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Suo Z, Cummings DA, Puri AW, Schaefer AL, Greenberg EP. A Mesorhizobium japonicum quorum sensing circuit that involves three linked genes and an unusual acyl-homoserine lactone signal. mBio 2023; 14:e0101023. [PMID: 37227303 PMCID: PMC10470506 DOI: 10.1128/mbio.01010-23] [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: 04/25/2023] [Accepted: 04/27/2023] [Indexed: 05/26/2023] Open
Abstract
Members of the genus Mesorhizobium, which are core components of the rhizosphere and specific symbionts of legume plants, possess genes for acyl-homoserine lactone (AHL) quorum sensing (QS). Here we show Mesorhizobium japonicum MAFF 303099 (formerly M. loti) synthesizes and responds to N-[(2E, 4E)-2,4-dodecadienoyl] homoserine lactone (2E, 4E-C12:2-HSL). We show that the 2E, 4E-C12:2-HSL QS circuit involves one of four luxR-luxI-type genes found in the sequenced genome of MAFF 303099. We refer to this circuit, which appears to be conserved among Mesorhizobium species, as R1-I1. We show that two other Mesorhizobium strains also produce 2E, 4E-C12:2-HSL. The 2E, 4E-C12:2-HSL is unique among known AHLs in its arrangement of two trans double bonds. The R1 response to 2E, 4E-C12:2-HSL is extremely selective in comparison with other LuxR homologs, and the trans double bonds appear critical for R1 signal recognition. Most well-studied LuxI-like proteins use S-adenosylmethionine and an acyl-acyl carrier protein as substrates for synthesis of AHLs. Others that form a subgroup of LuxI-type proteins use acyl-coenzyme A substrates rather than acyl-acyl carrier proteins. I1 clusters with the acyl-coenzyme A-type AHL synthases. We show that a gene linked to the I1 AHL synthase is involved in the production of the QS signal. The discovery of the unique I1 product enforces the view that further study of acyl-coenzyme A-dependent LuxI homologs will expand our knowledge of AHL diversity. The involvement of an additional enzyme in AHL generation leads us to consider this system a three-component QS circuit. IMPORTANCE We report a Mesorhizobium japonicum quorum sensing (QS) system involving a novel acyl-homoserine lactone (AHL) signal. This system is known to be involved in root nodule symbiosis with host plants. The chemistry of the newly described QS signal indicated that there may be a dedicated cellular enzyme involved in its synthesis in addition to the types known for production of other AHLs. Indeed, we report that an additional gene is required for synthesis of the unique signal, and we propose that this is a three-component QS circuit as opposed to the canonical two-component AHL QS circuits. The signaling system is exquisitely selective. The selectivity may be important when this species resides in the complex microbial communities around host plants and may make this system useful in various synthetic biology applications of QS circuits.
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Affiliation(s)
- Zehui Suo
- Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, China
| | - Dale A. Cummings
- Department of Chemistry and the Henry Eyring Center for Cell and Genomes Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Aaron W. Puri
- Department of Chemistry and the Henry Eyring Center for Cell and Genomes Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Amy L. Schaefer
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - E. Peter Greenberg
- Department of Microbiology, University of Washington, Seattle, Washington, USA
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2
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Li S, Wu S, Ren Y, Meng Q, Yin J, Yu Z. Characterization of differentiated autoregulation of LuxI/LuxR-type quorum sensing system in Pseudoalteromonas. Biochem Biophys Res Commun 2022; 590:177-183. [PMID: 34990892 DOI: 10.1016/j.bbrc.2021.12.107] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 12/27/2021] [Indexed: 11/24/2022]
Abstract
Gram-negative bacteria usually use acyl-homoserine lactones (AHLs)-mediated LuxI/LuxR-type quorum sensing (QS) systems for cell-cell cooperation and/or bacteria-environment communication. LuxI and LuxR are AHLs synthase and receptor, respectively. These two parts could form a positive regulatory feedback loop, controlling various types of group behaviors. However, the autoregulation mechanisms between them are fragmented and could be highly differentiated in different bacteria. Here, we clarified the autoregulation mechanism between LuxI and LuxR in Pseudoalteromonas sp. R3. YasI (LuxI in strain R3) synthesizes two types of AHLs, C8-HSL and 3-OH-C8-HSL. It is worth noting that YasR (LuxR in strain R3) only responds to C8-HSL rather than 3-OH-C8-HSL. YasR-C8HSL can activate the yasI transcription by recognizing "lux box" at yasI upstream. Interestingly, YasR can directly promote the yasR expression with AHL-independent manner, but AHL absence caused by the yasI-deficiency led to the significant decrease in the yasR expression. Further study demonstrated that the yasI-deficiency can result in the decrease in the yasR mRNA stability. Notably, both yasI-deficiency and yasR-deficiency led to the significant decrease in the expression of hfq encoding RNA chaperone. Therefore, it was speculated that not only YasR itself can directly regulate the yasR transcription, but YasR-C8HSL complex indirectly affects the yasR mRNA stability by regulating Hfq.
