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Klepa MS, diCenzo GC, Hungria M. Comparative genomic analysis of Bradyrhizobium strains with natural variability in the efficiency of nitrogen fixation, competitiveness, and adaptation to stressful edaphoclimatic conditions. Microbiol Spectr 2024; 12:e0026024. [PMID: 38842312 PMCID: PMC11218460 DOI: 10.1128/spectrum.00260-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2024] [Accepted: 05/01/2024] [Indexed: 06/07/2024] Open
Abstract
Bradyrhizobium is known for fixing atmospheric nitrogen in symbiosis with agronomically important crops. This study focused on two groups of strains, each containing eight natural variants of the parental strains, Bradyrhizobium japonicum SEMIA 586 (=CNPSo 17) or Bradyrhizobium diazoefficiens SEMIA 566 (=CNPSo 10). CNPSo 17 and CNPSo 10 were used as commercial inoculants for soybean crops in Brazil at the beginning of the crop expansion in the southern region in the 1960s-1970s. Variants derived from these parental strains were obtained in the late 1980s through a strain selection program aimed at identifying elite strains adapted to a new cropping frontier in the central-western Cerrado region, with a higher capacity of biological nitrogen fixation (BNF) and competitiveness. Here, we aimed to detect genetic variations possibly related to BNF, competitiveness for nodule occupancy, and adaptation to the stressful conditions of the Brazilian Cerrado soils. High-quality genome assemblies were produced for all strains. The core genome phylogeny revealed that strains of each group are closely related, as confirmed by high average nucleotide identity values. However, variants accumulated divergences resulting from horizontal gene transfer, genomic rearrangements, and nucleotide polymorphisms. The B. japonicum group presented a larger pangenome and a higher number of nucleotide polymorphisms than the B. diazoefficiens group, possibly due to its longer adaptation time to the Cerrado soil. Interestingly, five strains of the B. japonicum group carry two plasmids. The genetic variability found in both groups is discussed considering the observed differences in their BNF capacity, competitiveness for nodule occupancy, and environmental adaptation.IMPORTANCEToday, Brazil is a global leader in the study and use of biological nitrogen fixation with soybean crops. As Brazilian soils are naturally void of soybean-compatible bradyrhizobia, strain selection programs were established, starting with foreign isolates. Selection searched for adaptation to the local edaphoclimatic conditions, higher efficiency of nitrogen fixation, and strong competitiveness for nodule occupancy. We analyzed the genomes of two parental strains of Bradyrhizobium japonicum and Bradyrhizobium diazoefficiens and eight variant strains derived from each parental strain. We detected two plasmids in five strains and several genetic differences that might be related to adaptation to the stressful conditions of the soils of the Brazilian Cerrado biome. We also detected genetic variations in specific regions that may impact symbiotic nitrogen fixation. Our analysis contributes to new insights into the evolution of Bradyrhizobium, and some of the identified differences may be applied as genetic markers to assist strain selection programs.
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Affiliation(s)
- Milena Serenato Klepa
- Soil Biotechnology Laboratory, Embrapa Soja, Londrina, Paraná, Brazil
- CNPq, Brasília, Brazil
| | | | - Mariangela Hungria
- Soil Biotechnology Laboratory, Embrapa Soja, Londrina, Paraná, Brazil
- CNPq, Brasília, Brazil
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2
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Ghosh P, Chakraborty J. Exploring the role of symbiotic modifier peptidases in the legume - rhizobium symbiosis. Arch Microbiol 2024; 206:147. [PMID: 38462552 DOI: 10.1007/s00203-024-03920-w] [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: 11/21/2023] [Revised: 02/27/2024] [Accepted: 02/28/2024] [Indexed: 03/12/2024]
Abstract
Legumes can establish a mutual association with soil-derived nitrogen-fixing bacteria called 'rhizobia' forming lateral root organs called root nodules. Rhizobia inside the root nodules get transformed into 'bacteroids' that can fix atmospheric nitrogen to ammonia for host plants in return for nutrients and shelter. A substantial 200 million tons of nitrogen is fixed annually through biological nitrogen fixation. Consequently, the symbiotic mechanism of nitrogen fixation is utilized worldwide for sustainable agriculture and plays a crucial role in the Earth's ecosystem. The development of effective nitrogen-fixing symbiosis between legumes and rhizobia is very specialized and requires coordinated signaling. A plethora of plant-derived nodule-specific cysteine-rich (NCR or NCR-like) peptides get actively involved in this complex and tightly regulated signaling process of symbiosis between some legumes of the IRLC (Inverted Repeat-Lacking Clade) and Dalbergioid clades and nitrogen-fixing rhizobia. Recent progress has been made in identifying two such peptidases that actively prevent bacterial differentiation, leading to symbiotic incompatibility. In this review, we outlined the functions of NCRs and two nitrogen-fixing blocking peptidases: HrrP (host range restriction peptidase) and SapA (symbiosis-associated peptidase A). SapA was identified through an overexpression screen from the Sinorhizobium meliloti 1021 core genome, whereas HrrP is inherited extra-chromosomally. Interestingly, both peptidases affect the symbiotic outcome by degrading the NCR peptides generated from the host plants. These NCR-degrading peptidases can shed light on symbiotic incompatibility, helping to elucidate the reasons behind the inefficiency of nitrogen fixation observed in certain groups of rhizobia with specific legumes.
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Affiliation(s)
- Prithwi Ghosh
- Department of Botany, Narajole Raj College, Vidyasagar University, Midnapore, 721211, India.
| | - Joydeep Chakraborty
- School of Plant Sciences and Food Security, Tel Aviv University, Tel-Aviv, Israel
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3
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Ma Y, Zhu W, Zhao W, Zhang B, He J, Zhang C, Li P, Hu Y, Zhou Z, Yan Z, Li J, Cai W, Ren G, Chen R. MtESN2 is a subgroup II sulphate transporter required for symbiotic nitrogen fixation and prevention of nodule early senescence in Medicago truncatula. PLANT, CELL & ENVIRONMENT 2023; 46:3558-3574. [PMID: 37545348 DOI: 10.1111/pce.14678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 07/07/2023] [Accepted: 07/24/2023] [Indexed: 08/08/2023]
Abstract
Adequate distribution of mineral sulphur (S) nutrition to nodules mediated by sulphate transporters is crucial for nitrogen fixation in symbiosis establishment process. However, the molecular mechanisms underlying this process remain largely unknown. In this study, we characterized the function of Early Senescent Nodule 2 (MtESN2), a gene crucial to nitrogen fixation in Medicago truncatula. Mutations in MtESN2 resulted in severe developmental and functional defects including dwarf shoots, early senescent nodules, and lower nitrogenase activity under symbiotic conditions compared to wild-type plants. MtESN2 encodes an M. truncatula sulphate transporter that is expressed only in roots and nodules, with the highest expression levels in the transition zone and nitrogen-fixing zone of nodules. MtESN2 exhibited sulphate transport activity when expressed in yeast. Immunolocalization analysis showed that MtESN2-yellow fluorescent protein fusion protein was localized to the plasma membranes of both uninfected and infected cells of nodules, where it might transport sulphate into both rhizobia-infected and uninfected cells within the nodules. Our results reveal an unreported sulphate transporter that contributes to effective symbiosis and prevents nodule early senescence in M. truncatula.
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Affiliation(s)
- Yanlin Ma
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
- State Key Laboratory of Grassland Agro-Ecosystem, College of Ecology, Lanzhou University, Lanzhou, China
| | - Weike Zhu
- College of Cuiying Honors, Lanzhou University, Lanzhou, China
| | - Weichen Zhao
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Beihong Zhang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Juanxia He
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Chenyan Zhang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Peng Li
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Yibo Hu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Zaicai Zhou
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Zezhang Yan
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Juanjuan Li
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Wenkai Cai
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
| | - Guangpeng Ren
- State Key Laboratory of Grassland Agro-Ecosystem, College of Ecology, Lanzhou University, Lanzhou, China
| | - Rujin Chen
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, China
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Long S, Su M, Chen X, Hu A, Yu F, Zou Q, Cheng G. Proteomic and Mutant Analysis of Hydrogenase Maturation Protein Gene hypE in Symbiotic Nitrogen Fixation of Mesorhizobium huakuii. Int J Mol Sci 2023; 24:12534. [PMID: 37628715 PMCID: PMC10454058 DOI: 10.3390/ijms241612534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/01/2023] [Accepted: 08/04/2023] [Indexed: 08/27/2023] Open
Abstract
Hydrogenases catalyze the simple yet important redox reaction between protons and electrons and H2, thus mediating symbiotic interactions. The contribution of hydrogenase to this symbiosis and anti-oxidative damage was investigated using the M. huakuii hypE (encoding hydrogenase maturation protein) mutant. The hypE mutant grew a little faster than its parental 7653R and displayed decreased antioxidative capacity under H2O2-induced oxidative damage. Real-time quantitative PCR showed that hypE gene expression is significantly up-regulated in all the detected stages of nodule development. Although the hypE mutant can form nodules, the symbiotic ability was severely impaired, which led to an abnormal nodulation phenotype coupled to a 47% reduction in nitrogen fixation capacity. This phenotype was linked to the formation of smaller abnormal nodules containing disintegrating and prematurely senescent bacteroids. Proteomics analysis allowed a total of ninety differentially expressed proteins (fold change > 1.5 or <0.67, p < 0.05) to be identified. Of these proteins, 21 are related to stress response and virulence, 21 are involved in transporter activity, and 18 are involved in energy and nitrogen metabolism. Overall, the HypE protein is essential for symbiotic nitrogen fixation, playing independent roles in supplying energy and electrons, in bacterial detoxification, and in the control of bacteroid differentiation and senescence.
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Affiliation(s)
| | | | | | | | | | | | - Guojun Cheng
- Hubei Provincial Engineering and Technology Research Center for Resources and Utilization of Microbiology, College of Life Sciences, South-Central Minzu University, Wuhan 430074, China
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5
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Soto MJ, Pérez J, Muñoz-Dorado J, Contreras-Moreno FJ, Moraleda-Muñoz A. Transcriptomic response of Sinorhizobium meliloti to the predatory attack of Myxococcus xanthus. Front Microbiol 2023; 14:1213659. [PMID: 37405170 PMCID: PMC10315480 DOI: 10.3389/fmicb.2023.1213659] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 06/01/2023] [Indexed: 07/06/2023] Open
Abstract
Bacterial predation impacts microbial community structures, which can have both positive and negative effects on plant and animal health and on environmental sustainability. Myxococcus xanthus is an epibiotic soil predator with a broad range of prey, including Sinorhizobium meliloti, which establishes nitrogen-fixing symbiosis with legumes. During the M. xanthus-S. meliloti interaction, the predator must adapt its transcriptome to kill and lyse the target (predatosome), and the prey must orchestrate a transcriptional response (defensome) to protect itself against the biotic stress caused by the predatory attack. Here, we describe the transcriptional changes taking place in S. meliloti in response to myxobacterial predation. The results indicate that the predator induces massive changes in the prey transcriptome with up-regulation of protein synthesis and secretion, energy generation, and fatty acid (FA) synthesis, while down-regulating genes required for FA degradation and carbohydrate transport and metabolism. The reconstruction of up-regulated pathways suggests that S. meliloti modifies the cell envelop by increasing the production of different surface polysaccharides (SPSs) and membrane lipids. Besides the barrier role of SPSs, additional mechanisms involving the activity of efflux pumps and the peptide uptake transporter BacA, together with the production of H2O2 and formaldehyde have been unveiled. Also, the induction of the iron-uptake machinery in both predator and prey reflects a strong competition for this metal. With this research we complete the characterization of the complex transcriptional changes that occur during the M. xanthus-S. meliloti interaction, which can impact the establishment of beneficial symbiosis with legumes.
