type cells did not reach the maximum growth capacity, and their population decreased drastically after the stationary phase in LB medium. BLONN-type cells were defective in the biosynthesis of quorum sensing (QS) signals and exhibited reduced oxalate biosynthetic activity, causing environmental alkaline toxicity and population collapse. Addition of excessive N-octanoyl-homoserine lactone (C8-HSL) to BLONN-type cell cultures did not fully restore oxalate biosynthesis, suggesting that the decrease in oxalate biosynthesis in BLONN-type cells was not due to insufficient C8-HSL. Co-expression of lon and tofR in Escherichia coli suggested that Lon negatively affects the TofR level in a C8-HSL-dependent manner. Lon protease interacted with the oxalate biosynthetic enzymes, ObcA and ObcB, indicating potential roles for the oxalate biosynthetic activity. These results suggest that Lon protease influences colony morphology, growth, QS system, and oxalate biosynthesis in B. glumae.
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Affiliation(s)
- Eunhye Goo
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
- * E-mail:
| | - Ingyu Hwang
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
- Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
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Ortega L, Rojas CM. Bacterial Panicle Blight and Burkholderia glumae: From Pathogen Biology to Disease Control. PHYTOPATHOLOGY 2021; 111:772-778. [PMID: 33206007 DOI: 10.1094/phyto-09-20-0401-rvw] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Bacterial panicle blight (BPB), caused by the bacterium Burkholderia glumae, has affected rice production worldwide. Despite its importance, neither the disease nor the causal agent are well understood. Moreover, methods to manage BPB are still lacking. Nevertheless, the emerging importance of this pathogen has stimulated research to identify the mechanisms of pathogenicity, to gain insight into plant disease resistance, and to develop strategies to manage the disease. In this review, we consolidate current information regarding the virulence factors that have been identified in B. glumae and present a model of the disease and the pathogen. We also provide an update on the current research status to develop methods to control the disease especially through biological control approaches and through the development of resistant cultivars.
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Affiliation(s)
- Laura Ortega
- Department of Entomology and Plant Pathology, University of Arkansas, Fayetteville, AR 72701
| | - Clemencia M Rojas
- Department of Entomology and Plant Pathology, University of Arkansas, Fayetteville, AR 72701
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6
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Genome Sequence and Adaptation Analysis of the Human and Rice Pathogenic Strain Burkholderia glumae AU6208. Pathogens 2021; 10:pathogens10020087. [PMID: 33498266 PMCID: PMC7909282 DOI: 10.3390/pathogens10020087] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 01/13/2021] [Accepted: 01/14/2021] [Indexed: 12/01/2022] Open
Abstract
Burkholderia glumae causes rice (Oryza sativa) bacterial panicle blight, which is an increasingly economically important disease worldwide. As the first B. glumae strain isolated from patients with chronic infections, AU6208 has been reported as an opportunistic clinic pathogen. However, our understanding of the molecular mechanism underlying human pathogenesis by B. glumae remains rudimentary. In this study, we report the complete genome sequence of the human-isolated B. glumae strain AU6208 and compare this to the genome of the rice-pathogenic B. glumae type strain LMG 2196T. Analysis of the average nucleotide identity demonstrated 99.4% similarity between the human- and plant-pathogenic strains. However, the phenotypic results from this study suggest a history of niche adaptation and divergence. In particular, we found 44 genes were predicted to be horizontally transferred into AU6208, and most of these genes were upregulated in conditions that mimic clinical conditions. In these, the gene pair sbnAB encodes key enzymes in antibiotic biosynthesis. These results suggest that horizontal gene transfer in AU6208 may be responsible for selective advantages in its pathogenicity in humans. Our analysis of the AU6208 genome and comparison with that of LMG 2196T reveal the evolutionary signatures of B. glumae in the process of switching niches from plants to humans.
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Lelis T, Peng J, Barphagha I, Chen R, Ham JH. The Virulence Function and Regulation of the Metalloprotease Gene prtA in the Plant-Pathogenic Bacterium Burkholderia glumae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:841-852. [PMID: 30694091 DOI: 10.1094/mpmi-11-18-0312-r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Bacterial panicle blight caused by Burkholderia glumae is a major bacterial disease of rice. Our preliminary RNA-seq study showed that a serine metalloprotease gene, prtA, is regulated in a similar manner to the genes for the biosynthesis and transport of toxoflavin, which is a known major virulence factor of B. glumae. prtA null mutants of the virulent strain B. glumae 336gr-1 did not show a detectable extracellular protease activity, indicating that prtA is the solely responsible gene for the extracellular protease activity detected from this bacterium. In addition, inoculation of rice panicles with the prtA mutants resulted in a significant reduction of disease severity compared with the wild-type parent strain, suggesting the requirement of prtA for the full virulence of B. glumae. A double mutant deficient in both serine metalloprotease and toxoflavin (ΔtoxA/prtA-) exhibited a further numeric but not statistically significant decrease of disease development compared with the ΔtoxA strain. Both the prtA-driven extracellular protease activity and the toxoflavin production were dependent on both the tofI/tofR quorum-sensing and the global regulatory gene qsmR, indicating the important roles of the two global regulatory factors for the bacterial pathogenesis by this pathogen.
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Affiliation(s)
- Tiago Lelis
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, U.S.A
| | - Jingyu Peng
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, U.S.A
| | - Inderjit Barphagha
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, U.S.A
| | - Ruoxi Chen
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, U.S.A
| | - Jong Hyun Ham
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, U.S.A
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8
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Nguyen TT, Chon TS, Kim J, Seo YS, Heo M. Comparative and bioinformatics analyses of pathogenic bacterial secretomes identified by mass spectrometry in Burkholderia species. J Microbiol 2017; 55:568-582. [PMID: 28664514 DOI: 10.1007/s12275-017-7085-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/02/2017] [Accepted: 06/12/2017] [Indexed: 10/19/2022]
Abstract
Secreted proteins (secretomes) play crucial roles during bacterial pathogenesis in both plant and human hosts. The identification and characterization of secretomes in the two plant pathogens Burkholderia glumae BGR1 and B. gladioli BSR3, which cause diseases in rice such as seedling blight, panicle blight, and grain rot, are important steps to not only understand the disease-causing mechanisms but also find remedies for the diseases. Here, we identified two datasets of secretomes in B. glumae BGR1 and B. gladioli BSR3, which consist of 118 and 111 proteins, respectively, using mass spectrometry approach and literature curation. Next, we characterized the functional properties, potential secretion pathways and sequence information properties of secretomes of two plant pathogens in a comparative analysis by various computational approaches. The ratio of potential non-classically secreted proteins (NCSPs) to classically secreted proteins (CSPs) in B. glumae BGR1 was greater than that in B. gladioli BSR3. For CSPs, the putative hydrophobic regions (PHRs) which are essential for secretion process of CSPs were screened in detail at their N-terminal sequences using hidden Markov model (HMM)-based method. Total 31 pairs of homologous proteins in two bacterial secretomes were indicated based on the global alignment (identity ≥ 70%). Our results may facilitate the understanding of the species-specific features of secretomes in two plant pathogenic Burkholderia species.
