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Huang J, Yao C, Sun Y, Ji Q, Deng X. Virulence-related regulatory network of Pseudomonas syringae. Comput Struct Biotechnol J 2022; 20:6259-6270. [PMID: 36420163 PMCID: PMC9678800 DOI: 10.1016/j.csbj.2022.11.011] [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: 07/30/2022] [Revised: 11/05/2022] [Accepted: 11/05/2022] [Indexed: 11/11/2022] Open
Abstract
Transcription factors (TFs) play important roles in regulating multiple biological processes by binding to promoter regions and regulating the global gene transcription levels. Pseudomonas syringae is a Gram-negative phytopathogenic bacterium harbouring 301 putative TFs in its genome, approximately 50 of which are responsible for virulence-related gene and pathway regulation. Over the past decades, RNA sequencing, chromatin immunoprecipitation sequencing, high-throughput systematic evolution of ligands by exponential enrichment, and other technologies have been applied to identify the functions of master regulators and their interactions in virulence-related pathways. This review summarises the recent advances in the regulatory networks of TFs involved in the type III secretion system (T3SS) and non-T3SS virulence-associated pathways, including motility, biofilm formation, quorum sensing, nucleotide-based secondary messengers, phytotoxins, siderophore production, and oxidative stress. Moreover, this review discusses the future perspectives in terms of TF-mediated pathogenesis mechanisms and provides novel insights that will help combat P. syringae infections based on the regulatory networks of TFs.
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Affiliation(s)
- Jiadai Huang
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR 999077 China
| | - Chunyan Yao
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR 999077 China
| | - Yue Sun
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR 999077 China
| | - Quanjiang Ji
- Gene Editing Center, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xin Deng
- Department of Biomedical Sciences, City University of Hong Kong, Kowloon Tong, Hong Kong SAR 999077 China
- Shenzhen Research Institute, City University of Hong Kong, Shenzhen 518057, China
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Liu J, Yu M, Ge Y, Tian Y, Hu B, Zhao Y. The RsmA RNA-Binding Proteins in Pseudomonas syringae Exhibit Distinct and Overlapping Roles in Modulating Virulence and Survival Under Different Nutritional Conditions. FRONTIERS IN PLANT SCIENCE 2021; 12:637595. [PMID: 33719314 PMCID: PMC7952654 DOI: 10.3389/fpls.2021.637595] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 01/27/2021] [Indexed: 06/12/2023]
Abstract
The post-transcriptional regulator RsmA globally controls gene expression in bacteria. Previous studies showed that RsmA2 and RsmA3 played critical roles in regulating type III secretion system (T3SS), motility, syringafactin, and alginate productions in Pseudomonas syringae pv. tomato strain DC3000 (PstDC3000). In this study, we investigated global gene expression profiles of the wild-type PstDC3000, the rsmA3 mutant, and the rsmA2/A3 double mutant in the hrp-inducing minimum medium (HMM) and King's B (KB) medium. By comparing the rsmA2/A3 and rsmA3 mutants to PstDC3000, a total of 1358 and 1074 differentially expressed genes (DEGs) in HMM, and 870 and 1463 DEGs in KB were uncovered, respectively. When comparing the rsmA2/A3 mutant with the rsmA3 mutant, 277 and 741 DEGs in HMM and KB, respectively, were revealed. Transcriptomic analysis revealed that the rsmY, rsmZ, and rsmX1-5 non-coding small RNAs (ncsRNAs) were positively affected by RsmA2 and RsmA3, while RsmA3 positively regulates the expression of the rsmA2 gene and negatively regulates both rsmA1 and rsmA5 gene expression. Comparative transcriptomic analysis showed that RsmA2 and RsmA3 synergistically influenced the expression of genes involved in T3SS and alginate biosynthesis in HMM and chemotaxis in KB. RsmA2 and RsmA3 inversely affected genes involved in syringafactin production in HMM and ribosomal protein biosynthesis in KB. In addition, RsmA2 played a major role in influencing genes involved in sarcosine and thiamine biosynthesis in HMM and in mannitol and phosphate metabolism in KB. On the other hand, genes involved in fatty acid metabolism, cellulose biosynthesis, signal transduction, and stress responses were mainly impacted by RsmA3 in both HMM and KB; whereas RsmA3 played a major role in controlling genes involved in c-di-GMP, phosphate metabolism, chemotaxis, and capsular polysaccharide in HMM. Furthermore, regulation of syringafactin production and oxidative stress by RsmA2 and RsmA3 was experimentally verified. Our results suggested the potential interplay among the RsmA proteins, which exhibit distinct and overlapping roles in modulating virulence and survival in P. syringae under different nutritional conditions.