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Affiliation(s)
- María José Soto
- Departamento de Biotecnología y Protección Ambiental, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Juana Pérez
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | - José Muñoz-Dorado
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
| | | | - Aurelio Moraleda-Muñoz
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Granada, Spain
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Panteleev PV, Safronova VN, Kruglikov RN, Bolosov IA, Ovchinnikova TV. Genomic Insights into Bacterial Resistance to Proline-Rich Antimicrobial Peptide Bac7. MEMBRANES 2023; 13:438. [PMID: 37103865 PMCID: PMC10145973 DOI: 10.3390/membranes13040438] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 04/10/2023] [Accepted: 04/16/2023] [Indexed: 06/19/2023]
Abstract
Proline-rich antimicrobial peptides (PrAMPs) having a potent antimicrobial activity and a modest toxicity toward mammalian cells attract much attention as new templates for the development of antibiotic drugs. However, a comprehensive understanding of mechanisms of bacterial resistance development to PrAMPs is necessary before their clinical application. In this study, development of the resistance to the proline-rich bovine cathelicidin Bac71-22 derivative was characterized in the multidrug-resistant Escherichia coli clinical isolate causing the urinary tract infection. Three Bac71-22-resistant strains with ≥16-fold increase in minimal inhibitory concentrations (MICs) were selected by serially passaging after four-week experimental evolution. It was shown that in salt-containing medium, the resistance was mediated by inactivation of the SbmA transporter. The absence of salt in the selection media affected both dynamics and main molecular targets under selective pressure: a point mutation leading to the amino acid substitution N159H in the WaaP kinase responsible for heptose I phosphorylation in the LPS structure was also found. This mutation led to a phenotype with a decreased susceptibility to both the Bac71-22 and polymyxin B. Screening of antimicrobial activities with the use of a wide panel of known AMPs, including the human cathelicidin LL-37 and conventional antibiotics, against selected strains indicated no significant cross-resistance effects.
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7
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Chen WF, Meng XF, Jiao YS, Tian CF, Sui XH, Jiao J, Wang ET, Ma SJ. Bacteroid Development, Transcriptome, and Symbiotic Nitrogen-Fixing Comparison of Bradyrhizobium arachidis in Nodules of Peanut (Arachis hypogaea) and Medicinal Legume Sophora flavescens. Microbiol Spectr 2023; 11:e0107922. [PMID: 36656008 PMCID: PMC9927569 DOI: 10.1128/spectrum.01079-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 12/29/2022] [Indexed: 01/20/2023] Open
Abstract
Bradyrhizobium arachidis strain CCBAU 051107 could differentiate into swollen and nonswollen bacteroids in determinate root nodules of peanut (Arachis hypogaea) and indeterminate nodules of Sophora flavescens, respectively, with different N2 fixation efficiencies. To reveal the mechanism of bacteroid differentiation and symbiosis efficiency in association with different hosts, morphologies, transcriptomes, and nitrogen fixation efficiencies of the root nodules induced by strain CCBAU 051107 on these two plants were compared. Our results indicated that the nitrogenase activity of peanut nodules was 3 times higher than that of S. flavescens nodules, demonstrating the effects of rhizobium-host interaction on symbiotic effectiveness. With transcriptome comparisons, genes involved in biological nitrogen fixation (BNF) and energy metabolism were upregulated, while those involved in DNA replication, bacterial chemotaxis, and flagellar assembly were significantly downregulated in both types of bacteroids compared with those in free-living cells. However, expression levels of genes involved in BNF, the tricarboxylic acid (TCA) cycle, the pentose phosphate pathway, hydrogenase synthesis, poly-β-hydroxybutyrate (PHB) degradation, and peptidoglycan biosynthesis were significantly greater in the swollen bacteroids of peanut than those in the nonswollen bacteroids of S. flavescens, while contrasting situations were found in expression of genes involved in urea degradation, PHB synthesis, and nitrogen assimilation. Especially higher expression of ureABEF and aspB genes in bacteroids of S. flavescens might imply that the BNF product and nitrogen transport pathway were different from those in peanut. Our study revealed the first differences in bacteroid differentiation and metabolism of these two hosts and will be helpful for us to explore higher-efficiency symbiosis between rhizobia and legumes. IMPORTANCE Rhizobial differentiation into bacteroids in leguminous nodules attracts scientists to investigate its different aspects. The development of bacteroids in the nodule of the important oil crop peanut was first investigated and compared to the status in the nodule of the extremely promiscuous medicinal legume Sophora flavescens by using just a single rhizobial strain of Bradyrhizobium arachidis, CCBAU 051107. This strain differentiates into swollen bacteroids in peanut nodules and nonswollen bacteroids in S. flavescens nodules. The N2-fixing efficiency of the peanut nodules is three times higher than that of S. flavescens. By comparing the transcriptomes of their bacteroids, we found that they have similar gene expression spectra, such as nitrogen fixation and motivity, but different spectra in terms of urease activity and peptidoglycan biosynthesis. Those altered levels of gene expression might be related to their functions and differentiation in respective nodules. Our studies provided novel insight into the rhizobial differentiation and metabolic alteration in different hosts.
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Affiliation(s)
- Wen Feng Chen
- State Key Laboratory of Agrobiotechnology, Beijing, People’s Republic of China
- College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing, People’s Republic of China
| | - Xiang Fei Meng
- State Key Laboratory of Agrobiotechnology, Beijing, People’s Republic of China
- College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing, People’s Republic of China
| | - Yin Shan Jiao
- State Key Laboratory of Agrobiotechnology, Beijing, People’s Republic of China
- College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing, People’s Republic of China
| | - Chang Fu Tian
- State Key Laboratory of Agrobiotechnology, Beijing, People’s Republic of China
- College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing, People’s Republic of China
| | - Xin Hua Sui
- State Key Laboratory of Agrobiotechnology, Beijing, People’s Republic of China
- College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing, People’s Republic of China
| | - Jian Jiao
- State Key Laboratory of Agrobiotechnology, Beijing, People’s Republic of China
- College of Biological Sciences and Rhizobium Research Center, China Agricultural University, Beijing, People’s Republic of China
| | - En Tao Wang
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, México City, México
| | - Sheng Jun Ma
- College of Food Science and Pharmacy, Xinjiang Agricultural University, Urumqi, Xinjiang Uygur Autonomous Region, People’s Republic of China
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Zhang S, Wang T, Lima RM, Pettkó-Szandtner A, Kereszt A, Downie JA, Kondorosi E. Widely conserved AHL transcription factors are essential for NCR gene expression and nodule development in Medicago. NATURE PLANTS 2023; 9:280-288. [PMID: 36624259 PMCID: PMC9946822 DOI: 10.1038/s41477-022-01326-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 12/02/2022] [Indexed: 05/13/2023]
Abstract
Symbiotic nitrogen fixation by Rhizobium bacteria in the cells of legume root nodules alleviates the need for nitrogen fertilizers. Nitrogen fixation requires the endosymbionts to differentiate into bacteroids which can be reversible or terminal. The latter is controlled by the plant, it is more beneficial and has evolved in multiple clades of the Leguminosae family. The plant effectors of terminal differentiation in inverted repeat-lacking clade legumes (IRLC) are nodule-specific cysteine-rich (NCR) peptides, which are absent in legumes such as soybean where there is no terminal differentiation of rhizobia. It was assumed that NCRs co-evolved with specific transcription factors, but our work demonstrates that expression of NCR genes does not require NCR-specific transcription factors. Introduction of the Medicago truncatula NCR169 gene under its own promoter into soybean roots resulted in its nodule-specific expression, leading to bacteroid changes associated with terminal differentiation. We identified two AT-Hook Motif Nuclear Localized (AHL) transcription factors from both M. truncatula and soybean nodules that bound to AT-rich sequences in the NCR169 promoter inducing its expression. Whereas mutation of NCR169 arrested bacteroid development at a late stage, the absence of MtAHL1 or MtAHL2 completely blocked bacteroid differentiation indicating that they also regulate other NCR genes required for the development of nitrogen-fixing nodules. Regulation of NCRs by orthologous transcription factors in non-IRLC legumes opens up the possibility of increasing the efficiency of nitrogen fixation in legumes lacking NCRs.
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Affiliation(s)
- Senlei Zhang
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
| | - Ting Wang
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
| | - Rui M Lima
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
| | | | - Attila Kereszt
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
| | - J Allan Downie
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary
- John Innes Centre, Norwich, UK
| | - Eva Kondorosi
- Institute of Plant Biology, Biological Research Centre, Szeged, Hungary.
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Huang R, Snedden WA, diCenzo GC. Reference nodule transcriptomes for Melilotus officinalis and Medicago sativa cv. Algonquin. PLANT DIRECT 2022; 6:e408. [PMID: 35774624 PMCID: PMC9219011 DOI: 10.1002/pld3.408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 05/14/2022] [Accepted: 05/19/2022] [Indexed: 05/10/2023]
Abstract
Host/symbiont compatibility is a hallmark of the symbiotic nitrogen-fixing interaction between rhizobia and legumes, mediated in part by plant-produced nodule-specific cysteine-rich (NCR) peptides and the bacterial BacA membrane protein that can act as a NCR peptide transporter. In addition, the genetic and metabolic properties supporting symbiotic nitrogen fixation often differ between compatible partners, including those sharing a common partner, highlighting the need for multiple study systems. Here, we report high-quality nodule transcriptome assemblies for Medicago sativa cv. Algonquin and Melilotus officinalis, two legumes able to form compatible symbioses with Sinorhizobium meliloti. The compressed M. sativa and M. officinalis assemblies consisted of 79,978 and 64,593 contigs, respectively, of which 33,341 and 28,278 were assigned putative annotations, respectively. As expected, the two transcriptomes showed broad similarity at a global level. We were particularly interested in the NCR peptide profiles of these plants, as these peptides drive bacterial differentiation during the symbiosis. A total of 412 and 308 NCR peptides were predicted from the M. sativa and M. officinalis transcriptomes, respectively, with approximately 9% of the transcriptome of both species consisting of NCR transcripts. Notably, transcripts encoding highly cationic NCR peptides (isoelectric point > 9.5), which are known to have antimicrobial properties, were ∼2-fold more abundant in M. sativa than in M. officinalis, and ∼27-fold more abundant when considering only NCR peptides in the six-cysteine class. We hypothesize that the difference in abundance of highly cationic NCR peptides explains our previous observation that some rhizobial bacA alleles which can support symbiosis with M. officinalis are unable to support symbiosis with M. sativa.
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Affiliation(s)
- Rui Huang
- Department of BiologyQueen's UniversityKingstonOntarioCanada
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10
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Translocation of non-lytic antimicrobial peptides and bacteria penetrating peptides across the inner membrane of the bacterial envelope. Curr Genet 2021; 68:83-90. [PMID: 34750687 PMCID: PMC8801401 DOI: 10.1007/s00294-021-01217-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 09/28/2021] [Accepted: 10/06/2021] [Indexed: 11/02/2022]
Abstract
The increase in multidrug-resistant pathogenic bacteria has become a problem worldwide. Currently there is a strong focus on the development of novel antimicrobials, including antimicrobial peptides (AMP) and antimicrobial antisense agents. While the majority of AMP have membrane activity and kill bacteria through membrane disruption, non-lytic AMP are non-membrane active, internalize and have intracellular targets. Antimicrobial antisense agents such as peptide nucleic acids (PNA) and phosphorodiamidate morpholino oligomers (PMO), show great promise as novel antibacterial agents, killing bacteria by inhibiting translation of essential target gene transcripts. However, naked PNA and PMO are unable to translocate across the cell envelope of bacteria, to reach their target in the cytosol, and are conjugated to bacteria penetrating peptides (BPP) for cytosolic delivery. Here, we discuss how non-lytic AMP and BPP-PMO/PNA conjugates translocate across the cytoplasmic membrane via receptor-mediated transport, such as the cytoplasmic membrane transporters SbmA, MdtM/YjiL, and/or YgdD, or via a less well described autonomous process.
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11
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Ghilarov D, Inaba-Inoue S, Stepien P, Qu F, Michalczyk E, Pakosz Z, Nomura N, Ogasawara S, Walker GC, Rebuffat S, Iwata S, Heddle JG, Beis K. Molecular mechanism of SbmA, a promiscuous transporter exploited by antimicrobial peptides. SCIENCE ADVANCES 2021; 7:eabj5363. [PMID: 34516884 PMCID: PMC8442886 DOI: 10.1126/sciadv.abj5363] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 07/16/2021] [Indexed: 05/12/2023]
Abstract
Antibiotic metabolites and antimicrobial peptides mediate competition between bacterial species. Many of them hijack inner and outer membrane proteins to enter cells. Sensitivity of enteric bacteria to multiple peptide antibiotics is controlled by the single inner membrane protein SbmA. To establish the molecular mechanism of peptide transport by SbmA and related BacA, we determined their cryo–electron microscopy structures at 3.2 and 6 Å local resolution, respectively. The structures show a previously unknown fold, defining a new class of secondary transporters named SbmA-like peptide transporters. The core domain includes conserved glutamates, which provide a pathway for proton translocation, powering transport. The structures show an outward-open conformation with a large cavity that can accommodate diverse substrates. We propose a molecular mechanism for antibacterial peptide uptake paving the way for creation of narrow-targeted therapeutics.
