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Petrova O, Semenova E, Parfirova O, Tsers I, Gogoleva N, Gogolev Y, Nikolaichik Y, Gorshkov V. RpoS-Regulated Genes and Phenotypes in the Phytopathogenic Bacterium Pectobacterium atrosepticum. Int J Mol Sci 2023; 24:17348. [PMID: 38139177 PMCID: PMC10743746 DOI: 10.3390/ijms242417348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 12/04/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
The alternative sigma factor RpoS is considered to be one of the major regulators providing stress resistance and cross-protection in bacteria. In phytopathogenic bacteria, the effects of RpoS have not been analyzed with regard to cross-protection, and genes whose expression is directly or indirectly controlled by RpoS have not been determined at the whole-transcriptome level. Our study aimed to determine RpoS-regulated genes and phenotypes in the phytopathogenic bacterium Pectobacterium atrosepticum. Knockout of the rpoS gene in P. atrosepticum affected the long-term starvation response, cross-protection, and virulence toward plants with enhanced immune status. The whole-transcriptome profiles of the wild-type P. atrosepticum strain and its ΔrpoS mutant were compared under different experimental conditions, and functional gene groups whose expression was affected by RpoS were determined. The RpoS promoter motif was inferred within the promoter regions of the genes affected by rpoS deletion, and the P. atrosepticum RpoS regulon was predicted. Based on RpoS-controlled phenotypes, transcriptome profiles, and RpoS regulon composition, the regulatory role of RpoS in P. atrosepticum is discussed.
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Affiliation(s)
- Olga Petrova
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
| | - Elizaveta Semenova
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
| | - Olga Parfirova
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
| | - Ivan Tsers
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
| | - Natalia Gogoleva
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
| | - Yuri Gogolev
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Yevgeny Nikolaichik
- Department of Molecular Biology, Belarusian State University, 220030 Minsk, Belarus;
| | - Vladimir Gorshkov
- Kazan Institute of Biochemistry and Biophysics, Federal Research Center “Kazan Scientific Center of the Russian Academy of Sciences”, 420111 Kazan, Russia; (O.P.); (E.S.); (O.P.); (I.T.); (N.G.); (Y.G.)
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
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Deblais L, Ranjit S, Vrisman C, Antony L, Scaria J, Miller SA, Rajashekara G. Role of Stress-Induced Proteins RpoS and YicC in the Persistence of Salmonella enterica subsp. enterica Serotype Typhimurium in Tomato Plants. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2023; 36:109-118. [PMID: 36394339 DOI: 10.1094/mpmi-07-22-0152-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Understanding the functional role of bacterial genes in the persistence of Salmonella in plant organs can facilitate the development of agricultural practices to mitigate food safety risks associated with the consumption of fresh produce contaminated with Salmonella spp. Our study showed that Salmonella enterica subsp. enterica serotype Typhimurium (strain MDD14) persisted less in inoculated tomato plants than other Salmonella Typhimurium strains tested (JSG210, JSG626, JSG634, JSG637, JSG3444, and EV030415; P < 0.01). In-vitro assays performed in limited-nutrient conditions (growth rate, biofilm production, and motility) were inconclusive in explaining the in-planta phenotype observed with MDD14. Whole-genome sequencing combined with non-synonymous single nucleotide variations analysis was performed to identify genomic differences between MDD14 and the other Salmonella Typhimurium strains. The genome of MDD14 contained a truncated version (123 bp N-terminal) of yicC and a mutated version of rpoS (two non-synonymous substitutions, i.e., G66E and R82C), which are two stress-induced proteins involved in iron acquisition, environmental sensing, and cell envelope integrity. The rpoS and yicC genes were deleted in Salmonella Typhimurium JSG210 with the Lambda Red recombining system. Both mutants had limited persistence in tomato plant organs, similar to that of MDD14. In conclusion, we demonstrated that YicC and RpoS are involved in the persistence of Salmonella in tomato plants in greenhouse conditions and, thus, could represent potential targets to mitigate persistence of Salmonella spp. in planta. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.
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Affiliation(s)
- Loïc Deblais
- Department of Animal Sciences, The Ohio State University, Wooster, OH, U.S.A
| | - Sochina Ranjit
- Department of Animal Sciences, The Ohio State University, Wooster, OH, U.S.A
| | - Claudio Vrisman
- Department of Plant Pathology, The Ohio State University, Wooster, OH, U.S.A
| | - Linto Antony
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, U.S.A
| | - Joy Scaria
- Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD, U.S.A
| | - Sally A Miller
- Department of Plant Pathology, The Ohio State University, Wooster, OH, U.S.A
| | - Gireesh Rajashekara
- Department of Animal Sciences, The Ohio State University, Wooster, OH, U.S.A
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Anti-Fungal Analysis of Bacillus subtilis DL76 on Conidiation, Appressorium Formation, Growth, Multiple Stress Response, and Pathogenicity in Magnaporthe oryzae. Int J Mol Sci 2022; 23:ijms23105314. [PMID: 35628122 PMCID: PMC9141136 DOI: 10.3390/ijms23105314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/03/2022] [Accepted: 05/06/2022] [Indexed: 02/04/2023] Open
Abstract
In recent years, biological control has gained more attention as a promising method to combat plant disease. Such severe diseases cited include rice blasts caused by Magnaporthe oryzae. However, more effective microbial strains with strong adaptability still need to be identified. Therefore, we sought to assess the conidia germination, and formation of appressorium of DL76 in Magnaporthe oryzae. Besides, we also aimed at understanding the growth, multiple stress response and pathogenicity in Magnaporthe oryzae. We isolated Bacillus subtilis DL76 from a rice farm, which observed a strong antimicrobial effect on M. oryzae. The sterilized culture filtrate of DL76 inhibited the growth of M. oryzae, which motivated us to deduce the influence of DL76 on the pathogenicity of M. oryzae. We screened the effect of Bacillus subtilis DL76 on M. oryzae guy11. It demonstrated that sterilized culture filtrate (1 × 107 CFU/mL) of DL76 can delay and even suppress the germination of conidia and (1 × 107 and 1 × 106 CFU/mL) prevent the formation of appressorium in vitro and in vivo. DL76 became hypersensitive to osmotic, oxidative, and cell wall degrading agents. In addition, the relative transcript levels of stress-responsive genes oxidative and osmotic were down-regulated by DL76 except for sod1, cat1, and cat2. In vivo assessment of the antifungal activity of Bacillus subtilis using conidia suspension of DL76 reduced the incidence and severity of rice blast. Conclusively, our results show that DL76 is essential for controlling rice blast by inhibiting conidiation, growth, multiple stress tolerance, and pathogenicity in M. oryzae.
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Li X, Liu Y, Tan X, Li D, Yang X, Zhang X, Zhang D. The high-affinity phosphodiesterase PcPdeH is involved in the polarized growth and pathogenicity of Phytophthora capsici. Fungal Biol 2020; 124:164-173. [PMID: 32220377 DOI: 10.1016/j.funbio.2020.01.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/15/2020] [Accepted: 01/20/2020] [Indexed: 01/04/2023]
Abstract
The cAMP signaling pathway has been shown to be important in controlling morphological changes and pathogenicity in plant pathogens. In the present study, we identified PcPdeH, a gene encoding a high-affinity phosphodiesterase (PDE), which is a key regulator of the cAMP signaling pathway. To elucidate the function of PcPdeH, PcPdeH-knockout mutants were obtained using a type II CRISPR/Cas9 system in Phytophthora capsici. The knockout transformants of PcPdeH showed vegetative growth defects and abnormal cyst germination. Infection assays indicated that compared with the wild type, PcPdeH-knockout mutants showed significantly reduced virulence on pepper and tobacco leaves and exhibited increased (1.5-2-fold) cAMP levels relative to the wild-type and CK strains. Based on these phenotypic features, we propose that PcPdeH is crucial for vegetative growth, cyst germination and pathogenicity in P. capsici.