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Affiliation(s)
- Thao Thi Nguyen
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea
| | - Tae-Soo Chon
- Department of Biological Sciences, Pusan National University, Busan, 46241, Republic of Korea
| | - Jaehan Kim
- Department of Food and Nutrition, Chungnam National University, Daejeon, 34134, Republic of Korea
| | - Young-Su Seo
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea.
| | - Muyoung Heo
- Department of Physics, Pusan National University, Busan, 46241, Republic of Korea.
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Schuster M, Sexton DJ, Hense BA. Why Quorum Sensing Controls Private Goods. Front Microbiol 2017; 8:885. [PMID: 28579979 PMCID: PMC5437708 DOI: 10.3389/fmicb.2017.00885] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/02/2017] [Indexed: 12/22/2022] Open
Abstract
Cell-cell communication, also termed quorum sensing (QS), is a widespread process that coordinates gene expression in bacterial populations. The generally accepted view is that QS optimizes the cell density-dependent benefit attained from cooperative behaviors, often in the form of secreted products referred to as "public goods." This view is challenged by an increasing number of cell-associated products or "private goods" reported to be under QS-control for which a collective benefit is not apparent. A prominent example is nucleoside hydrolase from Pseudomonas aeruginosa, a periplasmic enzyme that catabolizes adenosine. Several recent studies have shown that private goods can function to stabilize cooperation by co-regulated public goods, seemingly explaining their control by QS. Here we argue that this property is a by-product of selection for other benefits rather than an adaptation. Emphasizing ecophysiological context, we propose alternative explanations for the QS control of private goods. We suggest that the benefit attained from private goods is associated with high cell density, either because a relevant ecological condition correlates with density, or because the private good is, directly or indirectly, involved in cooperative behavior. Our analysis helps guide a systems approach to QS, with implications for antivirulence drug design and synthetic biology.
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Affiliation(s)
- Martin Schuster
- Department of Microbiology, Oregon State UniversityCorvallis, OR, United States
| | - D Joseph Sexton
- Department of Microbiology, Oregon State UniversityCorvallis, OR, United States
| | - Burkhard A Hense
- Institute of Computational Biology, Helmholtz Zentrum MünchenNeuherberg, Germany
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10
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Abstract
Type II secretion (T2S) is one means by which Gram-negative pathogens secrete proteins into the extracellular milieu and/or host organisms. Based upon recent genome sequencing, it is clear that T2S is largely restricted to the Proteobacteria, occurring in many, but not all, genera in the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, and Deltaproteobacteria classes. Prominent human and/or animal pathogens that express a T2S system(s) include Acinetobacter baumannii, Burkholderia pseudomallei, Chlamydia trachomatis, Escherichia coli, Klebsiella pneumoniae, Legionella pneumophila, Pseudomonas aeruginosa, Stenotrophomonas maltophilia, Vibrio cholerae, and Yersinia enterocolitica T2S-expressing plant pathogens include Dickeya dadantii, Erwinia amylovora, Pectobacterium carotovorum, Ralstonia solanacearum, Xanthomonas campestris, Xanthomonas oryzae, and Xylella fastidiosa T2S also occurs in nonpathogenic bacteria, facilitating symbioses, among other things. The output of a T2S system can range from only one to dozens of secreted proteins, encompassing a diverse array of toxins, degradative enzymes, and other effectors, including novel proteins. Pathogenic processes mediated by T2S include the death of host cells, degradation of tissue, suppression of innate immunity, adherence to host surfaces, biofilm formation, invasion into and growth within host cells, nutrient assimilation, and alterations in host ion flux. The reach of T2S is perhaps best illustrated by those bacteria that clearly use it for both environmental survival and virulence; e.g., L. pneumophila employs T2S for infection of amoebae, growth within lung cells, dampening of cytokines, and tissue destruction. This minireview provides an update on the types of bacteria that have T2S, the kinds of proteins that are secreted via T2S, and how T2S substrates promote infection.
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11
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Haack FS, Poehlein A, Kröger C, Voigt CA, Piepenbring M, Bode HB, Daniel R, Schäfer W, Streit WR. Molecular Keys to the Janthinobacterium and Duganella spp. Interaction with the Plant Pathogen Fusarium graminearum. Front Microbiol 2016; 7:1668. [PMID: 27833590 PMCID: PMC5080296 DOI: 10.3389/fmicb.2016.01668] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 10/05/2016] [Indexed: 11/18/2022] Open
Abstract
Janthinobacterium and Duganella are well-known for their antifungal effects. Surprisingly, almost nothing is known on molecular aspects involved in the close bacterium-fungus interaction. To better understand this interaction, we established the genomes of 11 Janthinobacterium and Duganella isolates in combination with phylogenetic and functional analyses of all publicly available genomes. Thereby, we identified a core and pan genome of 1058 and 23,628 genes. All strains encoded secondary metabolite gene clusters and chitinases, both possibly involved in fungal growth suppression. All but one strain carried a single gene cluster involved in the biosynthesis of alpha-hydroxyketone-like autoinducer molecules, designated JAI-1. Genome-wide RNA-seq studies employing the background of two isolates and the corresponding JAI-1 deficient strains identified a set of 45 QS-regulated genes in both isolates. Most regulated genes are characterized by a conserved sequence motif within the promoter region. Among the most strongly regulated genes were secondary metabolite and type VI secretion system gene clusters. Most intriguing, co-incubation studies of J. sp. HH102 or its corresponding JAI-1 synthase deletion mutant with the plant pathogen Fusarium graminearum provided first evidence of a QS-dependent interaction with this pathogen.