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Affiliation(s)
- Dmitry Ghilarov
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | - Satomi Inaba-Inoue
- Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, UK
- Rutherford Appleton Laboratory, Research Complex at Harwell, Didcot, Oxfordshire OX11 0FA, UK
- Diffraction and Scattering Division, Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1, Kouto, Sayo, Hyogo 679-5198, Japan
| | - Piotr Stepien
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | - Feng Qu
- Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, UK
- Rutherford Appleton Laboratory, Research Complex at Harwell, Didcot, Oxfordshire OX11 0FA, UK
| | | | - Zuzanna Pakosz
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
- Postgraduate School of Molecular Medicine, Warsaw, Poland
| | - Norimichi Nomura
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Satoshi Ogasawara
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Graham Charles Walker
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sylvie Rebuffat
- Molecules of Communication and Adaptation of Microorganisms Laboratory (MCAM, UMR 7245 CNRS-MNHN), Muséum National d’Histoire Naturelle, Sorbonne Universités, Centre National de la Recherche Scientifique, CP 54, 57 rue Cuvier, Paris 75005, France
| | - So Iwata
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
- Research Acceleration Program, Membrane Protein Crystallography Project, Japan Science and Technology Agency, Kyoto, Japan
| | | | - Konstantinos Beis
- Department of Life Sciences, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, UK
- Rutherford Appleton Laboratory, Research Complex at Harwell, Didcot, Oxfordshire OX11 0FA, UK
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12
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McCutcheon JP. The Genomics and Cell Biology of Host-Beneficial Intracellular Infections. Annu Rev Cell Dev Biol 2021; 37:115-142. [PMID: 34242059 DOI: 10.1146/annurev-cellbio-120219-024122] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microbes gain access to eukaryotic cells as food for bacteria-grazing protists, for host protection by microbe-killing immune cells, or for microbial benefit when pathogens enter host cells to replicate. But microbes can also gain access to a host cell and become an important-often required-beneficial partner. The oldest beneficial microbial infections are the ancient eukaryotic organelles now called the mitochondrion and plastid. But numerous other host-beneficial intracellular infections occur throughout eukaryotes. Here I review the genomics and cell biology of these interactions with a focus on intracellular bacteria. The genomes of host-beneficial intracellular bacteria have features that span a previously unfilled gap between pathogens and organelles. Host cell adaptations to allow the intracellular persistence of beneficial bacteria are found along with evidence for the microbial manipulation of host cells, but the cellular mechanisms of beneficial bacterial infections are not well understood. Expected final online publication date for the Annual Review of Cell and Developmental Biology, Volume 37 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- John P McCutcheon
- Biodesign Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe, Arizona 85287, USA;
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13
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Abstract
Rhizobia are a phylogenetically diverse group of soil bacteria that engage in mutualistic interactions with legume plants. Although specifics of the symbioses differ between strains and plants, all symbioses ultimately result in the formation of specialized root nodule organs which host the nitrogen-fixing microsymbionts called bacteroids. Inside nodules, bacteroids encounter unique conditions that necessitate global reprogramming of physiological processes and rerouting of their metabolism. Decades of research have addressed these questions using genetics, omics approaches, and more recently computational modelling. Here we discuss the common adaptations of rhizobia to the nodule environment that define the core principles of bacteroid functioning. All bacteroids are growth-arrested and perform energy-intensive nitrogen fixation fueled by plant-provided C4-dicarboxylates at nanomolar oxygen levels. At the same time, bacteroids are subject to host control and sanctioning that ultimately determine their fitness and have fundamental importance for the evolution of a stable mutualistic relationship.
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14
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Slotboom DJ, Ettema TW, Nijland M, Thangaratnarajah C. Bacterial multi-solute transporters. FEBS Lett 2020; 594:3898-3907. [PMID: 32810294 DOI: 10.1002/1873-3468.13912] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/30/2020] [Accepted: 07/31/2020] [Indexed: 12/20/2022]
Abstract
Bacterial membrane proteins of the SbmA/BacA family are multi-solute transporters that mediate the uptake of structurally diverse hydrophilic molecules, including aminoglycoside antibiotics and antimicrobial peptides. Some family members are full-length ATP-binding cassette (ABC) transporters, whereas other members are truncated homologues that lack the nucleotide-binding domains and thus mediate ATP-independent transport. A recent cryo-EM structure of the ABC transporter Rv1819c from Mycobacterium tuberculosis has shed light on the structural basis for multi-solute transport and has provided insight into the mechanism of transport. Here, we discuss how the protein architecture makes SbmA/BacA family transporters prone to inadvertent import of antibiotics and speculate on the question which physiological processes may benefit from multi-solute transport.
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Affiliation(s)
- Dirk J Slotboom
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Thijs W Ettema
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Mark Nijland
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
| | - Chancievan Thangaratnarajah
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, the Netherlands
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15
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Lindström K, Mousavi SA. Effectiveness of nitrogen fixation in rhizobia. Microb Biotechnol 2020; 13:1314-1335. [PMID: 31797528 PMCID: PMC7415380 DOI: 10.1111/1751-7915.13517] [Citation(s) in RCA: 130] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 11/13/2019] [Accepted: 11/13/2019] [Indexed: 12/01/2022] Open
Abstract
Biological nitrogen fixation in rhizobia occurs primarily in root or stem nodules and is induced by the bacteria present in legume plants. This symbiotic process has fascinated researchers for over a century, and the positive effects of legumes on soils and their food and feed value have been recognized for thousands of years. Symbiotic nitrogen fixation uses solar energy to reduce the inert N2 gas to ammonia at normal temperature and pressure, and is thus today, especially, important for sustainable food production. Increased productivity through improved effectiveness of the process is seen as a major research and development goal. The interaction between rhizobia and their legume hosts has thus been dissected at agronomic, plant physiological, microbiological and molecular levels to produce ample information about processes involved, but identification of major bottlenecks regarding efficiency of nitrogen fixation has proven to be complex. We review processes and results that contributed to the current understanding of this fascinating system, with focus on effectiveness of nitrogen fixation in rhizobia.
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Affiliation(s)
- Kristina Lindström
- Faculty of Biological and Environmental Sciences and Helsinki Institute of Sustainability Science (HELSUS)University of HelsinkiFI‐00014HelsinkiFinland
| | - Seyed Abdollah Mousavi
- Faculty of Biological and Environmental Sciences and Helsinki Institute of Sustainability Science (HELSUS)University of HelsinkiFI‐00014HelsinkiFinland
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16
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Roy P, Achom M, Wilkinson H, Lagunas B, Gifford ML. Symbiotic Outcome Modified by the Diversification from 7 to over 700 Nodule-Specific Cysteine-Rich Peptides. Genes (Basel) 2020; 11:E348. [PMID: 32218172 PMCID: PMC7230169 DOI: 10.3390/genes11040348] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 03/11/2020] [Accepted: 03/22/2020] [Indexed: 12/31/2022] Open
Abstract
Legume-rhizobium symbiosis represents one of the most successfully co-evolved mutualisms. Within nodules, the bacterial cells undergo distinct metabolic and morphological changes and differentiate into nitrogen-fixing bacteroids. Legumes in the inverted repeat lacking clade (IRLC) employ an array of defensin-like small secreted peptides (SSPs), known as nodule-specific cysteine-rich (NCR) peptides, to regulate bacteroid differentiation and activity. While most NCRs exhibit bactericidal effects in vitro, studies confirm that inside nodules they target the bacterial cell cycle and other cellular pathways to control and extend rhizobial differentiation into an irreversible (or terminal) state where the host gains control over bacteroids. While NCRs are well established as positive regulators of effective symbiosis, more recent findings also suggest that NCRs affect partner compatibility. The extent of bacterial differentiation has been linked to species-specific size and complexity of the NCR gene family that varies even among closely related species, suggesting a more recent origin of NCRs followed by rapid expansion in certain species. NCRs have diversified functionally, as well as in their expression patterns and responsiveness, likely driving further functional specialisation. In this review, we evaluate the functions of NCR peptides and their role as a driving force underlying the outcome of rhizobial symbiosis, where the plant is able to determine the outcome of rhizobial interaction in a temporal and spatial manner.
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Affiliation(s)
- Proyash Roy
- School of Life Sciences, Gibbet Hill Road, University of Warwick, Coventry CV4 7AL, UK; (P.R.); (M.A.); (H.W.); (B.L.)
- Department of Genetic Engineering and Biotechnology, University of Dhaka, Dhaka 1205, Bangladesh
| | - Mingkee Achom
- School of Life Sciences, Gibbet Hill Road, University of Warwick, Coventry CV4 7AL, UK; (P.R.); (M.A.); (H.W.); (B.L.)
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, NY 14853, USA
| | - Helen Wilkinson
- School of Life Sciences, Gibbet Hill Road, University of Warwick, Coventry CV4 7AL, UK; (P.R.); (M.A.); (H.W.); (B.L.)
| | - Beatriz Lagunas
- School of Life Sciences, Gibbet Hill Road, University of Warwick, Coventry CV4 7AL, UK; (P.R.); (M.A.); (H.W.); (B.L.)
| | - Miriam L. Gifford
- School of Life Sciences, Gibbet Hill Road, University of Warwick, Coventry CV4 7AL, UK; (P.R.); (M.A.); (H.W.); (B.L.)
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17
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Medicago-Sinorhizobium-Ralstonia Co-infection Reveals Legume Nodules as Pathogen Confined Infection Sites Developing Weak Defenses. Curr Biol 2020; 30:351-358.e4. [DOI: 10.1016/j.cub.2019.11.066] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 08/02/2019] [Accepted: 11/21/2019] [Indexed: 11/20/2022]
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18
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Collin F, Maxwell A. The Microbial Toxin Microcin B17: Prospects for the Development of New Antibacterial Agents. J Mol Biol 2019; 431:3400-3426. [PMID: 31181289 PMCID: PMC6722960 DOI: 10.1016/j.jmb.2019.05.050] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 05/28/2019] [Accepted: 05/30/2019] [Indexed: 01/03/2023]
Abstract
Microcin B17 (MccB17) is an antibacterial peptide produced by strains of Escherichia coli harboring the plasmid-borne mccB17 operon. MccB17 possesses many notable features. It is able to stabilize the transient DNA gyrase-DNA cleavage complex, a very efficient mode of action shared with the highly successful fluoroquinolone drugs. MccB17 stabilizes this complex by a distinct mechanism making it potentially valuable in the fight against bacterial antibiotic resistance. MccB17 was the first compound discovered from the thiazole/oxazole-modified microcins family and the linear azole-containing peptides; these ribosomal peptides are post-translationally modified to convert serine and cysteine residues into oxazole and thiazole rings. These chemical moieties are found in many other bioactive compounds like the vitamin thiamine, the anti-cancer drug bleomycin, the antibacterial sulfathiazole and the antiviral nitazoxanide. Therefore, the biosynthetic machinery that produces these azole rings is noteworthy as a general method to create bioactive compounds. Our knowledge of MccB17 now extends to many aspects of antibacterial-bacteria interactions: production, transport, interaction with its target, and resistance mechanisms; this knowledge has wide potential applicability. After a long time with limited progress on MccB17, recent publications have addressed critical aspects of MccB17 biosynthesis as well as an explosion in the discovery of new related compounds in the thiazole/oxazole-modified microcins/linear azole-containing peptides family. It is therefore timely to summarize the evidence gathered over more than 40 years about this still enigmatic molecule and place it in the wider context of antibacterials.
