1
|
Sun K, Li Z, Lian M, Li Q, Wang R, Gu Y, Lei P, He H, Xu H, Sha F, Sun L. Characterization of a novel exopolysaccharide from Acinetobacter rhizosphaerae with ability to enhance the salt stress resistance of rice seedlings. Int J Biol Macromol 2024; 256:128438. [PMID: 38042318 DOI: 10.1016/j.ijbiomac.2023.128438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 11/13/2023] [Accepted: 11/24/2023] [Indexed: 12/04/2023]
Abstract
We here describe the isolation of a novel exopolysaccharide from Acinetobacter rhizosphaerae, named ArEPS. The structure of ArEPS was characterized by analysis of the monosaccharide composition, molecular weight, infrared spectrum, methylation, and nuclear magnetic resonance spectrum. ArEPS was found to be an acidic heteropolysaccharide composed of glucose, galactose, galacturonic acid, glucuronic acid, mannose, and glucosamine; the molecular weight was 1533 kDa. Structural analysis showed that the main-chain structure of ArEPS predominantly comprised 1,3,6-β-Glcp, 1,3,4-α-Galp, 1,2-β-Glcp, 1,4-β-GlcpA, 1,4-β-GalpA, and the side-chain structure comprised 1,6-β-Glcp, 1,3-β-Galp, 1-α-Glcp, 1-β-Galp, 1-α-Manp, 1,4,6-α-Glcp, 1,2,4-β-Glcp, 1,2,3-β-Glcp, and 1,3-β-GlcpN. ArEPS significantly enhanced the tolerance of rice seedlings to salt stress. Specifically, plant height, fresh weight, chlorophyll content, and the K+/Na+ ratio increased by 51 %, 63 %, 29 %, and 162 %, respectively, and the malondialdehyde content was reduced by 45 % after treatment with 100 mg/kg ArEPS compared to treatment with 100 mM NaCl. Finally, based on the quadratic regression between fresh weight and ArEPS addition, the optimal ArEPS addition level was estimated to be 135.12 mg/kg. These results indicate the prospects of ArEPS application in agriculture.
Collapse
Affiliation(s)
- Ke Sun
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China; Suzhou Cornigs Polyols CO., LTD., Suzhou 215000, China
| | - Zhen Li
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Mengyu Lian
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Quan Li
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Rui Wang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Yian Gu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Peng Lei
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Hongjie He
- Westa College, Southwest University, Chongqing 400715, China
| | - Hong Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Feng Sha
- Suzhou Cornigs Polyols CO., LTD., Suzhou 215000, China; School of Chemical Biology & Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
| | - Liang Sun
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
| |
Collapse
|
2
|
Zhu YG, Peng J, Chen C, Xiong C, Li S, Ge A, Wang E, Liesack W. Harnessing biological nitrogen fixation in plant leaves. TRENDS IN PLANT SCIENCE 2023; 28:1391-1405. [PMID: 37270352 DOI: 10.1016/j.tplants.2023.05.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 05/11/2023] [Accepted: 05/15/2023] [Indexed: 06/05/2023]
Abstract
The importance of biological nitrogen fixation (BNF) in securing food production for the growing world population with minimal environmental cost has been increasingly acknowledged. Leaf surfaces are one of the biggest microbial habitats on Earth, harboring diverse free-living N2-fixers. These microbes inhabit the epiphytic and endophytic phyllosphere and contribute significantly to plant N supply and growth. Here, we summarize the contribution of phyllosphere-BNF to global N cycling, evaluate the diversity of leaf-associated N2-fixers across plant hosts and ecosystems, illustrate the ecological adaptation of N2-fixers to the phyllosphere, and identify the environmental factors driving BNF. Finally, we discuss potential BNF engineering strategies to improve the nitrogen uptake in plant leaves and thus sustainable food production.