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Affiliation(s)
- Frederike S Haack
- Department of Microbiology and Biotechnology, Biocenter Klein Flottbek, University of Hamburg Hamburg, Germany
| | - Anja Poehlein
- Department of Genomic and Applied Microbiology and Goettingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Germany
| | - Cathrin Kröger
- Department of Molecular Phytopathology, Biocenter Klein Flottbek, University of Hamburg Hamburg, Germany
| | - Christian A Voigt
- Department of Phytopathology and Biochemistry, Biocenter Klein Flottbek, University of Hamburg Hamburg, Germany
| | - Meike Piepenbring
- Department of Mycology, Goethe University Frankfurt Frankfurt am Main, Germany
| | - Helge B Bode
- Merck-Stiftungsprofessur für Molekulare Biotechnologie Fachbereich Biowissenschaften and Buchmann Institute for Molecular Life Sciences, Goethe Universität Frankfurt Frankfurt am Main, Germany
| | - Rolf Daniel
- Department of Genomic and Applied Microbiology and Goettingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University Göttingen, Germany
| | - Wilhelm Schäfer
- Department of Molecular Phytopathology, Biocenter Klein Flottbek, University of Hamburg Hamburg, Germany
| | - Wolfgang R Streit
- Department of Microbiology and Biotechnology, Biocenter Klein Flottbek, University of Hamburg Hamburg, Germany
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12
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Nickzad A, Déziel E. Adaptive Significance of Quorum Sensing-Dependent Regulation of Rhamnolipids by Integration of Growth Rate in Burkholderia glumae: A Trade-Off between Survival and Efficiency. Front Microbiol 2016; 7:1215. [PMID: 27540372 PMCID: PMC4972832 DOI: 10.3389/fmicb.2016.01215] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 07/21/2016] [Indexed: 01/18/2023] Open
Abstract
Quorum sensing (QS) is a cell density-dependent mechanism which enables a population of bacteria to coordinate cooperative behaviors in response to the accumulation of self-produced autoinducer signals in their local environment. An emerging framework is that the adaptive significance of QS in the regulation of production of costly extracellular metabolites ("public goods") is to maintain the homeostasis of cooperation. We investigated this model using the phytopathogenic bacterium Burkholderia glumae, which we have previously demonstrated uses QS to regulate the production of rhamnolipids, extracellular surface-active glycolipids promoting the social behavior called "swarming motility." Using mass spectrometric quantification and chromosomal lux-based gene expression, we made the unexpected finding that when unrestricted nutrient resources are provided, production of rhamnolipids is carried out completely independently of QS regulation. This is a unique observation among known QS-controlled factors in bacteria. On the other hand, under nutrient-limited conditions, QS then becomes the main regulating mechanism, significantly enhancing the specific rhamnolipids yield. Accordingly, decreasing nutrient concentrations amplifies rhamnolipid biosynthesis gene expression, revealing a system where QS-dependent regulation is specifically triggered by the growth rate of the population, rather than by its cell density. Furthermore, a gradual increase in QS signal specific concentration upon decrease of specific growth rate suggests a reduction in quorum threshold, which reflects an increase in cellular demand for production of QS-dependent target gene product at low density populations. Integration of growth rate with QS as a decision-making mechanism for biosynthesis of costly metabolites, such as rhamnolipids, could serve to assess the demand and timing for expanding the carrying capacity of a population through spatial expansion mechanisms, such as swarming motility, thus promoting the chances of survival, even if the cell density might not be high enough for an otherwise efficient production of rhamnolipids. In conclusion, we propose that the adaptive significance of growth rate-dependent functionality of QS in biosynthesis of costly public goods lies within providing a regulatory mechanism for selecting the optimal trade-off between survival and efficiency.
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Affiliation(s)
| | - Eric Déziel
- Institut National de la Recherche Scientifique – Institut Armand-Frappier, LavalQC, Canada
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13
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Knapp A, Voget S, Gao R, Zaburannyi N, Krysciak D, Breuer M, Hauer B, Streit WR, Müller R, Daniel R, Jaeger KE. Mutations improving production and secretion of extracellular lipase by Burkholderia glumae PG1. Appl Microbiol Biotechnol 2016; 100:1265-1273. [PMID: 26476653 PMCID: PMC4717159 DOI: 10.1007/s00253-015-7041-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 09/15/2015] [Accepted: 09/24/2015] [Indexed: 01/05/2023]
Abstract
Burkholderia glumae is a Gram-negative phytopathogenic bacterium known as the causative agent of rice panicle blight. Strain B. glumae PG1 is used for the production of a biotechnologically relevant lipase, which is secreted into the culture supernatant via a type II secretion pathway. We have comparatively analyzed the genome sequences of B. glumae PG1 wild type and a lipase overproducing strain obtained by classical strain mutagenesis. Among a total number of 72 single nucleotide polymorphisms (SNPs) identified in the genome of the production strain, two were localized in front of the lipAB operon and were analyzed in detail. Both mutations contribute to a 100-fold overproduction of extracellular lipase in B. glumae PG1 by affecting transcription of the lipAB operon and efficiency of lipase secretion. We analyzed each of the two SNPs separately and observed a stronger influence of the promoter mutation than of the signal peptide modification but also a cumulative effect of both mutations. Furthermore, fusion of the mutated LipA signal peptide resulted in a 2-fold increase in secretion of the heterologous reporter alkaline phosphatase from Escherichia coli.
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Affiliation(s)
- Andreas Knapp
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Sonja Voget
- Institute of Microbiology and Genetics, Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Georg-August University Göttingen, Göttingen, Germany
| | - Rong Gao
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Nestor Zaburannyi
- Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research and Pharmaceutical Biotechnology, Saarland University, Saarbrücken, Germany
| | - Dagmar Krysciak
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Michael Breuer
- BASF SE, Biocatalysis and Fine Chemicals Research, Ludwigshafen, Germany
| | - Bernhard Hauer
- BASF SE, Biocatalysis and Fine Chemicals Research, Ludwigshafen, Germany
- Institute of Technical Biochemistry, University of Stuttgart, Stuttgart, Germany
| | - Wolfgang R Streit
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Rolf Müller
- Helmholtz Institute for Pharmaceutical Research Saarland, Helmholtz Centre for Infection Research and Pharmaceutical Biotechnology, Saarland University, Saarbrücken, Germany
| | - Rolf Daniel
- Institute of Microbiology and Genetics, Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Georg-August University Göttingen, Göttingen, Germany
| | - Karl-Erich Jaeger
- Institute of Molecular Enzyme Technology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany.
- Forschungszentrum Jülich GmbH, Institute of Bio- and Geosciences IBG-1: Biotechnology, Jülich, Germany.