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Affiliation(s)
- X Li
- Longping Branch, Graduate College, Hunan University, Changsha, 410125, China; Hunan Plant Protection Institute, Hunan Academy of Agricultural Sciences, Changsha, 410125, China.
| | - Yong Liu
- Longping Branch, Graduate College, Hunan University, Changsha, 410125, China; Hunan Plant Protection Institute, Hunan Academy of Agricultural Sciences, Changsha, 410125, China.
| | - Xinqiu Tan
- Longping Branch, Graduate College, Hunan University, Changsha, 410125, China; Hunan Plant Protection Institute, Hunan Academy of Agricultural Sciences, Changsha, 410125, China.
| | - Delong Li
- College of Plant Health and Medicine, The Key Laboratory of Integrated Crop Pest Management of Shandong Province, Qingdao Agricultural University, Qingdao, 266109, China.
| | - Xinyu Yang
- Shenyang Agricultural University, Plant Protection College, Shenyang, 110866, China.
| | - Xin Zhang
- Hunan Plant Protection Institute, Hunan Academy of Agricultural Sciences, Changsha, 410125, China.
| | - Deyong Zhang
- Longping Branch, Graduate College, Hunan University, Changsha, 410125, China; Hunan Plant Protection Institute, Hunan Academy of Agricultural Sciences, Changsha, 410125, China.
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MoGrr1, a novel F-box protein, is involved in conidiogenesis and cell wall integrity and is critical for the full virulence of Magnaporthe oryzae. Appl Microbiol Biotechnol 2015; 99:8075-88. [DOI: 10.1007/s00253-015-6820-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 07/01/2015] [Accepted: 07/05/2015] [Indexed: 12/17/2022]
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Santander RD, Monte-Serrano M, Rodríguez-Herva JJ, López-Solanilla E, Rodríguez-Palenzuela P, Biosca EG. Exploring new roles for the rpoS gene in the survival and virulence of the fire blight pathogen Erwinia amylovora. FEMS Microbiol Ecol 2014; 90:895-907. [PMID: 25331301 DOI: 10.1111/1574-6941.12444] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 10/13/2014] [Accepted: 10/18/2014] [Indexed: 01/19/2023] Open
Abstract
Erwinia amylovora causes fire blight in economically important plants of the family Rosaceae. This bacterial pathogen spends part of its life cycle coping with starvation and other fluctuating environmental conditions. In many Gram-negative bacteria, starvation and other stress responses are regulated by the sigma factor RpoS. We obtained an E. amylovora rpoS mutant to explore the role of this gene in starvation responses and its potential implication in other processes not yet studied in this pathogen. Results showed that E. amylovora needs rpoS to develop normal starvation survival and viable but nonculturable (VBNC) responses. Furthermore, this gene contributed to stationary phase cross-protection against oxidative, osmotic, and acid stresses and was essential for cross-protection against heat shock, but nonessential against acid shock. RpoS also mediated regulation of motility, exopolysaccharide synthesis, and virulence in immature loquats, but not in pear plantlets, and contributed to E. amylovora survival in nonhost tissues during incompatible interactions. Our results reveal some unique roles for the rpoS gene in E. amylovora and provide new knowledge on the regulation of different processes related to its ecology, including survival in different environments and virulence in immature fruits.
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Affiliation(s)
- Ricardo D Santander
- Departmento de Microbiología y Ecología, Universitat de València, Burjassot, Valencia, Spain; Centro de Biotecnología y Genómica de Plantas (CBGP), Universidad Politécnica de Madrid-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Parque Científico y Tecnológico de la UPM, Madrid, Spain
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Laasik E, Põllumaa L, Pasanen M, Mattinen L, Pirhonen M, Mäe A. Expression of nipP.w of Pectobacterium wasabiae is dependent on functional flgKL flagellar genes. MICROBIOLOGY (READING, ENGLAND) 2014; 160:179-186. [PMID: 24173527 DOI: 10.1099/mic.0.071092-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
While flagellum-driven motility is hypothesized to play a role in the virulence of Pectobacterium species, there is no direct evidence that genes involved in flagellum assembly regulate the synthesis of virulence factors. The purpose of this study was to identify genes that affect the production or secretion of necrosis-inducing protein (Nip) in the strain SCC3193. Transposon mutagenesis of an RpoS strain overexpressing NipP.w was performed, and a mutant associated with decreased necrosis of tobacco leaves was detected. The mutant contained a transposon in the regulatory region upstream of the flagellar genes flgK and flgL. Additional mutants were generated related to the flagellar genes fliC and fliA. The mutation in flgKL, but not those in fliC and fliA, inhibited nipP.w transcription. Moreover, the regulatory effect of the flgKL mutation on nipP.w transcription was partially dependent on the Rcs phosphorelay. Secretion of NipP.w was also dependent on a type II secretion mechanism. Overall, the results of this study indicate that the flgKL mutation is responsible for reduced motility and lower levels of nipP.w expression.
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Affiliation(s)
- Eve Laasik
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, Tartu 51010, Estonia
| | - Lee Põllumaa
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, Tartu 51010, Estonia
| | - Miia Pasanen
- Department of Agricultural Sciences, PO Box 27, 00014 University of Helsinki, Finland
| | - Laura Mattinen
- Department of Agricultural Sciences, PO Box 27, 00014 University of Helsinki, Finland
| | - Minna Pirhonen
- Department of Agricultural Sciences, PO Box 27, 00014 University of Helsinki, Finland
| | - Andres Mäe
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, 23 Riia Street, Tartu 51010, Estonia
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Nykyri J, Niemi O, Koskinen P, Nokso-Koivisto J, Pasanen M, Broberg M, Plyusnin I, Törönen P, Holm L, Pirhonen M, Palva ET. Revised phylogeny and novel horizontally acquired virulence determinants of the model soft rot phytopathogen Pectobacterium wasabiae SCC3193. PLoS Pathog 2012; 8:e1003013. [PMID: 23133391 PMCID: PMC3486870 DOI: 10.1371/journal.ppat.1003013] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 09/18/2012] [Indexed: 11/19/2022] Open
Abstract
Soft rot disease is economically one of the most devastating bacterial diseases affecting plants worldwide. In this study, we present novel insights into the phylogeny and virulence of the soft rot model Pectobacterium sp. SCC3193, which was isolated from a diseased potato stem in Finland in the early 1980s. Genomic approaches, including proteome and genome comparisons of all sequenced soft rot bacteria, revealed that SCC3193, previously included in the species Pectobacterium carotovorum, can now be more accurately classified as Pectobacterium wasabiae. Together with the recently revised phylogeny of a few P. carotovorum strains and an increasing number of studies on P. wasabiae, our work indicates that P. wasabiae has been unnoticed but present in potato fields worldwide. A combination of genomic approaches and in planta experiments identified features that separate SCC3193 and other P. wasabiae strains from the rest of soft rot bacteria, such as the absence of a type III secretion system that contributes to virulence of other soft rot species. Experimentally established virulence determinants include the putative transcriptional regulator SirB, two partially redundant type VI secretion systems and two horizontally acquired clusters (Vic1 and Vic2), which contain predicted virulence genes. Genome comparison also revealed other interesting traits that may be related to life in planta or other specific environmental conditions. These traits include a predicted benzoic acid/salicylic acid carboxyl methyltransferase of eukaryotic origin. The novelties found in this work indicate that soft rot bacteria have a reservoir of unknown traits that may be utilized in the poorly understood latent stage in planta. The genomic approaches and the comparison of the model strain SCC3193 to other sequenced Pectobacterium strains, including the type strain of P. wasabiae, provides a solid basis for further investigation of the virulence, distribution and phylogeny of soft rot bacteria and, potentially, other bacteria as well.