Collapse
Affiliation(s)
- Yong-Guan Zhu
- State Key Laboratory of Urban and Regional Ecology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
| | - Jingjing Peng
- State Key Laboratory of Nutrient Use and Management, College of Resources and Environmental Sciences, National Academy of Agriculture Green Development, China Agricultural University, Beijing, 100193, China
| | - Cai Chen
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Chao Xiong
- College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China
| | - Shule Li
- Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China
| | - Anhui Ge
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, SIBS, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Ertao Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, SIBS, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Werner Liesack
- Max Planck Institute for Terrestrial Microbiology, Marburg, 35043, Germany
| |
Collapse
|
3
|
Mao Y, Cui X, Wang H, Qin X, Liu Y, Yin Y, Su X, Tang J, Wang F, Ma F, Duan N, Zhang D, Hu Y, Wang W, Wei S, Chen X, Mao Z, Chen X, Shen X. De novo assembly provides new insights into the evolution of Elaeagnus angustifolia L. PLANT METHODS 2022; 18:84. [PMID: 35717244 PMCID: PMC9206267 DOI: 10.1186/s13007-022-00915-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 05/26/2022] [Indexed: 05/04/2023]
Abstract
BACKGROUND Elaeagnus angustifolia L. is a deciduous tree in the family Elaeagnaceae. It is widely used to study abiotic stress tolerance in plants and to improve desertification-affected land because of its ability to withstand diverse types of environmental stress, such as drought, salt, cold, and wind. However, no studies have examined the mechanisms underlying the resistance of E. angustifolia to environmental stress and its adaptive evolution. METHODS Here, we used PacBio, Hi-C, resequencing, and RNA-seq to construct the genome and transcriptome of E. angustifolia and explore its adaptive evolution. RESULTS The reconstructed genome of E. angustifolia was 526.80 Mb, with a contig N50 of 12.60 Mb and estimated divergence time of 84.24 Mya. Gene family expansion and resequencing analyses showed that the evolution of E. angustifolia was closely related to environmental conditions. After exposure to salt stress, GO pathway analysis showed that new genes identified from the transcriptome were related to ATP-binding, metal ion binding, and nucleic acid binding. CONCLUSION The genome sequence of E. angustifolia could be used for comparative genomic analyses of Elaeagnaceae family members and could help elucidate the mechanisms underlying the response of E. angustifolia to drought, salt, cold, and wind stress. Generally, these results provide new insights that could be used to improve desertification-affected land.
Collapse
Affiliation(s)
- Yunfei Mao
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Xueli Cui
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Haiyan Wang
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Xin Qin
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Yangbo Liu
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Yijun Yin
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Xiafei Su
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Juan Tang
- Biomarker Technologies Corporation, Beijing, China
| | | | - Fengwang Ma
- College of Horticulture, Northwest Agriculture and Forestry University, Yangling, China
| | - Naibin Duan
- Germplasm Resource Center of Shandong Province, Shandong Academy of Agricultural Sciences, Jinan, China
| | - Donglin Zhang
- Department of Horticulture, University of Georgia, Athens, USA
| | - Yanli Hu
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Wenli Wang
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Shaochong Wei
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Xiaoliu Chen
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Zhiquan Mao
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Xuesen Chen
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China
| | - Xiang Shen
- College of Horticultural Science and Engineering/State Key Laboratory of Crop Biology, Shandong Agricultural University, Tai'an, China.
| |
Collapse
|
4
|
Role of Hfq in glucose utilization, biofilm formation and quorum sensing system in Bacillus subtilis. Biotechnol Lett 2022; 44:845-855. [PMID: 35614284 DOI: 10.1007/s10529-022-03262-x] [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: 12/02/2021] [Accepted: 05/09/2022] [Indexed: 11/02/2022]
Abstract
Hfq is an RNA-binding protein, its main function is to participate in post-transcriptional regulation of bacteria and regulate small regulatory RNA (sRNA) and messenger RNA (mRNA) stability, but the Hfq function of Bacillus subtilis (B. subtilis) has not been fully explained. In this study, we used the strains of B. subtilis168 (BS168), BS168Δhfq and BS168Δhfq-C to explore the effects of Hfq on the glucose utilization, biofilm formation and quorum sensing (QS) system of B. subtilis. The results showed that the knockout of hfq resulted in growth defects when bacteria were cultured in the Luria-Bertani (LB) medium, but we did not observe the same effects in Nitrogen medium (NM) and Inorganic Salt-free medium (ISM). We further found that the growth of strains under different glucose concentrations was also different, which was related to the expression of CcpA. Interestingly, the hfq mutant showed increased resistance to a high-glucose environment. Furthermore, the biofilm and extracellular poly saccharides (EPS) formation of BS168Δhfq decreased significantly. At the same time, changes were observed in the morphology of the biofilm, such as larger intercellular space of the biofilm and thinner edge. The qRT-PCR results confirmed that the hfq knockout caused significant up-regulation or down-regulation of gene expression in QS system, and down-regulated genes were involved in the positive regulation of biofilm formation. Taken together, we demonstrated that Hfq plays a vital role in glucose utilization, biofilm formation and QS of B. subtilis, which provides a new perspective for subsequent related research.
