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Baukova A, Bogun A, Sushkova S, Minkina T, Mandzhieva S, Alliluev I, Jatav HS, Kalinitchenko V, Rajput VD, Delegan Y. New Insights into Pseudomonas spp.-Produced Antibiotics: Genetic Regulation of Biosynthesis and Implementation in Biotechnology. Antibiotics (Basel) 2024; 13:597. [PMID: 39061279 PMCID: PMC11273644 DOI: 10.3390/antibiotics13070597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 06/20/2024] [Accepted: 06/25/2024] [Indexed: 07/28/2024] Open
Abstract
Pseudomonas bacteria are renowned for their remarkable capacity to synthesize antibiotics, namely mupirocin, gluconic acid, pyrrolnitrin, and 2,4-diacetylphloroglucinol (DAPG). While these substances are extensively employed in agricultural biotechnology to safeguard plants against harmful bacteria and fungi, their potential for human medicine and healthcare remains highly promising for common science. However, the challenge of obtaining stable producers that yield higher quantities of these antibiotics continues to be a pertinent concern in modern biotechnology. Although the interest in antibiotics of Pseudomonas bacteria has persisted over the past century, many uncertainties still surround the regulation of the biosynthetic pathways of these compounds. Thus, the present review comprehensively studies the genetic organization and regulation of the biosynthesis of these antibiotics and provides a comprehensive summary of the genetic organization of antibiotic biosynthesis pathways in pseudomonas strains, appealing to both molecular biologists and biotechnologists. In addition, attention is also paid to the application of antibiotics in plant protection.
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Affiliation(s)
- Alexandra Baukova
- Institute of Biochemistry and Physiology of Microorganisms, Federal Research Center “Pushchino Scientific Center for Biological Research of Russian Academy of Sciences” (FRC PSCBR RAS), 142290 Pushchino, Moscow Region, Russia; (A.B.); (A.B.)
- Pushchino Branch of Federal State Budgetary Educational Institution of Higher Education “Russian Biotechnology University (ROSBIOTECH)”, 142290 Pushchino, Moscow Region, Russia
| | - Alexander Bogun
- Institute of Biochemistry and Physiology of Microorganisms, Federal Research Center “Pushchino Scientific Center for Biological Research of Russian Academy of Sciences” (FRC PSCBR RAS), 142290 Pushchino, Moscow Region, Russia; (A.B.); (A.B.)
| | - Svetlana Sushkova
- Academy of Biology and Biotechnology behalf D.I. Ivanovskyi, Southern Federal University, 344006 Rostov-on-Don, Russia; (S.S.); (T.M.); (S.M.); (I.A.); (V.D.R.)
| | - Tatiana Minkina
- Academy of Biology and Biotechnology behalf D.I. Ivanovskyi, Southern Federal University, 344006 Rostov-on-Don, Russia; (S.S.); (T.M.); (S.M.); (I.A.); (V.D.R.)
| | - Saglara Mandzhieva
- Academy of Biology and Biotechnology behalf D.I. Ivanovskyi, Southern Federal University, 344006 Rostov-on-Don, Russia; (S.S.); (T.M.); (S.M.); (I.A.); (V.D.R.)
| | - Ilya Alliluev
- Academy of Biology and Biotechnology behalf D.I. Ivanovskyi, Southern Federal University, 344006 Rostov-on-Don, Russia; (S.S.); (T.M.); (S.M.); (I.A.); (V.D.R.)
| | - Hanuman Singh Jatav
- Soil Science & Agricultural Chemistry, S.K.N. Agriculture University-Jobner, Jaipur 303329, Rajasthan, India;
| | - Valery Kalinitchenko
- Institute of Fertility of Soils of South Russia, 346493 Persianovka, Rostov Region, Russia;
- All-Russian Research Institute for Phytopathology of the Russian Academy of Sciences, Institute St., 5, 143050 Big Vyazyomy, Moscow Region, Russia
| | - Vishnu D. Rajput
- Academy of Biology and Biotechnology behalf D.I. Ivanovskyi, Southern Federal University, 344006 Rostov-on-Don, Russia; (S.S.); (T.M.); (S.M.); (I.A.); (V.D.R.)
| | - Yanina Delegan
- Institute of Biochemistry and Physiology of Microorganisms, Federal Research Center “Pushchino Scientific Center for Biological Research of Russian Academy of Sciences” (FRC PSCBR RAS), 142290 Pushchino, Moscow Region, Russia; (A.B.); (A.B.)
- Academy of Biology and Biotechnology behalf D.I. Ivanovskyi, Southern Federal University, 344006 Rostov-on-Don, Russia; (S.S.); (T.M.); (S.M.); (I.A.); (V.D.R.)
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2
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Chen H, Lu Q, An H, Li J, Shen S, Zheng X, Chen W, Wang L, Li J, Du Y, Wang Y, Liu X, Baumann M, Tacke M, Zou L, Wang J. The synergistic activity of SBC3 in combination with Ebselen against Escherichia coli infection. Front Pharmacol 2022; 13:1080281. [PMID: 36588729 PMCID: PMC9797518 DOI: 10.3389/fphar.2022.1080281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 11/28/2022] [Indexed: 12/23/2022] Open
Abstract
Escherichia coli ranks as the number one clinical isolate in the past years in China according to The China Antimicrobial Surveillance Network (CHINET), and its multidrug-resistant (MDR) pathogenic strains account for over 160 million cases of dysentery and one million deaths per year. Here, our work demonstrates that E. coli is highly sensitive to the synergistic combination of SBC3 [1,3-Dibenzyl-4,5-diphenyl-imidazol-2-ylidene silver (I) acetate] and Ebselen, which shows no synergistic toxicity on mammalian cells. The proposed mechanism for the synergistic antibacterial effect of SBC3 in combination with Ebselen is based on directly inhibiting E. coli thioredoxin reductase and rapidly depleting glutathione, resulting in the increase of reactive oxygen species that cause bacterial cell death. Furthermore, the bactericidal efficacy of SBC3 in combination with Ebselen has been confirmed in mild and acute peritonitis mice. In addition, the five most difficult to treat Gram-negative bacteria (including E. coli, Acinetobacter baumannii, Enterobacter cloacae, Klebsiella pneumoniae, and Pseudomonas aeruginosa) are also highly sensitive to a synergistic combination of SBC3 and Ebselen. Thus, SBC3 in combination with Ebselen has potential as a treatment for clinically important Gram-negative bacterial infections.
