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The Ferredoxin-Like Protein FerR Regulates PrbP Activity in Liberibacter asiaticus. Appl Environ Microbiol 2019; 85:AEM.02605-18. [PMID: 30552192 DOI: 10.1128/aem.02605-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 12/08/2018] [Indexed: 12/26/2022] Open
Abstract
In Liberibacter asiaticus, PrbP is an important transcriptional accessory protein that regulates gene expression through interactions with the RNA polymerase β-subunit and a specific sequence on the promoter region. The constitutive expression of prbP observed upon chemical inactivation of PrbP-DNA interactions in vivo indicated that the expression of prbP was not autoregulated at the level of transcription. This observation suggested that a modulatory mechanism via protein-protein interactions may be involved. In silico genome association analysis identified FerR (CLIBASIA_01505), a putative ferredoxin-like protein, as a PrbP-interacting protein. Using a bacterial two-hybrid system and immunoprecipitation assays, interactions between PrbP and FerR were confirmed. In vitro transcription assays were used to show that FerR can increase the activity of PrbP by 16-fold when present in the PrbP-RNA polymerase reaction mixture. The FerR protein-protein interaction surface was predicted by structural modeling and followed by site-directed mutagenesis. Amino acids V20, V23, and C40 were identified as the most important residues in FerR involved in the modulation of PrbP activity in vitro The regulatory mechanism of FerR abundance was examined at the transcription level. In contrast to prbP of L. asiaticus (prbP Las), mRNA levels of ferR of L. asiaticus (ferR Las) are induced by an increase in osmotic pressure. The results of this study revealed that the activity of the transcriptional activator PrbPLas is modulated via interactions with FerRLas The induction of ferR Las expression by osmolarity provides insight into the mechanisms of adjusting gene expression in response to host environmental signals in L. asiaticus IMPORTANCE The rapid spread and aggressive progression of huanglongbing (HLB) in the major citrus-producing areas have raised global recognition of and vigilance to this disease. As a result, the causative agent, Liberibacter asiaticus, has been investigated from various perspectives. However, gene expression regulatory mechanisms that are important for the survival and persistence of this intracellular pathogen remain largely unexplored. PrbP is a transcriptional accessory protein important for L. asiaticus survival in the plant host. In this study, we investigated the interactions between PrbP in L. asiaticus (PrbPLas) and a ferredoxin-like protein (FerR) in L. asiaticus, FerRLas We show that the presence of FerR stabilizes and augments the activity of PrbPLas In addition, we demonstrate that the expression of ferR is induced by increases in osmolarity in Liberibacter crescens Altogether, these results suggest that FerRLas and PrbPLas may play important roles in the regulation of gene expression in response to changing environmental signals during L. asiaticus infection in the citrus host.
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Localized expression of antimicrobial proteins mitigates huanglongbing symptoms in Mexican lime. J Biotechnol 2018; 285:74-83. [DOI: 10.1016/j.jbiotec.2018.08.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 07/16/2018] [Accepted: 08/24/2018] [Indexed: 11/19/2022]
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Clark K, Franco JY, Schwizer S, Pang Z, Hawara E, Liebrand TWH, Pagliaccia D, Zeng L, Gurung FB, Wang P, Shi J, Wang Y, Ancona V, van der Hoorn RAL, Wang N, Coaker G, Ma W. An effector from the Huanglongbing-associated pathogen targets citrus proteases. Nat Commun 2018; 9:1718. [PMID: 29712915 PMCID: PMC5928222 DOI: 10.1038/s41467-018-04140-9] [Citation(s) in RCA: 110] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 04/06/2018] [Indexed: 01/29/2023] Open
Abstract
The citrus industry is facing an unprecedented challenge from Huanglongbing (HLB). All cultivars can be affected by the HLB-associated bacterium 'Candidatus Liberibacter asiaticus' (CLas) and there is no known resistance. Insight into HLB pathogenesis is urgently needed in order to develop effective management strategies. Here, we use Sec-delivered effector 1 (SDE1), which is conserved in all CLas isolates, as a molecular probe to understand CLas virulence. We show that SDE1 directly interacts with citrus papain-like cysteine proteases (PLCPs) and inhibits protease activity. PLCPs are defense-inducible and exhibit increased protein accumulation in CLas-infected trees, suggesting a role in citrus defense responses. We analyzed PLCP activity in field samples, revealing specific members that increase in abundance but remain unchanged in activity during infection. SDE1-expressing transgenic citrus also exhibit reduced PLCP activity. These data demonstrate that SDE1 inhibits citrus PLCPs, which are immune-related proteases that enhance defense responses in plants.