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Affiliation(s)
- Frederic Collin
- Department Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Anthony Maxwell
- Department Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
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19
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From Intracellular Bacteria to Differentiated Bacteroids: Transcriptome and Metabolome Analysis in Aeschynomene Nodules Using the Bradyrhizobium sp. Strain ORS285 bclA Mutant. J Bacteriol 2019; 201:JB.00191-19. [PMID: 31182497 DOI: 10.1128/jb.00191-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 05/31/2019] [Indexed: 01/08/2023] Open
Abstract
Soil bacteria called rhizobia trigger the formation of root nodules on legume plants. The rhizobia infect these symbiotic organs and adopt an intracellular lifestyle within the nodule cells, where they differentiate into nitrogen-fixing bacteroids. Several legume lineages force their symbionts into an extreme cellular differentiation, comprising cell enlargement and genome endoreduplication. The antimicrobial peptide transporter BclA is a major determinant of this process in Bradyrhizobium sp. strain ORS285, a symbiont of Aeschynomene spp. In the absence of BclA, the bacteria proceed until the intracellular infection of nodule cells, but they cannot differentiate into enlarged polyploid and functional bacteroids. Thus, the bclA nodule bacteria constitute an intermediate stage between the free-living soil bacteria and the nitrogen-fixing bacteroids. Metabolomics on whole nodules of Aeschynomene afraspera and Aeschynomene indica infected with the wild type or the bclA mutant revealed 47 metabolites that differentially accumulated concomitantly with bacteroid differentiation. Bacterial transcriptome analysis of these nodules demonstrated that the intracellular settling of the rhizobia in the symbiotic nodule cells is accompanied by a first transcriptome switch involving several hundred upregulated and downregulated genes and a second switch accompanying the bacteroid differentiation, involving fewer genes but ones that are expressed to extremely elevated levels. The transcriptomes further suggested a dynamic role for oxygen and redox regulation of gene expression during nodule formation and a nonsymbiotic function of BclA. Together, our data uncover the metabolic and gene expression changes that accompany the transition from intracellular bacteria into differentiated nitrogen-fixing bacteroids.IMPORTANCE Legume-rhizobium symbiosis is a major ecological process, fueling the biogeochemical nitrogen cycle with reduced nitrogen. It also represents a promising strategy to reduce the use of chemical nitrogen fertilizers in agriculture, thereby improving its sustainability. This interaction leads to the intracellular accommodation of rhizobia within plant cells of symbiotic organs, where they differentiate into nitrogen-fixing bacteroids. In specific legume clades, this differentiation process requires the bacterial transporter BclA to counteract antimicrobial peptides produced by the host. Transcriptome analysis of Bradyrhizobium wild-type and bclA mutant bacteria in culture and in symbiosis with Aeschynomene host plants dissected the bacterial transcriptional response in distinct phases and highlighted functions of the transporter in the free-living stage of the bacterial life cycle.
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20
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Uchi N, Fukudome M, Nozaki N, Suzuki M, Osuki KI, Shigenobu S, Uchiumi T. Antimicrobial Activities of Cysteine-rich Peptides Specific to Bacteriocytes of the Pea Aphid Acyrthosiphon pisum. Microbes Environ 2019; 34:155-160. [PMID: 30905896 PMCID: PMC6594739 DOI: 10.1264/jsme2.me18148] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Aphids have a mutualistic relationship with the bacterial endosymbiont Buchnera aphidicola. We previously reported seven cysteine-rich peptides in the pea aphid Acyrthosiphon pisum and named them Bacteriocyte-specific Cysteine-Rich (BCR) peptides; these peptides are exclusively expressed in bacteriocytes, special aphid cells that harbor symbionts. Similar symbiotic organ-specific cysteine-rich peptides identified in the root nodules of leguminous plants are named Nodule-specific Cysteine-Rich (NCR) peptides. NCR peptides target rhizobia in the nodules and are essential for symbiotic nitrogen fixation. A BacA (membrane protein) mutant of Sinorhizobium is sensitive to NCR peptides and is unable to establish symbiosis. Based on the structural and expressional similarities between BCR peptides and NCR peptides, we hypothesized that aphid BCR peptides exhibit antimicrobial activity, similar to some NCR peptides. We herein synthesized BCR peptides and investigated their antimicrobial activities and effects on the bacterial membrane of Escherichia coli. The peptides BCR1, BCR3, BCR5, and BCR8 exhibited antimicrobial activities with increased membrane permeability. An sbmA mutant of E. coli, a homolog of bacA of S. meliloti, was more sensitive to BCR peptides than the wild type. Our results suggest that BCR peptides have properties that may be required to control the endosymbiont, similar to NCR peptides in legumes.
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Affiliation(s)
- Nahoko Uchi
- Graduate School of Science and Engineering, Kagoshima University
| | | | - Narumi Nozaki
- Graduate School of Science and Engineering, Kagoshima University
| | | | - Ken-Ichi Osuki
- Graduate School of Science and Engineering, Kagoshima University
| | | | - Toshiki Uchiumi
- Graduate School of Science and Engineering, Kagoshima University
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21
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Berrabah F, Ratet P, Gourion B. Legume Nodules: Massive Infection in the Absence of Defense Induction. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:35-44. [PMID: 30252618 DOI: 10.1094/mpmi-07-18-0205-fi] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Plants of the legume family host massive intracellular bacterial populations in the tissues of specialized organs, the nodules. In these organs, the bacteria, named rhizobia, can fix atmospheric nitrogen and transfer it to the plant. This special metabolic skill provides to the legumes an advantage when they grow on nitrogen-scarce substrates. While packed with rhizobia, the nodule cells remain alive, metabolically active, and do not develop defense reactions. Here, we review our knowledge on the control of plant immunity during the rhizobia-legume symbiosis. We present the results of an evolutionary process that selected both divergence of microbial-associated molecular motifs and active suppressors of immunity on the rhizobial side and, on the legume side, active mechanisms that contribute to suppression of immunity.
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Affiliation(s)
- Fathi Berrabah
- 1 Laboratory of Exploration and Valorization of Steppic Ecosystems, Faculty of Nature and Life Sciences, University of Ziane Achour, 17000 Djelfa, Algeria
| | - Pascal Ratet
- 2 Institute of Plant Sciences Paris-Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, Bâtiment 630, 91405 Orsay, France
- 3 Institute of Plant Sciences Paris-Saclay IPS2, Paris Diderot, Sorbonne Paris-Cité, Bâtiment 630, 91405, Orsay, France; and
| | - Benjamin Gourion
- 4 LIPM, Université de Toulouse, INRA, CNRS, Castanet-Tolosan, France
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22
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Unveiling the Multifaceted Mechanisms of Antibacterial Activity of Buforin II and Frenatin 2.3S Peptides from Skin Micro-Organs of the Orinoco Lime Treefrog ( Sphaenorhynchus lacteus). Int J Mol Sci 2018; 19:ijms19082170. [PMID: 30044391 PMCID: PMC6121439 DOI: 10.3390/ijms19082170] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 07/19/2018] [Indexed: 12/15/2022] Open
Abstract
Amphibian skin is a rich source of natural compounds with diverse antimicrobial and immune defense properties. Our previous studies showed that the frog skin secretions obtained by skin micro-organs from various species of Colombian anurans have antimicrobial activities against bacteria and viruses. We purified for the first time two antimicrobial peptides from the skin micro-organs of the Orinoco lime treefrog (Sphaenorhynchus lacteus) that correspond to Buforin II (BF2) and Frenatin 2.3S (F2.3S). Here, we have synthesized the two peptides and tested them against Gram-negative and Gram-positive bacteria, observing an effective bactericidal activity at micromolar concentrations. Evaluation of BF2 and F2.3S membrane destabilization activity on bacterial cell cultures and synthetic lipid bilayers reveals a distinct membrane interaction mechanism. BF2 agglutinates E. coli cells and synthetic vesicles, whereas F2.3S shows a high depolarization and membrane destabilization activities. Interestingly, we found that F2.3S is able to internalize within bacterial cells and can bind nucleic acids, as previously reported for BF2. Moreover, bacterial exposure to both peptides alters the expression profile of genes related to stress and resistance response. Overall, these results show the multifaceted mechanism of action of both antimicrobial peptides that can provide alternative tools in the fight against bacterial resistance.
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23
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Lang C, Smith LS, Haney CH, Long SR. Characterization of Novel Plant Symbiosis Mutants Using a New Multiple Gene-Expression Reporter Sinorhizobium meliloti Strain. FRONTIERS IN PLANT SCIENCE 2018; 9:76. [PMID: 29467773 PMCID: PMC5808326 DOI: 10.3389/fpls.2018.00076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/15/2018] [Indexed: 06/08/2023]
Abstract
The formation of nitrogen fixing root nodules by Medicago truncatula and Sinorhizobium meliloti requires communication between both organisms and coordinated differentiation of plant and bacterial cells. After an initial signal exchange, the bacteria invade the tissue of the growing nodule via plant-derived tubular structures, called infection threads. The bacteria are released from the infection threads into invasion-competent plant cells, where they differentiate into nitrogen-fixing bacteroids. Both organisms undergo dramatic transcriptional, metabolic and morphological changes during nodule development. To identify plant processes that are essential for the formation of nitrogen fixing nodules after nodule development has been initiated, large scale mutageneses have been conducted to discover underlying plant symbiosis genes. Such screens yield numerous uncharacterized plant lines with nitrogen fixation deficient nodules. In this study, we report construction of a S. meliloti strain carrying four distinct reporter constructs to reveal stages of root nodule development. The strain contains a constitutively expressed lacZ reporter construct; a PexoY-mTFP fusion that is expressed in infection threads but not in differentiated bacteroids; a PbacA-mcherry construct that is expressed in infection threads and during bacteroid differentiation; and a PnifH-uidA construct that is expressed during nitrogen fixation. We used this strain together with fluorescence microscopy to study nodule development over time in wild type nodules and to characterize eight plant mutants from a fast neutron bombardment screen. Based on the signal intensity and the localization patterns of the reporter genes, we grouped mutants with similar phenotypes and placed them in a developmental context.
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Affiliation(s)
| | | | | | - Sharon R. Long
- Gilbert Lab, Department of Biology, Stanford University, Stanford, CA, United States
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24
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Domonkos Á, Kovács S, Gombár A, Kiss E, Horváth B, Kováts GZ, Farkas A, Tóth MT, Ayaydin F, Bóka K, Fodor L, Ratet P, Kereszt A, Endre G, Kaló P. NAD1 Controls Defense-Like Responses in Medicago truncatula Symbiotic Nitrogen Fixing Nodules Following Rhizobial Colonization in a BacA-Independent Manner. Genes (Basel) 2017; 8:E387. [PMID: 29240711 PMCID: PMC5748705 DOI: 10.3390/genes8120387] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/04/2017] [Accepted: 12/11/2017] [Indexed: 11/19/2022] Open
Abstract
Legumes form endosymbiotic interaction with host compatible rhizobia, resulting in the development of nitrogen-fixing root nodules. Within symbiotic nodules, rhizobia are intracellularly accommodated in plant-derived membrane compartments, termed symbiosomes. In mature nodule, the massively colonized cells tolerate the existence of rhizobia without manifestation of visible defense responses, indicating the suppression of plant immunity in the nodule in the favur of the symbiotic partner. Medicago truncatulaDNF2 (defective in nitrogen fixation 2) and NAD1 (nodules with activated defense 1) genes are essential for the control of plant defense during the colonization of the nitrogen-fixing nodule and are required for bacteroid persistence. The previously identified nodule-specific NAD1 gene encodes a protein of unknown function. Herein, we present the analysis of novel NAD1 mutant alleles to better understand the function of NAD1 in the repression of immune responses in symbiotic nodules. By exploiting the advantage of plant double and rhizobial mutants defective in establishing nitrogen-fixing symbiotic interaction, we show that NAD1 functions following the release of rhizobia from the infection threads and colonization of nodule cells. The suppression of plant defense is self-dependent of the differentiation status of the rhizobia. The corresponding phenotype of nad1 and dnf2 mutants and the similarity in the induction of defense-associated genes in both mutants suggest that NAD1 and DNF2 operate close together in the same pathway controlling defense responses in symbiotic nodules.
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Affiliation(s)
- Ágota Domonkos
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Szilárd Kovács
- Institute of Plant Biology, Biological Research Center, 6726 Szeged, Hungary.
- Institute of Genetics, Biological Research Center, 6726 Szeged, Hungary.
| | - Anikó Gombár
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Ernő Kiss
- Institute of Genetics, Biological Research Center, 6726 Szeged, Hungary.
| | - Beatrix Horváth
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Gyöngyi Z Kováts
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Attila Farkas
- Institute of Plant Biology, Biological Research Center, 6726 Szeged, Hungary.
| | - Mónika T Tóth
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Ferhan Ayaydin
- Cellular Imaging Laboratory, Biological Research Center, 6726 Szeged, Hungary.
| | - Károly Bóka
- Department of Plant Anatomy, Eötvös Loránd University, 1117 Budapest, Hungary.
| | - Lili Fodor
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
| | - Pascal Ratet
- Institute of Plant Sciences Paris-Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, Bâtiment 630, 91405 Orsay, France.