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Affiliation(s)
- Johanna Nykyri
- Department of Agricultural Sciences, Plant Pathology, University of Helsinki, Helsinki, Finland
| | - Outi Niemi
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki, Finland
| | - Patrik Koskinen
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki, Finland
| | | | - Miia Pasanen
- Department of Agricultural Sciences, Plant Pathology, University of Helsinki, Helsinki, Finland
| | - Martin Broberg
- Department of Agricultural Sciences, Plant Pathology, University of Helsinki, Helsinki, Finland
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki, Finland
| | - Ilja Plyusnin
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Petri Törönen
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Liisa Holm
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki, Finland
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Minna Pirhonen
- Department of Agricultural Sciences, Plant Pathology, University of Helsinki, Helsinki, Finland
| | - E. Tapio Palva
- Department of Biosciences, Division of Genetics, University of Helsinki, Helsinki, Finland
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Guo M, Chen Y, Du Y, Dong Y, Guo W, Zhai S, Zhang H, Dong S, Zhang Z, Wang Y, Wang P, Zheng X. The bZIP transcription factor MoAP1 mediates the oxidative stress response and is critical for pathogenicity of the rice blast fungus Magnaporthe oryzae. PLoS Pathog 2011; 7:e1001302. [PMID: 21383978 PMCID: PMC3044703 DOI: 10.1371/journal.ppat.1001302] [Citation(s) in RCA: 226] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Accepted: 01/20/2011] [Indexed: 01/05/2023] Open
Abstract
Saccharomyces cerevisiae Yap1 protein is an AP1-like transcription factor involved in the regulation of the oxidative stress response. An ortholog of Yap1, MoAP1, was recently identified from the rice blast fungus Magnaporthe oryzae genome. We found that MoAP1 is highly expressed in conidia and during invasive hyphal growth. The Moap1 mutant was sensitive to H2O2, similar to S. cerevisiae yap1 mutants, and MoAP1 complemented Yap1 function in resistance to H2O2, albeit partially. The Moap1 mutant also exhibited various defects in aerial hyphal growth, mycelial branching, conidia formation, the production of extracellular peroxidases and laccases, and melanin pigmentation. Consequently, the Moap1 mutant was unable to infect the host plant. The MoAP1-eGFP fusion protein is localized inside the nucleus upon exposure to H2O2, suggesting that MoAP1 also functions as a redox sensor. Moreover, through RNA sequence analysis, many MoAP1-regulated genes were identified, including several novel ones that were also involved in pathogenicity. Disruption of respective MGG_01662 (MoAAT) and MGG_02531 (encoding hypothetical protein) genes did not result in any detectable changes in conidial germination and appressorium formation but reduced pathogenicity, whereas the mutant strains of MGG_01230 (MoSSADH) and MGG_15157 (MoACT) showed marketed reductions in aerial hyphal growth, mycelial branching, and loss of conidiation as well as pathogenicity, similar to the Moap1 mutant. Taken together, our studies identify MoAP1 as a positive transcription factor that regulates transcriptions of MGG_01662, MGG_02531, MGG_01230, and MGG_15157 that are important in the growth, development, and pathogenicity of M. oryzae. Magnaporthe oryzae is a causal agent of rice blast disease and an important model for understanding of fungal development and pathogenicity. To examine the molecular mechanisms involved in conidium formation and appressorium development of M. oryzae, we identified the transcriptional factor MoAP1 as a regulator of the oxidative stress response. Our results indicated that MoAP1 is a stage-specific regulator for conidium formation, morphology, aerial hyphal growth, and also growth in planta. Additionally, we identified four novel genes whose functions were linked to MoAP1 and pathogenicity. Disruption of MGG_01662 (encoding aminobutyrate aminotransferase, MoAat) and MGG_02531 (hypothetical protein) caused minor phenotypic changes but attenuated virulence, and disruption of MGG_01230 (encoding succinic semialdehyde dehydrogenase, MoSsadh) and MGG_15157 (encoding acetyltransferase, MoAct) resulted in drastic reductions in the growth of aerial hyphae and hyphal branching as well as loss of conidiation and pathogenicity. Our studies extend the current understanding of AP1 functions in fungi and reveal that the MoAP1-mediated regulatory network is associated with the pathogenicity of M. oryzae.
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Affiliation(s)
- Min Guo
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Yue Chen
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Yan Du
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Yanhan Dong
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Wang Guo
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Su Zhai
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Suomeng Dong
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
- * E-mail:
| | - Yuanchao Wang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
| | - Ping Wang
- Department of Pediatrics and the Research Institute for Children, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Xiaobo Zheng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing, China
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10
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Yamazaki A, Li J, Hutchins WC, Wang L, Ma J, Ibekwe AM, Yang CH. Commensal effect of pectate lyases secreted from Dickeya dadantii on proliferation of Escherichia coli O157:H7 EDL933 on lettuce leaves. Appl Environ Microbiol 2011; 77:156-62. [PMID: 21075884 PMCID: PMC3019694 DOI: 10.1128/aem.01079-10] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 10/31/2010] [Indexed: 11/20/2022] Open
Abstract
The outbreaks caused by enterohemorrhagic Escherichia coli O157:H7 on leafy greens have raised serious and immediate food safety concerns. It has been suggested that several phytopathogens aid in the persistence and proliferation of the human enteropathogens in the phyllosphere. In this work, we examined the influence of virulence mechanisms of Dickeya dadantii 3937, a broad-host-range phytopathogen, on the proliferation of the human pathogen E. coli O157:H7 EDL933 (EDL933) on postharvest lettuce by coinoculation of EDL933 with D. dadantii 3937 derivatives that have mutations in virulence-related genes. A type II secretion system (T2SS)-deficient mutant of D. dadantii 3937, A1919 (ΔoutC), lost the capability to promote the multiplication of EDL933, whereas Ech159 (ΔrpoS), a stress-responsive σ factor RpoS-deficient mutant, increased EDL933 proliferation on lettuce leaves. A spectrophotometric enzyme activity assay revealed that A1919 (ΔoutC) was completely deficient in the secretion of pectate lyases (Pels), which play a major role in plant tissue maceration. In contrast to A1919 (ΔoutC), Ech159 (ΔrpoS) showed more than 2-fold-greater Pel activity than the wild-type D. dadantii 3937. Increased expression of pelD (encodes an endo-pectate lyase) was observed in Ech159 (ΔrpoS) in planta. These results suggest that the pectinolytic activity of D. dadantii 3937 is the dominant determinant of enhanced EDL933 proliferation on the lettuce leaves. In addition, RpoS, the general stress response σ factor involved in cell survival in suboptimal conditions, plays a role in EDL933 proliferation by controlling the production of pectate lyases in D. dadantii 3937.