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Affiliation(s)
- Kelley Clark
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA
| | | | - Simon Schwizer
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA.,Center for Plant Cell Biology, University of California, Riverside, 92521, CA, USA
| | - Zhiqian Pang
- Citrus Research and Education Center, University of Florida, Lake Alfred, 33850, FL, USA
| | - Eva Hawara
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA
| | - Thomas W H Liebrand
- Department of Plant Pathology, University of California, Davis, 95616, CA, USA
| | - Deborah Pagliaccia
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA
| | - Liping Zeng
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA.,Center for Plant Cell Biology, University of California, Riverside, 92521, CA, USA
| | - Fatta B Gurung
- Citrus Center, Texas A&M University, Weslaco, 78599, TX, USA
| | - Pengcheng Wang
- Department of Chemistry, University of California, Riverside, 92521, CA, USA
| | - Jinxia Shi
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA.,College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Yinsheng Wang
- Department of Chemistry, University of California, Riverside, 92521, CA, USA
| | - Veronica Ancona
- Citrus Center, Texas A&M University, Weslaco, 78599, TX, USA
| | | | - Nian Wang
- Citrus Research and Education Center, University of Florida, Lake Alfred, 33850, FL, USA
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, 95616, CA, USA.
| | - Wenbo Ma
- Department of Microbiology and Plant Pathology, University of California, Riverside, 92521, CA, USA. .,Center for Plant Cell Biology, University of California, Riverside, 92521, CA, USA.
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Where are we going with genomics in plant pathogenic bacteria? Genomics 2018; 111:729-736. [PMID: 29678682 DOI: 10.1016/j.ygeno.2018.04.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 04/13/2018] [Indexed: 12/12/2022]
Abstract
Genome sequencing is commonly used in research laboratories right now thanks to the rise of high-throughput sequencing with higher speed and output-to-cost ratios. Here, we summarized the application of genomics in different aspects of plant bacterial pathosystems. Genomics has been used in studying the mechanisms of plant-bacteria interactions, and host specificity. It also helps with taxonomy, study of non-cultured bacteria, identification of causal agent, single cell sequencing, population genetics, and meta-transcriptomic. Overall, genomics has significantly improved our understanding of plant-microbe interaction.
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Pagliaccia D, Shi J, Pang Z, Hawara E, Clark K, Thapa SP, De Francesco AD, Liu J, Tran TT, Bodaghi S, Folimonova SY, Ancona V, Mulchandani A, Coaker G, Wang N, Vidalakis G, Ma W. A Pathogen Secreted Protein as a Detection Marker for Citrus Huanglongbing. Front Microbiol 2017; 8:2041. [PMID: 29403441 PMCID: PMC5776943 DOI: 10.3389/fmicb.2017.02041] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 10/06/2017] [Indexed: 11/26/2022] Open
Abstract
The citrus industry is facing an unprecedented crisis due to Huanglongbing (HLB, aka citrus greening disease), a bacterial disease associated with the pathogen Candidatus Liberibacter asiaticus (CLas) that affects all commercial varieties. Transmitted by the Asian citrus psyllid (ACP), CLas colonizes citrus phloem, leading to reduced yield and fruit quality, and eventually tree decline and death. Since adequate curative measures are not available, a key step in HLB management is to restrict the spread of the disease by identifying infected trees and removing them in a timely manner. However, uneven distribution of CLas cells in infected trees and the long latency for disease symptom development makes sampling of trees for CLas detection challenging. Here, we report that a CLas secreted protein can be used as a biomarker for detecting HLB infected citrus. Proteins secreted from CLas cells can presumably move along the phloem, beyond the site of ACP inoculation and CLas colonized plant cells, thereby increasing the chance of detecting infected trees. We generated a polyclonal antibody that effectively binds to the secreted protein and developed serological assays that can successfully detect CLas infection. This work demonstrates that antibody-based diagnosis using a CLas secreted protein as the detection marker for infected trees offers a high-throughput and economic approach that complements the approved quantitative polymerase chain reaction-based methods to enhance HLB management programs.