- Institute of Plant Sciences Paris-Saclay IPS2, Paris Diderot, Sorbonne Paris-Cité, Bâtiment 630, 91405 Orsay, France.
| | - Attila Kereszt
- Institute of Plant Biology, Biological Research Center, 6726 Szeged, Hungary.
| | - Gabriella Endre
- Institute of Plant Biology, Biological Research Center, 6726 Szeged, Hungary.
- Institute of Genetics, Biological Research Center, 6726 Szeged, Hungary.
| | - Péter Kaló
- National Agricultural and Innovation Center, Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary.
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25
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Genome-Wide Sensitivity Analysis of the Microsymbiont Sinorhizobium meliloti to Symbiotically Important, Defensin-Like Host Peptides. mBio 2017; 8:mBio.01060-17. [PMID: 28765224 PMCID: PMC5539429 DOI: 10.1128/mbio.01060-17] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The model legume species Medicago truncatula expresses more than 700 nodule-specific cysteine-rich (NCR) signaling peptides that mediate the differentiation of Sinorhizobium meliloti bacteria into nitrogen-fixing bacteroids. NCR peptides are essential for a successful symbiosis in legume plants of the inverted-repeat-lacking clade (IRLC) and show similarity to mammalian defensins. In addition to signaling functions, many NCR peptides exhibit antimicrobial activity in vitro and in vivo. Bacterial resistance to these antimicrobial activities is likely to be important for symbiosis. However, the mechanisms used by S. meliloti to resist antimicrobial activity of plant peptides are poorly understood. To address this, we applied a global genetic approach using transposon mutagenesis followed by high-throughput sequencing (Tn-seq) to identify S. meliloti genes and pathways that increase or decrease bacterial competitiveness during exposure to the well-studied cationic NCR247 peptide and also to the unrelated model antimicrobial peptide polymyxin B. We identified 78 genes and several diverse pathways whose interruption alters S. meliloti resistance to NCR247. These genes encode the following: (i) cell envelope polysaccharide biosynthesis and modification proteins, (ii) inner and outer membrane proteins, (iii) peptidoglycan (PG) effector proteins, and (iv) non-membrane-associated factors such as transcriptional regulators and ribosome-associated factors. We describe a previously uncharacterized yet highly conserved peptidase, which protects S. meliloti from NCR247 and increases competitiveness during symbiosis. Additionally, we highlight a considerable number of uncharacterized genes that provide the basis for future studies to investigate the molecular basis of symbiotic development as well as chronic pathogenic interactions. Soil rhizobial bacteria enter into an ecologically and economically important symbiotic interaction with legumes, in which they differentiate into physiologically distinct bacteroids that provide essential ammonia to the plant in return for carbon sources. Plant signal peptides are essential and specific to achieve these physiological changes. These peptides show similarity to mammalian defensin peptides which are part of the first line of defense to control invading bacterial populations. A number of these legume peptides are indeed known to possess antimicrobial activity, and so far, only the bacterial BacA protein is known to protect rhizobial bacteria against their antimicrobial action. This study identified numerous additional bacterial factors that mediate protection and belong to diverse biological pathways. Our results significantly contribute to our understanding of the molecular roles of bacterial factors during legume symbioses and, second, provide insights into the mechanisms that pathogenic bacteria may use to resist the antimicrobial effects of defensins during infections.
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diCenzo GC, Zamani M, Ludwig HN, Finan TM. Heterologous Complementation Reveals a Specialized Activity for BacA in the Medicago-Sinorhizobium meliloti Symbiosis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:312-324. [PMID: 28398123 DOI: 10.1094/mpmi-02-17-0030-r] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The bacterium Sinorhizobium meliloti Rm2011 forms N2-fixing root nodules on alfalfa and other leguminous plants. The pSymB chromid contains a 110-kb region (the ETR region) showing high synteny to a chromosomally located region in Sinorhizobium fredii NGR234 and related rhizobia. We recently introduced the ETR region from S. fredii NGR234 into the S. meliloti chromosome. Here, we report that, unexpectedly, the S. fredii NGR234 ETR region did not complement deletion of the S. meliloti ETR region in symbiosis with Medicago sativa. This phenotype was due to the bacA gene of NGR234 not being functionally interchangeable with the S. meliloti bacA gene during M. sativa symbiosis. Further analysis revealed that, whereas bacA genes from S. fredii or Rhizobium leguminosarum bv. viciae 3841 failed to complement the Fix- phenotype of a S. meliloti bacA mutant with M. sativa, they allowed for further developmental progression prior to a loss of viability. In contrast, with Melilotus alba, bacA from S. fredii and R. leguminosarum supported N2 fixation by a S. meliloti bacA mutant. Additionally, the S. meliloti bacA gene can support N2 fixation of a R. leguminosarum bacA mutant during symbiosis with Pisum sativum. A phylogeny of BacA proteins illustrated that S. meliloti BacA has rapidly diverged from most rhizobia and has converged toward the sequence of pathogenic genera Brucella and Escherichia. These data suggest that the S. meliloti BacA has evolved toward a specific interaction with Medicago and highlights the limitations of using a single model system for the study of complex biological topics.
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Affiliation(s)
- George C diCenzo
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada
| | - Maryam Zamani
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada
| | - Hannah N Ludwig
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada
| | - Turlough M Finan
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, Ontario L8S 4K1, Canada
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The Mechanism of Killing by the Proline-Rich Peptide Bac7(1-35) against Clinical Strains of Pseudomonas aeruginosa Differs from That against Other Gram-Negative Bacteria. Antimicrob Agents Chemother 2017; 61:AAC.01660-16. [PMID: 28137800 DOI: 10.1128/aac.01660-16] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 01/15/2017] [Indexed: 12/13/2022] Open
Abstract
Pseudomonas aeruginosa infections represent a serious threat to worldwide health. Proline-rich antimicrobial peptides (PR-AMPs), a particular group of peptide antibiotics, have demonstrated in vitro activity against P. aeruginosa strains. Here we show that the mammalian PR-AMP Bac7(1-35) is active against some multidrug-resistant cystic fibrosis isolates of P. aeruginosa By confocal microscopy and cytometric analyses, we investigated the mechanism of killing against P. aeruginosa strain PAO1 and three selected isolates, and we observed that the peptide inactivated the target cells by disrupting their cellular membranes. This effect is deeply different from that previously described for PR-AMPs in Escherichia coli and Salmonella enterica serovar Typhimurium, where these peptides act intracellularly after having been internalized by means of the transporter SbmA without membranolytic effects. The heterologous expression of SbmA in PAO1 cells enhanced the internalization of Bac7(1-35) into the cytoplasm, making the bacteria more susceptible to the peptide but at the same time more resistant to the membrane lysis, similarly to what occurs in E. coli The results evidenced a new mechanism of action for PR-AMPs and indicate that Bac7 has multiple and variable modes of action that depend on the characteristics of the different target species and the possibility to be internalized by bacterial transporters. This feature broadens the spectrum of activity of the peptide and makes the development of peptide-resistant bacteria a more difficult process.
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Satgé C, Moreau S, Sallet E, Lefort G, Auriac MC, Remblière C, Cottret L, Gallardo K, Noirot C, Jardinaud MF, Gamas P. Reprogramming of DNA methylation is critical for nodule development in Medicago truncatula. NATURE PLANTS 2016; 2:16166. [PMID: 27797357 DOI: 10.1038/nplants.2016.166] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 09/28/2016] [Indexed: 05/25/2023]
Abstract
The legume-Rhizobium symbiosis leads to the formation of a new organ, the root nodule, involving coordinated and massive induction of specific genes. Several genes controlling DNA methylation are spatially regulated within the Medicago truncatula nodule, notably the demethylase gene, DEMETER (DME), which is mostly expressed in the differentiation zone. Here, we show that MtDME is essential for nodule development and regulates the expression of 1,425 genes, some of which are critical for plant and bacterial cell differentiation. Bisulphite sequencing coupled to genomic capture enabled the identification of 474 regions that are differentially methylated during nodule development, including nodule-specific cysteine-rich peptide genes. Decreasing DME expression by RNA interference led to hypermethylation and concomitant downregulation of 400 genes, most of them associated with nodule differentiation. Massive reprogramming of gene expression through DNA demethylation is a new epigenetic mechanism controlling a key stage of indeterminate nodule organogenesis during symbiotic interactions.
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Affiliation(s)
- Carine Satgé
- LIPM, Université de Toulouse, INRA, CNRS, 31326 Castanet-Tolosan, France
| | - Sandra Moreau
- LIPM, Université de Toulouse, INRA, CNRS, 31326 Castanet-Tolosan, France
| | - Erika Sallet
- LIPM, Université de Toulouse, INRA, CNRS, 31326 Castanet-Tolosan, France
| | - Gaëlle Lefort
- MIAT, Université de Toulouse, Plate-forme Bio-informatique Genotoul, INRA, Castanet-Tolosan, France
| | | | - Céline Remblière
- LIPM, Université de Toulouse, INRA, CNRS, 31326 Castanet-Tolosan, France
| | - Ludovic Cottret
- LIPM, Université de Toulouse, INRA, CNRS, 31326 Castanet-Tolosan, France
| | - Karine Gallardo
- INRA, UMR 1347 Agroécologie, BP 86510, Dijon F-21000, France
| | - Céline Noirot
- MIAT, Université de Toulouse, Plate-forme Bio-informatique Genotoul, INRA, Castanet-Tolosan, France
| | - Marie-Françoise Jardinaud
- LIPM, Université de Toulouse, INRA, CNRS, 31326 Castanet-Tolosan, France
- INPT-Université de Toulouse, ENSAT, Avenue de l'Agrobiopole, Castanet-Tolosan, France
| | - Pascal Gamas
- LIPM, Université de Toulouse, INRA, CNRS, 31326 Castanet-Tolosan, France
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Disulfide cross-linking influences symbiotic activities of nodule peptide NCR247. Proc Natl Acad Sci U S A 2016; 113:10157-62. [PMID: 27551097 DOI: 10.1073/pnas.1610724113] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Interactions of rhizobia with legumes establish the chronic intracellular infection that underlies symbiosis. Within nodules of inverted repeat-lacking clade (IRLC) legumes, rhizobia differentiate into nitrogen-fixing bacteroids. This terminal differentiation is driven by host nodule-specific cysteine-rich (NCR) peptides that orchestrate the adaptation of free-living bacteria into intracellular residents. Medicago truncatula encodes a family of >700 NCR peptides that have conserved cysteine motifs. NCR247 is a cationic peptide with four cysteines that can form two intramolecular disulfide bonds in the oxidized forms. This peptide affects Sinorhizobium meliloti transcription, translation, and cell division at low concentrations and is antimicrobial at higher concentrations. By preparing the three possible disulfide-cross-linked NCR247 regioisomers, the reduced peptide, and a variant lacking cysteines, we performed a systematic study of the effects of intramolecular disulfide cross-linking and cysteines on the activities of an NCR peptide. The relative activities of the five NCR247 variants differed strikingly among the various bioassays, suggesting that the NCR peptide-based language used by plants to control the development of their bacterial partners during symbiosis is even greater than previously recognized. These patterns indicate that certain NCR bioactivities require cysteines whereas others do not. The results also suggest that NCR247 may exert some of its effects within the cell envelope whereas other activities occur in the cytoplasm. BacA, a membrane protein that is critical for symbiosis, provides protection against all bactericidal forms of NCR247. Oxidative folding protects NCR247 from degradation by the symbiotically relevant metalloprotease HrrP (host range restriction peptidase), suggesting that disulfide bond formation may additionally stabilize NCR peptides during symbiosis.