Collapse
|
5
|
Sun L, Cheng L, Ma Y, Lei P, Wang R, Gu Y, Li S, Zhang F, Xu H. Exopolysaccharides from Pantoea alhagi NX-11 specifically improve its root colonization and rice salt resistance. Int J Biol Macromol 2022; 209:396-404. [PMID: 35413311 DOI: 10.1016/j.ijbiomac.2022.04.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 03/31/2022] [Accepted: 04/03/2022] [Indexed: 12/13/2022]
Abstract
Plant growth-promoting rhizobacteria (PGPR) and their extracellular polymers such as exopolysaccharides can enhance rice salt stress resistance, however, the relevant mechanism remains unclear. In this study, an exopolysaccharides-deficient strain, named ΔpspD, was obtained from Pantoea alhagi NX-11 by chromosomal pspD deletion. The yield and characteristics of ΔpspD exopolysaccharides was obviously different from P. alhagi NX-11 exopolysaccharides (PAPS). Subsequently, hydroponic experiments showed that NX-11 or PAPS could enhance rice salt tolerance, but ΔpspD could not. Furthermore, it was found that PAPS promoted P. alhagi rhizosphere colonization through a direct effect on biofilm formation, as well as through an indirect impact of enhancing the abilities of biofilm formation and chemotaxis by altering rice root exudates. Importantly, the effect of PAPS in promoting the root colonization of NX-11 was specific. Through transcriptome and RT-qPCR analysis, we revealed that this specificity correlated with PAPS-induced lectin overexpression. The specificity between exopolysaccharides and the host microorganism ensures the colonization of the latter, and prevents other microorganisms from hitchhiking to the rice roots.
Collapse
Affiliation(s)
- Liang Sun
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Lifangyu Cheng
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Yuhang Ma
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Peng Lei
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
| | - Rui Wang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Yian Gu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
| | - Sha Li
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China
| | - Fuhai Zhang
- Agricultural and Rural Bureau of Yantai, Yantai 264000, China
| | - Hong Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing 211816, China.
| |
Collapse
|
6
|
Neetu N, Katiki M, Mahto JK, Sharma M, Narayanan A, Maity S, Tomar S, Ambatipudi K, Sharma AK, Yernool D, Kumar P. Deciphering the enigma of missing DNA binding domain of LacI family transcription factors. Arch Biochem Biophys 2021; 713:109060. [PMID: 34666048 DOI: 10.1016/j.abb.2021.109060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 10/09/2021] [Accepted: 10/11/2021] [Indexed: 11/19/2022]
Abstract
Catabolite repressor activator (Cra) is a member of the LacI family transcriptional regulator distributed across a wide range of bacteria and regulates the carbon metabolism and virulence gene expression. In numerous studies to crystallize the apo form of the LacI family transcription factor, the N-terminal domain (NTD), which functions as a DNA-binding domain, has been enigmatically missing from the final resolved structures. It was speculated that the NTD is disordered or unstable and gets cleaved during crystallization. Here, we have determined the crystal structure of Cra from Escherichia coli (EcCra). The structure revealed a well-defined electron density for the C-terminal domain (CTD). However, electron density was missing for the first 56 amino acids (NTD). Our data reveal for the first time that EcCra undergoes a spontaneous cleavage at the conserved Asn 50 (N50) site, which separates the N-terminal DNA binding domain from the C-terminal effector molecule binding domain. With the site-directed mutagenesis, we confirm the involvement of residue N50 in the spontaneous cleavage phenomenon. Furthermore, the Isothermal titration calorimetry (ITC) assay of the EcCra-NTD with DNA showed EcCra-NTD is in a functional conformation state and retains its DNA binding activity.
Collapse
Affiliation(s)
- Neetu Neetu
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Madhusudhanarao Katiki
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Jai Krishna Mahto
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Monica Sharma
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Anoop Narayanan
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Sudipa Maity
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Shailly Tomar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Kiran Ambatipudi
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Ashwani Kumar Sharma
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India
| | - Dinesh Yernool
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47906, USA
| | - Pravindra Kumar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, 247667, India.