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Affiliation(s)
- Hao Chen
- The Second People’s Hospital of China Three Gorges University, Yichang, Hubei, China,The Second People’s Hospital of Yichang, Yichang, Hubei, China
| | - Qianqian Lu
- Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China
| | - Haoyue An
- Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China
| | - Juntong Li
- Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China
| | - Shuchu Shen
- Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China
| | - Xi Zheng
- Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China
| | - Wei Chen
- Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China
| | - Lu Wang
- Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China
| | - Jihong Li
- Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China
| | - Youqin Du
- Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China
| | - Yueqing Wang
- Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China
| | - Xiaowen Liu
- Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China
| | - Marcus Baumann
- The School of Chemistry, University College Dublin, Belfield, Dublin, Ireland
| | - Matthias Tacke
- The School of Chemistry, University College Dublin, Belfield, Dublin, Ireland,*Correspondence: Lili Zou, ; Jun Wang, ; Matthias Tacke,
| | - Lili Zou
- The Second People’s Hospital of China Three Gorges University, Yichang, Hubei, China,The Second People’s Hospital of Yichang, Yichang, Hubei, China,Hubei Key Laboratory of Tumor Microenvironment and Immunotherapy, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,The Institute of Infection and Inflammation, College of Basic Medical Sciences, China Three Gorges University, Yichang, Hubei, China,*Correspondence: Lili Zou, ; Jun Wang, ; Matthias Tacke,
| | - Jun Wang
- The People’s Hospital of China Three Gorges University, Yichang, Hubei, China,*Correspondence: Lili Zou, ; Jun Wang, ; Matthias Tacke,
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Zhang N, Wu J, Zhang S, Yuan M, Xu H, Li J, Zhang P, Wang M, Kempher ML, Tao X, Zhang LQ, Ge H, He YX. Molecular basis for coordinating secondary metabolite production by bacterial and plant signaling molecules. J Biol Chem 2022; 298:102027. [PMID: 35568198 PMCID: PMC9163588 DOI: 10.1016/j.jbc.2022.102027] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 05/03/2022] [Accepted: 05/05/2022] [Indexed: 11/28/2022] Open
Abstract
The production of secondary metabolites is a major mechanism used by beneficial rhizobacteria to antagonize plant pathogens. These bacteria have evolved to coordinate the production of different secondary metabolites due to the heavy metabolic burden imposed by secondary metabolism. However, for most secondary metabolites produced by bacteria, it is not known how their biosynthesis is coordinated. Here, we showed that PhlH from the rhizobacterium Pseudomonas fluorescens is a TetR-family regulator coordinating the expression of enzymes related to the biosynthesis of several secondary metabolites, including 2,4-diacetylphloroglucinol (2,4-DAPG), mupirocin, and pyoverdine. We present structures of PhlH in both its apo form and 2,4-DAPG-bound form and elucidate its ligand-recognizing and allosteric switching mechanisms. Moreover, we found that dissociation of 2,4-DAPG from the ligand-binding domain of PhlH was sufficient to allosterically trigger a pendulum-like movement of the DNA-binding domains within the PhlH dimer, leading to a closed-to-open conformational transition. Finally, molecular dynamics simulations confirmed that two distinct conformational states were stabilized by specific hydrogen bonding interactions and that disruption of these hydrogen bonds had profound effects on the conformational transition. Our findings not only reveal a well-conserved route of allosteric signal transduction in TetR-family regulators but also provide novel mechanistic insights into bacterial metabolic coregulation.
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Affiliation(s)
- Nannan Zhang
- School of Life Sciences, Anhui University, Hefei 230601, P.R. China; Key Laboratory of Human Microenvironment and Precision Medicine of Anhui Higher Education Institutes, Anhui University, Hefei 230601, Anhui, China.
| | - Jin Wu
- School of Life Sciences, Anhui University, Hefei 230601, P.R. China; Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Material Science and Information Technology, Anhui University, Hefei 230601, P.R. China
| | - Siping Zhang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, P.R. China
| | - Maoran Yuan
- School of Life Sciences, Anhui University, Hefei 230601, P.R. China; Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Material Science and Information Technology, Anhui University, Hefei 230601, P.R. China
| | - Hang Xu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, P.R. China
| | - Jie Li
- School of Life Sciences, Anhui University, Hefei 230601, P.R. China; Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Material Science and Information Technology, Anhui University, Hefei 230601, P.R. China
| | - Pingping Zhang
- School of Life Sciences, Anhui University, Hefei 230601, P.R. China; Key Laboratory of Human Microenvironment and Precision Medicine of Anhui Higher Education Institutes, Anhui University, Hefei 230601, Anhui, China
| | - Mingzhu Wang
- School of Life Sciences, Anhui University, Hefei 230601, P.R. China; Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Material Science and Information Technology, Anhui University, Hefei 230601, P.R. China
| | - Megan L Kempher
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, and School of Civil Engineering and Environmental Sciences, University of Oklahoma, Norman, Ok, USA
| | - Xuanyu Tao
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, and School of Civil Engineering and Environmental Sciences, University of Oklahoma, Norman, Ok, USA
| | - Li-Qun Zhang
- College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Honghua Ge
- School of Life Sciences, Anhui University, Hefei 230601, P.R. China; Information Materials and Intelligent Sensing Laboratory of Anhui Province, Institutes of Material Science and Information Technology, Anhui University, Hefei 230601, P.R. China.
| | - Yong-Xing He
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, P.R. China.
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Pseudomonas protegens FJKB0103 Isolated from Rhizosphere Exhibits Anti-Methicillin-Resistant Staphylococcus aureus Activity. Microorganisms 2022; 10:microorganisms10020315. [PMID: 35208770 PMCID: PMC8877278 DOI: 10.3390/microorganisms10020315] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2021] [Revised: 01/14/2022] [Accepted: 01/19/2022] [Indexed: 02/01/2023] Open
Abstract
Staphylococcus aureus is amongst the most virulent pathogens, causing chronic and life-threatening human infections. Methicillin-resistant S. aureus (MRSA) are multidrug-resistant strains, and the ability of forming a biofilm reduces their sensitivity to antibiotics. Thus, the alternative compounds inhibiting both resistant strains and biofilm formation are in high demand. In our study, the strain FJKB0103 was isolated from the rhizosphere of Garcinia mangostana, showing strong anti-MRSA activity. We performed molecular phylogenic analysis, analyzed average nucleotide identity (ANI), in silico DNA-DNA hybridization (isDDH), and biochemical characteristics to identify strain FJKB0103 as Pseudomonas protegens. Herein, the genome of strain FJKB0103 was sequenced and subjected to antiSMASH platform, mutational, and functional analyses. The FJKB0103 draft genome was 6,776,967 bp with a 63.4% G + C content, and 16 potential secondary compound biosynthetic clusters in P. protegens FJKB0103 were predicted. The deletion mutant and complementary analysis suggested that DAPG was the anti-MRSA compound. Further tests showed that MRSA strains were sensitive to DAPG, and the lysis of bacterial cells was observed at a high concentration of DAPG. Additionally, DAPG inhibited the biofilm formation of MRSA at subinhibitory concentration. These results suggested that DAPG might be a good alternative treatment to control infections caused by MRSA.
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Schwanemann T, Otto M, Wierckx N, Wynands B. Pseudomonasas Versatile Aromatics Cell Factory. Biotechnol J 2020; 15:e1900569. [DOI: 10.1002/biot.201900569] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 09/08/2020] [Indexed: 12/18/2022]
Affiliation(s)
- Tobias Schwanemann
- Institute of Bio‐ and Geosciences, IBG‐1: Biotechnology Forschungszentrum Jülich, GmbH 52425 Jülich Germany
| | - Maike Otto
- Institute of Bio‐ and Geosciences, IBG‐1: Biotechnology Forschungszentrum Jülich, GmbH 52425 Jülich Germany
| | - Nick Wierckx
- Institute of Bio‐ and Geosciences, IBG‐1: Biotechnology Forschungszentrum Jülich, GmbH 52425 Jülich Germany
| | - Benedikt Wynands
- Institute of Bio‐ and Geosciences, IBG‐1: Biotechnology Forschungszentrum Jülich, GmbH 52425 Jülich Germany
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Liu W, Zhang R, Xian M. Biosynthesis of 2,4-diacetylphloroglucinol from glucose using engineered Escherichia coli. World J Microbiol Biotechnol 2020; 36:130. [PMID: 32712706 DOI: 10.1007/s11274-020-02906-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 07/19/2020] [Indexed: 11/24/2022]
Abstract
In order to produce 2,4-diacetylphloroglucinol (2,4-DAPG) in E. coli, the key synthases coding by phlACBD gene cluster from the strain Pseudomonas fluorescens CHA0 were overexpressed in E. coli BL21 (DE3). The marA, phlE and acc genes were also overexpressed to enhance 2,4-DAPG biosynthesis. Then the fermentation conditions were optimized to improve the concentration of 2,4-DAPG. The results showed that the recombinant E. coli could produce few 2,4-DAPG with only the phlACBD gene cluster. The synthetic ability of 2,4-DAPG could be increased by expressing the acc, marA and phlE genes in shake-flasks cultivation. The effects of phloroglucinol, initial pH, temperature and trace elements on 2,4-DAPG biosynthesis were also investigated. Based on the optimal fermentation conditions obtained from the shake-flasks cultivation, fed-batch fermentation of strain Z3 in a 5 L bioreactor was conducted to produce 2,4-DAPG. Finally, the concentration of 2,4-DAPG was 179 mg/L after induction for 36 h by fed-batch fermentation. To the best of our knowledge, this is the highest 2,4-DAPG production reported in E. coli. This work showed the potential application of engineered E. coli to get high production of target compounds.