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Affiliation(s)
- Jun Liu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Menghao Yu
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Yixin Ge
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Yanli Tian
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
| | - Baishi Hu
- College of Plant Protection and Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
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Liang F, Zhang B, Yang Q, Zhang Y, Zheng D, Zhang LQ, Yan Q, Wu X. Cyclic-di-GMP Regulates the Quorum-Sensing System and Biocontrol Activity of Pseudomonas fluorescens 2P24 through the RsmA and RsmE Proteins. Appl Environ Microbiol 2020; 86:e02016-20. [PMID: 33036989 PMCID: PMC7688223 DOI: 10.1128/aem.02016-20] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 10/04/2020] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas fluorescens 2P24 is a rhizosphere bacterium that protects many crop plants against soilborne diseases caused by phytopathogens. The PcoI/PcoR quorum-sensing (QS) system and polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) are particularly relevant to the strain's biocontrol potential. In this study, we investigated the effects of c-di-GMP on the biocontrol activity of strain 2P24. The expression of the Escherichia coli diguanylate cyclase (YedQ) and phosphodiesterase (YhjH) in P. fluorescens 2P24 significantly increased and decreased the cellular concentration of c-di-GMP, respectively. The production of the QS signals N-acyl homoserine lactones (AHLs) and 2,4-DAPG was negatively regulated by c-di-GMP in 2P24. The regulatory proteins RsmA and RsmE were positively regulated by c-di-GMP. Genomic analysis revealed that 2P24 has 23 predicted proteins that contain c-di-GMP-synthesizing or -degrading domains. Among these proteins, C0J56_12915, C0J56_13325, and C0J56_27925 contributed to the production of c-di-GMP and were also involved in the regulation of the QS signal and antibiotic 2,4-DAPG production in P. fluorescens Overexpression of C0J56_12915, C0J56_13325, and C0J56_27925 in 2P24 impaired its root colonization and biocontrol activities. Taken together, these results demonstrated that c-di-GMP played an important role in fine-tuning the biocontrol traits of P. fluorescensIMPORTANCE In various bacteria, the bacterial second messenger c-di-GMP influences a wide range of cellular processes. However, the function of c-di-GMP on biocontrol traits in the plant-beneficial rhizobacteria remains largely unclear. The present work shows that the QS system and polyketide antibiotic 2,4-DAPG production are regulated by c-di-GMP through RsmA and RsmE proteins in P. fluorescens 2P24. The diguanylate cyclases (DGCs) C0J56_12915, C0J56_13325, and C0J56_27925 are especially involved in regulating the biocontrol traits of 2P24. Our work also demonstrated a connection between the Gac/Rsm cascade and the c-di-GMP signaling pathway in P. fluorescens.
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Affiliation(s)
- Fei Liang
- College of Agriculture, Guangxi University, Nanning, China
| | - Bo Zhang
- College of Agriculture, Guangxi University, Nanning, China
| | - Qingqing Yang
- College of Agriculture, Guangxi University, Nanning, China
| | - Yang Zhang
- College of Agriculture, Guangxi University, Nanning, China
| | - Dehong Zheng
- College of Agriculture, Guangxi University, Nanning, China
| | - Li-Qun Zhang
- College of Plant Protection, China Agricultural University, Beijing, China
| | - Qing Yan
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, Montana, USA
| | - Xiaogang Wu
- College of Agriculture, Guangxi University, Nanning, China
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Liu J, Yu M, Chatnaparat T, Lee JH, Tian Y, Hu B, Zhao Y. Comparative transcriptomic analysis of global gene expression mediated by (p) ppGpp reveals common regulatory networks in Pseudomonas syringae. BMC Genomics 2020; 21:296. [PMID: 32272893 PMCID: PMC7146990 DOI: 10.1186/s12864-020-6701-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/25/2020] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Pseudomonas syringae is an important plant pathogen, which could adapt many different environmental conditions. Under the nutrient-limited and other stress conditions, P. syringae produces nucleotide signal molecules, i.e., guanosine tetra/pentaphosphate ((p)ppGpp), to globally regulate gene expression. Previous studies showed that (p) ppGpp played an important role in regulating virulence factors in P. syringae pv. tomato DC3000 (PstDC3000) and P. syringae pv. syringae B728a (PssB728a). Here we present a comparative transcriptomic analysis to uncover the overall effects of (p)ppGpp-mediated stringent response in P. syringae. RESULTS In this study, we investigated global gene expression profiles of PstDC3000 and PssB728a and their corresponding (p)ppGpp0 mutants in hrp-inducing minimal medium (HMM) using RNA-seq. A total of 1886 and 1562 differentially expressed genes (DEGs) were uncovered between the (p)ppGpp0 mutants and the wild-type in PstDC3000 and PssB728a, respectively. Comparative transcriptomics identified 1613 common DEGs, as well as 444 and 293 unique DEGs in PstDC3000 and PssB728a, respectively. Functional cluster analysis revealed that (p) ppGpp positively regulated a variety of virulence-associated genes, including type III secretion system (T3SS), type VI secretion system (T6SS), cell motility, cell division, and alginate biosynthesis, while negatively regulated multiple basic physiological processes, including DNA replication, RNA processes, nucleotide biosynthesis, fatty acid metabolism, ribosome protein biosynthesis, and amino acid metabolism in both PstDC3000 and PssB728a. Furthermore, (p) ppGpp had divergent effects on other processes in PstDC3000 and PssB728a, including phytotoxin, nitrogen regulation and general secretion pathway (GSP). CONCLUSION In this study, comparative transcriptomic analysis reveals common regulatory networks in both PstDC3000 and PssB728a mediated by (p) ppGpp in HMM. In both P. syringae systems, (p) ppGpp re-allocate cellular resources by suppressing multiple basic physiological activities and enhancing virulence gene expression, suggesting a balance between growth, survival and virulence. Our research is important in that due to similar global gene expression mediated by (p) ppGpp in both PstDC3000 and PssB728a, it is reasonable to propose that (p) ppGpp could be used as a target to develop novel control measures to fight against important plant bacterial diseases.