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Affiliation(s)
- Shuangjia Li
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Shijun Wu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Yixuan Ren
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Qiu Meng
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Jianhua Yin
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Zhiliang Yu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China.
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Isaac A, Francis B, Amann RI, Amin SA. Tight Adherence (Tad) Pilus Genes Indicate Putative Niche Differentiation in Phytoplankton Bloom Associated Rhodobacterales. Front Microbiol 2021; 12:718297. [PMID: 34447362 PMCID: PMC8383342 DOI: 10.3389/fmicb.2021.718297] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 07/19/2021] [Indexed: 11/14/2022] Open
Abstract
The multiple interactions of phytoplankton and bacterioplankton are central for our understanding of aquatic environments. A prominent example of those is the consistent association of diatoms with Alphaproteobacteria of the order Rhodobacterales. These photoheterotrophic bacteria have traditionally been described as generalists that scavenge dissolved organic matter. Many observations suggest that members of this clade are specialized in colonizing the microenvironment of diatom cells, known as the phycosphere. However, the molecular mechanisms that differentiate Rhodobacterales generalists and phycosphere colonizers are poorly understood. We investigated Rhodobacterales in the North Sea during the 2010–2012 spring blooms using a time series of 38 deeply sequenced metagenomes and 10 metaproteomes collected throughout these events. Rhodobacterales metagenome assembled genomes (MAGs) were recurrently abundant. They exhibited the highest gene enrichment and protein expression of small-molecule transporters, such as monosaccharides, thiamine and polyamine transporters, and anaplerotic pathways, such as ethylmalonyl and propanoyl-CoA metabolic pathways, all suggestive of a generalist lifestyle. Metaproteomes indicated that the species represented by these MAGs were the dominant suppliers of vitamin B12 during the blooms, concomitant with a significant enrichment of genes related to vitamin B12 biosynthesis suggestive of association with diatom phycospheres. A closer examination of putative generalists and colonizers showed that putative generalists had persistently higher relative abundance throughout the blooms and thus produced more than 80% of Rhodobacterales transport proteins, suggesting rapid growth. In contrast, putative phycosphere colonizers exhibited large fluctuation in relative abundance across the different blooms and correlated strongly with particular diatom species that were dominant during the blooms each year. The defining feature of putative phycosphere colonizers is the presence of the tight adherence (tad) gene cluster, which is responsible for the assembly of adhesive pili that presumably enable attachment to diatom hosts. In addition, putative phycosphere colonizers possessed higher prevalence of secondary metabolite biosynthetic gene clusters, particularly homoserine lactones, which can regulate bacterial attachment through quorum sensing. Altogether, these findings suggest that while many members of Rhodobacterales are competitive during diatom blooms, only a subset form close associations with diatoms by colonizing their phycospheres.