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Affiliation(s)
- Wen Liu
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China
| | - Rubing Zhang
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
| | - Mo Xian
- CAS Key Laboratory of Bio-Based Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China.
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Zhang Y, Zhang B, Wu H, Wu X, Yan Q, Zhang LQ. Pleiotropic effects of RsmA and RsmE proteins in Pseudomonas fluorescens 2P24. BMC Microbiol 2020; 20:191. [PMID: 32615927 PMCID: PMC7331252 DOI: 10.1186/s12866-020-01880-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 06/26/2020] [Indexed: 11/11/2022] Open
Abstract
Background Pseudomonas fluorescens 2P24 is a rhizosphere bacterium that produces 2,4-diacetyphloroglucinol (2,4-DAPG) as the decisive secondary metabolite to suppress soilborne plant diseases. The biosynthesis of 2,4-DAPG is strictly regulated by the RsmA family proteins RsmA and RsmE. However, mutation of both of rsmA and rsmE genes results in reduced bacterial growth. Results In this study, we showed that overproduction of 2,4-DAPG in the rsmA rsmE double mutant influenced the growth of strain 2P24. This delay of growth could be partially reversal when the phlD gene was deleted or overexpression of the phlG gene encoding the 2,4-DAPG hydrolase in the rsmA rsmE double mutant. RNA-seq analysis of the rsmA rsmE double mutant revealed that a substantial portion of the P. fluorescens genome was regulated by RsmA family proteins. These genes are involved in the regulation of 2,4-DAPG production, cell motility, carbon metabolism, and type six secretion system. Conclusions These results suggest that RsmA and RsmE are the important regulators of genes involved in the plant-associated strain 2P24 ecologic fitness and operate a sophisticated mechanism for fine-tuning the concentration of 2,4-DAPG in the cells.
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Affiliation(s)
- Yang Zhang
- College of Agriculture, Guangxi University, Nanning, 530004, China
| | - Bo Zhang
- College of Agriculture, Guangxi University, Nanning, 530004, China
| | - Haiyan Wu
- College of Agriculture, Guangxi University, Nanning, 530004, China
| | - Xiaogang Wu
- College of Agriculture, Guangxi University, Nanning, 530004, China.
| | - Qing Yan
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, 59717, USA.
| | - Li-Qun Zhang
- College of Plant Protection, China Agricultural University, Beijing, 100193, China.
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Yu XQ, Yan X, Zhang MY, Zhang LQ, He YX. Flavonoids repress the production of antifungal 2,4-DAPG but potentially facilitate root colonization of the rhizobacterium Pseudomonas fluorescens. Environ Microbiol 2020; 22:5073-5089. [PMID: 32363709 DOI: 10.1111/1462-2920.15052] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Accepted: 04/28/2020] [Indexed: 11/25/2022]
Abstract
In the well-known legume-rhizobia symbiosis, flavonoids released by legume roots induce expression of the Nod factors and trigger early plant responses involved in root nodulation. However, it remains largely unknown how the plant-derived flavonoids influence the physiology of non-symbiotic beneficial rhizobacteria. In this work, we demonstrated that the flavonoids apigenin and/or phloretin enhanced the swarming motility and production of cellulose and curli in Pseudomonas fluorescens 2P24, both traits of which are essential for root colonization. Using a label-free quantitative proteomics approach, we showed that apigenin and phloretin significantly reduced the biosynthesis of the antifungal metabolite 2,4-DAPG and further identified a novel flavonoid-sensing TetR regulator PhlH, which was shown to modulate 2,4-DAPG production by regulating the expression of 2,4-DAPG hydrolase PhlG. Although having similar structures, apigenin and phloretin could also influence different physiological characteristics of P. fluorescens 2P24, with apigenin decreasing the biofilm formation and phloretin inducing expression of proteins involved in the denitrification and arginine fermentation processes. Taken together, our results suggest that plant-derived flavonoids could be sensed by the TetR regulator PhlH in P. fluorescens 2P24 and acts as important signalling molecules that strengthen mutually beneficial interactions between plants and non-symbiotic beneficial rhizobacteria.
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Affiliation(s)
- Xiao-Quan Yu
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Xu Yan
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Meng-Yuan Zhang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Li-Qun Zhang
- Department of Plant Pathology, China Agricultural University, Beijing, China
| | - Yong-Xing He
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
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Zhang B, Zhao H, Wu X, Zhang LQ. The Oxidoreductase DsbA1 negatively influences 2,4-diacetylphloroglucinol biosynthesis by interfering the function of Gcd in Pseudomonas fluorescens 2P24. BMC Microbiol 2020; 20:39. [PMID: 32093646 PMCID: PMC7041245 DOI: 10.1186/s12866-020-1714-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 01/27/2020] [Indexed: 02/03/2023] Open
Abstract
Background The polyketide antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG), produced by Pseudomonas fluorescens 2P24, is positively regulated by the GacS-GacA two-component system. Results Here we reported on the characterization of DsbA1 (disulfide oxidoreductase) as novel regulator of biocontrol activity in P. fluorescens. Our data showed that mutation of dsbA1 caused the accumulation of 2,4-DAPG in a GacA-independent manner. Further analysis indicated that DsbA1 interacts with membrane-bound glucose dehydrogenase Gcd, which positively regulates the production of 2,4-DAPG. Mutation of cysteine (C)-235, C275, and C578 of Gcd, significantly reduced the interaction with DsbA1, enhanced the activity of Gcd and increased 2,4-DAPG production. Conclusions Our results suggest that DsbA1 regulates the 2,4-DAPG concentration via fine-tuning the function of Gcd in P. fluorescens 2P24.
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Affiliation(s)
- Bo Zhang
- College of Agriculture, Guangxi University, Nanning, 530004, China
| | - Hui Zhao
- College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Xiaogang Wu
- College of Agriculture, Guangxi University, Nanning, 530004, China.
| | - Li-Qun Zhang
- College of Plant Protection, China Agricultural University, Beijing, 100193, China.
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10
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Severi E, Thomas GH. Antibiotic export: transporters involved in the final step of natural product production. Microbiology (Reading) 2019; 165:805-818. [DOI: 10.1099/mic.0.000794] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Affiliation(s)
- Emmanuele Severi
- Department of Biology, University of York, Wentworth Way, York, UK
| | - Gavin H. Thomas
- Department of Biology, University of York, Wentworth Way, York, UK
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Syed B, Nagendra Prasad MN, Mohan Kumar K, Satish S. Bioconjugated nano-bactericidal complex for potent activity against human and phytopathogens with concern of global drug resistant crisis. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 637-638:274-281. [PMID: 29753223 DOI: 10.1016/j.scitotenv.2018.04.405] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 03/19/2018] [Accepted: 04/30/2018] [Indexed: 06/08/2023]
Abstract
The present study emphasizes the need for novel antimicrobial agents to combat the global drug resistant crisis. The development of novel nanomaterials is reported to be of the alternative tool to combat drug resistant pathogens. In present investigation, bioconjugated nano-complex was developed from secondary metabolite secreted from endosymbiont. The endosymbiont capable of secreting antimicrobial metabolite was subjected to fermentation and the culture supernatant was assessed for purification of antimicrobial metabolite via bio-assay guided fraction techniques such as thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and column chromatography. The metabolite was characterized as 2,4-Diacetylphloroglucinol (2,4 DAPG) which was used to develop bioconjugated nano-complex by treating with 1 mM silver nitrate under optimized conditions. The purified metabolite 2,4 DAPG reduced silver nitrate to form bioconjugated nano-complex to form association with silver nanoparticles. The oxidized form of DAPG consists of four hard ligands that can conjugate on to the surface of silver nanoparticles cluster. The bioconjugation was confirmed with UV-visible spectroscopy which displayed the shift and shoulder peak in the absorbance spectra. This biomolecular interaction was further determined by the Fourier-transform spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses which displayed different signals ascertaining the molecular binding of 2,4,DAPG with silver nanoparticles. The transmission electron microscopy (TEM) analysis revealed the cluster formation due to bioconjugation. The XRD analysis revealed the crystalline nature of nano-complex with the characteristic peaks indexed to Bragg's reflection occurring at 2θ angle which indicated the (111), (200), (220) and (311) planes. The activity of bioconjugated nano-complex was tested against 12 significant human and phytopathogens. Among all the test pathogens, Shigella flexneri (MTCC 1457) was the most sensitive organisms with 38.33 ± 0.33 zone of inhibition. The results obtained in the present investigation attribute development of nano-complex as one of the effective tools against multi-drug resistant infections across the globe.