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Affiliation(s)
- Jun Liu
- College of Plant Protection, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, 210095, P. R. China.,Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL, 61801, USA
| | - Menghao Yu
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL, 61801, USA
| | - Tiyakhon Chatnaparat
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL, 61801, USA
| | - Jae Hoon Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL, 61801, USA
| | - Yanli Tian
- College of Plant Protection, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, 210095, P. R. China
| | - Baishi Hu
- College of Plant Protection, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, 210095, P. R. China.
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr., Urbana, IL, 61801, USA.
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Abstract
σN (also σ54) is an alternative sigma factor subunit of the RNA polymerase complex that regulates the expression of genes from many different ontological groups. It is broadly conserved in the Eubacteria with major roles in nitrogen metabolism, membrane biogenesis, and motility. σN is encoded as the first gene of a five-gene operon including rpoN (σN), ptsN, hpf, rapZ, and npr that has been genetically retained among species of Escherichia, Shigella, and Salmonella. In an increasing number of bacteria, σN has been implicated in the control of genes essential to pathogenic behavior, including those involved in adherence, secretion, immune subversion, biofilm formation, toxin production, and resistance to both antimicrobials and biological stressors. For most pathogens how this is achieved is unknown. In enterohemorrhagic Escherichia coli (EHEC) O157, Salmonella enterica, and Borrelia burgdorferi, regulation of virulence by σN requires another alternative sigma factor, σS, yet the model by which σN-σS virulence regulation is predicted to occur is varied in each of these pathogens. In this review, the importance of σN to bacterial pathogenesis is introduced, and common features of σN-dependent virulence regulation discussed. Emphasis is placed on the molecular mechanisms underlying σN virulence regulation in E. coli O157. This includes a review of the structure and function of regulatory pathways connecting σN to virulence expression, predicted input signals for pathway stimulation, and the role for cognate σN activators in initiation of gene systems determining pathogenic behavior.
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Newberry EA, Jardini TM, Rubio I, Roberts PD, Babu B, Koike ST, Bouzar H, Goss EM, Jones JB, Bull CT, Paret ML. Angular Leaf Spot of Cucurbits is Associated With Genetically Diverse Pseudomonas syringae Strains. PLANT DISEASE 2016; 100:1397-1404. [PMID: 30686200 DOI: 10.1094/pdis-11-15-1332-re] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Angular leaf spot of cucurbits is generally considered to be caused by Pseudomonas syringae pv. lachrymans. It has a worldwide distribution and has been observed to emerge sporadically under humid and wet conditions. Reports of multiple P. syringae pathovars associated with the disease and lack of molecular analysis has left the true diversity of populations in the United States unclear. In this study, we collected 27 P. syringae strains causing foliar lesions and blighting on watermelon, cantaloupe, and squash in Florida, Georgia, and California over several years. Strains were fluorescent on King's medium B agar and displayed the typical phenotypic and biochemical characteristics of P. syringae. P. syringae pv. lachrymans is a member of genomospecies 2. However, the genetic profiles obtained through both MLSA (gyrB, rpoD, gapA, and gltA) and BOX-PCR (BOXA1R) identified 26 of the P. syringae strains to be distributed among three clades within genomospecies 1, and phylogenetically distinct from genomospecies 2 member P. syringae pv. lachrymans. A novel MLSA haplotype of the pathogen common to all states and cucurbit hosts was identified. Considerable genetic diversity among P. syringae strains infecting cucurbits is associated with the same disease, and reflects the larger ecological diversity of P. syringae populations from genomospecies 1.