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14
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Naughton LM, An SQ, Hwang I, Chou SH, He YQ, Tang JL, Ryan RP, Dow JM. Functional and genomic insights into the pathogenesis of B
urkholderia
species to rice. Environ Microbiol 2016; 18:780-90. [DOI: 10.1111/1462-2920.13189] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 12/10/2015] [Accepted: 12/13/2015] [Indexed: 02/05/2023]
Affiliation(s)
- Lynn M. Naughton
- School of Microbiology; Biosciences Institute; University College Cork; Cork Ireland
| | - Shi-qi An
- Division of Molecular Microbiology; College of Life Sciences; University of Dundee; Dundee UK
| | - Ingyu Hwang
- Institute of Biochemistry and Department of Agricultural Biotechnology; Seoul National University; Seoul 151-921 South Korea
| | - Shan-Ho Chou
- National Chung Hsing University Biotechnology Center; National Chung Hsing University; Taichung 40227 Taiwan
| | - Yong-Qiang He
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources; The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering; College of Life Science and Technology; Guangxi University; 100 Daxue Road Nanning Guangxi 530004 China
| | - Ji-Liang Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources; The Key Laboratory of Ministry of Education for Microbial and Plant Genetic Engineering; College of Life Science and Technology; Guangxi University; 100 Daxue Road Nanning Guangxi 530004 China
| | - Robert P. Ryan
- Division of Molecular Microbiology; College of Life Sciences; University of Dundee; Dundee UK
| | - J. Maxwell Dow
- School of Microbiology; Biosciences Institute; University College Cork; Cork Ireland
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15
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Akanuma G, Yoshizawa R, Nagakura M, Shiwa Y, Watanabe S, Yoshikawa H, Ushio K, Ishizuka M. EliA is required for inducing the stearyl alcohol-mediated expression of secretory proteins and production of polyester in Ralstonia sp. NT80. MICROBIOLOGY-SGM 2015; 162:408-419. [PMID: 26673629 DOI: 10.1099/mic.0.000225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Addition of stearyl alcohol to the culture medium of Ralstonia sp. NT80 induced expression of a significant amount of secretory lipase. Comparative proteomic analysis of extracellular proteins from NT80 cells grown in the presence or absence of stearyl alcohol revealed that stearyl alcohol induced expression of several secretory proteins including lipase, haemolysin-coregulated protein and nucleoside diphosphate kinase. Expression of these secreted proteins was upregulated at the transcriptional level. Stearyl alcohol also induced the synthesis of polyhydroxyalkanoate. Secretory protein EliA was required for all these responses of NT80 cells to stearyl alcohol. Accordingly, the effects of stearyl alcohol were significantly reduced in the eliA deletion mutant cells of NT80 (ΔeliA). The remaining concentration of stearyl alcohol in the culture supernatant of the wild-type cells, but not that in the culture supernatant of the ΔeliA cells, clearly decreased during the course of growth. These observed phenotypes of the ΔeliA mutant were rescued by gene complementation. The results suggested that EliA is essential for these cells to respond to stearyl alcohol, and that it plays an important role in the recognition and assimilation of stearyl alcohol by NT80 cells.
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Affiliation(s)
- Genki Akanuma
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan.,Department of Life Science and Research Center for Life Science, College of Science, Rikkyo University, Toshima-ku, Tokyo, Japan
| | - Rie Yoshizawa
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan
| | - Mari Nagakura
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan
| | - Yuh Shiwa
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, Setagaya-ku, Tokyo, Japan
| | - Satoru Watanabe
- Department of Bioscience, Tokyo University of Agriculture, Setagaya-ku, Tokyo, Japan
| | - Hirofumi Yoshikawa
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture, Setagaya-ku, Tokyo, Japan.,Department of Bioscience, Tokyo University of Agriculture, Setagaya-ku, Tokyo, Japan
| | - Kazutoshi Ushio
- Department of Applied Chemistry and Biotechnology, Niihama National College of Technology, Niihama, Ehime, Japan
| | - Morio Ishizuka
- Department of Applied Chemistry, Faculty of Science and Engineering, Chuo University, Bunkyo-ku, Tokyo, Japan
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16
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Gao R, Krysciak D, Petersen K, Utpatel C, Knapp A, Schmeisser C, Daniel R, Voget S, Jaeger KE, Streit WR. Genome-wide RNA sequencing analysis of quorum sensing-controlled regulons in the plant-associated Burkholderia glumae PG1 strain. Appl Environ Microbiol 2015; 81:7993-8007. [PMID: 26362987 PMCID: PMC4651095 DOI: 10.1128/aem.01043-15] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 09/01/2015] [Indexed: 01/16/2023] Open
Abstract
Burkholderia glumae PG1 is a soil-associated motile plant-pathogenic bacterium possessing a cell density-dependent regulation system called quorum sensing (QS). Its genome contains three genes, here designated bgaI1 to bgaI3, encoding distinct autoinducer-1 (AI-1) synthases, which are capable of synthesizing QS signaling molecules. Here, we report on the construction of B. glumae PG1 ΔbgaI1, ΔbgaI2, and ΔbgaI3 mutants, their phenotypic characterization, and genome-wide transcriptome analysis using RNA sequencing (RNA-seq) technology. Knockout of each of these bgaI genes resulted in strongly decreased motility, reduced extracellular lipase activity, a reduced ability to cause plant tissue maceration, and decreased pathogenicity. RNA-seq analysis of all three B. glumae PG1 AI-1 synthase mutants performed in the transition from exponential to stationary growth phase revealed differential expression of a significant number of predicted genes. In comparison with the levels of gene expression by wild-type strain B. glumae PG1, 481 genes were differentially expressed in the ΔbgaI1 mutant, 213 were differentially expressed in the ΔbgaI2 mutant, and 367 were differentially expressed in the ΔbgaI3 mutant. Interestingly, only a minor set of 78 genes was coregulated in all three mutants. The majority of the QS-regulated genes were linked to metabolic activities, and the most pronounced regulation was observed for genes involved in rhamnolipid and Flp pilus biosynthesis and the type VI secretion system and genes linked to a clustered regularly interspaced short palindromic repeat (CRISPR)-cas gene cluster.
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Affiliation(s)
- Rong Gao
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Dagmar Krysciak
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Katrin Petersen
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Christian Utpatel
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Andreas Knapp
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany
| | - Christel Schmeisser
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Rolf Daniel
- Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg August University Göttingen, Göttingen, Germany
| | - Sonja Voget
- Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg August University Göttingen, Göttingen, Germany
| | - Karl-Erich Jaeger
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich, Jülich, Germany
| | - Wolfgang R Streit
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
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17
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Goo E, An JH, Kang Y, Hwang I. Control of bacterial metabolism by quorum sensing. Trends Microbiol 2015; 23:567-76. [DOI: 10.1016/j.tim.2015.05.007] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 05/07/2015] [Accepted: 05/20/2015] [Indexed: 01/03/2023]
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18
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Nickzad A, Lépine F, Déziel E. Quorum Sensing Controls Swarming Motility of Burkholderia glumae through Regulation of Rhamnolipids. PLoS One 2015; 10:e0128509. [PMID: 26047513 PMCID: PMC4457897 DOI: 10.1371/journal.pone.0128509] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Accepted: 04/29/2015] [Indexed: 11/18/2022] Open
Abstract
Burkholderia glumae is a plant pathogenic bacterium that uses an acyl-homoserine lactone-mediated quorum sensing system to regulate protein secretion, oxalate production and major virulence determinants such as toxoflavin and flagella. B. glumae also releases surface-active rhamnolipids. In Pseudomonas aeruginosa and Burkholderia thailandensis, rhamnolipids, along with flagella, are required for the social behavior called swarming motility. In the present study, we demonstrate that quorum sensing positively regulates the production of rhamnolipids in B. glumae and that rhamnolipids are necessary for swarming motility also in this species. We show that a rhlA- mutant, which is unable to produce rhamnolipids, loses its ability to swarm, and that this can be complemented by providing exogenous rhamnolipids. Impaired rhamnolipid production in a quorum sensing-deficient B. glumae mutant is the main factor responsible for its defective swarming motility behaviour.