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Affiliation(s)
- Baker Syed
- Siberian Federal University, 79 Svobodny pr., Krasnoyarsk 660041, Russia; Bionanotechnological Laboratory, Department of Studies in Microbiology, Manasagangotri, University of Mysore, Mysore 570 006, Karnataka, India
| | - M N Nagendra Prasad
- Department of Biotechnology, Sri Jayachamarajendra College of Engineering, JSS Science and Technology University, JSS Technical Institutional Campus, Mysore 570006, India
| | - K Mohan Kumar
- Department of Chemistry, Madanapalle Institute of Technology & Science, Post Box No: 14, Kadiri Road, Angallu (V), Madanapalle, 517325 Chittoor District, Andhra Pradesh, India
| | - S Satish
- Bionanotechnological Laboratory, Department of Studies in Microbiology, Manasagangotri, University of Mysore, Mysore 570 006, Karnataka, India.
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12
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Molecular cloning, expression, and characterization of acyltransferase from Pseudomonas protegens. Appl Microbiol Biotechnol 2018; 102:6057-6068. [PMID: 29754162 PMCID: PMC6013524 DOI: 10.1007/s00253-018-9052-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 04/17/2018] [Accepted: 04/24/2018] [Indexed: 10/26/2022]
Abstract
The formation of C-C bonds by using CoA independent acyltransferases may have significant impact for novel methods for biotechnology. We report the identification of Pseudomonas strains with CoA-independent acyltransferase activity as well as the heterologous expression of the enzyme in E. coli. The cloning strategies and selected expression studies are discussed. The recombinant acyltransferases were characterized with regard to thermal and storage stability, pH,- and co-solvent tolerance. Moreover, the impact of bivalent metals, inhibitors, and other additives was tested. Careful selection of expression and working conditions led to obtain recombinant acyltransferase form Pseudomonas protegens with up to 11 U mL-1 activity.
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13
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Transcriptional Regulator PhlH Modulates 2,4-Diacetylphloroglucinol Biosynthesis in Response to the Biosynthetic Intermediate and End Product. Appl Environ Microbiol 2017; 83:AEM.01419-17. [PMID: 28821548 DOI: 10.1128/aem.01419-17] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 08/11/2017] [Indexed: 11/20/2022] Open
Abstract
Certain strains of biocontrol bacterium Pseudomonas fluorescens produce the secondary metabolite 2,4-diacetylphloroglucinol (2,4-DAPG) to antagonize soilborne phytopathogens in the rhizosphere. The gene cluster responsible for the biosynthesis of 2,4-DAPG is named phlACBDEFGH and it is still unclear how the pathway-specific regulator phlH within this gene cluster regulates the metabolism of 2,4-DAPG. Here, we found that PhlH in Pseudomonas fluorescens strain 2P24 represses the expression of the phlG gene encoding the 2,4-DAPG hydrolase by binding to a sequence motif overlapping with the -35 site recognized by σ70 factors. Through biochemical screening of PhlH ligands we identified the end product 2,4-DAPG and its biosynthetic intermediate monoacetylphloroglucinol (MAPG), which can act as signaling molecules to modulate the binding of PhlH to the target sequence and activate the expression of phlG Comparison of 2,4-DAPG production between the ΔphlH, ΔphlG, and ΔphlHG mutants confirmed that phlH and phlG impose negative feedback regulation over 2,4-DAPG biosynthesis. It was further demonstrated that the 2,4-DAPG degradation catalyzed by PhlG plays an insignificant role in 2,4-DAPG tolerance but contributes to bacterial growth advantages under carbon/nitrogen starvation conditions. Taken together, our data suggest that by monitoring and down-tuning in situ levels of 2,4-DAPG, the phlHG genes could dynamically modulate the metabolic loads attributed to 2,4-DAPG production and potentially contribute to rhizosphere adaptation.IMPORTANCE 2,4-DAPG, which is synthesized by biocontrol pseudomonad bacteria, is a broad-spectrum antibiotic against bacteria, fungi, oomycetes, and nematodes and plays an important role in suppressing soilborne plant pathogens. Although most of the genes in the 2,4-DAPG biosynthetic gene cluster (phl) have been characterized, it is still not clear how the pathway-specific regulator phlH is involved in 2,4-DAPG metabolism. This work revealed the role of PhlH in modulating 2,4-DAPG levels by controlling the expression of 2,4-DAPG hydrolase PhlG in response to 2,4-DAPG and MAPG. Since 2,4-DAPG biosynthesis imposes a metabolic burden on biocontrol pseudomonads, it is expected that the fine regulation of phlG by PhlH offers a way to dynamically modulate the metabolic loads attributed to 2,4-DAPG production.
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Almario J, Bruto M, Vacheron J, Prigent-Combaret C, Moënne-Loccoz Y, Muller D. Distribution of 2,4-Diacetylphloroglucinol Biosynthetic Genes among the Pseudomonas spp. Reveals Unexpected Polyphyletism. Front Microbiol 2017; 8:1218. [PMID: 28713346 PMCID: PMC5491608 DOI: 10.3389/fmicb.2017.01218] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 06/15/2017] [Indexed: 11/13/2022] Open
Abstract
Fluorescent pseudomonads protecting plant roots from phytopathogens by producing 2,4-diacetylphloroglucinol (DAPG) are considered to form a monophyletic lineage comprised of DAPG+Pseudomonas strains in the "P. corrugata" and "P. protegens" subgroups of the "Pseudomonas fluorescens" group. However, DAPG production ability has not been investigated for many species of these two subgroups, and whether or not the DAPG+Pseudomonas are truly monophyletic remained to be verified. Thus, the distribution of the DAPG biosynthetic operon (phlACBD genes) in the Pseudomonas spp. was investigated in sequenced genomes and type strains. Results showed that the DAPG+Pseudomonas include species of the "P. fluorescens" group, i.e., P. protegens, P. brassicacearum, P. kilonensis, and P. thivervalensis, as expected, as well as P. gingeri in which it had not been documented. Surprisingly, they also include bacteria outside the "P. fluorescens" group, as exemplified by Pseudomonas sp. OT69, and even two Betaproteobacteria genera. The phl operon-based phylogenetic tree was substantially congruent with the one inferred from concatenated housekeeping genes rpoB, gyrB, and rrs. Contrariwise to current supposition, ancestral character reconstructions favored multiple independent acquisitions rather that one ancestral event followed by vertical inheritance. Indeed, based on synteny analyses, these acquisitions appeared to vary according to the Pseudomonas subgroup and even the phylogenetic groups within the subgroups. In conclusion, our study shows that the phl+Pseudomonas populations form a polyphyletic group and suggests that DAPG biosynthesis might not be restricted to this genus. This is important to consider when assessing the ecological significance of phl+ bacterial populations in rhizosphere ecosystems.