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Affiliation(s)
- E A Newberry
- North Florida Research & Education Center, University of Florida, Quincy, FL
| | | | - I Rubio
- USDA-ARS, Salinas, CA; and Undergraduate Research Opportunities Center, Seaside, California State University, Monterey Bay, CA
| | - P D Roberts
- Southwest Florida Research and Education Center, University of Florida, Immokalee, FL
| | - B Babu
- North Florida Research & Education Center, University of Florida, Quincy, FL
| | - S T Koike
- University of California Cooperative Extension, Monterey County, Salinas, CA
| | - H Bouzar
- Sakata Seed America, Inc., Salinas, CA
| | - E M Goss
- Department of Plant Pathology, University of Florida, Gainesville, FL
| | - J B Jones
- Department of Plant Pathology, University of Florida, Gainesville, FL
| | - C T Bull
- USDA-ARS, Salinas, CA (current address: Department of Plant Pathology and Environmental Microbiology, Pennsylvania State University, University Park, PA)
| | - M L Paret
- North Florida Research & Education Center, University of Florida, Quincy, FL
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Miller DP, Frederick JR, Sarkar J, Marconi RT. The Treponema denticola AtcR LytTR domain-containing response regulator interacts with three architecturally distinct promoter elements: implications for understanding the molecular signaling mechanisms that drive the progression of periodontal disease. Mol Oral Microbiol 2014; 29:219-32. [PMID: 24890414 DOI: 10.1111/omi.12059] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2014] [Indexed: 12/27/2022]
Abstract
Treponema denticola is an oral spirochete and periopathogen that transitions from low abundance in healthy subgingival crevices to high abundance in periodontal pockets. The T. denticola response regulator AtcR harbors the relatively rare, LytTR DNA-binding domain. LytTR domain containing response regulators control critical transcriptional responses required for environmental adaptation. Using a multi-step bioinformatics approach, 26 strong lytTR recognition motifs were identified in the genome of T. denticola strain 35405. Electrophoretic mobility shift assays demonstrated that AtcR binds to these recognition motifs. High specificity-high affinity complexes formed with phosphorylated AtcR. The LytTR recognition sequences were found to exist in three distinct promoter architectures designated as LytTR1, LytTR2 and LytTR3 promoters. LytTR1 and LytTR2 promoters harbor σ(54) binding sites. The functional diversity of the proteins encoded by the putative AtcR regulon suggests that AtcR sits at the top of a regulatory cascade that plays a central role in facilitating T. denticola's ability to adapt to changing environmental conditions and thrive in periodontal pockets.
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Affiliation(s)
- D P Miller
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, Richmond, VA, USA
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Okkotsu Y, Little AS, Schurr MJ. The Pseudomonas aeruginosa AlgZR two-component system coordinates multiple phenotypes. Front Cell Infect Microbiol 2014; 4:82. [PMID: 24999454 PMCID: PMC4064291 DOI: 10.3389/fcimb.2014.00082] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 06/02/2014] [Indexed: 01/28/2023] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that causes a multitude of infections. These infections can occur at almost any site in the body and are usually associated with a breach of the innate immune system. One of the prominent sites where P. aeruginosa causes chronic infections is within the lungs of cystic fibrosis patients. P. aeruginosa uses two-component systems that sense environmental changes to differentially express virulence factors that cause both acute and chronic infections. The P. aeruginosa AlgZR two component system is one of its global regulatory systems that affects the organism's fitness in a broad manner. This two-component system is absolutely required for two P. aeruginosa phenotypes: twitching motility and alginate production, indicating its importance in both chronic and acute infections. Additionally, global transcriptome analyses indicate that it regulates the expression of many different genes, including those associated with quorum sensing, type IV pili, type III secretion system, anaerobic metabolism, cyanide and rhamnolipid production. This review examines the complex AlgZR regulatory network, what is known about the structure and function of each protein, and how it relates to the organism's ability to cause infections.
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Affiliation(s)
- Yuta Okkotsu
- Department of Microbiology, University of Colorado School of Medicine Aurora, CO, USA
| | - Alexander S Little
- Department of Microbiology, University of Colorado School of Medicine Aurora, CO, USA
| | - Michael J Schurr
- Department of Microbiology, University of Colorado School of Medicine Aurora, CO, USA
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Ancona V, Li W, Zhao Y. Alternative sigma factor RpoN and its modulation protein YhbH are indispensable for Erwinia amylovora virulence. MOLECULAR PLANT PATHOLOGY 2014; 15:58-66. [PMID: 23937726 PMCID: PMC6638869 DOI: 10.1111/mpp.12065] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
In Erwinia amylovora, ECF (extracytoplasmic functions) alternative sigma factor HrpL regulates the transcription of hrp (hypersensitive response and pathogenicity)-type III secretion system (T3SS) genes by binding to a consensus sequence known as the hrp box in hrp gene promoters. In turn, the expression of hrpL has been proposed to be positively controlled by alternative sigma factor 54 (σ(54)) (RpoN) and HrpS, a member of the σ(54) enhancer-binding proteins (EBPs). However, the function of RpoN has not been characterized genetically in E. amylovora. In this study, we investigated the role of RpoN, a nitrogen limitation sigma factor, and its modulation protein YhbH, a novel ribosome-associated protein, in E. amylovora virulence. Our results showed that mutations in hrpS, hrpL, rpoN and yhbH, but not yfiA and rmf3, resulted in a nonpathogenic phenotype on immature pear fruits and apple shoots. Consistently, the expression of T3SS genes, including hrpL, dspE, hrpN and hrpA, was barely detected in hrpS, hrpL, rpoN and yhbH mutants. These mutants were also not capable of eliciting a hypersensitive response (HR) on tobacco; however, the overexpression of hrpL using an inducible promoter rescued the HR-eliciting abilities of these mutants. These results suggest that a sigma factor cascade exists in the regulatory networks of E. amylovora and regulates important virulence factors. On the basis of this study and previously reported data, a model is proposed for the regulation of T3SS in E. amylovora.