| |
Collapse
|
7
|
Sun L, Yang Y, Lei P, Li S, Xu H, Wang R, Qiu Y, Zhang W. Structure characterization, antioxidant and emulsifying capacities of exopolysaccharide derived from Pantoea alhagi NX-11. Carbohydr Polym 2021; 261:117872. [PMID: 33766359 DOI: 10.1016/j.carbpol.2021.117872] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/24/2021] [Accepted: 02/24/2021] [Indexed: 12/12/2022]
Abstract
Pantoea alhagi exopolysaccharides (PAPS) have been shown to enhance crop resistance to abiotic stress. However, physicochemical properties and structure of PAPS have not yet been analyzed. In this study, two PAPSs, named PAPS1 and PAPS2, were isolated and purified from the P. alhagi NX-11. The results showed PAPS1 and PAPS2 were composed of glucose, galactose, glucuronic acid, glucosamine and mannose with average molecular weight of 1.326 × 106 Da and 1.959 × 106 Da, respectively. Moreover, the structure of PAPS1 and PAPS2 was investigated by FT-IR and NMR analysis. PAPS1 was identified to have the backbone structure of →4)-β-D-GlcpA-(1→2)-α-D-Galp-(1→3)-β-D-Galp-(1→3)-β-D-GlcpN- (1→3)-α-D-Galp-(1→3)-β-D-Galp-(1→. PAPS2 had the backbone structure of →4)-β-D-GlcpA-(1→2)-α-D-Galp-(1→3)-β-D-Glcp-(1→3)-β-D-GlcpN-(1→3)-α-D-Galp-(1→3)-α-D-GlcpN-(1→. In addition, PAPS1 and PAPS2 had moderate antioxidant and emulsifying capacities. Overall, the structure analysis of PAPS may point out the direction for the subsequent study of PAPS-mediated microbial and plant interactions, and further exploration of the application of PAPS.
Collapse
Affiliation(s)
- Liang Sun
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, China; Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China
| | - Yanbo Yang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, China; Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China
| | - Peng Lei
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, China; Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China.
| | - Sha Li
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, China; Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China
| | - Hong Xu
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, China; Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China
| | - Rui Wang
- State Key Laboratory of Materials-Oriented Chemical Engineering, College of Food Science and Light Industry, Nanjing Tech University, Nanjing, 211816, China; Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China.
| | - Yibin Qiu
- College of Light Industry and Food Engineering, Nanjing Forestry University, Nanjing, 210037, China
| | - Wen Zhang
- Hubei Sanning Chemical Industry CO., Ltd, Yichang, 443200, China
| |
Collapse
|
8
|
Song L, Pan J, Yang Y, Zhang Z, Cui R, Jia S, Wang Z, Yang C, Xu L, Dong TG, Wang Y, Shen X. Contact-independent killing mediated by a T6SS effector with intrinsic cell-entry properties. Nat Commun 2021; 12:423. [PMID: 33462232 PMCID: PMC7813860 DOI: 10.1038/s41467-020-20726-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 12/10/2020] [Indexed: 02/08/2023] Open
Abstract
Bacterial type VI secretion systems (T6SSs) inject toxic effectors into adjacent eukaryotic and prokaryotic cells. It is generally thought that this process requires physical contact between the two cells. Here, we provide evidence of contact-independent killing by a T6SS-secreted effector. We show that the pathogen Yersinia pseudotuberculosis uses a T6SS (T6SS-3) to secrete a nuclease effector that kills other bacteria in vitro and facilitates gut colonization in mice. The effector (Tce1) is a small protein that acts as a Ca2+- and Mg2+-dependent DNase, and its toxicity is inhibited by a cognate immunity protein, Tci1. As expected, T6SS-3 mediates canonical, contact-dependent killing by directly injecting Tce1 into adjacent cells. In addition, T6SS-3 also mediates killing of neighboring cells in the absence of cell-to-cell contact, by secreting Tce1 into the extracellular milieu. Efficient contact-independent entry of Tce1 into target cells requires proteins OmpF and BtuB in the outer membrane of target cells. The discovery of a contact-independent, long-range T6SS toxin delivery provides a new perspective for understanding the physiological roles of T6SS in competition. However, the mechanisms mediating contact-independent uptake of Tce1 by target cells remain unclear. Bacteria can use type VI secretion systems (T6SSs) to inject toxic effector proteins into adjacent cells, in a contact-dependent manner. Here, the authors provide evidence of contact-independent killing by a T6SS effector that is secreted into the extracellular milieu and then taken up by other bacterial cells.
Collapse
Affiliation(s)
- Li Song
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China
| | - Junfeng Pan
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China
| | - Yantao Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China
| | - Zhenxing Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China
| | - Rui Cui
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China
| | - Shuangkai Jia
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China
| | - Zhuo Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China
| | - Changxing Yang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China
| | - Lei Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China
| | - Tao G Dong
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 200240, Shanghai, China.,Department of Ecosystem and Public Health, University of Calgary, Calgary, AB, T2N 4Z6, Canada
| | - Yao Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China.