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Paulsen VS, Mardirossian M, Blencke HM, Benincasa M, Runti G, Nepa M, Haug T, Stensvåg K, Scocchi M. Inner membrane proteins YgdD and SbmA are required for the complete susceptibility of Escherichia coli to the proline-rich antimicrobial peptide arasin 1(1–25). Microbiology (Reading) 2016; 162:601-609. [DOI: 10.1099/mic.0.000249] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Victoria S. Paulsen
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Mario Mardirossian
- Department of Life Sciences, University of Trieste, Via Giorgieri 5, 34127 Trieste, Italy
| | - Hans-Matti Blencke
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Monica Benincasa
- Department of Life Sciences, University of Trieste, Via Giorgieri 5, 34127 Trieste, Italy
| | - Giulia Runti
- Department of Life Sciences, University of Trieste, Via Giorgieri 5, 34127 Trieste, Italy
| | - Matteo Nepa
- Department of Life Sciences, University of Trieste, Via Giorgieri 5, 34127 Trieste, Italy
| | - Tor Haug
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Klara Stensvåg
- Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Marco Scocchi
- Department of Life Sciences, University of Trieste, Via Giorgieri 5, 34127 Trieste, Italy
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Geddes BA, Oresnik IJ. The Mechanism of Symbiotic Nitrogen Fixation. ADVANCES IN ENVIRONMENTAL MICROBIOLOGY 2016. [DOI: 10.1007/978-3-319-28068-4_4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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32
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Crespo-Rivas JC, Guefrachi I, Mok KC, Villaécija-Aguilar JA, Acosta-Jurado S, Pierre O, Ruiz-Sainz JE, Taga ME, Mergaert P, Vinardell JM. Sinorhizobium fredii HH103 bacteroids are not terminally differentiated and show altered O-antigen in nodules of the Inverted Repeat-Lacking Clade legume Glycyrrhiza uralensis. Environ Microbiol 2015; 18:2392-404. [PMID: 26521863 DOI: 10.1111/1462-2920.13101] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 10/20/2015] [Indexed: 11/28/2022]
Abstract
In rhizobial species that nodulate inverted repeat-lacking clade (IRLC) legumes, such as the interaction between Sinorhizobium meliloti and Medicago, bacteroid differentiation is driven by an endoreduplication event that is induced by host nodule-specific cysteine rich (NCR) antimicrobial peptides and requires the participation of the bacterial protein BacA. We have studied bacteroid differentiation of Sinorhizobium fredii HH103 in three host plants: Glycine max, Cajanus cajan and the IRLC legume Glycyrrhiza uralensis. Flow cytometry, microscopy analyses and viability studies of bacteroids as well as confocal microscopy studies carried out in nodules showed that S. fredii HH103 bacteroids, regardless of the host plant, had deoxyribonucleic acid (DNA) contents, cellular sizes and survival rates similar to those of free-living bacteria. Contrary to S. meliloti, S. fredii HH103 showed little or no sensitivity to Medicago NCR247 and NCR335 peptides. Inactivation of S. fredii HH103 bacA neither affected symbiosis with Glycyrrhiza nor increased bacterial sensitivity to Medicago NCRs. Finally, HH103 bacteroids isolated from Glycyrrhiza, but not those isolated from Cajanus or Glycine, showed an altered lipopolysaccharide. Our studies indicate that, in contrast to the S. meliloti-Medicago model symbiosis, bacteroids in the S. fredii HH103-Glycyrrhiza symbiosis do not undergo NCR-induced and bacA-dependent terminal differentiation.
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Affiliation(s)
- Juan C Crespo-Rivas
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, CP, 41012, Sevilla, Spain
| | - Ibtissem Guefrachi
- Institute for Integrative Biology of the Cell, Centre National de la Recherche Scientifique, UMR 9198, 91198, Gif-sur-Yvette, France
| | - Kenny C Mok
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
| | - José A Villaécija-Aguilar
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, CP, 41012, Sevilla, Spain.,Institute for Integrative Biology of the Cell, Centre National de la Recherche Scientifique, UMR 9198, 91198, Gif-sur-Yvette, France
| | - Sebastián Acosta-Jurado
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, CP, 41012, Sevilla, Spain
| | - Olivier Pierre
- Institute for Integrative Biology of the Cell, Centre National de la Recherche Scientifique, UMR 9198, 91198, Gif-sur-Yvette, France
| | - José E Ruiz-Sainz
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, CP, 41012, Sevilla, Spain
| | - Michiko E Taga
- Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, USA
| | - Peter Mergaert
- Institute for Integrative Biology of the Cell, Centre National de la Recherche Scientifique, UMR 9198, 91198, Gif-sur-Yvette, France
| | - José M Vinardell
- Departamento de Microbiología, Facultad de Biología, Universidad de Sevilla, Avda. Reina Mercedes 6, CP, 41012, Sevilla, Spain
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Meumann EM, Globan M, Fyfe JAM, Leslie D, Porter JL, Seemann T, Denholm J, Stinear TP. Genome sequence comparisons of serial multi-drug-resistant Mycobacterium tuberculosis isolates over 21 years of infection in a single patient. Microb Genom 2015; 1:e000037. [PMID: 28348821 PMCID: PMC5320678 DOI: 10.1099/mgen.0.000037] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 09/28/2015] [Indexed: 11/18/2022] Open
Abstract
We report a case of chronic pulmonary multi-drug-resistant tuberculosis. Despite 14 years of treatment, Mycobacterium tuberculosis was persistently isolated from sputum. Following treatment cessation the patient remained well, although M. tuberculosis was isolated from sputum for a further 8 years. Genome sequencing of eight serial M. tuberculosis isolates cultured between 1991 and 2011 revealed 17 mutations (0.8 mutations per genome year- 1). Eight of these were persisting mutations and only two mutations were detected in the 7 years following cessation of treatment in 2004. In four isolates there were mixed alleles, suggesting the likely presence of bacterial subpopulations. The initial 1991 isolate demonstrated genotypic resistance to isoniazid (katG W91R), rifampicin (rpoB S531L), ethambutol (embB M306V), streptomycin (gidB L16R), quinolones (gyrA S95T) and P-aminosalicylic acid (thyA T202A). Subsequent resistance mutations developed for pyrazinamide (pncA I31F) and ethionamide (ethA frameshift). Such information might have been instructive when developing a treatment regimen. In retrospect and with the benefit of high-resolution genomic hindsight we were able to determine that the patient received only one or two active anti-tuberculous agents for most of their treatment. Additionally, mutations in bacA and Rv2326c were detected, which may have contributed to the persistent but mild disease course. BacA is likely to be associated with maintenance of chronic infection and Rv2326c with a decreased bacterial metabolic state. These results expand our understanding of M. tuberculosis evolution during human infection and underline the link between antibiotic resistance and clinical persistence.
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Affiliation(s)
- Ella M Meumann
- Victorian Infectious Disease Service, Melbourne Health, Melbourne, Victoria 3000, Australia.,Doherty Institute for Infection and Immunity, Victoria 3000, Australia
| | - Maria Globan
- Doherty Institute for Infection and Immunity, Victoria 3000, Australia.,Mycobacterium Reference Laboratory, Victorian Infectious Diseases Reference Laboratory, Melbourne Health, Melbourne, Victoria 3000, Australia
| | - Janet A M Fyfe
- Doherty Institute for Infection and Immunity, Victoria 3000, Australia.,Mycobacterium Reference Laboratory, Victorian Infectious Diseases Reference Laboratory, Melbourne Health, Melbourne, Victoria 3000, Australia
| | - David Leslie
- Doherty Institute for Infection and Immunity, Victoria 3000, Australia.,Mycobacterium Reference Laboratory, Victorian Infectious Diseases Reference Laboratory, Melbourne Health, Melbourne, Victoria 3000, Australia
| | - Jessica L Porter
- Doherty Institute for Infection and Immunity, Victoria 3000, Australia.,Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria 3000, Australia
| | - Torsten Seemann
- Victorian Life Sciences Computation Initiative, University of Melbourne, Parkville, Victoria 3010, Australia.,Doherty Applied Microbial Genomics, Doherty Institute for Infection and Immunity, Melbourne, Victoria 3000, Australia
| | - Justin Denholm
- Victorian Tuberculosis Program, Melbourne, Victoria 3000, Australia.,Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria 3000, Australia.,Doherty Institute for Infection and Immunity, Victoria 3000, Australia.,Victorian Infectious Disease Service, Melbourne Health, Melbourne, Victoria 3000, Australia
| | - Timothy P Stinear
- Department of Microbiology and Immunology, University of Melbourne, Melbourne, Victoria 3000, Australia.,Doherty Applied Microbial Genomics, Doherty Institute for Infection and Immunity, Melbourne, Victoria 3000, Australia.,Doherty Institute for Infection and Immunity, Victoria 3000, Australia
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Guefrachi I, Pierre O, Timchenko T, Alunni B, Barrière Q, Czernic P, Villaécija-Aguilar JA, Verly C, Bourge M, Fardoux J, Mars M, Kondorosi E, Giraud E, Mergaert P. Bradyrhizobium BclA Is a Peptide Transporter Required for Bacterial Differentiation in Symbiosis with Aeschynomene Legumes. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:1155-66. [PMID: 26106901 DOI: 10.1094/mpmi-04-15-0094-r] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Nodules of legume plants are highly integrated symbiotic systems shaped by millions of years of evolution. They harbor nitrogen-fixing rhizobium bacteria called bacteroids. Several legume species produce peptides called nodule-specific cysteine-rich (NCR) peptides in the symbiotic nodule cells which house the bacteroids. NCR peptides are related to antimicrobial peptides of innate immunity. They induce the endosymbionts into a differentiated, enlarged, and polyploid state. The bacterial symbionts, on their side, evolved functions for the response to the NCR peptides. Here, we identified the bclA gene of Bradyrhizobium sp. strains ORS278 and ORS285, which is required for the formation of differentiated and functional bacteroids in the nodules of the NCR peptide-producing Aeschynomene legumes. The BclA ABC transporter promotes the import of NCR peptides and provides protection against the antimicrobial activity of these peptides. Moreover, BclA can complement the role of the related BacA transporter of Sinorhizobium meliloti, which has a similar symbiotic function in the interaction with Medicago legumes.
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Affiliation(s)
- Ibtissem Guefrachi
- 1 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, Gif-sur-Yvette, France
- 2 Research Unit Biodiversity & Valorization of Arid Areas Bioressources (BVBAA), Faculty of Sciences, Gabès, Tunisia
| | - Olivier Pierre
- 1 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, Gif-sur-Yvette, France
| | - Tatiana Timchenko
- 1 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, Gif-sur-Yvette, France
| | - Benoît Alunni
- 1 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, Gif-sur-Yvette, France
| | - Quentin Barrière
- 1 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, Gif-sur-Yvette, France
| | - Pierre Czernic
- 3 Laboratoire des Symbioses Tropicales et Méditerranéennes, Institut pour la Recherche et le Développement, UMR IRD/SupAgro/INRA/UM2/CIRAD, Montpellier, France
| | | | - Camille Verly
- 1 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, Gif-sur-Yvette, France
| | - Mickaël Bourge
- 1 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, Gif-sur-Yvette, France
| | - Joël Fardoux
- 3 Laboratoire des Symbioses Tropicales et Méditerranéennes, Institut pour la Recherche et le Développement, UMR IRD/SupAgro/INRA/UM2/CIRAD, Montpellier, France
| | - Mohamed Mars
- 2 Research Unit Biodiversity & Valorization of Arid Areas Bioressources (BVBAA), Faculty of Sciences, Gabès, Tunisia
| | - Eva Kondorosi
- 1 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, Gif-sur-Yvette, France
- 4 Institute of Biochemistry, Hungarian Academy of Sciences, Biological Research Centre, Szeged, Hungary
| | - Eric Giraud
- 3 Laboratoire des Symbioses Tropicales et Méditerranéennes, Institut pour la Recherche et le Développement, UMR IRD/SupAgro/INRA/UM2/CIRAD, Montpellier, France
| | - Peter Mergaert
- 1 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, Gif-sur-Yvette, France
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35
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Berrabah F, Bourcy M, Eschstruth A, Cayrel A, Guefrachi I, Mergaert P, Wen J, Jean V, Mysore KS, Gourion B, Ratet P. A nonRD receptor-like kinase prevents nodule early senescence and defense-like reactions during symbiosis. THE NEW PHYTOLOGIST 2014; 203:1305-1314. [PMID: 24916161 DOI: 10.1111/nph.12881] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 04/30/2014] [Indexed: 05/11/2023]
Abstract
Rhizobia and legumes establish symbiotic interactions leading to the production of root nodules, in which bacteria fix atmospheric nitrogen for the plant's benefit. This symbiosis is efficient because of the high rhizobia population within nodules. Here, we investigated how legumes accommodate such bacterial colonization. We used a reverse genetic approach to identify a Medicago truncatula gene, SymCRK, which encodes a cysteine-rich receptor-like kinase that is required for rhizobia maintenance within the plant cells, and performed detailed phenotypic analyses of the corresponding mutant. The Medicago truncatula symCRK mutant developed nonfunctional and necrotic nodules. A nonarginine asparate (nonRD) motif, typical of receptors involved in innate immunity, is present in the SymCRK kinase domain. Similar to the dnf2 mutant, bacteroid differentiation defect, defense-like reactions and early senescence were observed in the symCRK nodules. However, the dnf2 and symCRK nodules differ by their degree of colonization, which is higher in symCRK. Furthermore, in contrast to dnf2, symCRK is not a conditional mutant. These results suggest that in M. truncatula at least two genes are involved in the symbiotic control of immunity. Furthermore, phenotype differences between the two mutants suggest that two distinct molecular mechanisms control suppression of plant immunity during nodulation.