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Affiliation(s)
- Veronica Ancona
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
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10
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Draft genome sequence of Pseudomonas syringae pathovar syringae strain FF5, causal agent of stem tip dieback disease on ornamental pear. J Bacteriol 2012; 194:3733-4. [PMID: 22740663 DOI: 10.1128/jb.00567-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas syringae FF5 causes stem tip dieback disease on ornamental pear (Pyrus calleryana). Its genome encodes a complete type III secretion system (T3SS) and HopAC1, HopM1, AvrE1, HopI1, HopAA1, HopJ1, HopAH2, HopAH1, HopAG1, and HopAZ1. Lacking detectable homologues of other T3SS effectors, it may encode novel, undiscovered effectors.
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11
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de Keijzer J, van den Broek LAM, Ketelaar T, van Lammeren AAM. Histological examination of horse chestnut infection by Pseudomonas syringae pv. aesculi and non-destructive heat treatment to stop disease progression. PLoS One 2012; 7:e39604. [PMID: 22808044 PMCID: PMC3392261 DOI: 10.1371/journal.pone.0039604] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 05/23/2012] [Indexed: 11/19/2022] Open
Abstract
Since its emergence in Northwest Europe as a pathogen that infects trunks and branches of Aesculus spp. (the horse chestnuts) approximately one decade ago, Pseudomonas syringae pv. aesculi has rapidly established itself as major threat to these trees. Infected trees exhibit extensive necrosis of phloem and cambium, which can ultimately lead to dieback. The events after host entry leading to extensive necrosis are not well documented. In this work, the histopathology of this interaction is investigated and heat-treatment is explored as method to eradicate bacteria associated with established infections. The early wound-repair responses of A. hippocastanum, both in absence and presence of P. s. pv. aesculi, included cell wall lignification by a distinct layer of phloem and cortex parenchyma cells. The same cells also deposited suberin lamellae later on, suggesting this layer functions in compartmentalizing healthy from disrupted tissues. However, monitoring bacterial ingress, its construction appeared inadequate to constrain pathogen spread. Microscopic evaluation of bacterial dispersal in situ using immunolabelling and GFP-tagging of P. s. pv. aesculi, revealed two discriminative types of bacterial colonization. The forefront of lesions was found to contain densely packed bacteria, while necrotic areas housed bacterial aggregates with scattered individuals embedded in an extracellular matrix of bacterial origin containing alginate. The endophytic localization and ability of P. s. pv aesculi to create a protective matrix render it poorly accessible for control agents. To circumvent this, a method based on selective bacterial lethality at 39 °C was conceived and successfully tested on A. hippocastanum saplings, providing proof of concept for controlling this disease by heat-treatment. This may be applicable for curing other tree cankers, caused by related phytopathogens.
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Affiliation(s)
- Jeroen de Keijzer
- Laboratory of Cell Biology, Wageningen University and Research Centre, Wageningen, The Netherlands
| | | | - Tijs Ketelaar
- Laboratory of Cell Biology, Wageningen University and Research Centre, Wageningen, The Netherlands
| | - André A. M. van Lammeren
- Laboratory of Cell Biology, Wageningen University and Research Centre, Wageningen, The Netherlands
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Augmented production of alginate oligosaccharides by the Pseudomonas mendocina NK-01 mutant. Carbohydr Res 2012; 352:109-16. [DOI: 10.1016/j.carres.2012.02.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2011] [Revised: 02/21/2012] [Accepted: 02/23/2012] [Indexed: 11/20/2022]
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13
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Mishra S, Mishra A, Chauhan P, Mishra S, Kumari M, Niranjan A, Nautiyal C. Pseudomonas putida NBRIC19 dihydrolipoamide succinyltransferase (SucB) gene controls degradation of toxic allelochemicals produced by Parthenium hysterophorus. J Appl Microbiol 2012; 112:793-808. [DOI: 10.1111/j.1365-2672.2012.05256.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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14
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Regulation of type VI secretion gene clusters by sigma54 and cognate enhancer binding proteins. J Bacteriol 2011; 193:2158-67. [PMID: 21378190 DOI: 10.1128/jb.00029-11] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Type VI secretion systems (T6SS) are bacteriophage-derived macromolecular machines responsible for the release of at least two proteins in the milieu, which are thought to form an extracellular appendage. Although several T6SS have been shown to be involved in the virulence of animal and plant pathogens, clusters encoding these machines are found in the genomes of most species of gram-negative bacteria, including soil, marine, and environmental isolates. T6SS have been associated with several phenotypes, ranging from virulence to biofilm formation or stress sensing. Their various environmental niches and large diversity of functions are correlated with their broad variety of regulatory mechanisms. Using a bioinformatic approach, we identified several clusters, including those of Vibrio cholerae, Aeromonas hydrophila, Pectobacterium atrosepticum, Pseudomonas aeruginosa, Pseudomonas syringae pv. tomato, and a Marinomonas sp., which possess typical -24/-12 sequences, recognized by the alternate sigma factor sigma 54 (σ(54) or σ(N)). σ(54), which directs the RNA polymerase to these promoters, requires the action of a bacterial enhancer binding protein (bEBP), which binds to cis-acting upstream activating sequences. Putative bEBPs are encoded within the T6SS gene clusters possessing σ(54) boxes. Using in vitro binding experiments and in vivo reporter fusion assays, we showed that the expression of these clusters is dependent on both σ(54) and bEBPs.