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Affiliation(s)
- Arvin Nickzad
- INRS—Institut Armand-Frappier, Laval, Québec, Canada
| | | | - Eric Déziel
- INRS—Institut Armand-Frappier, Laval, Québec, Canada
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19
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Xu H, Zhao Y, Qian G, Liu F. XocR, a LuxR solo required for virulence in Xanthomonas oryzae pv. oryzicola. Front Cell Infect Microbiol 2015; 5:37. [PMID: 25932456 PMCID: PMC4399327 DOI: 10.3389/fcimb.2015.00037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 03/31/2015] [Indexed: 01/15/2023] Open
Abstract
Xanthomonas oryzae pv. oryzicola (Xoc) causes bacterial leaf streak (BLS) in rice, a serious bacterial disease of rice in Asia and parts of Africa. The virulence mechanisms of Xoc are not entirely clear and control measures for BLS are poorly developed. The solo LuxR proteins are widespread and shown to be involved in virulence in some plant associated bacteria (PAB). Here, we have cloned and characterized a PAB LuxR solo from Xoc, named as XocR. Mutation of xocR almost completely impaired the virulence ability of Xoc on host rice, but did not alter the ability to trigger HR (hypersensitive response, a programmed cell death) on non-host (plant) tobacco, suggesting the diversity of function of xocR in host and non-host plants. We also provide evidence to show that xocR is involved in the regulation of growth-independent cell motility in response to a yet-to-be-identified rice signal, as mutation of xocR impaired cell swimming motility of wild-type Rs105 in the presence but not absence of rice macerate. We further found that xocR regulated the transcription of two characterized virulence-associated genes (recN and trpE) in the presence of rice macerate. The promoter regions of recN and trpE possessed a potential binding motif (an imperfect pip box-like element) of XocR, raising the possibility that XocR might directly bind the promoter regions of these two genes to regulate their transcriptional activity. Our studies add a new member of PAB LuxR solos and also provide new insights into the role of PAB LuxR solo in the virulence of Xanthomonas species.
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Affiliation(s)
- Huiyong Xu
- Institute of Plant Protection, Jiangsu Academy of Agricultural ScienceNanjing, China
- College of Plant Protection, Nanjing Agricultural UniversityNanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of EducationNanjing, China
| | - Yancun Zhao
- Institute of Plant Protection, Jiangsu Academy of Agricultural ScienceNanjing, China
| | - Guoliang Qian
- College of Plant Protection, Nanjing Agricultural UniversityNanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of EducationNanjing, China
| | - Fengquan Liu
- Institute of Plant Protection, Jiangsu Academy of Agricultural ScienceNanjing, China
- College of Plant Protection, Nanjing Agricultural UniversityNanjing, China
- Key Laboratory of Integrated Management of Crop Diseases and Pests (Nanjing Agricultural University), Ministry of EducationNanjing, China
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20
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Chen R, Barphagha IK, Ham JH. Identification of potential genetic components involved in the deviant quorum-sensing signaling pathways of Burkholderia glumae through a functional genomics approach. Front Cell Infect Microbiol 2015; 5:22. [PMID: 25806356 PMCID: PMC4354385 DOI: 10.3389/fcimb.2015.00022] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2014] [Accepted: 02/22/2015] [Indexed: 12/21/2022] Open
Abstract
Burkholderia glumae is the chief causal agent for bacterial panicle blight of rice. The acyl-homoserine lactone (AHL)-mediated quorum-sensing (QS) system dependent on a pair of luxI and luxR homologs, tofI and tofR, is the primary cell-to-cell signaling mechanism determining the virulence of this bacterium. Production of toxoflavin, a major virulence factor of B. glumae, is known to be dependent on the tofI/tofR QS system. In our previous study, however, it was observed that B. glumae mutants defective in tofI or tofR produced toxoflavin if they grew on the surface of a solid medium, suggesting that alternative signaling pathways independent of tofI or tofR are activated in that growth condition for the production of toxoflavin. In this study, potential genetic components involved in the tofI- and tofR-independent signaling pathways for toxoflavin production were sought through screening random mini-Tn5 mutants of B. glumae to better understand the intercellular signaling pathways of this pathogen. Fifteen and three genes were initially identified as the potential genetic elements of the tofI- and tofR-independent pathways, respectively. Especially, the ORF (bglu_2g06320) divergently transcribed from toxJ, which encodes an orphan LuxR protein and controls toxoflavin biosynthesis, was newly identified in this study as a gene required for the tofR-independent toxoflavin production and named as toxK. Among those genes, flhD, dgcB, and wzyB were further studied to validate their functions in the tofI-independent toxoflavin production, and similar studies were also conducted with qsmR and toxK for their functions in the tofR-independent toxoflavin production. This work provides a foundation for future comprehensive studies of the intercellular signaling systems of B. glumae and other related pathogenic bacteria.
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Affiliation(s)
- Ruoxi Chen
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center Baton Rouge, LA, USA
| | - Inderjit K Barphagha
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center Baton Rouge, LA, USA
| | - Jong Hyun Ham
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center Baton Rouge, LA, USA
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21
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Bacterial quorum sensing and metabolic slowing in a cooperative population. Proc Natl Acad Sci U S A 2014; 111:14912-7. [PMID: 25267613 DOI: 10.1073/pnas.1412431111] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Acyl-homoserine lactone (AHL)-mediated quorum sensing (QS) controls the production of numerous intra- and extracellular products across many species of Proteobacteria. Although these cooperative activities are often costly at an individual level, they provide significant benefits to the group. Other potential roles for QS include the restriction of nutrient acquisition and maintenance of metabolic homeostasis of individual cells in a crowded but cooperative population. Under crowded conditions, QS may function to modulate and coordinate nutrient utilization and the homeostatic primary metabolism of individual cells. Here, we show that QS down-regulates glucose uptake, substrate level and oxidative phosphorylation, and de novo nucleotide biosynthesis via the activity of the QS-dependent transcriptional regulator QsmR (quorum sensing master regulator R) in the rice pathogen Burkholderia glumae. Systematic analysis of glucose uptake and core primary metabolite levels showed that QS deficiency perturbed nutrient acquisition, and energy and nucleotide metabolism, of individuals within the group. The QS mutants grew more rapidly than the wild type at the early exponential stage and outcompeted wild-type cells in coculture. Metabolic slowing of individuals in a QS-dependent manner indicates that QS acts as a metabolic brake on individuals when cells begin to mass, implying a mechanism by which AHL-mediated QS might have evolved to ensure homeostasis of the primary metabolism of individuals under crowded conditions.