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Affiliation(s)
- Fathi Berrabah
- Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France
| | - Marie Bourcy
- Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France
| | - Alexis Eschstruth
- Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France
| | - Anne Cayrel
- Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France
| | - Ibtissem Guefrachi
- Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France
| | - Peter Mergaert
- Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France
| | - Jiangqi Wen
- Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
| | - Viviane Jean
- Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France
| | - Kirankumar S Mysore
- Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK, 73401, USA
| | - Benjamin Gourion
- Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France
| | - Pascal Ratet
- Institut des sciences du végétal, CNRS, Saclay Plant Sciences, Avenue de la terrasse, 91198, Gif Sur Yvette, France
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Peng J, Hao B, Liu L, Wang S, Ma B, Yang Y, Xie F, Li Y. RNA-Seq and microarrays analyses reveal global differential transcriptomes of Mesorhizobium huakuii 7653R between bacteroids and free-living cells. PLoS One 2014; 9:e93626. [PMID: 24695521 PMCID: PMC3973600 DOI: 10.1371/journal.pone.0093626] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 03/04/2014] [Indexed: 11/18/2022] Open
Abstract
Mesorhizobium huakuii 7653R occurs either in nitrogen-fixing symbiosis with its host plant, Astragalus sinicus, or free-living in the soil. The M. huakuii 7653R genome has recently been sequenced. To better understand the complex biochemical and developmental changes that occur in 7653R during bacteroid development, RNA-Seq and Microarrays were used to investigate the differential transcriptomes of 7653R bacteroids and free-living cells. The two approaches identified several thousand differentially expressed genes. The most prominent up-regulation occurred in the symbiosis plasmids, meanwhile gene expression is concentrated to a set of genes (clusters) in bacteroids to fulfill corresponding functional requirements. The results suggested that the main energy metabolism is active while fatty acid metabolism is inactive in bacteroid and that most of genes relevant to cell cycle are down-regulated accordingly. For a global analysis, we reconstructed a protein-protein interaction (PPI) network for 7653R and integrated gene expression data into the network using Cytoscape. A highly inter-connected subnetwork, with function enrichment for nitrogen fixation, was found, and a set of hubs and previously uncharacterized genes participating in nitrogen fixation were identified. The results described here provide a broader biological landscape and novel insights that elucidate rhizobial bacteroid differentiation, nitrogen fixation and related novel gene functions.
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Affiliation(s)
- Jieli Peng
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, P. R. China
| | - Baohai Hao
- Center for Bioinformatics, School of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, P. R. China
| | - Liu Liu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, P. R. China
| | - Shanming Wang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, P. R. China
| | - Binguang Ma
- Center for Bioinformatics, School of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, P. R. China
| | - Yi Yang
- Center for Bioinformatics, School of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, P. R. China
| | - Fuli Xie
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, P. R. China
| | - Youguo Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, P. R. China
- * E-mail:
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37
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Kondorosi E, Mergaert P, Kereszt A. A paradigm for endosymbiotic life: cell differentiation of Rhizobium bacteria provoked by host plant factors. Annu Rev Microbiol 2014; 67:611-28. [PMID: 24024639 DOI: 10.1146/annurev-micro-092412-155630] [Citation(s) in RCA: 120] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Symbiosis between Rhizobium bacteria and legumes leads to the formation of the root nodule. The endosymbiotic bacteria reside in polyploid host cells as membrane-surrounded vesicles where they reduce atmospheric nitrogen to support plant growth by supplying ammonia in exchange for carbon sources and energy. The morphology and physiology of endosymbionts, despite their common function, are highly divergent in different hosts. In galegoid plants, the endosymbionts are terminally differentiated, uncultivable polyploid cells, with remarkably elongated and even branched Y-shaped cells. Bacteroid differentiation is controlled by host peptides, many of which have antibacterial activity and require the bacterial function of BacA. Although the precise and combined action of several hundred host peptides and BacA has yet to be discovered, similarities, especially to certain insect-bacterium symbioses involving likewise host peptides for manipulation of endosymbionts, suggest convergent evolution. Rhizobium-legume symbiosis provides a rich source of information for understanding host-controlled endosymbiotic life in eukaryotic cells.
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Affiliation(s)
- Eva Kondorosi
- Institut des Sciences du Végétal, CNRS UPR 2355, Gif sur Yvette 91198, France; ,
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38
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Berrabah F, Bourcy M, Cayrel A, Eschstruth A, Mondy S, Ratet P, Gourion B. Growth conditions determine the DNF2 requirement for symbiosis. PLoS One 2014; 9:e91866. [PMID: 24632747 PMCID: PMC3954807 DOI: 10.1371/journal.pone.0091866] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 02/17/2014] [Indexed: 11/18/2022] Open
Abstract
Rhizobia and legumes are able to interact in a symbiotic way leading to the development of root nodules. Within nodules, rhizobia fix nitrogen for the benefit of the plant. These interactions are efficient because spectacularly high densities of nitrogen fixing rhizobia are maintained in the plant cells. DNF2, a Medicago truncatula gene has been described as required for nitrogen fixation, bacteroid's persistence and to prevent defense-like reactions in the nodules. This manuscript shows that a Rhizobium mutant unable to differentiate is not sufficient to trigger defense-like reactions in this organ. Furthermore, we show that the requirement of DNF2 for effective symbiosis can be overcome by permissive growth conditions. The dnf2 knockout mutants grown in vitro on agarose or Phytagel as gelling agents are able to produce nodules fixing nitrogen with the same efficiency as the wild-type. However, when agarose medium is supplemented with the plant defense elicitor ulvan, the dnf2 mutant recovers the fix- phenotype. Together, our data show that plant growth conditions impact the gene requirement for symbiotic nitrogen fixation and suggest that they influence the symbiotic suppression of defense reactions in nodules.
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Affiliation(s)
- Fathi Berrabah
- Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, Gif sur Yvette, France
| | - Marie Bourcy
- Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, Gif sur Yvette, France
| | - Anne Cayrel
- Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, Gif sur Yvette, France
| | - Alexis Eschstruth
- Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, Gif sur Yvette, France
| | - Samuel Mondy
- Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, Gif sur Yvette, France
| | - Pascal Ratet
- Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, Gif sur Yvette, France
- * E-mail:
| | - Benjamin Gourion
- Institut des Sciences du Végétal, Centre National de la Recherche Scientifique, Gif sur Yvette, France
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39
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Host plant peptides elicit a transcriptional response to control the Sinorhizobium meliloti cell cycle during symbiosis. Proc Natl Acad Sci U S A 2014; 111:3561-6. [PMID: 24501120 DOI: 10.1073/pnas.1400450111] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The α-proteobacterium Sinorhizobium meliloti establishes a chronic intracellular infection during the symbiosis with its legume hosts. Within specialized host cells, S. meliloti differentiates into highly polyploid, enlarged nitrogen-fixing bacteroids. This differentiation is driven by host cells through the production of defensin-like peptides called "nodule-specific cysteine-rich" (NCR) peptides. Recent research has shown that synthesized NCR peptides exhibit antimicrobial activity at high concentrations but cause bacterial endoreduplication at sublethal concentrations. We leveraged synchronized S. meliloti populations to determine how treatment with a sublethal NCR peptide affects the cell cycle and physiology of bacteria at the molecular level. We found that at sublethal levels a representative NCR peptide specifically blocks cell division and antagonizes Z-ring function. Gene-expression profiling revealed that the cell division block was produced, in part, through the substantial transcriptional response elicited by sublethal NCR treatment that affected ∼15% of the genome. Expression of critical cell-cycle regulators, including ctrA, and cell division genes, including genes required for Z-ring function, were greatly attenuated in NCR-treated cells. In addition, our experiments identified important symbiosis functions and stress responses that are induced by sublethal levels of NCR peptides and other antimicrobial peptides. Several of these stress-response pathways also are found in related α-proteobacterial pathogens and might be used by S. meliloti to sense host cues during infection. Our data suggest a model in which, in addition to provoking stress responses, NCR peptides target intracellular regulatory pathways to drive S. meliloti endoreduplication and differentiation during symbiosis.
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40
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Enteric YaiW is a surface-exposed outer membrane lipoprotein that affects sensitivity to an antimicrobial peptide. J Bacteriol 2013; 196:436-44. [PMID: 24214946 DOI: 10.1128/jb.01179-13] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
yaiW is a previously uncharacterized gene found in enteric bacteria that is of particular interest because it is located adjacent to the sbmA gene, whose bacA ortholog is required for Sinorhizobium meliloti symbiosis and Brucella abortus pathogenesis. We show that yaiW is cotranscribed with sbmA in Escherichia coli and Salmonella enterica serovar Typhi and Typhimurium strains. We present evidence that the YaiW is a palmitate-modified surface exposed outer membrane lipoprotein. Since BacA function affects the very-long-chain fatty acid (VLCFA) modification of S. meliloti and B. abortus lipid A, we tested whether SbmA function might affect either the fatty acid modification of the YaiW lipoprotein or the fatty acid modification of enteric lipid A but found that it did not. Interestingly, we did observe that E. coli SbmA suppresses deficiencies in the VLCFA modification of the lipopolysaccharide of an S. meliloti bacA mutant despite the absence of VLCFA in E. coli. Finally, we found that both YaiW and SbmA positively affect the uptake of proline-rich Bac7 peptides, suggesting a possible connection between their cellular functions.
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Pierre O, Engler G, Hopkins J, Brau F, Boncompagni E, Hérouart D. Peribacteroid space acidification: a marker of mature bacteroid functioning in Medicago truncatula nodules. PLANT, CELL & ENVIRONMENT 2013; 36:2059-2070. [PMID: 23586685 DOI: 10.1111/pce.12116] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 03/27/2013] [Accepted: 04/02/2013] [Indexed: 06/02/2023]
Abstract
Legumes form a symbiotic interaction with Rhizobiaceae bacteria, which differentiate into nitrogen-fixing bacteroids within nodules. Here, we investigated in vivo the pH of the peribacteroid space (PBS) surrounding the bacteroid and pH variation throughout symbiosis. In vivo confocal microscopy investigations, using acidotropic probes, demonstrated the acidic state of the PBS. In planta analysis of nodule senescence induced by distinct biological processes drastically increased PBS pH in the N2 -fixing zone (zone III). Therefore, the PBS acidification observed in mature bacteroids can be considered as a marker of bacteroid N2 fixation. Using a pH-sensitive ratiometric probe, PBS pH was measured in vivo during the whole symbiotic process. We showed a progressive acidification of the PBS from the bacteroid release up to the onset of N2 fixation. Genetic and pharmacological approaches were conducted and led to disruption of the PBS acidification. Altogether, our findings shed light on the role of PBS pH of mature bacteroids in nodule functioning, providing new tools to monitor in vivo bacteroid physiology.
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Affiliation(s)
- Olivier Pierre
- UMR INRA 1355-CNRS 7254-Université de Nice Sophia-Antipolis, Institut Sophia Agrobiotech, 400 route des Chappes, F-06903, Sophia Antipolis, France
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42
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Functional characterization of SbmA, a bacterial inner membrane transporter required for importing the antimicrobial peptide Bac7(1-35). J Bacteriol 2013; 195:5343-51. [PMID: 24078610 DOI: 10.1128/jb.00818-13] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SbmA is an inner membrane protein of Gram-negative bacteria that is involved in the internalization of glycopeptides and prokaryotic and eukaryotic antimicrobial peptides, as well as of peptide nucleic acid (PNA) oligomers. The SbmA homolog BacA is required for the development of Sinorhizobium meliloti bacteroids within plant cells and favors chronic infections with Brucella abortus and Mycobacterium tuberculosis in mice. Here, we investigated functional features of SbmA/BacA using the proline-rich antimicrobial peptide Bac7(1-35) as a substrate. Circular dichroism and affinity chromatography studies were used to investigate the ability of SbmA to bind the peptide, and a whole-cell transport assay with fluorescently labeled peptide allowed the determination of transport kinetic parameters with a calculated Km value of 6.95 ± 0.89 μM peptide and a Vmax of 53.91 ± 3.17 nmol/min/mg SbmA. Use of a bacterial two-hybrid system coupled to SEC-MALLS (size exclusion chromatography coupled with multiangle laser light scattering) analyses established that SbmA is a homodimer in the membrane, and treatment of the cells with arsenate or ionophores indicated that the peptide transport mediated by SbmA is driven by the electrochemical gradient. Overall, these results shed light on the SbmA-mediated internalization of peptide substrates and suggest that the transport of an unknown substrate(s) represents the function of this protein.