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Affiliation(s)
- Akihiro Yamazaki
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - Jin Li
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - William C. Hutchins
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - Lixia Wang
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - Jincai Ma
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - A. Mark Ibekwe
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
| | - Ching-Hong Yang
- Department of Biological Sciences, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, Department of Civil Engineering and Mechanics, University of Wisconsin—Milwaukee, Milwaukee, Wisconsin 53211, USDA-ARS U.S. Salinity Laboratory, Riverside, California 92507
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11
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Guo M, Guo W, Chen Y, Dong S, Zhang X, Zhang H, Song W, Wang W, Wang Q, Lv R, Zhang Z, Wang Y, Zheng X. The basic leucine zipper transcription factor Moatf1 mediates oxidative stress responses and is necessary for full virulence of the rice blast fungus Magnaporthe oryzae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2010; 23:1053-1068. [PMID: 20615116 DOI: 10.1094/mpmi-23-8-1053] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Magnaporthe oryzae is the causal agent of rice blast disease, leading to enormous losses of rice production. Here, we characterized a basic leucine zipper (bZIP) transcription factor, Moatf1, in M. oryzae, a homolog of Schizosaccharomyces pombe ATF/CREB that regulates the oxidative stress response. Moatf1 deletion caused retarded vegetative growth of mycelia, and the Moatf1 mutant exhibited higher sensitivity to hydrogen peroxide (H(2)O(2)) than did the wild-type strain. The mutant showed severely reduced activity of extracellular enzymes and transcription level of laccases and peroxidases and exhibited significantly reduced virulence on rice cultivar CO-39. On rice leaf sheath, most of the infectious hyphae of the mutant became swollen and displayed restricted growth in primary infected cells. Defense response was strongly activated in plants infected by the mutant. Diamino benzidine staining revealed an accumulation of H(2)O(2) around Moatf1 mutant appressoria and rice cells with Moatf1 hyphae that was absent in the wild type. Inhibition of the plant NADPH oxidase by diphenyleneiodonium prevented host-derived H(2)O(2) accumulation and restored infectious hyphal growth of the mutant in rice cells. Thus, we conclude that Moatf1 is necessary for full virulence of M. oryzae by regulating the transcription of laccases and peroxidases to impair reactive oxygen species-mediated plant defense.
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Affiliation(s)
- Min Guo
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, China
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12
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Andresen L, Sala E, Kõiv V, Mäe A. A role for the Rcs phosphorelay in regulating expression of plant cell wall degrading enzymes in Pectobacterium carotovorum subsp. carotovorum. MICROBIOLOGY-SGM 2010; 156:1323-1334. [PMID: 20110299 DOI: 10.1099/mic.0.033936-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Rcs phosphorelay is a signal transduction system that influences the virulence phenotype of several pathogenic bacteria. In the plant pathogen Pectobacterium carotovorum subsp. carotovorum (Pcc) the response regulator of the Rcs phosphorelay, RcsB, represses expression of plant cell wall degrading enzymes (PCWDE) and motility. The focus of this study was to identify genes directly regulated by the binding of RcsB that also regulate expression of PCWDE genes in Pcc. RcsB-binding sites within the regulatory regions of the flhDC operon and the rprA and rsmB genes were identified using DNase I protection assays, while in vivo studies using flhDC : : gusA, rsmB : : gusA and rprA : : gusA gene fusions revealed gene regulation. These experiments demonstrated that the operon flhDC, a flagellar master regulator, was repressed by RcsB, and transcription of rprA was activated by RcsB. Regulation of the rsmB promoter by RcsB is more complicated. Our results show that RcsB represses rsmB expression mainly through modulating flhDC transcription. Neverthless, direct binding of RcsB on the rsmB promoter region is possible in certain conditions. Using an rprA-negative mutant, it was further demonstrated that RprA RNA is not essential for regulating expression of PCWDE under the conditions tested, whereas overexpression of rprA increased protease expression in wild-type cells. Stationary-phase sigma factor, RpoS, is the only known target gene for RprA RNA in Escherichia coli; however, in Pcc the effect of RprA RNA was found to be rpoS-independent. Overall, our results show that the Rcs phosphorelay negatively affects expression of PCWDE by inhibiting expression of flhDC and rsmB.
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Affiliation(s)
- Liis Andresen
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Estonian Biocenter, 23 Riia Street, Tartu 51010, Estonia
| | - Erki Sala
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Estonian Biocenter, 23 Riia Street, Tartu 51010, Estonia
| | - Viia Kõiv
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Estonian Biocenter, 23 Riia Street, Tartu 51010, Estonia
| | - Andres Mäe
- Department of Genetics, Institute of Molecular and Cell Biology, University of Tartu, Estonian Biocenter, 23 Riia Street, Tartu 51010, Estonia
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13
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Smits THM, Jaenicke S, Rezzonico F, Kamber T, Goesmann A, Frey JE, Duffy B. Complete genome sequence of the fire blight pathogen Erwinia pyrifoliae DSM 12163T and comparative genomic insights into plant pathogenicity. BMC Genomics 2010; 11:2. [PMID: 20047678 PMCID: PMC2827408 DOI: 10.1186/1471-2164-11-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2009] [Accepted: 01/04/2010] [Indexed: 11/10/2022] Open
Abstract
Background Erwinia pyrifoliae is a newly described necrotrophic pathogen, which causes fire blight on Asian (Nashi) pear and is geographically restricted to Eastern Asia. Relatively little is known about its genetics compared to the closely related main fire blight pathogen E. amylovora. Results The genome of the type strain of E. pyrifoliae strain DSM 12163T, was sequenced using both 454 and Solexa pyrosequencing and annotated. The genome contains a circular chromosome of 4.026 Mb and four small plasmids. Based on their respective role in virulence in E. amylovora or related organisms, we identified several putative virulence factors, including type III and type VI secretion systems and their effectors, flagellar genes, sorbitol metabolism, iron uptake determinants, and quorum-sensing components. A deletion in the rpoS gene covering the most conserved region of the protein was identified which may contribute to the difference in virulence/host-range compared to E. amylovora. Comparative genomics with the pome fruit epiphyte Erwinia tasmaniensis Et1/99 showed that both species are overall highly similar, although specific differences were identified, for example the presence of some phage gene-containing regions and a high number of putative genomic islands containing transposases in the E. pyrifoliae DSM 12163T genome. Conclusions The E. pyrifoliae genome is an important addition to the published genome of E. tasmaniensis and the unfinished genome of E. amylovora providing a foundation for re-sequencing additional strains that may shed light on the evolution of the host-range and virulence/pathogenicity of this important group of plant-associated bacteria.
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Affiliation(s)
- Theo H M Smits
- Swiss National Competence Center for Fire Blight, Division of Plant Protection, Agroscope Changins-Wädenswil ACW, Wädenswil, Switzerland
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14
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Abstract
Understanding mechanisms of bacterial pathogenesis is critical for infectious disease control and treatment. Infection is a sophisticated process that requires the participation of global regulators to coordinate expression of not only genes coding for virulence factors but also those involved in other physiological processes, such as stress response and metabolic flux, to adapt to host environments. RpoS is a key response regulator to stress conditions in Escherichia coli and many other proteobacteria. In contrast to its conserved well-understood role in stress response, effects of RpoS on pathogenesis are highly variable and dependent on species. RpoS contributes to virulence through either enhancing survival against host defense systems or directly regulating expression of virulence factors in some pathogens, while RpoS is dispensable, or even inhibitory, to virulence in others. In this review, we focus on the distinct and niche-dependent role of RpoS in virulence by surveying recent findings in many pathogens.