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Affiliation(s)
- Juliana Almario
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
| | - Maxime Bruto
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
| | - Jordan Vacheron
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
| | - Claire Prigent-Combaret
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
| | - Yvan Moënne-Loccoz
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
| | - Daniel Muller
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
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15
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Almario J, Bruto M, Vacheron J, Prigent-Combaret C, Moënne-Loccoz Y, Muller D. Distribution of 2,4-Diacetylphloroglucinol Biosynthetic Genes among the Pseudomonas spp. Reveals Unexpected Polyphyletism. Front Microbiol 2017; 8:1218. [PMID: 28713346 DOI: 10.3389/fmibc.2017.01218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 06/15/2017] [Indexed: 05/26/2023] Open
Abstract
Fluorescent pseudomonads protecting plant roots from phytopathogens by producing 2,4-diacetylphloroglucinol (DAPG) are considered to form a monophyletic lineage comprised of DAPG+Pseudomonas strains in the "P. corrugata" and "P. protegens" subgroups of the "Pseudomonas fluorescens" group. However, DAPG production ability has not been investigated for many species of these two subgroups, and whether or not the DAPG+Pseudomonas are truly monophyletic remained to be verified. Thus, the distribution of the DAPG biosynthetic operon (phlACBD genes) in the Pseudomonas spp. was investigated in sequenced genomes and type strains. Results showed that the DAPG+Pseudomonas include species of the "P. fluorescens" group, i.e., P. protegens, P. brassicacearum, P. kilonensis, and P. thivervalensis, as expected, as well as P. gingeri in which it had not been documented. Surprisingly, they also include bacteria outside the "P. fluorescens" group, as exemplified by Pseudomonas sp. OT69, and even two Betaproteobacteria genera. The phl operon-based phylogenetic tree was substantially congruent with the one inferred from concatenated housekeeping genes rpoB, gyrB, and rrs. Contrariwise to current supposition, ancestral character reconstructions favored multiple independent acquisitions rather that one ancestral event followed by vertical inheritance. Indeed, based on synteny analyses, these acquisitions appeared to vary according to the Pseudomonas subgroup and even the phylogenetic groups within the subgroups. In conclusion, our study shows that the phl+Pseudomonas populations form a polyphyletic group and suggests that DAPG biosynthesis might not be restricted to this genus. This is important to consider when assessing the ecological significance of phl+ bacterial populations in rhizosphere ecosystems.
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Affiliation(s)
- Juliana Almario
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
| | - Maxime Bruto
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
| | - Jordan Vacheron
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
| | - Claire Prigent-Combaret
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
| | - Yvan Moënne-Loccoz
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
| | - Daniel Muller
- Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université de Lyon, Université Claude Bernard Lyon1, VetAgro Sup, UMR Ecologie MicrobienneVilleurbanne, France
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16
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Abdel-Ghany SE, Day I, Heuberger AL, Broeckling CD, Reddy ASN. Production of Phloroglucinol, a Platform Chemical, in Arabidopsis using a Bacterial Gene. Sci Rep 2016; 6:38483. [PMID: 27924918 PMCID: PMC5141504 DOI: 10.1038/srep38483] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 11/10/2016] [Indexed: 12/15/2022] Open
Abstract
Phloroglucinol (1,3,5-trihydroxybenzene; PG) and its derivatives are phenolic compounds that are used for various industrial applications. Current methods to synthesize PG are not sustainable due to the requirement for carbon-based precursors and co-production of toxic byproducts. Here, we describe a more sustainable production of PG using plants expressing a native bacterial or a codon-optimized synthetic PhlD targeted to either the cytosol or chloroplasts. Transgenic lines were analyzed for the production of PG using gas and liquid chromatography coupled to mass spectroscopy. Phloroglucinol was produced in all transgenic lines and the line with the highest PhlD transcript level showed the most accumulation of PG. Over 80% of the produced PG was glycosylated to phlorin. Arabidopsis leaves have the machinery to glycosylate PG to form phlorin, which can be hydrolyzed enzymatically to produce PG. Furthermore, the metabolic profile of plants with PhlD in either the cytosol or chloroplasts was altered. Our results provide evidence that plants can be engineered to produce PG using a bacterial gene. Phytoproduction of PG using a bacterial gene paves the way for further genetic manipulations to enhance the level of PG with implications for the commercial production of this important platform chemical in plants.
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Affiliation(s)
- Salah E Abdel-Ghany
- Department of Biology, Program in Molecular Plant Biology, Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA.,Department of Botany, Faculty of Science, Zagazig University, Zagazig, 44519, Egypt
| | - Irene Day
- Department of Biology, Program in Molecular Plant Biology, Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Adam L Heuberger
- Proteomics and Metabolomics Facility, Colorado State University, Fort Collins, CO 80523, USA
| | - Corey D Broeckling
- Proteomics and Metabolomics Facility, Colorado State University, Fort Collins, CO 80523, USA
| | - Anireddy S N Reddy
- Department of Biology, Program in Molecular Plant Biology, Program in Cell and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
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17
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Clifford JC, Buchanan A, Vining O, Kidarsa TA, Chang JH, McPhail KL, Loper JE. Phloroglucinol functions as an intracellular and intercellular chemical messenger influencing gene expression in Pseudomonas protegens. Environ Microbiol 2015; 18:3296-3308. [PMID: 26337778 DOI: 10.1111/1462-2920.13043] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 07/24/2015] [Accepted: 08/22/2015] [Indexed: 12/13/2022]
Abstract
Bacteria can be both highly communicative and highly competitive in natural habitats and antibiotics are thought to play a role in both of these processes. The soil bacterium Pseudomonas protegens Pf-5 produces a spectrum of antibiotics, two of which, pyoluteorin and 2,4-diacetylphloroglucinol (DAPG), function in intracellular and intercellular communication, both as autoinducers of their own production. Here, we demonstrate that phloroglucinol, an intermediate in DAPG biosynthesis, can serve as an intercellular signal influencing the expression of pyoluteorin biosynthesis genes, the production of pyoluteorin, and inhibition of Pythium ultimum, a phytopathogenic oomycete sensitive to pyoluteorin. Through analysis of RNAseq data sets, we show that phloroglucinol had broad effects on the transcriptome of Pf-5, significantly altering the transcription of more than two hundred genes. The effects of nanomolar versus micromolar concentrations of phloroglucinol differed both quantitatively and qualitatively, influencing the expression of distinct sets of genes or having opposite effects on transcript abundance of certain genes. Therefore, our results support the concept of hormesis, a phenomenon associated with signalling molecules that elicit distinct responses at different concentrations. Phloroglucinol is the first example of an intermediate of antibiotic biosynthesis that functions as a chemical messenger influencing gene expression in P. protegens.
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Affiliation(s)
- Jennifer C Clifford
- US Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR, USA
| | - Alex Buchanan
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
| | - Oliver Vining
- College of Pharmacy, Oregon State University, Corvallis, OR, USA
| | - Teresa A Kidarsa
- US Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR, USA
| | - Jeff H Chang
- Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA
| | - Kerry L McPhail
- College of Pharmacy, Oregon State University, Corvallis, OR, USA
| | - Joyce E Loper
- US Department of Agriculture, Agricultural Research Service, Horticultural Crops Research Laboratory, Corvallis, OR, USA. .,Department of Botany and Plant Pathology and Center for Genome Research and Biocomputing, Oregon State University, Corvallis, OR, USA.
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18
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Philmus B, Shaffer BT, Kidarsa TA, Yan Q, Raaijmakers JM, Begley TP, Loper JE. Investigations into the Biosynthesis, Regulation, and Self-Resistance of Toxoflavin in Pseudomonas protegens Pf-5. Chembiochem 2015; 16:1782-90. [PMID: 26077901 DOI: 10.1002/cbic.201500247] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Indexed: 11/10/2022]
Abstract
Pseudomonas spp. are prolific producers of natural products from many structural classes. Here we show that the soil bacterium Pseudomonas protegens Pf-5 is capable of producing trace levels of the triazine natural product toxoflavin (1) under microaerobic conditions. We evaluated toxoflavin production by derivatives of Pf-5 with deletions in specific biosynthesis genes, which led us to propose a revised biosynthetic pathway for toxoflavin that shares the first two steps with riboflavin biosynthesis. We also report that toxM, which is not present in the well-characterized cluster of Burkholderia glumae, encodes a monooxygenase that degrades toxoflavin. The toxoflavin degradation product of ToxM is identical to that of TflA, the toxoflavin lyase from Paenibacillus polymyxa. Toxoflavin production by P. protegens causes inhibition of several plant-pathogenic bacteria, and introduction of toxM into the toxoflavin-sensitive strain Pseudomonas syringae DC3000 results in resistance to toxoflavin.