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22
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Jang MS, Goo E, An JH, Kim J, Hwang I. Quorum sensing controls flagellar morphogenesis in Burkholderia glumae. PLoS One 2014; 9:e84831. [PMID: 24416296 PMCID: PMC3885665 DOI: 10.1371/journal.pone.0084831] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 11/19/2013] [Indexed: 12/30/2022] Open
Abstract
Burkholderia glumae is a motile plant pathogenic bacterium that has multiple polar flagella and one LuxR/LuxI-type quorum sensing (QS) system, TofR/TofI. A QS-dependent transcriptional regulator, QsmR, activates flagellar master regulator flhDC genes. FlhDC subsequently activates flagellar gene expression in B. glumae at 37°C. Here, we confirm that the interplay between QS and temperature is critical for normal polar flagellar morphogenesis in B. glumae. In the wild-type bacterium, flagellar gene expression and flagellar number were greater at 28°C compared to 37°C. The QS-dependent flhC gene was significantly expressed at 28°C in two QS-defective (tofI::Ω and qsmR::Ω) mutants. Thus, flagella were present in both tofI::Ω and qsmR::Ω mutants at 28°C, but were absent at 37°C. Most tofI::Ω and qsmR::Ω mutant cells possessed polar or nonpolar flagella at 28°C. Nonpolarly flagellated cells processing flagella around cell surface of both tofI::Ω and qsmR::Ω mutants exhibited tumbling and spinning movements. The flhF gene encoding GTPase involved in regulating the correct placement of flagella in other bacteria was expressed in QS mutants in a FlhDC-dependent manner at 28°C. However, FlhF was mislocalized in QS mutants, and was associated with nonpolar flagellar formation in QS mutants at 28°C. These results indicate that QS-independent expression of flagellar genes at 28°C allows flagellar biogenesis, but is not sufficient for normal polar flagellar morphogenesis in B. glumae. Our findings demonstrate that QS functions together with temperature to control flagellar morphogenesis in B. glumae.
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Affiliation(s)
- Moon Sun Jang
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Eunhye Goo
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Jae Hyung An
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Jinwoo Kim
- Division of Applied Life Science and Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju, Republic of Korea
| | - Ingyu Hwang
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
- * E-mail:
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23
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Abstract
Cell-cell communication, or quorum sensing, is a widespread phenomenon in bacteria that is used to coordinate gene expression among local populations. Its use by bacterial pathogens to regulate genes that promote invasion, defense, and spread has been particularly well documented. With the ongoing emergence of antibiotic-resistant pathogens, there is a current need for development of alternative therapeutic strategies. An antivirulence approach by which quorum sensing is impeded has caught on as a viable means to manipulate bacterial processes, especially pathogenic traits that are harmful to human and animal health and agricultural productivity. The identification and development of chemical compounds and enzymes that facilitate quorum-sensing inhibition (QSI) by targeting signaling molecules, signal biogenesis, or signal detection are reviewed here. Overall, the evidence suggests that QSI therapy may be efficacious against some, but not necessarily all, bacterial pathogens, and several failures and ongoing concerns that may steer future studies in productive directions are discussed. Nevertheless, various QSI successes have rightfully perpetuated excitement surrounding new potential therapies, and this review highlights promising QSI leads in disrupting pathogenesis in both plants and animals.
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24
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Qian G, Zhou Y, Zhao Y, Song Z, Wang S, Fan J, Hu B, Venturi V, Liu F. Proteomic analysis reveals novel extracellular virulence-associated proteins and functions regulated by the diffusible signal factor (DSF) in Xanthomonas oryzae pv. oryzicola. J Proteome Res 2013; 12:3327-41. [PMID: 23688240 DOI: 10.1021/pr4001543] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quorum sensing (QS) in Xanthomonas oryzae pv. oryzicola (Xoc), the causal agent of bacterial leaf streak, is mediated by the diffusible signal factor (DSF). DSF-mediating QS has been shown to control virulence and a set of virulence-related functions; however, the expression profiles and functions of extracellular proteins controlled by DSF signal remain largely unclear. In the present study, 33 DSF-regulated extracellular proteins, whose functions include small-protein mediating QS, oxidative adaptation, macromolecule metabolism, cell structure, biosynthesis of small molecules, intermediary metabolism, cellular process, protein catabolism, and hypothetical function, were identified by proteomics in Xoc. Of these, 15 protein encoding genes were in-frame deleted, and 4 of them, including three genes encoding type II secretion system (T2SS)-dependent proteins and one gene encoding an Ax21 (activator of XA21-mediated immunity)-like protein (a novel small-protein type QS signal) were determined to be required for full virulence in Xoc. The contributions of these four genes to important virulence-associated functions, including bacterial colonization, extracellular polysaccharide, cell motility, biofilm formation, and antioxidative ability, are presented. To our knowledge, our analysis is the first complete list of DSF-regulated extracellular proteins and functions in a Xanthomonas species. Our results show that DSF-type QS played critical roles in regulation of T2SS and Ax21-mediating QS, which sheds light on the role of DSF signaling in Xanthomonas.
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Affiliation(s)
- Guoliang Qian
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
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25
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Ham JH. Intercellular and intracellular signalling systems that globally control the expression of virulence genes in plant pathogenic bacteria. MOLECULAR PLANT PATHOLOGY 2013; 14. [PMID: 23186372 PMCID: PMC6638695 DOI: 10.1111/mpp.12005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Plant pathogenic bacteria utilize complex signalling systems to control the expression of virulence genes at the cellular level and within populations. Quorum sensing (QS), an important intercellular communication mechanism, is mediated by different types of small molecules, including N-acyl homoserine lactones (AHLs), fatty acids and small proteins. AHL-mediated signalling systems dependent on the LuxI and LuxR family proteins play critical roles in the virulence of a wide range of Gram-negative plant pathogenic bacteria belonging to the Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria. Xanthomonas spp. and Xylella fastidiosa, members of the Gammaproteobacteria, however, possess QS systems that are mediated by fatty acid-type diffusible signal factors (DSFs). Recent studies have demonstrated that Ax21, a 194-amino-acid protein in Xanthomonas oryzae pv. oryzae, plays dual functions in activating a rice innate immune pathway through binding to the rice XA21 pattern recognition receptor and in regulating bacterial virulence and biofilm formation as a QS signal molecule. In xanthomonads, DSF-mediated QS systems are connected with the signalling pathways mediated by cyclic diguanosine monophosphate (c-di-GMP), which functions as a second messenger for the control of virulence gene expression in these bacterial pathogens.
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Affiliation(s)
- Jong Hyun Ham
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA.