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A&F University, 712100, Yangling, Shaanxi, China.
| |
Collapse
|
9
|
Kang X, Wang L, Guo Y, Ul Arifeen MZ, Cai X, Xue Y, Bu Y, Wang G, Liu C. A Comparative Transcriptomic and Proteomic Analysis of Hexaploid Wheat's Responses to Colonization by Bacillus velezensis and Gaeumannomyces graminis, Both Separately and Combined. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1336-1347. [PMID: 31125282 DOI: 10.1094/mpmi-03-19-0066-r] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Tritrophic interactions involving a biocontrol agent, a pathogen, and a plant have been analyzed predominantly from the perspective of the biocontrol agent. To explore the adaptive strategies of wheat in response to beneficial, pathogenic, and combined microorganisms, we performed the first comprehensive transcriptomic, proteomic, and biochemical analysis in wheat roots after exposure to Bacillus velezensis CC09, Gaeumannomyces graminis var. tritici, and their combined colonization, respectively. The transcriptional or translational programming of wheat roots inoculated with beneficial B. velezensis showed mild alterations compared with that of pathogenic G. graminis var. tritici. However, the combination of B. velezensis and G. graminis var. tritici activated a larger transcriptional or translational program than for each single microorganism, although the gene expression pattern was similar to that of individual infection by G. graminis var. tritici, suggesting a prioritization of defense against G. graminis var. tritici infection. Surprisingly, pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity made wheat pretreated with B. velezensis more sensitive to subsequent G. graminis var. tritici infection. Additionally, B. velezensis triggered a salicylic acid (SA)-dependent mode of induced systemic resistance that resembles pathogen-induced systemic acquired resistance. Wheat plants mainly depend on SA-mediated resistance, and not that mediated by jasmonic acid (JA), against the necrotrophic pathogen G. graminis var. tritici. Moreover, SA-JA interactions resulted in antagonistic effects regardless of the type of microorganisms in wheat. Further enhancement of SA-dependent defense responses such as lignification to the combined infection was shown to reduce the level of induced JA-dependent defense against subsequent infection with G. graminis var. tritici. Altogether, our results demonstrate how the hexaploid monocot wheat responds to beneficial or pathogenic microorganisms and prolongs the onset of take-all disease through modulation of cell reprogramming and signaling events.
Collapse
Affiliation(s)
- Xingxing Kang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Lanhua Wang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Yu Guo
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Muhammad Zain Ul Arifeen
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Xunchao Cai
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Yarong Xue
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Yuanqin Bu
- Nanjing Institute of Environmental Sciences, Key Laboratory of Pesticide Environmental Assessment and Pollution Control, Ministry of Ecology and Environment, Nanjing, China
| | - Gang Wang
- State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, Henan, China
| | - Changhong Liu
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| |
Collapse
|
10
|
Pleiotropic Effects of c-di-GMP Content in Pseudomonas syringae. Appl Environ Microbiol 2019; 85:AEM.00152-19. [PMID: 30850427 PMCID: PMC6498148 DOI: 10.1128/aem.00152-19] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 02/27/2019] [Indexed: 12/27/2022] Open
Abstract
The present work comprehensively analyzed the transcriptome and phenotypes that were regulated by c-di-GMP in P. syringae. Given that the majority of diguanylate cyclases and phosphodiesterases have not been characterized in P. syringae, this work provided a very useful database for the future study on regulatory mechanism (especially its relationship with T3SS) of c-di-GMP in P. syringae. In particular, we identified three promoters that were sensitive to elevated c-di-GMP levels and inserted them into luciferase-based reporters that effectively respond to intracellular levels of c-di-GMP in P. syringae, which could be used as an economic and efficient way to measure relative c-di-GMP levels in vivo in the future. Although the ubiquitous bacterial secondary messenger cyclic diguanylate (c-di-GMP) has important cellular functions in a wide range of bacteria, its function in the model plant pathogen Pseudomonas syringae remains largely elusive. To this end, we overexpressed Escherichia coli diguanylate cyclase (YedQ) and phosphodiesterase (YhjH) in P. syringae, resulting in high and low in vivo levels of c-di-GMP, respectively. Via genome-wide RNA sequencing of these two strains, we found that c-di-GMP regulates (i) fliN, fliE, and flhA, which