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Affiliation(s)
- Benjamin Philmus
- College of Pharmacy, Oregon State University, 203 Pharmacy Building, Corvallis, OR 97331 (USA).
| | - Brenda T Shaffer
- Agricultural Research Service, US Department of Agriculture, 3420 N.W. Orchard Avenue, Corvallis, OR 97330 (USA)
| | - Teresa A Kidarsa
- Agricultural Research Service, US Department of Agriculture, 3420 N.W. Orchard Avenue, Corvallis, OR 97330 (USA)
| | - Qing Yan
- Department of Botany and Plant Pathology, Oregon State University, 2082 Cordley Hall, Corvallis, OR 97331 (USA)
| | - Jos M Raaijmakers
- Department of Microbial Ecology, Netherlands Institute of Ecology, Droevendaalsesteeg 10, 6708 PB Wageningen (The Netherlands).,Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE Leiden (The Netherlands)
| | - Tadhg P Begley
- Department of Chemistry, Texas A&M University, College Station, TX 77843 (USA)
| | - Joyce E Loper
- Agricultural Research Service, US Department of Agriculture, 3420 N.W. Orchard Avenue, Corvallis, OR 97330 (USA). .,Department of Botany and Plant Pathology, Oregon State University, 2082 Cordley Hall, Corvallis, OR 97331 (USA).
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Posttranscriptional regulation of 2,4-diacetylphloroglucinol production by GidA and TrmE in Pseudomonas fluorescens 2P24. Appl Environ Microbiol 2014; 80:3972-81. [PMID: 24747907 DOI: 10.1128/aem.00455-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas fluorescens 2P24 is a soilborne bacterium that synthesizes and excretes multiple antimicrobial metabolites. The polyketide compound 2,4-diacetylphloroglucinol (2,4-DAPG), synthesized by the phlACBD locus, is its major biocontrol determinant. This study investigated two mutants defective in antagonistic activity against Rhizoctonia solani. Deletion of the gidA (PM701) or trmE (PM702) gene from strain 2P24 completely inhibited the production of 2,4-DAPG and its precursors, monoacetylphloroglucinol (MAPG) and phloroglucinol (PG). The transcription of the phlA gene was not affected, but the translation of the phlA and phlD genes was reduced significantly. Two components of the Gac/Rsm pathway, RsmA and RsmE, were found to be regulated by gidA and trmE, whereas the other components, RsmX, RsmY, and RsmZ, were not. The regulation of 2,4-DAPG production by gidA and trmE, however, was independent of the Gac/Rsm pathway. Both the gidA and trmE mutants were unable to produce PG but could convert PG to MAPG and MAPG to 2,4-DAPG. Overexpression of PhlD in the gidA and trmE mutants could restore the production of PG and 2,4-DAPG. Taken together, these findings suggest that GidA and TrmE are positive regulatory elements that influence the biosynthesis of 2,4-DAPG posttranscriptionally.
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20
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Fighting Plant Diseases Through the Application of Bacillus and Pseudomonas Strains. SOIL BIOLOGY 2013. [DOI: 10.1007/978-3-642-39317-4_9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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21
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Molecular and catalytic properties of 2,4-diacetylphloroglucinol hydrolase (PhlG) from Pseudomonas sp. YGJ3. Biosci Biotechnol Biochem 2012; 76:1239-41. [PMID: 22790955 DOI: 10.1271/bbb.120054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Gene phlG encoding 2,4-diacetylphloroglucinol hydrolase was cloned from Pseudomonas sp. YGJ3 and expressed in Escherichia coli. Recombinant PhlG was purified homogeneously. It required 2-mercaptoethanol for stability. Km for 2,4-diacetylphloroglucinol and kcat were determined to be 24 µM and 5.8 s(-1) respectively. CoCl2 specifically and significantly activated PhlG.
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22
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Yang F, Cao Y. Biosynthesis of phloroglucinol compounds in microorganisms--review. Appl Microbiol Biotechnol 2011; 93:487-95. [PMID: 22101786 DOI: 10.1007/s00253-011-3712-6] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 10/23/2011] [Accepted: 11/05/2011] [Indexed: 12/24/2022]
Abstract
Phloroglucinol derivatives are a major class of secondary metabolites of wide occurrence in biological systems. In the bacteria kingdom, these compounds can only be synthesized by some species of Pseudomonads. Pseudomonas spp. could produce 2,4-diacetylphloroglucinol (DAPG) that plays an important role in the biological control of many plant pathogens. In this review, we summarize knowledge about synthesis of phloroglucinol compounds based on the DAPG biosynthetic pathway. Recent advances that have been made in understanding phloroglucinol compound biosynthesis and regulation are highlighted. From these studies, researchers have identified the biosynthesis pathway of DAPG. Most of the genes involved in the biosynthesis pathway have been cloned and characterized. Additionally, heterologous systems of the model microorganism Escherichia coli are constructed to produce phloroglucinol. Although further work is still required, a full understanding of phloroglucinol compound biosynthesis is almost within reach. This review also suggests new directions and attempts to gain some insights for better understanding of the biosynthesis and regulation of DAPG. The combination of traditional biochemistry and molecular biology with new systems biology and synthetic biology tools will provide a better view of phloroglucinol compound biosynthesis and a greater potential of microbial production.
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Affiliation(s)
- Fang Yang
- Ningbo Institute of Material Technology & Engineering, Chinese Academy of Sciences, 315201, Ningbo, China
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Susi P, Aktuganov G, Himanen J, Korpela T. Biological control of wood decay against fungal infection. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2011; 92:1681-1689. [PMID: 21440981 DOI: 10.1016/j.jenvman.2011.03.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2010] [Revised: 01/18/2011] [Accepted: 03/06/2011] [Indexed: 05/30/2023]
Abstract
Wood (timber) is an important raw material for various purposes, and having biological composition it is susceptible to deterioration by various agents. The history of wood protection by impregnation with synthetic chemicals is almost two hundred years old. However, the ever-increasing public concern and the new environmental regulations on the use of chemicals have created the need for the development and the use of alternative methods for wood protection. Biological wood protection by antagonistic microbes alone or in combination with (bio)chemicals, is one of the most promising ways for the environmentally sound wood protection. The most effective biocontrol antagonists belong to genera Trichoderma, Gliocladium, Bacillus, Pseudomonas and Streptomyces. They compete for an ecological niche by consuming available nutrients as well as by secreting a spectrum of biochemicals effective against various fungal pathogens. The biochemicals include cell wall-degrading enzymes, siderophores, chelating iron and a wide variety of volatile and non-volatile antibiotics. In this review, the nature and the function of the antagonistic microbes in wood protection are discussed.
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Affiliation(s)
- Petri Susi
- Institute of Microbiology and Pathology, Department of Virology, University of Turku, Kiinamyllynkatu 13, 20520 Turku, Finland.
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Kidarsa TA, Goebel NC, Zabriskie TM, Loper JE. Phloroglucinol mediates cross-talk between the pyoluteorin and 2,4-diacetylphloroglucinol biosynthetic pathways in Pseudomonas fluorescens Pf-5. Mol Microbiol 2011; 81:395-414. [PMID: 21564338 DOI: 10.1111/j.1365-2958.2011.07697.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The antibiotics pyoluteorin and 2,4-diacetylphloroglucinol (DAPG) contribute to the biological control of soilborne plant diseases by some strains of Pseudomonas fluorescens, including Pf-5. These secondary metabolites also have signalling functions with each compound reported to induce its own production and repress the other's production. The first step in DAPG biosynthesis is production of phloroglucinol (PG) by PhlD. In this study, we show that PG is required at nanomolar concentrations for pyoluteorin production in Pf-5. At higher concentrations, PG is responsible for the inhibition of pyoluteorin production previously attributed to DAPG. DAPG had no effect on pyoluteorin production, and monoacetylphloroglucinol showed both stimulatory and inhibitory activities but at concentrations 100-fold greater than the levels of PG required for similar effects. We also demonstrate that PG regulates pyoluteorin production in P. aeruginosa and that a phlD gene adjacent to the pyoluteorin biosynthetic gene cluster in P. aeruginosa strain LESB58 can restore pyoluteorin biosynthesis to a ΔphlD mutant of Pf-5. Bioinformatic analyses show that the dual role of PhlD in the biosynthesis of DAPG and the regulation of pyoluteorin production could have arisen within the pseudomonads during the assembly of these biosynthetic gene clusters from genes and gene subclusters of diverse origins.