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15
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Bourassa L, Camilli A. Glycogen contributes to the environmental persistence and transmission of Vibrio cholerae. Mol Microbiol 2009; 72:124-38. [PMID: 19226328 DOI: 10.1111/j.1365-2958.2009.06629.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Pathogenic Vibrio cholerae cycle between the nutrient-rich human intestinal tract and nutrient-poor aquatic environments and currently few bacterial factors are known that aid in the transition between these disparate environments. We hypothesized that the ability to store carbon as glycogen would facilitate both bacterial fitness in the aquatic environment and transmission of V. cholerae to new hosts. To investigate the role of glycogen in V. cholerae transmission, we constructed mutants that cannot store or degrade glycogen. Here, we provide the first report of glycogen metabolism in V. cholerae and demonstrate that glycogen prolongs survival in nutrient-poor environments that are known ecological niches of V. cholerae, including pond water and rice-water stool. Additionally, glycogen contributes to the pathogenesis of V. cholerae in a transmission model of cholera. A role for glycogen in the transmission of V. cholerae is further supported by the presence of glycogen granules in rice-water stool vibrios from cholera patients, indicating that glycogen is stored during human infection. Collectively, our findings indicate that glycogen metabolism is critical for V. cholerae to transition between host and aquatic environments.
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Affiliation(s)
- Lori Bourassa
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111, USA
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16
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Sjöblom S, Harjunpää H, Brader G, Palva ET. A novel plant ferredoxin-like protein and the regulator Hor are quorum-sensing targets in the plant pathogen Erwinia carotovora. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:967-978. [PMID: 18533837 DOI: 10.1094/mpmi-21-7-0967] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Quorum sensing (QS), a population-density-sensing mechanism, controls the production of the main virulence determinants, the plant cell-wall-degrading enzymes (PCWDEs) of the soft-rot phytopathogen Erwinia carotovora subsp. carotovora. In this study, we used random transposon mutagenesis with a gusA reporter construct to identify two new QS-controlled genes encoding the regulator Hor and a plant ferredoxin-like protein, FerE. The QS control of the identified genes was executed by the QS regulators ExpR1 and ExpR2 and mediated by the global repressor RsmA. Hor was shown to contribute to bacterial virulence at least partly through its control of PCWDE production. Our results showed that FerE contributes to oxidative stress tolerance and in planta fitness of the bacteria and suggest that QS could be central to control of oxidative stress tolerance. The presence of the FerE protein appears to be rather unique in heterotrophic bacteria and suggests an acquisition of the corresponding gene from plant host by horizontal gene transfer.
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Affiliation(s)
- Solveig Sjöblom
- Viikki Biocenter, Faculty of Biosciences, Department of Biological and Environmental Sciences, Division of Genetics, University of Helsinki, P.O.Box 56, FIN-00014, Helsinki, Finland
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17
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Wang J, Gardiol N, Burr T, Salmond GPC, Welch M. RelA-dependent (p)ppGpp production controls exoenzyme synthesis in Erwinia carotovora subsp. atroseptica. J Bacteriol 2007; 189:7643-52. [PMID: 17766416 PMCID: PMC2168740 DOI: 10.1128/jb.00920-07] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 08/22/2007] [Indexed: 11/20/2022] Open
Abstract
In this report, we investigate the link between nutrient limitation, RelA-mediated (p)ppGpp production, and virulence in the phytopathogen Erwinia carotovora subsp. atroseptica. A relA null mutant (JWC7) was constructed by allelic exchange, and we confirmed that, unlike the wild-type progenitor, this mutant did not produce elevated levels of (p)ppGpp upon nutrient downshift. However, (p)ppGpp production could be restored in strain JWC7 during nutrient limitation by supplying relA in trans. During growth on exoenzyme-inducing minimal medium, the relA mutant showed a diminution in secreted pectate lyase and protease activities and a severe defect in motility. The relA mutant was also impaired in its ability to cause rot in potato tubers. In the presence of serine hydroxamate (a competitive inhibitor of seryl tRNA synthase and a potent inducer of the stringent response in wild-type E. carotovora subsp. atroseptica), exoenzyme production was essentially abolished in JWC7 but could be restored in the presence of plasmid-borne relA. The inhibition of exoenzyme production in JWC7 caused by serine hydroxamate could not be overcome by addition of the quorum-sensing signal molecule, N-3-oxohexanoyl-l-homoserine lactone. Quantitative reverse transcription-PCR analysis of selected RNA species confirmed that the effects of relA on secreted pectate lyase activity and motility could be attributed to a reduction in transcription of the corresponding genes. We conclude that nutrient limitation is a potent environmental cue that triggers (p)ppGpp-dependent exoenzyme production in E. carotovora subsp. atroseptica. Furthermore, our data suggest that nutrient limitation [or rather, (p)ppGpp accumulation] is a prerequisite for effective quorum-sensing-dependent activation of exoenzyme production.
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Affiliation(s)
- Jinhong Wang
- Department of Biochemistry, Tennis Court Road, University of Cambridge, Cambridge CB2 1QW, United Kingdom
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18
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Devescovi G, Bigirimana J, Degrassi G, Cabrio L, LiPuma JJ, Kim J, Hwang I, Venturi V. Involvement of a quorum-sensing-regulated lipase secreted by a clinical isolate of Burkholderia glumae in severe disease symptoms in rice. Appl Environ Microbiol 2007; 73:4950-8. [PMID: 17557855 PMCID: PMC1951028 DOI: 10.1128/aem.00105-07] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 05/30/2007] [Indexed: 11/20/2022] Open
Abstract
Burkholderia glumae is an emerging rice pathogen in several areas around the world. Closely related Burkholderia species are important opportunistic human pathogens for specific groups of patients, such as patients with cystic fibrosis and patients with chronic granulomatous disease. Here we report that the first clinical isolate of B. glumae, strain AU6208, has retained its capability to be very pathogenic to rice. As previously reported for rice isolate B. glumae BGR1 (and also for the clinical isolate AU6208), TofI or TofR acyl homoserine lactone (AHL) quorum sensing played a pivotal role in rice virulence. We report that AHL quorum sensing in B. glumae AU6208 regulates secreted LipA lipase and toxoflavin, the phytotoxin produced by B. glumae. B. glumae AU6208 lipA mutants were no longer pathogenic to rice, indicating that the lipase is an important virulence factor. It was also established that type strain B. glumae ATCC 33617 did not produce toxoflavin and lipase and was nonpathogenic to rice. It was determined that in strain ATCC 33617 the LuxR family quorum-sensing sensor/regulator TofR was inactive. Introducing the tofR gene of B. glumae AU6208 in strain ATCC 33617 restored its ability to produce toxoflavin and the LipA lipase. This study extends the role of AHL quorum sensing in rice pathogenicity through the regulation of a lipase which was demonstrated to be a virulence factor. It is the first report of a clinical B. glumae isolate retaining strong rice pathogenicity and finally determined that B. glumae can undergo phenotypic conversion through a spontaneous mutation in the tofR regulator.
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Affiliation(s)
- Giulia Devescovi
- Bacteriology Group, International Centre for Genetic Engineering and Biotechnology, Padriciano 99, Trieste, Italy
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19
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Barnard AM, Bowden SD, Burr T, Coulthurst SJ, Monson RE, Salmond GP. Quorum sensing, virulence and secondary metabolite production in plant soft-rotting bacteria. Philos Trans R Soc Lond B Biol Sci 2007; 362:1165-83. [PMID: 17360277 PMCID: PMC2435580 DOI: 10.1098/rstb.2007.2042] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Quorum sensing describes the ability of bacteria to sense their population density and respond by modulating gene expression. In the plant soft-rotting bacteria, such as Erwinia, an arsenal of plant cell wall-degrading enzymes is produced in a cell density-dependent manner, which causes maceration of plant tissue. However, quorum sensing is central not only to controlling the production of such destructive enzymes, but also to the control of a number of other virulence determinants and secondary metabolites. Erwinia synthesizes both N-acylhomoserine lactone (AHL) and autoinducer-2 types of quorum sensing signal, which both play a role in regulating gene expression in the phytopathogen. We review the models for AHL-based regulation of carbapenem antibiotic production in Erwinia. We also discuss the importance of quorum sensing in the production and secretion of virulence determinants by Erwinia, and its interplay with other regulatory systems.