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43
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Abstract
SbmA protein has been proposed as a dimeric secondary transporter. The protein is involved in the transport of microcins B17 and J25, bleomycin, proline-rich antimicrobial peptides, antisense peptide phosphorodiamidate morpholino oligomers, and peptide nucleic acids into the Escherichia coli cytoplasm. The sbmA homologue is found in a variety of bacteria, though the physiological role of the protein is hitherto unknown. In this work, we carried out a functional and structural analysis to determine which amino acids are critical for the transport properties of SbmA. We created a set of 15 site-directed sbmA mutants in which single conserved amino acids were replaced by glycine residues. Our work demonstrated that strains carrying the site-directed mutants V102G, F219G, and E276G had a null phenotype for SbmA transport functions. In contrast, strains carrying the single point mutants W19G, W53G, F60G, S69G, N155G, R190, L233G, A344G, T255G, N308G, and R385G showed transport capacities indistinguishable from those of strains harboring a wild-type sbmA. The strain carrying the Y116G mutant exhibited mixed phenotypic characteristics. We also demonstrated that those sbmA mutants with severely impaired transport capacity showed a dominant negative phenotype. Electron microscopy data and in silico three-dimensional (3D) homology modeling support the idea that SbmA forms a homodimeric complex, closely resembling the membrane-spanning region of the ATP-binding cassette transporter family. Direct mapping of the sbmA single point mutants on the protein surface allowed us to explain the observed phenotypic differences in transport ability.
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44
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Galardini M, Pini F, Bazzicalupo M, Biondi EG, Mengoni A. Replicon-dependent bacterial genome evolution: the case of Sinorhizobium meliloti. Genome Biol Evol 2013; 5:542-58. [PMID: 23431003 PMCID: PMC3622305 DOI: 10.1093/gbe/evt027] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Many bacterial species, such as the alphaproteobacterium Sinorhizobium meliloti, are characterized by open pangenomes and contain multipartite genomes consisting of a chromosome and other large-sized replicons, such as chromids, megaplasmids, and plasmids. The evolutionary forces in both functional and structural aspects that shape the pangenome of species with multipartite genomes are still poorly understood. Therefore, we sequenced the genomes of 10 new S. meliloti strains, analyzed with four publicly available additional genomic sequences. Results indicated that the three main replicons present in these strains (a chromosome, a chromid, and a megaplasmid) partly show replicon-specific behaviors related to strain differentiation. In particular, the pSymB chromid was shown to be a hot spot for positively selected genes, and, unexpectedly, genes resident in the pSymB chromid were also found to be more widespread in distant taxa than those located in the other replicons. Moreover, through the exploitation of a DNA proximity network, a series of conserved “DNA backbones” were found to shape the evolution of the genome structure, with the rest of the genome experiencing rearrangements. The presented data allow depicting a scenario where the pSymB chromid has a distinctive role in intraspecies differentiation and in evolution through positive selection, whereas the pSymA megaplasmid mostly contributes to structural fluidity and to the emergence of new functions, indicating a specific evolutionary role for each replicon in the pangenome evolution.
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Affiliation(s)
- Marco Galardini
- Department of Biology, University of Firenze, Firenze, Italy
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45
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Tang G, Lu D, Wang D, Luo L. Sinorhizobium meliloti lsrB is involved in alfalfa root nodule development and nitrogen-fixing bacteroid differentiation. ACTA ACUST UNITED AC 2013. [DOI: 10.1007/s11434-013-5960-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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46
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Haag AF, Arnold MFF, Myka KK, Kerscher B, Dall'Angelo S, Zanda M, Mergaert P, Ferguson GP. Molecular insights into bacteroid development duringRhizobium–legume symbiosis. FEMS Microbiol Rev 2013; 37:364-83. [DOI: 10.1111/1574-6976.12003] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Revised: 09/12/2012] [Accepted: 09/14/2012] [Indexed: 01/09/2023] Open
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47
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Nallu S, Silverstein KAT, Samac DA, Bucciarelli B, Vance CP, VandenBosch KA. Regulatory patterns of a large family of defensin-like genes expressed in nodules of Medicago truncatula. PLoS One 2013; 8:e60355. [PMID: 23573247 PMCID: PMC3613412 DOI: 10.1371/journal.pone.0060355] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 02/25/2013] [Indexed: 12/31/2022] Open
Abstract
Root nodules are the symbiotic organ of legumes that house nitrogen-fixing bacteria. Many genes are specifically induced in nodules during the interactions between the host plant and symbiotic rhizobia. Information regarding the regulation of expression for most of these genes is lacking. One of the largest gene families expressed in the nodules of the model legume Medicago truncatula is the nodule cysteine-rich (NCR) group of defensin-like (DEFL) genes. We used a custom Affymetrix microarray to catalog the expression changes of 566 NCRs at different stages of nodule development. Additionally, bacterial mutants were used to understand the importance of the rhizobial partners in induction of NCRs. Expression of early NCRs was detected during the initial infection of rhizobia in nodules and expression continued as nodules became mature. Late NCRs were induced concomitantly with bacteroid development in the nodules. The induction of early and late NCRs was correlated with the number and morphology of rhizobia in the nodule. Conserved 41 to 50 bp motifs identified in the upstream 1,000 bp promoter regions of NCRs were required for promoter activity. These cis-element motifs were found to be unique to the NCR family among all annotated genes in the M. truncatula genome, although they contain sub-regions with clear similarity to known regulatory motifs involved in nodule-specific expression and temporal gene regulation.
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Affiliation(s)
- Sumitha Nallu
- Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota, United States of America
| | - Kevin A. T. Silverstein
- Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota, United States of America
| | - Deborah A. Samac
- US Department of Agriculture-Agricultural Research Service-Plant Science Research Unit, Saint Paul, Minnesota, United States of America
| | - Bruna Bucciarelli
- US Department of Agriculture-Agricultural Research Service-Plant Science Research Unit, Saint Paul, Minnesota, United States of America
| | - Carroll P. Vance
- US Department of Agriculture-Agricultural Research Service-Plant Science Research Unit, Saint Paul, Minnesota, United States of America
| | - Kathryn A. VandenBosch
- Department of Plant Biology, University of Minnesota, Saint Paul, Minnesota, United States of America
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Puckett SE, Reese KA, Mitev GM, Mullen V, Johnson RC, Pomraning KR, Mellbye BL, Tilley LD, Iversen PL, Freitag M, Geller BL. Bacterial resistance to antisense peptide phosphorodiamidate morpholino oligomers. Antimicrob Agents Chemother 2012; 56:6147-53. [PMID: 22985881 PMCID: PMC3497173 DOI: 10.1128/aac.00850-12] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 06/25/2012] [Indexed: 12/16/2022] Open
Abstract
Peptide phosphorodiamidate morpholino oligomers (PPMOs) are synthetic DNA mimics that bind cRNA and inhibit bacterial gene expression. The PPMO (RFF)(3)RXB-AcpP (where R is arginine, F, phenylalanine, X is 6-aminohexanoic acid, B is β-alanine, and AcpP is acyl carrier protein) is complementary to 11 bases of the essential gene acpP (which encodes acyl carrier protein). The MIC of (RFF)(3)RXB-AcpP was 2.5 μM (14 μg/ml) in Escherichia coli W3110. The rate of spontaneous resistance of E. coli to (RFF)(3)RXB-AcpP was 4 × 10(-7) mutations/cell division. A spontaneous (RFF)(3)RXB-AcpP-resistant mutant (PR200.1) was isolated. The MIC of (RFF)(3)RXB-AcpP was 40 μM (224 μg/ml) for PR200.1. The MICs of standard antibiotics for PR200.1 and W3110 were identical. The sequence of acpP was identical in PR200.1 and W3110. PR200.1 was also resistant to other PPMOs conjugated to (RFF)(3)RXB or peptides with a similar composition or pattern of cationic and nonpolar residues. Genomic sequencing of PR200.1 identified a mutation in sbmA, which encodes an active transport protein. In separate experiments, a (RFF)(3)RXB-AcpP-resistant isolate (RR3) was selected from a transposome library, and the insertion was mapped to sbmA. Genetic complementation of PR200.1 or RR3 with sbmA restored susceptibility to (RFF)(3)RXB-AcpP. Deletion of sbmA caused resistance to (RFF)(3)RXB-AcpP. We conclude that resistance to (RFF)(3)RXB-AcpP was linked to the peptide and not the phosphorodiamidate morpholino oligomer, dependent on the composition or repeating pattern of amino acids, and caused by mutations in sbmA. The data further suggest that (RFF)(3)R-XB PPMOs may be transported across the plasma membrane by SbmA.
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Affiliation(s)
| | | | | | | | | | - Kyle R. Pomraning
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | | | | | | | - Michael Freitag
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon, USA
| | - Bruce L. Geller
- Department of Microbiology
- AVI BioPharma, Inc., Corvallis, Oregon, USA
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Partial complementation of Sinorhizobium meliloti bacA mutant phenotypes by the Mycobacterium tuberculosis BacA protein. J Bacteriol 2012; 195:389-98. [PMID: 23161027 DOI: 10.1128/jb.01445-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Sinorhizobium meliloti BacA ABC transporter protein plays an important role in its nodulating symbiosis with the legume alfalfa (Medicago sativa). The Mycobacterium tuberculosis BacA homolog was found to be important for the maintenance of chronic murine infections, yet its in vivo function is unknown. In the legume plant as well as in the mammalian host, bacteria encounter host antimicrobial peptides (AMPs). We found that the M. tuberculosis BacA protein was able to partially complement the symbiotic defect of an S. meliloti BacA-deficient mutant on alfalfa plants and to protect this mutant in vitro from the antimicrobial activity of a synthetic legume peptide, NCR247, and a recombinant human β-defensin 2 (HBD2). This finding was also confirmed using an M. tuberculosis insertion mutant. Furthermore, M. tuberculosis BacA-mediated protection of the legume symbiont S. meliloti against legume defensins as well as HBD2 is dependent on its attached ATPase domain. In addition, we show that M. tuberculosis BacA mediates peptide uptake of the truncated bovine AMP, Bac7(1-16). This process required a functional ATPase domain. We therefore suggest that M. tuberculosis BacA is important for the transport of peptides across the cytoplasmic membrane and is part of a complete ABC transporter. Hence, BacA-mediated protection against host AMPs might be important for the maintenance of latent infections.
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50
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Haag AF, Arnold MFF, Myka KK, Kerscher B, Dall'Angelo S, Zanda M, Mergaert P, Ferguson GP. Molecular insights into bacteroid development duringRhizobium-legume symbiosis. FEMS Microbiol Rev 2012. [DOI: 10.1111/1574-6976.2012.12003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Affiliation(s)
- Andreas F. Haag
- School of Medicine & Dentistry, Institute of Medical Sciences, University of Aberdeen; Aberdeen; UK
| | - Markus F. F. Arnold
- School of Medicine & Dentistry, Institute of Medical Sciences, University of Aberdeen; Aberdeen; UK
| | - Kamila K. Myka
- School of Medicine & Dentistry, Institute of Medical Sciences, University of Aberdeen; Aberdeen; UK
| | - Bernhard Kerscher
- School of Medicine & Dentistry, Institute of Medical Sciences, University of Aberdeen; Aberdeen; UK
| | - Sergio Dall'Angelo
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen; Aberdeen; UK
| | | | - Peter Mergaert
- Institut des Sciences du Végétal, Centre National de la Recherche Scientifique; Gif-sur-Yvette Cedex; France
| | - Gail P. Ferguson
- School of Medicine & Dentistry, Institute of Medical Sciences, University of Aberdeen; Aberdeen; UK
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