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Qi M, Wang D, Bradley CA, Zhao Y. Genome sequence analyses of Pseudomonas savastanoi pv. glycinea and subtractive hybridization-based comparative genomics with nine pseudomonads. PLoS One 2011; 6:e16451. [PMID: 21304594 PMCID: PMC3029378 DOI: 10.1371/journal.pone.0016451] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 12/16/2010] [Indexed: 11/19/2022] Open
Abstract
Bacterial blight, caused by Pseudomonas savastanoi pv. glycinea (Psg), is a common disease of soybean. In an effort to compare a current field isolate with one isolated in the early 1960s, the genomes of two Psg strains, race 4 and B076, were sequenced using 454 pyrosequencing. The genomes of both Psg strains share more than 4,900 highly conserved genes, indicating very low genetic diversity between Psg genomes. Though conserved, genome rearrangements and recombination events occur commonly within the two Psg genomes. When compared to each other, 437 and 163 specific genes were identified in B076 and race 4, respectively. Most specific genes are plasmid-borne, indicating that acquisition and maintenance of plasmids may represent a major mechanism to change the genetic composition of the genome and even acquire new virulence factors. Type three secretion gene clusters of Psg strains are near identical with that of P. savastanoi pv. phaseolicola (Pph) strain 1448A and they shared 20 common effector genes. Furthermore, the coronatine biosynthetic cluster is present on a large plasmid in strain B076, but not in race 4. In silico subtractive hybridization-based comparative genomic analyses with nine sequenced phytopathogenic pseudomonads identified dozens of specific islands (SIs), and revealed that the genomes of Psg strains are more similar to those belonging to the same genomospecies such as Pph 1448A than to other phytopathogenic pseudomonads. The number of highly conserved genes (core genome) among them decreased dramatically when more genomes were included in the subtraction, suggesting the diversification of pseudomonads, and further indicating the genome heterogeneity among pseudomonads. However, the number of specific genes did not change significantly, suggesting these genes are indeed specific in Psg genomes. These results reinforce the idea of a species complex of P. syringae and support the reclassification of P. syringae into different species.
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Affiliation(s)
- Mingsheng Qi
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Dongping Wang
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Carl A. Bradley
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
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Beattie GA. Water relations in the interaction of foliar bacterial pathogens with plants. ANNUAL REVIEW OF PHYTOPATHOLOGY 2011; 49:533-55. [PMID: 21438680 DOI: 10.1146/annurev-phyto-073009-114436] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
This review examines the many ways in which water influences the relations between foliar bacterial pathogens and plants. As a limited resource in aerial plant tissues, water is subject to manipulation by both plants and pathogens. A model is emerging that suggests that plants actively promote localized desiccation at the infection site and thus restrict pathogen growth as one component of defense. Similarly, many foliar pathogens manipulate water relations as one component of pathogenesis. Nonvascular pathogens do this using effectors and other molecules to alter hormonal responses and enhance intercellular watersoaking, whereas vascular pathogens use many mechanisms to cause wilt. Because of water limitations on phyllosphere surfaces, bacterial colonists, including pathogens, benefit from the protective effects of cellular aggregation, synthesis of hygroscopic polymers, and uptake and production of osmoprotective compounds. Moreover, these bacteria employ tactics for scavenging and distributing water to overcome water-driven barriers to nutrient acquisition, movement, and signal exchange on plant surfaces.
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Affiliation(s)
- Gwyn A Beattie
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, Iowa 50011-3211, USA.