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Affiliation(s)
| | | | | | | | | | - George P.C Salmond
- Department of Biochemistry, University of CambridgeTennis Court Road, Cambridge CB2 1QW, UK
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20
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Rasch M, Rasmussen TB, Andersen JB, Persson T, Nielsen J, Givskov M, Gram L. Well-known quorum sensing inhibitors do not affect bacterial quorum sensing-regulated bean sprout spoilage. J Appl Microbiol 2007; 102:826-37. [PMID: 17309633 DOI: 10.1111/j.1365-2672.2006.03121.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM To investigate the potential of quorum sensing inhibitors (QSI) as food preservative agents in a food product, where bacterial spoilage is controlled by quorum sensing (QS). METHODS AND RESULTS The effects of well-known QSI were tested on spoilage phenotypes and on QS-regulated genes of a bean sprout spoiling bacterial isolate (Pectobacterium A2JM) in laboratory substrates and in a bean sprout model system. The acylated homoserine lactones (AHL) analogues PenS-AHL and HepS-AHL decreased the specific protease activity of Pectobacterium A2JM in broth but did not reduce the expression of a QS-regulated secretion protein, and were without effect on soft rot of bean sprouts. The QSI ProS-AHL, furanone C-30, patulin, penicillic acid and 4-nitropyridine-N-oxide did not have any effect on protease activity, on gene expression or bean sprout appearance at nongrowth inhibitory concentrations. Extracts from garlic and bean sprouts induced the QS system of Pectobacterium in bean sprouts and a broth system, respectively. CONCLUSIONS Among the several well-known QSI compounds, only PenS-AHL and HepS-AHL, inhibited QS-regulated protease activity of Pectobacterium A2JM in broth cultures, but had no effect on bean sprout spoilage. SIGNIFICANCE AND IMPACT OF THE STUDY The QSI compounds must be selected in the specific system in which they are to function and they cannot easily be transferred from one QS system to another.
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Affiliation(s)
- M Rasch
- Danish Institute for Fisheries Research, Department of Seafood Research, Kgs. Lyngby, Denmark.
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21
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Santos JM, Freire P, Mesquita FS, Mika F, Hengge R, Arraiano CM. Poly(A)-polymerase I links transcription with mRNA degradation via sigmaS proteolysis. Mol Microbiol 2006; 60:177-88. [PMID: 16556229 DOI: 10.1111/j.1365-2958.2006.05078.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bacteria rapidly adapt to changes in growth conditions through control of transcription and specific mRNA degradation. Interplay of both mechanisms must exist in order to achieve fine-tuned regulation of gene expression. Transcription of the Escherichia coli bolA gene is mediated by the RpoS/sigmaS transcription factor in response to environmental signals. In this report it is shown that the mechanisms of bolA1p mRNA transcription and degradation are tightly connected at the onset of stationary phase and in response to sudden carbon starvation. In stationary phase, bolA1p mRNA levels were reduced 2.5-fold in a poly(A)-polymerase I (PAPI) mutant, explained by the significant threefold reduction in sigmaS protein levels in the same strain. Furthermore, fusions with the rpoS gene, analysis of the stability of sigmaS and the levels of RssB indicate that the absence of PAPI enhances RssB-mediated sigmaS proteolysis specifically in starved cells. The fact that PAPI induces higher cellular levels of a global regulator is a novel finding of wide biological significance. PAPI could work as a linker between transcription and mRNA degradation with the ultimate goal of adapting and surviving to growth-limiting conditions.
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Affiliation(s)
- Jorge M Santos
- Instituto de Tecnologia Química e Biológica (ITQB), Universidade Nova de Lisboa, Apt 127, 2781-901 Oeiras, Portugal
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22
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Solis R, Bertani I, Degrassi G, Devescovi G, Venturi V. Involvement of quorum sensing and RpoS in rice seedling blight caused byBurkholderia plantarii. FEMS Microbiol Lett 2006; 259:106-12. [PMID: 16684109 DOI: 10.1111/j.1574-6968.2006.00254.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Burkholderia plantarii is a plant pathogen responsible for causing rice seedling blight. The molecular mechanisms responsible for this pathogenicity are currently unknown. In this study, we report the identification and characterization of N-acyl homoserine lactone quorum sensing and the stationary phase RpoS sigma factor of B. plantarii. Both global regulatory systems are involved in causing rice seedling blight. This is the first report of gene regulators of B. plantarii implicated in the disease.
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Affiliation(s)
- Renando Solis
- Bacteriology Group, International Centre for Genetic Engineering & Biotechnology Area, Trieste, Italy
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23
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Toth IK, Pritchard L, Birch PRJ. Comparative genomics reveals what makes an enterobacterial plant pathogen. ANNUAL REVIEW OF PHYTOPATHOLOGY 2006; 44:305-36. [PMID: 16704357 DOI: 10.1146/annurev.phyto.44.070505.143444] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The bacterial family Enterobacteriaceae contains some of the most devastating human and animal pathogens, including Escherichia coli, Salmonella enterica and species of Yersinia and Shigella. These are among the best-studied of any organisms, yet there is much to be learned about the nature and evolution of interactions with their hosts and with the wider environment. Comparative and functional genomics have fundamentally improved our understanding of their modes of adaptation to different ecological niches and the genes that determine their pathogenicity. In addition to animal pathogens, Enterobacteriaceae include important plant pathogens, such as Erwinia carotovora subsp. atroseptica (Eca), the first plant-pathogenic enterobacterium to be sequenced. This review focuses on genomic comparisons between Eca and other enterobacteria, with particular emphasis on the differences that exemplify or explain the plant-associated lifestyle(s) of Eca. Horizontal gene transfer in Eca may directly have led to the acquisition of a number of determinants that mediate its interactions, pathogenic or otherwise, with plants, offering a glimpse into its evolutionary divergence from animal-pathogenic enterobacteria.
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Affiliation(s)
- Ian K Toth
- Plant Pathology Program, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, United Kingdom.
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24
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Barak JD, Gorski L, Naraghi-Arani P, Charkowski AO. Salmonella enterica virulence genes are required for bacterial attachment to plant tissue. Appl Environ Microbiol 2005; 71:5685-91. [PMID: 16204476 PMCID: PMC1265987 DOI: 10.1128/aem.71.10.5685-5691.2005] [Citation(s) in RCA: 184] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Numerous Salmonella enterica food-borne illness outbreaks have been associated with contaminated vegetables, in particular sprouted seeds, and the incidence of reported contamination has steadily risen. In order to understand the physiology of S. enterica serovar Newport on plants, a screen was developed to identify transposon mutants that were defective in attachment to alfalfa sprouts. Twenty independent mutants from a pool of 6,000 were selected for reduced adherence to alfalfa sprouts. Sixty-five percentage of these mutants had insertions in uncharacterized genes. Among the characterized genes were strains with insertions in the intergenic region between agfB, the surface-exposed aggregative fimbria (curli) nucleator, and agfD, a transcriptional regulator of the LuxR superfamily, and rpoS, the stationary-phase sigma factor. Both AgfD and RpoS have been reported to regulate curli and cellulose production and RpoS regulates other adhesins such as pili. The intergenic and rpoS mutants were reduced in initial attachment to alfalfa sprouts by 1 log unit compared to the wild type. Mutations of agfA, curli subunit, and agfB in S. enterica serovar Enteritidis differentially affected attachment to plant tissue. The agfA mutation was not reduced in ability to attach to or colonize alfalfa sprouts, whereas the agfB mutation was reduced. Thus, agfB alone can play a role in attachment of S. enterica to plant tissue. These results reveal that S. enterica genes important for virulence in animal systems are also required for colonization of plants, a secondary host that can serve as a vector of S. enterica from animal to animal.