are associated with flagellar assembly; (ii) alg8 and alg44, which are related to the exopolysaccharide biosynthesis pathway; (iii) pvdE, pvdP, and pvsA, which are associated with the siderophore biosynthesis pathway; and (iv) sodA, which encodes a superoxide dismutase. In particular, we identified three promoters that are sensitive to elevated levels of c-di-GMP and inserted them into luciferase-based reporters that respond effectively to the c-di-GMP levels in P. syringae; these promoters could be useful in the measurement of in vivo levels of c-di-GMP in real time. Further phenotypic assays validated the RNA sequencing (RNA-seq) results and confirmed the effect on c-di-GMP-associated pathways, such as repressing the type III secretion system (T3SS) and motility while inducing biofilm production, siderophore production, and oxidative stress resistance. Taken together, these results demonstrate that c-di-GMP regulates the virulence and stress response in P. syringae, which suggests that tuning its level could be a new strategy to protect plants from attacks by this pathogen. IMPORTANCE The present work comprehensively analyzed the transcriptome and phenotypes that were regulated by c-di-GMP in P. syringae. Given that the majority of diguanylate cyclases and phosphodiesterases have not been characterized in P. syringae, this work provided a very useful database for the future study on regulatory mechanism (especially its relationship with T3SS) of c-di-GMP in P. syringae. In particular, we identified three promoters that were sensitive to elevated c-di-GMP levels and inserted them into luciferase-based reporters that effectively respond to intracellular levels of c-di-GMP in P. syringae, which could be used as an economic and efficient way to measure relative c-di-GMP levels in vivo in the future.
Collapse
|
11
|
An Osmoregulatory Mechanism Operating through OmpR and LrhA Controls the Motile-Sessile Switch in the Plant Growth-Promoting Bacterium Pantoea alhagi. Appl Environ Microbiol 2019; 85:AEM.00077-19. [PMID: 30902852 DOI: 10.1128/aem.00077-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 03/14/2019] [Indexed: 11/20/2022] Open
Abstract
Adaptation to osmotic stress is crucial for bacterial growth and survival in changing environments. Although a large number of osmotic stress response genes have been identified in various bacterial species, how osmotic changes affect bacterial motility, biofilm formation, and colonization of host niches remains largely unknown. In this study, we report that the LrhA regulator is an osmoregulated transcription factor that directly binds to the promoters of the flhDC, eps, and opgGH operons and differentially regulates their expression, thus inhibiting motility and promoting exopolysaccharide (EPS) production, synthesis of osmoregulated periplasmic glucans (OPGs), biofilm formation, and root colonization of the plant growth-promoting bacterium Pantoea alhagi LTYR-11Z. Further, we observed that the LrhA-regulated OPGs control RcsCD-RcsB activation in a concentration-dependent manner, and a high concentration of OPGs induced by increased medium osmolarity is maintained to achieve the high level of activation of the Rcs phosphorelay, which results in enhanced EPS synthesis and decreased motility in P. alhagi Moreover, we showed that the osmosensing regulator OmpR directly binds to the promoter of lrhA and promotes its expression, while lrhA expression is feedback inhibited by the activated Rcs phosphorelay system. Overall, our data support a model whereby P. alhagi senses environmental osmolarity changes through the EnvZ-OmpR two-component system and LrhA to regulate the synthesis of OPGs, EPS production, and flagellum-dependent motility, thereby employing a hierarchical signaling cascade to control the transition between a motile lifestyle and a biofilm lifestyle.IMPORTANCE Many motile bacterial populations form surface-attached biofilms in response to specific environmental cues, including osmotic stress in a range of natural and host-related systems. However, cross talk between bacterial osmosensing, swimming, and biofilm formation regulatory networks is not fully understood. Here, we report that the pleiotropic regulator LrhA in Pantoea alhagi is involved in the regulation of flagellar motility, biofilm formation, and host colonization and responds to osmotic upshift. We further show that this sensing relies on the EnvZ-OmpR two-component system that was known to detect changes in external osmotic stress. The EnvZ-OmpR-LrhA osmosensing signal transduction cascade is proposed to increase bacterial fitness under hyperosmotic conditions inside the host. Our work proposes a novel regulatory mechanism that links osmosensing and motile-sessile lifestyle transitions, which may provide new approaches to prevent or promote the formation of biofilms and host colonization in P. alhagi and other bacteria possessing a similar osmoregulatory mechanism.
Collapse
|