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Rodríguez-Palenzuela P, Matas IM, Murillo J, López-Solanilla E, Bardaji L, Pérez-Martínez I, Rodríguez-Moskera ME, Penyalver R, López MM, Quesada JM, Biehl BS, Perna NT, Glasner JD, Cabot EL, Neeno-Eckwall E, Ramos C. Annotation and overview of thePseudomonas savastanoipv. savastanoi NCPPB 3335 draft genome reveals the virulence gene complement of a tumour-inducing pathogen of woody hosts. Environ Microbiol 2010; 12:1604-20. [DOI: 10.1111/j.1462-2920.2010.02207.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Penaloza-Vazquez A, Sreedharan A, Bender CL. Transcriptional studies of the hrpM/opgH gene in Pseudomonas syringae during biofilm formation and in response to different environmental challenges. Environ Microbiol 2010; 12:1452-67. [PMID: 20132277 DOI: 10.1111/j.1462-2920.2010.02160.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Pseudomonas syringae pv. syringae strain FF5 is a phytopathogen that causes a rapid dieback on ornamental pear trees. In the present study, the transcriptional expression of hrpM/opgH, algD, hrpR and rpoD was evaluated in P. syringae FF5 and FF5.M2 (hrpM/opgH mutant). The temporal expression of these genes was evaluated during biofilm formation, the hypersensitive reaction (HR) on tobacco plants, and when the bacteria were subjected to different environmental stresses. The results indicate that mutations in hrpM negatively impair several traits including biofilm formation, the ability to cause disease in host plants and the HR in non-host plants, and the expression of hrpR, a regulatory gene modulating the latter two traits. Furthermore, FF5.M2 was decreased in swarming motility and unable to respond to different environmental challenges. Interestingly, FF5.M2 showed an exponential increase in the expression of algD, which is the first gene to be transcribed during the biosynthesis of the alginate, a virulence factor in P. syringae. The expression of both hrpM and algD were required for biofilm formation, and hrpM was expressed earlier than algD during biofilm development. These findings indicate that hrpM expression is required for several traits in P. syringae and plays an important role in how this bacterium responds to environmental challenges.
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Affiliation(s)
- Alejandro Penaloza-Vazquez
- 127 Noble Research Center, Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
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An QD, Zhang GL, Wu HT, Zhang ZC, Zheng GS, Luan L, Murata Y, Li X. Alginate-deriving oligosaccharide production by alginase from newly isolated Flavobacterium sp. LXA and its potential application in protection against pathogens. J Appl Microbiol 2009; 106:161-70. [PMID: 19054241 DOI: 10.1111/j.1365-2672.2008.03988.x] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
AIMS To examine algino-oligosaccharide production by alginase from newly isolated Flavobacterium sp. LXA and its elicitor and antibacterial activity. METHODS AND RESULTS Algino-oligosaccharide production from alginate was carried out using alginase obtained from a newly isolated Flavobacterium sp. LXA. When alginase was partially purified by dual ammonium sulfate precipitation and used for alginate degradation, the viscosity loss correlated well with the release of reducing terminals. The optimal temperature and pH for alginate degradation was 40 degrees C and pH 7.0, respectively. When alginate was added at an initial concentration of more than 0.8%, the maximal degradation rate of alginate was obtained. Under these optimal reaction conditions and with partially purified alginase, the average degrees of polymerization (DP) of alginate-degraded products was about 6.0, which favoured algino-oligosaccharide production. The algino-oligosaccharides showed an elicitor activity stimulating the accumulation of phytoalexin and inducing phenylalanine ammonia lyase in soybean cotyledon, and antimicrobial activity on Pseudomonas aeruginosa. CONCLUSIONS Algino-oligosaccharide could be degraded from alginate by the partially purified alginase and its maximal bioactivity occurred on the oligosaccharide with average DP 6.8. SIGNIFICANCE AND IMPACT OF THE STUDY Algino-oligosaccharide was first reported to have elicitor and antibacterial activity and have potential as a biological agent for protection against plant or human disease.
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Affiliation(s)
- Q-D An
- Department of Chemical and Material Engineering, Dalian College of Light Industry, Dalian, PR China
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Schenk A, Weingart H, Ullrich MS. The alternative sigma factor AlgT, but not alginate synthesis, promotes in planta multiplication of Pseudomonas syringae pv. glycinea. MICROBIOLOGY (READING, ENGLAND) 2008; 154:413-421. [PMID: 18227245 DOI: 10.1099/mic.0.2007/012864-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
The phytopathogen Pseudomonas syringae pv. glycinea produces the exopolysaccharide (EPS) alginate, which is thought to function in epiphytic fitness and virulence. A key regulator for alginate biosynthesis in Pseudomonas aeruginosa and P. syringae is the alternative sigma factor AlgT (sigma(22)). In this study, the contribution of alginate synthesis and AlgT to in planta epiphytic fitness and virulence of P. syringae was examined. Alginate biosynthesis mutants were generated for the P. syringae pv. glycinea strains PG4180 and PG4180.muc, representing a comprehensive set of alginate- and AlgT-positive or -negative derivatives. Analysis of in vitro and in planta phenotypes revealed that AlgT strongly promoted in planta growth, survival and symptom development, but decreased the ability to grow in vitro. In contrast, alginate biosynthesis had only marginal impact. Quantitative in vitro and in planta gene expression analyses for alginate biosynthesis and algT were carried out at two temperatures in AlgT-negative and -positive backgrounds. algT as well as algD gene expression was AlgT-dependent, plant-inducible and temperature-dependent, with higher expression at 18 compared to 28 degrees C; however, no temperature dependence was observed in vitro. Our data suggest that AlgT may act as a global regulator for virulence and in planta fitness traits of P. syringae independent of its role in EPS biosynthesis.