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Affiliation(s)
- Jeri D Barak
- USDA, ARS, WRRC, Produce Safety and Microbiology, 800 Buchanan St., Albany, CA 94710, USA.
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25
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Mattinen L, Tshuikina M, Mäe A, Pirhonen M. Identification and characterization of Nip, necrosis-inducing virulence protein of Erwinia carotovora subsp. carotovora. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2004; 17:1366-75. [PMID: 15597742 DOI: 10.1094/mpmi.2004.17.12.1366] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Erwinia carotovora subsp. carotovora is a gram-negative bacterium that causes soft rot disease of many cultivated crops. When a collection of E. carotovora subsp. carotovora isolates was analyzed on a Southern blot using the harpin-encoding gene hrpN as probe, several harpinless isolates were found. Regulation of virulence determinants in one of these, strain SCC3193, has been characterized extensively. It is fully virulent on potato and in Arabidopsis thaliana. An RpoS (SigmaS) mutant of SCC3193, producing elevated levels of secreted proteins, was found to cause lesions resembling the hypersensitive response when infiltrated into tobacco leaf tissue. This phenotype was evident only when bacterial cells had been cultivated on solid minimal medium at low pH and temperature. The protein causing'the cell death was purified and sequenced, and the corresponding gene was cloned. The deduced sequence of the necrosis-inducing protein (Nip) showed homology to necrosis- and ethylene-inducing elicitors of fungi and oomycetes. A mutant strain of E. carotovora subsp. carotovora lacking the nip gene showed reduced virulence in potato tuber assay but was unaffected in virulence in potato stem or on other tested host plants.
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Affiliation(s)
- Laura Mattinen
- Department of Applied Biology, FIN-00014, University of Helsinki, Finland
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Matsumoto H, Jitareerat P, Baba Y, Tsuyumu S. Comparative study of regulatory mechanisms for pectinase production by Erwinia carotovora subsp. carotovora and Erwinia chrysanthemi. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2003; 16:226-237. [PMID: 12650454 DOI: 10.1094/mpmi.2003.16.3.226] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The production of pectinase, the major virulence determinant of soft-rot Erwinia species, is controlled by many regulatory factors. We focused on the major regulatory proteins, KdgR, CRP, Pir, and PecS, characterized mainly in E. chrysanthemi, and tested for their presence and function in the control of pectate lyase (Pel) and polygalacturonase (Peh) production in E. carotovora subsp. carotovora. Homologues of kdgR and crp but not of pir and pecS were detected by Southern blot analyses in E. carotovora subsp. carotovora. In fact, KdgR and CRP homologues of E. carotovora subsp. carotovora had high amino acid identities to those of E. chrysanthemi, including a complete match of the hypothetical helix-turn-helix DNA-binding motif. However, in Western blot analyses using anti-Pir (E. chrysanthemi) antibodies, a cross-reacting protein was present in both Erwinia species, although Pel production in E. carotovora subsp. carotovora was not further stimulated by adding plant extract into the medium containing PGA (polygalacturonic acid) in which hyperinduction by Pir has been reported in E. chrysanthemi EC16. When plasmids that contained each of these regulatory genes from E. chrysanthemi were introduced into E. carotovora subsp. carotovora, Pel production was controlled as predicted from their roles in E. chrysanthemi, except for PecS. PecS exerted a positive control in E. carotovora subsp. carotovora, in contrast to a negative control in E. chrysanthemi. DNA-binding assays demonstrated that KdgR, CRP, Pir, and PecS of E. chrysanthemi and KdgR and CRP homologues of E. carotovora subsp. carotovora could bind to the promoter regions of pel-1, pel-3, and peh of E. carotovora subsp. carotovora. Taken together, KdgR and CRP homologues of E. carotovora subsp. carotovora may regulate Pel and Peh production as in E. chrysanthemi. However, the presence of Pir and PecS homologues in E. carotovora subsp. carotovora was not identified in this study, though these proteins of E. chrysanthemi were functional on the promoter regions of the pectinase genes of E. carotovora subsp. carotovora.
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Affiliation(s)
- Hiroyuki Matsumoto
- United Graduate School of Agricultural Science, Gifu University (Shizuoka University), 836 Ohya, Shizuoka 422-8529, Japan
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Swift S, Downie JA, Whitehead NA, Barnard AM, Salmond GP, Williams P. Quorum sensing as a population-density-dependent determinant of bacterial physiology. Adv Microb Physiol 2002; 45:199-270. [PMID: 11450110 DOI: 10.1016/s0065-2911(01)45005-3] [Citation(s) in RCA: 211] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The discovery that bacterial cells can communicate with each other has led to the realization that bacteria are capable of exhibiting much more complex patterns of co-operative behaviour than would be expected for simple unicellular microorganisms. Now generically termed 'quorum sensing', bacterial cell-to-cell communication enables a bacterial population to mount a unified response that is advantageous to its survival by improving access to complex nutrients or environmental niches, collective defence against other competitive microorganisms or eukaryotic host defence mechanisms and optimization of population survival by differentiation into morphological forms better adapted to combating environmental threats. The principle of quorum sensing encompasses the production and release of signal molecules by bacterial cells within a population. Such molecules are released into the environment and, as cell numbers increase, so does the extracellular level of signal molecule, until the bacteria sense that a threshold has been reached and gene activation, or in some cases depression or repression, occurs via the activity of sensor-regulator systems. In this review, we will describe the biochemistry and molecular biology of a number of well-characterized N-acylhomoserine lactone quorum sensing systems to illustrate how bacteria employ cell-to-cell signalling to adjust their physiology in accordance with the prevailing high-population-density environment.
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Affiliation(s)
- S Swift
- Institute of Infections and Immunity, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2RD UK
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Hyytiäinen H, Montesano M, Palva ET. Global regulators ExpA (GacA) and KdgR modulate extracellular enzyme gene expression through the RsmA-rsmB system in Erwinia carotovora subsp. carotovora. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2001; 14:931-938. [PMID: 11497464 DOI: 10.1094/mpmi.2001.14.8.931] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The production of the main virulence determinants, the extracellular plant cell wall-degrading enzymes, and hence virulence of Erwinia carotovora subsp. carotovora is controlled by a complex regulatory network. One of the global regulators, the response regulator ExpA, a GacA homolog, is required for transcriptional activation of the extracellular enzyme genes of this soft-rot pathogen. To elucidate the mechanism of ExpA control as well as interactions with other regulatory systems, we isolated second-site transposon mutants that would suppress the enzyme-negative phenotype of an expA (gacA) mutant. Inactivation of kdgR resulted in partial restoration of extracellular enzyme production and virulence to the expA mutant, suggesting an interaction between the two regulatory pathways. This interaction was mediated by the RsmA-rsmB system. Northern analysis was used to show that the regulatory rsmB RNA was under positive control of ExpA. Conversely, the expression of rsmA encoding a global repressor was under negative control of ExpA and positive control of KdgR. This study indicates a central role for the RsmA-rsmB regulatory system during pathogenesis, integrating signals from the ExpA (GacA) and KdgR global regulators of extracellular enzyme production in E. carotovora subsp. carotovora.