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Affiliation(s)
- Teresa A Kidarsa
- USDA-ARS-Horticultural Crops Research Laboratory, Corvallis, OR 97330, USA
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25
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He YX, Huang L, Xue Y, Fei X, Teng YB, Rubin-Pitel SB, Zhao H, Zhou CZ. Crystal structure and computational analyses provide insights into the catalytic mechanism of 2,4-diacetylphloroglucinol hydrolase PhlG from Pseudomonas fluorescens. J Biol Chem 2010; 285:4603-11. [PMID: 20018877 PMCID: PMC2836065 DOI: 10.1074/jbc.m109.044180] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 11/03/2009] [Indexed: 12/24/2022] Open
Abstract
2,4-Diacetylphloroglucinol hydrolase PhlG from Pseudomonas fluorescens catalyzes hydrolytic carbon-carbon (C-C) bond cleavage of the antibiotic 2,4-diacetylphloroglucinol to form monoacetylphloroglucinol, a rare class of reactions in chemistry and biochemistry. To investigate the catalytic mechanism of this enzyme, we determined the three-dimensional structure of PhlG at 2.0 A resolution using x-ray crystallography and MAD methods. The overall structure includes a small N-terminal domain mainly involved in dimerization and a C-terminal domain of Bet v1-like fold, which distinguishes PhlG from the classical alpha/beta-fold hydrolases. A dumbbell-shaped substrate access tunnel was identified to connect a narrow interior amphiphilic pocket to the exterior solvent. The tunnel is likely to undergo a significant conformational change upon substrate binding to the active site. Structural analysis coupled with computational docking studies, site-directed mutagenesis, and enzyme activity analysis revealed that cleavage of the 2,4-diacetylphloroglucinol C-C bond proceeds via nucleophilic attack by a water molecule, which is coordinated by a zinc ion. In addition, residues Tyr(121), Tyr(229), and Asn(132), which are predicted to be hydrogen-bonded to the hydroxyl groups and unhydrolyzed acetyl group, can finely tune and position the bound substrate in a reactive orientation. Taken together, these results revealed the active sites and zinc-dependent hydrolytic mechanism of PhlG and explained its substrate specificity as well.
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Affiliation(s)
- Yong-Xing He
- From the Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
| | - Liang Huang
- From the Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
| | - Yanyan Xue
- From the Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
| | - Xue Fei
- From the Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
| | - Yan-Bin Teng
- From the Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
| | | | - Huimin Zhao
- the Departments of Chemical and Biomolecular Engineering and
- Chemistry and
- Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Cong-Zhao Zhou
- From the Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China and
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26
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Tian T, Wu XG, Duan HM, Zhang LQ. The resistance-nodulation-division efflux pump EmhABC influences the production of 2,4-diacetylphloroglucinol in Pseudomonas fluorescens 2P24. MICROBIOLOGY-SGM 2009; 156:39-48. [PMID: 19833777 DOI: 10.1099/mic.0.031161-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The polyketide metabolite 2,4-diacetylphloroglucinol (2,4-DAPG) plays a major role in the biological control of soil-borne plant diseases by Pseudomonas fluorescens 2P24. Two mutants (PM810 and PM820) with increased extracellular accumulation of 2,4-DAPG were isolated using transposon mutagenesis. The disrupted genes in these two mutants shared >80 % identity with the genes of the EmhR-EmhABC resistance-nodulation-division (RND) efflux system of P. fluorescens cLP6a. The deletion of emhA (PM802), emhB (PM803) or emhC (PM804) genes in strain 2P24 increased the extracellular accumulation of 2,4-DAPG, whereas the deletion of the emhR (PM801) gene decreased the biosynthesis of 2,4-DAPG. The promoter assay confirmed the elevated transcription of emhABC in the EmhR disrupted strain (PM801) and an indirect negative regulation of 2,4-DAPG biosynthetic locus transcription by the EmhABC efflux pump. Induction by exogenous 2,4-DAPG led to remarkable differences in transcription of chromosome-borne phlA : : lacZ fusion in PM901 and PM811 (emhA(-)) strains. Additionally, the EmhABC system in strain 2P24 was involved in the resistance to a group of toxic compounds, including ampicillin, chloramphenicol, tetracycline, ethidium bromide and crystal violet. In conclusion, our results suggest that the EmhABC system is an important element that influences the production of antibiotic 2,4-DAPG and enhances resistance to toxic compounds in P. fluorescens 2P24.
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Affiliation(s)
- Tao Tian
- Department of Plant Pathology, China Agricultural University, Beijing, 100193, PR China
| | - Xiao-Gang Wu
- Department of Plant Pathology, China Agricultural University, Beijing, 100193, PR China
| | - Hui-Mei Duan
- Department of Plant Pathology, China Agricultural University, Beijing, 100193, PR China
| | - Li-Qun Zhang
- The Key Laboratory of Plant Pathology, Ministry of Agriculture, Beijing, 100193, PR China.,Department of Plant Pathology, China Agricultural University, Beijing, 100193, PR China
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27
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Gross H, Loper JE. Genomics of secondary metabolite production by Pseudomonas spp. Nat Prod Rep 2009; 26:1408-46. [PMID: 19844639 DOI: 10.1039/b817075b] [Citation(s) in RCA: 393] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Harald Gross
- Institute for Pharmaceutical Biology, Nussallee 6, 53115, Bonn, Germany.
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28
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Ruocco M, Lanzuise S, Vinale F, Marra R, Turrà D, Woo SL, Lorito M. Identification of a new biocontrol gene in Trichoderma atroviride: the role of an ABC transporter membrane pump in the interaction with different plant-pathogenic fungi. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:291-301. [PMID: 19245323 DOI: 10.1094/mpmi-22-3-0291] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Successful biocontrol interactions often require that the beneficial microbes involved are resistant or tolerant to a variety of toxicants, including antibiotics produced by themselves or phytopathogens, plant antimicrobial compounds, and synthetic chemicals or contaminants. The ability of Trichoderma spp., the most widely applied biocontrol fungi, to withstand different chemical stresses, including those associated with mycoparasitism, is well known. In this work, we identified an ATP-binding cassette transporter cell membrane pump as an important component of the above indicated resistance mechanisms that appears to be supported by an extensive and powerful cell detoxification system. The encoding gene, named Taabc2, was cloned from a strain of Trichoderma atroviride and characterized. Its expression was found to be upregulated in the presence of pathogen-secreted metabolites, specific mycotoxins and some fungicides, and in conditions that stimulate the production in Trichoderma spp. of antagonism-related factors (toxins and enzymes). The key role of this gene in antagonism and biocontrol was demonstrated by the characterization of the obtained deletion mutants. They suffered an increased susceptibility to inhibitory compounds either secreted by pathogenic fungi or possibly produced by the biocontrol microbe itself and lost, partially or entirely, the ability to protect tomato plants from Pythium ultimum and Rhizoctonia solani attack.
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Affiliation(s)
- Michelina Ruocco
- CNR-Istituto per la Protezione delle Piante sez. Portici, Via Università 130, 80055 Portici, Napoli, Italy
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29
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Evolutionary history of the phl gene cluster in the plant-associated bacterium Pseudomonas fluorescens. Appl Environ Microbiol 2009; 75:2122-31. [PMID: 19181839 DOI: 10.1128/aem.02052-08] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas fluorescens is of agricultural and economic importance as a biological control agent largely because of its plant association and production of secondary metabolites, in particular 2,4-diacetylphloroglucinol (2,4-DAPG). This polyketide, which is encoded by the eight-gene phl cluster, has antimicrobial effects on phytopathogens, promotes amino acid exudation from plant roots, and induces systemic resistance in plants. Despite its importance, 2,4-DAPG production is limited to a subset of P. fluorescens strains. Determination of the evolution of the phl cluster and understanding the selective pressures promoting its retention or loss in lineages of P. fluorescens will help in the development of P. fluorescens as a viable and effective inoculant for application in agriculture. In this study, genomic and sequence-based approaches were integrated to reconstruct the phylogeny of P. fluorescens and the phl cluster. It was determined that 2,4-DAPG production is an ancestral trait in the species P. fluorescens but that most lineages have lost this capacity through evolution. Furthermore, intragenomic recombination has relocated the phl cluster within the P. fluorescens genome at least three times, but the integrity of the cluster has always been maintained. The possible evolutionary and functional implications for retention of the phl cluster and 2,4-DAPG production in some lineages of P. fluorescens are discussed.