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Affiliation(s)
- Alexander Schenk
- Jacobs University Bremen, School of Engineering and Sciences, Campus Ring 1, 28759 Bremen, Germany
| | - Helge Weingart
- Jacobs University Bremen, School of Engineering and Sciences, Campus Ring 1, 28759 Bremen, Germany
| | - Matthias S Ullrich
- Jacobs University Bremen, School of Engineering and Sciences, Campus Ring 1, 28759 Bremen, Germany
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Pseudomonas aeruginosa AlgR regulates type IV pilus biosynthesis by activating transcription of the fimU-pilVWXY1Y2E operon. J Bacteriol 2008; 190:2023-30. [PMID: 18178737 DOI: 10.1128/jb.01623-07] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The response regulator AlgR is required for Pseudomonas aeruginosa type IV pilus-dependent twitching motility, a flagellum-independent mode of solid surface translocation. Prior work showed that AlgR is phosphorylated at aspartate 54, and cells expressing an AlgR variant that cannot undergo phosphorylation (AlgRD54N) lack twitching motility. However, the mechanism by which AlgR controls twitching motility is not completely understood. We hypothesized that AlgR functioned by activating genes within the prepilin fimU-pilVWXY1Y2E cluster that are necessary for type IV pilin biogenesis. Reverse transcriptase PCR analysis showed that the fimU-pilVWXY1Y2E genes are cotranscribed in an operon, which is under the control of AlgR. This supports prior transcriptional profiling studies of wild-type strains and algR mutants. Moreover, expression of the fimU-pilVWXY1Y2E operon was reduced in strains expressing AlgRD54N. DNase footprinting and electrophoretic mobility shift assays demonstrate that AlgR but not AlgRD54N bound with high affinity to two sites upstream of the fimU-pilVWXY1Y2E operon. Altogether, our findings indicate that AlgR is essential for proper pilin localization and that phosphorylation of AlgR results in direct activation of the fimU-pilVWXY1Y2E operon, which is required for the assembly and export of a functional type IV pilus.
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Jones J, Studholme DJ, Knight CG, Preston GM. Integrated bioinformatic and phenotypic analysis of RpoN-dependent traits in the plant growth-promoting bacterium Pseudomonas fluorescens SBW25. Environ Microbiol 2007; 9:3046-64. [DOI: 10.1111/j.1462-2920.2007.01416.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Comparison of culturable Gram-negative bacterial community structures in the rhizosphere of three fruit plants. Biologia (Bratisl) 2006. [DOI: 10.2478/s11756-006-0138-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Schenk A, Berger M, Keith LM, Bender CL, Muskhelishvili G, Ullrich MS. The algT gene of Pseudomonas syringae pv. glycinea and new insights into the transcriptional organization of the algT-muc gene cluster. J Bacteriol 2006; 188:8013-21. [PMID: 17012388 PMCID: PMC1698189 DOI: 10.1128/jb.01160-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2006] [Accepted: 08/31/2006] [Indexed: 01/22/2023] Open
Abstract
The phytopathogenic bacterium Pseudomonas syringae pv. glycinea infects soybean plants and causes bacterial blight. In addition to P. syringae, the human pathogen Pseudomonas aeruginosa and the soil bacterium Azotobacter vinelandii produce the exopolysaccharide alginate, a copolymer of d-mannuronic and l-guluronic acids. Alginate production in P. syringae has been associated with increased fitness and virulence in planta. Alginate biosynthesis is tightly controlled by proteins encoded by the algT-muc regulatory gene cluster in P. aeruginosa and A. vinelandii. These genes encode the alternative sigma factor AlgT (sigma(22)), its anti-sigma factors MucA and MucB, MucC, a protein with a controversial function that is absent in P. syringae, and MucD, a periplasmic serine protease and homolog of HtrA in Escherichia coli. We compared an alginate-deficient algT mutant of P. syringae pv. glycinea with an alginate-producing derivative in which algT is intact. The alginate-producing derivative grew significantly slower in vitro growth but showed increased epiphytic fitness and better symptom development in planta. Evaluation of expression levels for algT, mucA, mucB, mucD, and algD, which encodes an alginate biosynthesis gene, showed that mucD transcription is not dependent on AlgT in P. syringae in vitro. Promoter mapping using primer extension experiments confirmed this finding. Results of reverse transcription-PCR demonstrated that algT, mucA, and mucB are cotranscribed as an operon in P. syringae. Northern blot analysis revealed that mucD was expressed as a 1.75-kb monocistronic mRNA in P. syringae.
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Affiliation(s)
- Alexander Schenk
- School of Engineering and Sciences, Campus Ring 1, International University Bremen, D-28759 Bremen, Germany
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