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Affiliation(s)
- H Hyytiäinen
- Department of Biosciences, University of Helsinki, Finland
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Cui Y, Chatterjee A, Chatterjee AK. Effects of the two-component system comprising GacA and GacS of Erwinia carotovora subsp. carotovora on the production of global regulatory rsmB RNA, extracellular enzymes, and harpinEcc. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2001; 14:516-526. [PMID: 11310739 DOI: 10.1094/mpmi.2001.14.4.516] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Posttranscriptional regulation mediated by the regulator of secondary metabolites (RSM) RsmA-rsmB pair is the most important factor in the expression of genes for extracellular enzymes and HarpinEcc in Erwinia carotovora subsp. carotovora. RsmA is a small RNA-binding protein, which acts by lowering the half-life of a mRNA species. rsmB specifies an untranslated regulatory RNA and neutralizes the RsmA effect. It has been speculated that GacA-GacS, members of a two-component system, may affect gene expression via RsmA. Because expA, a gacA homolog, and expS (or rpfA), a gacS homolog, have been identified in E. carotovora subsp. carotovora, we examined the effects of these gacA and gacS homologs on the expression of rsmA, rsmB, and an assortment of exoprotein genes. The gacA gene of E. carotovora subsp. carotovora strain 71 stimulated transcription of genes for several extracellular enzymes (pel-1, a pectate lyase gene; peh-1, a polygalacturonase gene; and celV, a cellulase gene), hrpNEcc (an E. carotovora subsp. carotovora gene specifying the elicitor of hypersensitive reaction), and rsmB in GacA+ and GacS+ E. carotovora subsp. carotovora strains. Similarly, the E. carotovora subsp. carotovora gacA gene stimulated csrB (rsmB) transcription in Escherichia coli. A GacS- mutant of E. carotovora subsp. carotovora strain AH2 and a GacA- mutant of E. carotovora subsp. carotovora strain Ecc71 compared with their parent strains produced very low levels of rsmB, pel-1, peh-1, celV, and hrpNEcc transcripts but produced similar levels of rsmA RNA and RsmA protein as well as transcripts of hyperproduction of extracellular enzymes (Hex) hexA, kdgR (repressor of genes for uronate and pectate catabolism), rsmC, and rpoS (gene for Sigma-S, an alternate Sigma factor). The levels of rsmB, pel-1, peh-1, celV, and hrpNEcc transcripts as well as production of pectate lyase, polygalacturonase, cellulase, protease, and HarpinEcc proteins were stimulated in GacS- and GacA- mutants by GacS+ or GacA+ plasmids, respectively. The GacA effect on exoenzyme genes and hrpNEcc was abrogated in E. carotovora subsp. carotovora mutants deficient in RsmA and RsmC or RsmA, RsmC, and rsmB RNA. The expression of lacZ transcriptional fusions of rsmB of Erwinia amylovora and Erwinia herbicola pv. gypsophilae was markedly reduced in a GacA- and a GacS- mutant of Pseudomonas syringae pv. syringae. Southern blot hybridization revealed the presence of gacA and gacS homologs in all tested strains of soft-rotting Erwinia spp. and several nonsoft-rotting Erwinia species such as E. amylovora, E. rhapontici, E. herbicola, E. stewartii, and E. herbicola pv. gypsophilae. These findings establish that the GacA-GacS system controls transcription of rsmB of E. carotovora subsp. carotovora, E. amylovora, and E. herbicola pv. gypsophilae and support the hypothesis that the effects of this two-component system on extracellular protein production in E. carotovora subsp. carotovora is mediated, at least in part, via the levels of rsmB transcripts.
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Affiliation(s)
- Y Cui
- Department of Plant Microbiology and Pathology, University of Missouri, Columbia 65211, USA
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Majdalani N, Chen S, Murrow J, St John K, Gottesman S. Regulation of RpoS by a novel small RNA: the characterization of RprA. Mol Microbiol 2001; 39:1382-94. [PMID: 11251852 DOI: 10.1111/j.1365-2958.2001.02329.x] [Citation(s) in RCA: 223] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Translational regulation of the stationary phase sigma factor RpoS is mediated by the formation of a double-stranded RNA stem-loop structure in the upstream region of the rpoS messenger RNA, occluding the translation initiation site. The interaction of the rpoS mRNA with a small RNA, DsrA, disrupts the double-strand pairing and allows high levels of translation initiation. We screened a multicopy library of Escherichia coli DNA fragments for novel activators of RpoS translation when DsrA is absent. Clones carrying rprA (RpoS regulator RNA) increased the translation of RpoS. The rprA gene encodes a 106 nucleotide regulatory RNA. As with DsrA, RprA is predicted to form three stem-loops and is highly conserved in Salmonella and Klebsiella species. Thus, at least two small RNAs, DsrA and RprA, participate in the positive regulation of RpoS translation. Unlike DsrA, RprA does not have an extensive region of complementarity to the RpoS leader, leaving its mechanism of action unclear. RprA is non-essential. Mutations in the gene interfere with the induction of RpoS after osmotic shock when DsrA is absent, demonstrating a physiological role for RprA. The existence of two very different small RNA regulators of RpoS translation suggests that such additional regulatory RNAs are likely to exist, both for regulation of RpoS and for regulation of other important cellular components.
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Affiliation(s)
- N Majdalani
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bldg. 37 Room 2E 18, Bethesda, MD 20892-4255, USA
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Andersson RA, Eriksson AR, Heikinheimo R, Mäe A, Pirhonen M, Kõiv V, Hyytiäinen H, Tuikkala A, Palva ET. Quorum sensing in the plant pathogen Erwinia carotovora subsp. carotovora: the role of expR(Ecc). MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2000; 13:384-93. [PMID: 10755301 DOI: 10.1094/mpmi.2000.13.4.384] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The production of the main virulence determinants of the plant pathogen Erwinia carotovora subsp. carotovora, the extracellular cell wall-degrading enzymes, is partly controlled by the diffusible signal molecule N-(3-oxohexanoyl)-L-homoserine lactone (OHHL). OHHL is synthesized by the product of the expI/carI gene. Linked to expI we found a gene encoding a putative transcriptional regulator of the LuxR-family. This gene, expR(Ecc), is transcribed convergently to the expI gene and the two open reading frames are partially overlapping. The ExpR(Ecc) protein showed extensive amino acid sequence similarity to the repressor EsaR from Pantoea stewartii subsp. stewartii (formerly Erwinia stewartii subsp. stewartii) and to the ExpR(Ech) protein of Erwinia chrysanthemi. Inactivation of the E. carotovora subsp. carotovora expR(Ecc) gene caused no decrease in virulence or production of virulence determinants in vitro. In contrast, there was a slight increase in the maceration capacity of the mutant strain. The effects of ExpR(Ecc) were probably mediated by changes in OHHL levels. Inactivation of expR(Ecc) resulted in increased OHHL levels during early logarithmic growth. In addition, overexpression of expR(Ecc) caused a clear decrease in the production of virulence determinants and part of this effect was likely to be caused by OHHL binding to ExpR(Ecc). ExpR(Ecc) did not appear to exhibit transcriptional regulation of expI, but the effect on OHHL was apparently due to other mechanisms.
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Affiliation(s)
- R A Andersson
- Department of Plant Biology, Uppsala Genetic Center, Swedish University of Agricultural Sciences
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