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30
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Mark G, Morrissey JP, Higgins P, O'gara F. Molecular-based strategies to exploit Pseudomonas biocontrol strains for environmental biotechnology applications. FEMS Microbiol Ecol 2006; 56:167-77. [PMID: 16629747 DOI: 10.1111/j.1574-6941.2006.00056.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Exploitation of beneficial plant-microbe interactions in the rhizosphere can result in the promotion of plant health and have significant implications for low input sustainable agriculture applications such as biocontrol. Bacteria such as Bacillus and Pseudomonas, and fungi such as Trichoderma, have been developed as commercial biocontrol products. Registration of microbial inocualants as biocontrol agents in either the European Union or the United States requires production of extensive dossiers covering efficacy, safety and risk assessment. Despite the fact that a number of Pseudomonas biocontrol products have been marketed there are still some limitations hampering the development of this technology for widespread use in agriculture. Although many strains show good performance in specific trials, this is often not translated into consistent, effective biocontrol in diverse field situations. Advances in 'Omics' technology and the publication of complete genome sequences of a number of plant-associative bacterial strains, has facilitated investigations into the molecular basis underpinning the establishment of beneficial plant-microbe interactions in the rhizosphere. The understanding of these molecular signalling processes and the functions they regulate is fundamental to promoting beneficial microbe-plant interactions, to overcome existing limitations and to designing improved strategies for the development of novel Pseudmonas biocontrol inoculant consortia.
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Affiliation(s)
- Genevievel Mark
- The BIOMERIT Research Centre, Department of Microbiology, National University of Ireland (University College Cork), Cork, Ireland
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31
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Kiely PD, Haynes JM, Higgins CH, Franks A, Mark GL, Morrissey JP, O'Gara F. Exploiting new systems-based strategies to elucidate plant-bacterial interactions in the rhizosphere. MICROBIAL ECOLOGY 2006; 51:257-66. [PMID: 16596439 DOI: 10.1007/s00248-006-9019-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Accepted: 12/16/2005] [Indexed: 05/08/2023]
Abstract
The rhizosphere is the site of intense interactions between plant, bacterial, and fungal partners. In plant-bacterial interactions, signal molecules exuded by the plant affect both primary initiation and subsequent behavior of the bacteria in complex beneficial associations such as biocontrol. However, despite this general acceptance that plant-root exudates have an effect on the resident bacterial populations, very little is still known about the influence of these signals on bacterial gene expression and the roles of genes found to have altered expression in plant-microbial interactions. Analysis of the rhizospheric communities incorporating both established techniques, and recently developed "omic technologies" can now facilitate investigations into the molecular basis underpinning the establishment of beneficial plant-microbial interactomes in the rhizosphere. The understanding of these signaling processes, and the functions they regulate, is fundamental to understanding the basis of beneficial microbial-plant interactions, to overcoming existing limitations, and to designing improved strategies for the development of novel Pseudomonas biocontrol strains.
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Affiliation(s)
- P D Kiely
- Biomerit Research Centre, Department of Microbiology, National University of Ireland (UCC), Cork, Ireland
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32
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Bottiglieri M, Keel C. Characterization of PhlG, a hydrolase that specifically degrades the antifungal compound 2,4-diacetylphloroglucinol in the biocontrol agent Pseudomonas fluorescens CHA0. Appl Environ Microbiol 2006; 72:418-27. [PMID: 16391073 PMCID: PMC1352262 DOI: 10.1128/aem.72.1.418-427.2006] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The potent antimicrobial compound 2,4-diacetylphloroglucinol (DAPG) is a major determinant of biocontrol activity of plant-beneficial Pseudomonas fluorescens CHA0 against root diseases caused by fungal pathogens. The DAPG biosynthetic locus harbors the phlG gene, the function of which has not been elucidated thus far. The phlG gene is located upstream of the phlACBD biosynthetic operon, between the phlF and phlH genes which encode pathway-specific regulators. In this study, we assigned a function to PhlG as a hydrolase specifically degrades DAPG to equimolar amounts of mildly toxic monoacetylphloroglucinol (MAPG) and acetate. DAPG added to cultures of a DAPG-negative DeltaphlA mutant of strain CHA0 was completely degraded, and MAPG was temporarily accumulated. In contrast, DAPG was not degraded in cultures of a DeltaphlA DeltaphlG double mutant. To confirm the enzymatic nature of PhlG in vitro, the protein was histidine tagged, overexpressed in Escherichia coli, and purified by affinity chromatography. Purified PhlG had a molecular mass of about 40 kDa and catalyzed the degradation of DAPG to MAPG. The enzyme had a kcat of 33 s(-1) and a Km of 140 microM at 30 degrees C and pH 7. The PhlG enzyme did not degrade other compounds with structures similar to DAPG, such as MAPG and triacetylphloroglucinol, suggesting strict substrate specificity. Interestingly, PhlG activity was strongly reduced by pyoluteorin, a further antifungal compound produced by the bacterium. Expression of phlG was not influenced by the substrate DAPG or the degradation product MAPG but was subject to positive control by the GacS/GacA two-component system and to negative control by the pathway-specific regulators PhlF and PhlH.
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Affiliation(s)
- Mélanie Bottiglieri
- Département de Microbiologie Fondamentale, Bātiment de Biologie, Université de Lausanne, CH-1015 Lausanne-Dorigny, Switzerland
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33
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Brodhagen M, Paulsen I, Loper JE. Reciprocal regulation of pyoluteorin production with membrane transporter gene expression in Pseudomonas fluorescens Pf-5. Appl Environ Microbiol 2005; 71:6900-9. [PMID: 16269724 PMCID: PMC1287665 DOI: 10.1128/aem.71.11.6900-6909.2005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pyoluteorin is a chlorinated polyketide antibiotic secreted by the rhizosphere bacterium Pseudomonas fluorescens Pf-5. Genes encoding enzymes and transcriptional regulators involved in pyoluteorin production are clustered in the genome of Pf-5. Sequence analysis of genes adjacent to the known pyoluteorin biosynthetic gene cluster revealed the presence of an ABC transporter system. We disrupted two putative ABC transporter genes by inserting transcriptional fusions to an ice nucleation reporter gene. Mutations in pltI and pltJ, which are predicted to encode a membrane fusion protein and an ATP-binding cassette of the ABC transporter, respectively, greatly reduced pyoluteorin production by Pf-5. During the transition from exponential growth to stationary phase, populations of a pltI mutant were lower than those of a pltI+ strain in a culture medium containing pyoluteorin, suggesting a role for the transport system in efflux and the resistance of Pf-5 to the antibiotic. Although pltI or pltJ mutant strains displayed low pyoluteorin production, they did not accumulate proportionately more of the antibiotic intracellularly, indicating that pltI and pltJ do not encode an exclusive exporter for pyoluteorin. Transcription of the putative pyoluteorin efflux genes pltI and pltJ was enhanced by exogenous pyoluteorin. These new observations parallel an earlier finding that pyoluteorin enhances the transcription of pyoluteorin biosynthesis genes and pyoluteorin production in Pf-5. This report provides evidence of a coordination of pyoluteorin production and the transcription of genes encoding a linked transport apparatus, wherein each requires the other for optimal expression.
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Affiliation(s)
- Marion Brodhagen
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
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34
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Improving biocontrol activity ofPseudomonas fluorescens through chromosomal integration of 2,4-diacetylphloroglucinol biosynthesis genes. ACTA ACUST UNITED AC 2005. [DOI: 10.1007/bf03183678] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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