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26
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Qian G, Liu C, Wu G, Yin F, Zhao Y, Zhou Y, Zhang Y, Song Z, Fan J, Hu B, Liu F. AsnB, regulated by diffusible signal factor and global regulator Clp, is involved in aspartate metabolism, resistance to oxidative stress and virulence in Xanthomonas oryzae pv. oryzicola. MOLECULAR PLANT PATHOLOGY 2013; 14:145-57. [PMID: 23157387 PMCID: PMC6638903 DOI: 10.1111/j.1364-3703.2012.00838.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Xanthomonas oryzae pv. oryzicola (Xoc) causes bacterial leaf streak in rice, which is a destructive disease worldwide. Xoc virulence factors are regulated by diffusible signal factor (DSF) and the global regulator Clp. In this study, we have demonstrated that asnB (XOC_3054), encoding an asparagine synthetase, is a novel virulence-related gene regulated by both DSF and Clp in Xoc. A sequence analysis revealed that AsnB is highly conserved in Xanthomonas. An asnB mutation in Xoc dramatically impaired pathogen virulence and growth rate in host rice, but did not affect the ability to trigger the hypersensitive response in nonhost (plant) tobacco. Compared with the wild-type strain, the asnB deletion mutant was unable to grow in basic MMX (-) medium (a minimal medium without ammonium sulphate as the nitrogen source) with or without 10 tested nitrogen sources, except asparagine. The disruption of asnB impaired pathogen resistance to oxidative stress and reduced the transcriptional expression of oxyR, katA and katG, which encode three important proteins responsible for hydrogen peroxide (H(2)O(2)) sensing and detoxification in Xanthomonas in the presence of H(2)O(2), and nine important known Xoc virulence-related genes in plant cell-mimicking medium. Furthermore, the asnB mutation did not affect extracellular protease activity, extracellular polysaccharide production, motility or chemotaxis. Taken together, our results demonstrate the role of asnB in Xanthomonas for the first time.
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Affiliation(s)
- Guoliang Qian
- College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China
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Gamberi T, Gamberi T, Magherini F, Citti L, Buroni S, Bazzini S, Udine C, Perrin E, Modesti A, Fani R, Rocchiccioli S, Papaleo MC. RND-4 efflux transporter gene deletion in Burkholderia cenocepacia J2315: a proteomic analysis. ACTA ACUST UNITED AC 2013. [DOI: 10.7243/2050-2273-2-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Bacterial quorum sensing, cooperativity, and anticipation of stationary-phase stress. Proc Natl Acad Sci U S A 2012; 109:19775-80. [PMID: 23150539 DOI: 10.1073/pnas.1218092109] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Acyl-homoserine lactone-mediated quorum sensing (QS) regulates diverse activities in many species of Proteobacteria. QS-controlled genes commonly code for production of secreted or excreted public goods. The acyl-homoserine lactones are synthesized by members of the LuxI signal synthase family and are detected by cognate members of the LuxR family of transcriptional regulators. QS affords a means of population density-dependent gene regulation. Control of public goods via QS provides a fitness benefit. Another potential role for QS is to anticipate overcrowding. As population density increases and stationary phase approaches, QS might induce functions important for existence in stationary phase. Here we provide evidence that in three related species of the genus Burkholderia QS allows individuals to anticipate and survive stationary-phase stress. Survival requires QS-dependent activation of cellular enzymes required for production of excreted oxalate, which serves to counteract ammonia-mediated alkaline toxicity during stationary phase. Our findings provide an example of QS serving as a means to anticipate stationary phase or life at the carrying capacity of a population by activating the expression of cytoplasmic enzymes, altering cellular metabolism, and producing a shared resource or public good, oxalate.
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González JF, Degrassi G, Devescovi G, De Vleesschauwer D, Höfte M, Myers MP, Venturi V. A proteomic study of Xanthomonas oryzae pv. oryzae in rice xylem sap. J Proteomics 2012; 75:5911-9. [PMID: 22835776 DOI: 10.1016/j.jprot.2012.07.019] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 06/22/2012] [Accepted: 07/15/2012] [Indexed: 11/16/2022]
Abstract
Xanthomonas oryzae pv. oryzae (Xoo) is the second most important rice pathogen, causing a disease called bacterial leaf blight. Xoo colonizes and infects the vascular tissue resulting in tissue necrosis and wilting causing significant yield losses worldwide. In this study Xoo infected vascular fluid (xylem sap) was recovered and analyzed for secreted Xoo proteins. Three independent experiments resulted in the identification of 324 different proteins, 64 proteins were found in all three samples which included many of the known virulence-associated factors. In addition, 10 genes encoding for the identified proteins were inactivated and one mutant displayed statistically a significant loss in virulence when compared to the wild type Xoo, suggesting that a new virulence-associated factor has been revealed. The usefulness of this approach in understanding the lifestyle and unraveling the virulence-associated factors of phytopathogenic vascular bacteria is discussed.
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Affiliation(s)
- Juan F González
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149, Trieste, Italy
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Wongtrakoongate P, Tumapa S, Tungpradabkul S. Regulation of a quorum sensing system by stationary phase sigma factor RpoS and their co-regulation of target genes
in Burkholderia pseudomallei. Microbiol Immunol 2012; 56:281-94. [DOI: 10.1111/j.1348-0421.2012.00447.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kim H, Goo E, Kang Y, Kim J, Hwang I. Regulation of universal stress protein genes by quorum sensing and RpoS in Burkholderia glumae. J Bacteriol 2012; 194:982-92. [PMID: 22178971 PMCID: PMC3294795 DOI: 10.1128/jb.06396-11] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Accepted: 12/08/2011] [Indexed: 11/20/2022] Open
Abstract
Burkholderia glumae possesses a quorum-sensing (QS) system mediated by N-octanoyl-homoserine lactone (C(8)-HSL) and its cognate receptor TofR. TofR/C(8)-HSL regulates the expression of a transcriptional regulator, qsmR. We identified one of the universal stress proteins (Usps), Usp2, from a genome-wide analysis of QS-dependent proteomes of B. glumae. In the whole genome of B. glumae BGR1, 11 usp genes (usp1 to usp11) were identified. Among the stress conditions tested, usp1 and usp2 mutants died 1 h after heat shock stress, whereas the other usp mutants and the wild-type strain survived for more than 3 h at 45°C. The expressions of all usp genes were positively regulated by QS, directly by QsmR. In addition, the expressions of usp1 and usp2 were dependent on RpoS in the stationary phase, as confirmed by the direct binding of RpoS-RNA holoenzyme to the promoter regions of the usp1 and usp2 genes. The expression of usp1 was upregulated upon a temperature shift from 37°C to either 28°C or 45°C, whereas the expression of usp2 was independent of temperature stress. This indicates that the regulation of usp1 and usp2 expression is different from what is known about Escherichia coli. Compared to the diverse roles of Usps in E. coli, Usps in B. glumae are dedicated to heat shock stress.