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Affiliation(s)
- Deborah Pagliaccia
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Jinxia Shi
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
- Center for Plant Cell Biology, University of California, Riverside, Riverside, CA, United States
| | - Zhiqian Pang
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, United States
| | - Eva Hawara
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Kelley Clark
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Shree P. Thapa
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Agustina D. De Francesco
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Jianfeng Liu
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Thien-Toan Tran
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA, United States
| | - Sohrab Bodaghi
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | | | - Veronica Ancona
- Texas A&M University – Kingsville Citrus Center, Weslaco, TX, United States
| | - Ashok Mulchandani
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA, United States
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Nian Wang
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL, United States
| | - Georgios Vidalakis
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
| | - Wenbo Ma
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, CA, United States
- Center for Plant Cell Biology, University of California, Riverside, Riverside, CA, United States
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Wang N, Pierson EA, Setubal JC, Xu J, Levy JG, Zhang Y, Li J, Rangel LT, Martins J. The Candidatus Liberibacter-Host Interface: Insights into Pathogenesis Mechanisms and Disease Control. ANNUAL REVIEW OF PHYTOPATHOLOGY 2017. [PMID: 28637377 DOI: 10.1146/annurev-phyto-080516-035513] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
"Candidatus Liberibacter" species are associated with economically devastating diseases of citrus, potato, and many other crops. The importance of these diseases as well as the proliferation of new diseases on a wider host range is likely to increase as the insects vectoring the "Ca. Liberibacter" species expand their territories worldwide. Here, we review the progress on understanding pathogenesis mechanisms of "Ca. Liberibacter" species and the control approaches for diseases they cause. We discuss the Liberibacter virulence traits, including secretion systems, putative effectors, and lipopolysaccharides (LPSs), as well as other important traits likely to contribute to disease development, e.g., flagella, prophages, and salicylic acid hydroxylase. The pathogenesis mechanisms of Liberibacters are discussed. Liberibacters secrete Sec-dependent effectors (SDEs) or other virulence factors into the phloem elements or companion cells to interfere with host targets (e.g., proteins or genes), which cause cell death, necrosis, or other phenotypes of phloem elements or companion cells, leading to localized cell responses and systemic malfunction of phloem. Receptors on the remaining organelles in the phloem, such as plastid, vacuole, mitochondrion, or endoplasmic reticulum, interact with secreted SDEs and/or other virulence factors secreted or located on the Liberibacter outer membrane to trigger cell responses. Some of the host genes or proteins targeted by SDEs or other virulence factors of Liberibacters serve as susceptibility genes that facilitate compatibility (e.g., promoting pathogen growth or suppressing immune responses) or disease development. In addition, Liberibacters trigger plant immunity response via pathogen-associated molecular patterns (PAMPs, such as lipopolysaccharides), which leads to premature cell death, callose deposition, or phloem protein accumulation, causing a localized response and/or systemic effect on phloem transportation. Physical presence of Liberibacters and their metabolic activities may disturb the function of phloem, via disrupting osmotic gradients, or the integrity of phloem conductivity. We also review disease management strategies, including promising new technologies. Citrus production in the presence of Huanglongbing is possible if the most promising management approaches are integrated. HLB management is discussed in the context of local, area-wide, and regional Huanglongbing/Asian Citrus Psyllid epidemiological zones. For zebra chip disease control, aggressive psyllid management enables potato production, although insecticide resistance is becoming an issue. Meanwhile, new technologies such as clustered regularly interspaced short palindromic repeat (CRISPR)-derived genome editing provide an unprecedented opportunity to provide long-term solutions.
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Affiliation(s)
- Nian Wang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Elizabeth A Pierson
- Department of Horticultural Sciences, Texas A&M University, College Station, Texas 77843
| | - João Carlos Setubal
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, 05508-000, Brazil
| | - Jin Xu
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Julien G Levy
- Department of Horticultural Sciences, Texas A&M University, College Station, Texas 77843
| | - Yunzeng Zhang
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Jinyun Li
- Citrus Research and Education Center, Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, Florida 33850;
| | - Luiz Thiberio Rangel
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, 05508-000, Brazil
| | - Joaquim Martins
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP, 05508-000, Brazil
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