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Affiliation(s)
- Hongsup Kim
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Eunhye Goo
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Yongsung Kang
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Jinwoo Kim
- Department of Applied Biology, Gyeongsang National University, Jinju, Republic of Korea
| | - Ingyu Hwang
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
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Small-molecule inhibitor binding to an N-acyl-homoserine lactone synthase. Proc Natl Acad Sci U S A 2011; 108:12089-94. [PMID: 21730159 DOI: 10.1073/pnas.1103165108] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Quorum sensing (QS) controls certain behaviors of bacteria in response to population density. In gram-negative bacteria, QS is often mediated by N-acyl-L-homoserine lactones (acyl-HSLs). Because QS influences the virulence of many pathogenic bacteria, synthetic inhibitors of acyl-HSL synthases might be useful therapeutically for controlling pathogens. However, rational design of a potent QS antagonist has been thwarted by the lack of information concerning the binding interactions between acyl-HSL synthases and their ligands. In the gram-negative bacterium Burkholderia glumae, QS controls virulence, motility, and protein secretion and is mediated by the binding of N-octanoyl-L-HSL (C8-HSL) to its cognate receptor, TofR. C8-HSL is synthesized by the acyl-HSL synthase TofI. In this study, we characterized two previously unknown QS inhibitors identified in a focused library of acyl-HSL analogs. Our functional and X-ray crystal structure analyses show that the first inhibitor, J8-C8, binds to TofI, occupying the binding site for the acyl chain of the TofI cognate substrate, acylated acyl-carrier protein. Moreover, the reaction byproduct, 5'-methylthioadenosine, independently binds to the binding site for a second substrate, S-adenosyl-L-methionine. Closer inspection of the mode of J8-C8 binding to TofI provides a likely molecular basis for the various substrate specificities of acyl-HSL synthases. The second inhibitor, E9C-3oxoC6, competitively inhibits C8-HSL binding to TofR. Our analysis of the binding of an inhibitor and a reaction byproduct to an acyl-HSL synthase may facilitate the design of a new class of QS-inhibiting therapeutic agents.
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Regulatory and metabolic network of rhamnolipid biosynthesis: traditional and advanced engineering towards biotechnological production. Appl Microbiol Biotechnol 2011; 91:251-64. [PMID: 21667084 DOI: 10.1007/s00253-011-3368-2] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 05/02/2011] [Accepted: 05/02/2011] [Indexed: 12/29/2022]
Abstract
During the last decade, the demand for economical and sustainable bioprocesses replacing petrochemical-derived products has significantly increased. Rhamnolipids are interesting biosurfactants that might possess a broad industrial application range. However, despite of 60 years of research in the area of rhamnolipid production, the economic feasibility of these glycolipids is pending. Although the biosynthesis and regulatory network are in a big part known, the actual incidents on the cellular and process level during bioreactor cultivation are not mastered. Traditional engineering by random and targeted genetic alteration, process design, and recombinant strategies did not succeed by now. For enhanced process development, there is an urgent need of in-depth information about the rhamnolipid production regulation during bioreactor cultivation to design knowledge-based genetic and process engineering strategies. Rhamnolipids are structurally comparable, simple secondary metabolites and thus have the potential to become instrumental in future secondary metabolite engineering by systems biotechnology. This review summarizes current knowledge about the regulatory and metabolic network of rhamnolipid synthesis and discusses traditional and advanced engineering strategies performed for rhamnolipid production improvement focusing on Pseudomonas aeruginosa. Finally, the opportunities of applying the systems biotechnology toolbox on the whole-cell biocatalyst and bioprocess level for further rhamnolipid production optimization are discussed.
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Eberl L, Riedel K. Mining quorum sensing regulated proteins - Role of bacterial cell-to-cell communication in global gene regulation as assessed by proteomics. Proteomics 2011; 11:3070-85. [PMID: 21548094 DOI: 10.1002/pmic.201000814] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 01/20/2011] [Accepted: 02/17/2011] [Indexed: 12/31/2022]
Affiliation(s)
- Leo Eberl
- Department of Microbiology, Institute of Plant Biology, University of Zürich, Zurich, Switzerland
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Abstract
UNLABELLED Burkholderia glumae causes bacterial panicle blight of rice, which is an increasingly important disease problem in global rice production. Toxoflavin and lipase are known to be major virulence factors of this pathogen, and their production is dependent on the TofI/TofR quorum-sensing system, which is mediated by N-octanoyl homoserine lactone. Flagellar biogenesis and a type III secretion system are also required for full virulence of B. glumae. Bacterial panicle blight is thought to be caused by seed-borne B. glumae; however, its disease cycle is not fully understood. In spite of its economic importance, neither effective control measures for bacterial panicle blight nor rice varieties showing complete resistance to the disease are currently available. A better understanding of the molecular mechanisms underlying B. glumae virulence and of the rice defence mechanisms against the pathogen would lead to the development of better methods of disease control for bacterial panicle blight. TAXONOMY Bacteria; Proteobacteria; Betaproteobacteria; Burkholderiales; Burkholderiaceae; Burkholderia. MICROBIOLOGICAL PROPERTIES Gram-negative, capsulated, motile, lophotrichous flagella, pectolytic. DISEASE SYMPTOMS Aborted seed, empty grains as a result of failure of grain filling, brown spots on panicles, seedling rot. DISEASE CONTROL Seed sterilization, planting partially resistant lines (no completely resistant line is available). KNOWN VIRULENCE FACTORS: Toxoflavin, lipase, type III effectors.
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Affiliation(s)
- Jong Hyun Ham
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA.
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The Burkholderia cenocepacia LysR-type transcriptional regulator ShvR influences expression of quorum-sensing, protease, type II secretion, and afc genes. J Bacteriol 2010; 193:163-76. [PMID: 20971902 DOI: 10.1128/jb.00852-10] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Burkholderia cenocepacia is a significant opportunistic pathogen in individuals with cystic fibrosis. ShvR, a LysR-type transcriptional regulator, has previously been shown to influence colony morphology, biofilm formation, virulence in plant and animal infection models, and some quorum-sensing-dependent phenotypes. In the present study, it was shown that ShvR negatively regulates its own expression, as is typical for LysR-type regulators. The production of quorum-sensing signal molecules was detected earlier in growth in the shvR mutant than in the wild type, and ShvR repressed expression of the quorum-sensing regulatory genes cepIR and cciIR. Microarray analysis and transcriptional fusions revealed that ShvR regulated over 1,000 genes, including the zinc metalloproteases zmpA and zmpB. The shvR mutant displayed increased gene expression of the type II secretion system and significantly increased protease and lipase activities. Both ShvR and CepR influence expression of a 24-kb genomic region adjacent to shvR that includes the afcA and afcC operons, required for the production of an antifungal agent; however, the reduction in expression was substantially greater in the shvR mutant than in the cepR mutant. Only the shvR mutation resulted in reduced antifungal activity against Rhizoctonia solani. ShvR, but not CepR, was shown to directly regulate expression of the afcA and afcC promoters. In summary, ShvR was determined to have a significant influence on the expression of quorum-sensing, protease, lipase, type II secretion, and afc genes.
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