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Affiliation(s)
- Ashley Isaac
- Marine Microbial Ecology Laboratory, Biology Program, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates.,Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Ben Francis
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Rudolf I Amann
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Shady A Amin
- Marine Microbial Ecology Laboratory, Biology Program, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
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Kusaba I, Nakao T, Maita H, Sato S, Chijiiwa R, Yamada E, Arima S, Kojoma M, Ishimaru K, Akashi R, Suzuki A. Mesorhizobium sp. J8 can establish symbiosis with Glycyrrhiza uralensis, increasing glycyrrhizin production. PLANT BIOTECHNOLOGY (TOKYO, JAPAN) 2021; 38:57-66. [PMID: 34177325 PMCID: PMC8215473 DOI: 10.5511/plantbiotechnology.20.1124a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 11/24/2020] [Indexed: 06/13/2023]
Abstract
Licorice (Glycyrrhiza uralensis) is a medicinal plant that contains glycyrrhizin (GL), which has various pharmacological activities. Because licorice is a legume, it can establish a symbiotic relationship with nitrogen-fixing rhizobial bacteria. However, the effect of this symbiosis on GL production is unknown. Rhizobia were isolated from root nodules of Glycyrrhiza glabra, and a rhizobium that can form root nodules in G. uralensis was selected. Whole-genome analysis revealed a single circular chromosome of 6.7 Mbp. This rhizobium was classified as Mesorhizobium by phylogenetic analysis and was designated Mesorhizobium sp. J8. When G. uralensis plants grown from cuttings were inoculated with J8, root nodules formed. Shoot biomass and SPAD values of inoculated plants were significantly higher than those of uninoculated controls, and the GL content of the roots was 3.2 times that of controls. Because uninoculated plants from cuttings showed slight nodule formation, we grew plants from seeds in plant boxes filled with sterilized vermiculite, inoculated half of the seedlings with J8, and grew them with or without 100 µM KNO3. The SPAD values of inoculated plants were significantly higher than those of uninoculated plants. Furthermore, the expression level of the CYP88D6 gene, which is a marker of GL synthesis, was 2.5 times higher than in inoculated plants. These results indicate that rhizobial symbiosis promotes both biomass and GL production in G. uralensis.
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Affiliation(s)
- Ikuko Kusaba
- Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga 840-8502, Japan
| | - Takahiro Nakao
- Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga 840-8502, Japan
| | - Hiroko Maita
- Tohoku University, 2-1-1 Katahira, Miyagi 980-8577, Japan
| | - Shusei Sato
- Tohoku University, 2-1-1 Katahira, Miyagi 980-8577, Japan
| | - Ryota Chijiiwa
- Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga 840-8502, Japan
| | - Emi Yamada
- Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga 840-8502, Japan
| | - Susumu Arima
- Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga 840-8502, Japan
- The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan
| | - Mareshige Kojoma
- Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, 1757 Kanazawa, Hokkaido 061-0293, Japan
| | - Kanji Ishimaru
- Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga 840-8502, Japan
- The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan
| | - Ryo Akashi
- Faculty of Agriculture, University of Miyazaki, 1-1 Nishi Gakuen-kibanadai, Miyazaki 889-2192, Japan
| | - Akihiro Suzuki
- Faculty of Agriculture, Saga University, 1 Honjo-machi, Saga 840-8502, Japan
- The United Graduate School of Agricultural Sciences, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan
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Yajima A, Katsuta R, Shimura M, Yoshihara A, Saito T, Ishigami K, Kai K. Disproof of the Proposed Structures of Bradyoxetin, a Putative Bradyrhizobium japonicum Signaling Molecule, and HMCP, a Putative Ralstonia solanacearum Quorum-Sensing Molecule. JOURNAL OF NATURAL PRODUCTS 2021; 84:495-502. [PMID: 33513023 DOI: 10.1021/acs.jnatprod.0c01369] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
First, we revisited the reported NMR data of bradyoxetin, a putative cell density factor of Bradyrhizobium japonicum, and found some inconsistencies in the proposed structure. To elucidate the correct structure, we synthesized model oxetane compounds and confirmed that the NMR data of the synthetic compounds did not match those of the reported bradyoxetin. After reinterpreting the reported NMR data, we concluded that bradyoxetin must be chloramphenicol. Next, some derivatives of 2-hydroxy-4-((methylamino)(phenyl)methyl)cyclopentanone (HMCP), which is a putative quorum-sensing molecule of Ralstonia solanacearum, were synthesized. The NMR spectra of the synthesized compounds were completely different from those of the reported natural products. Based on theoretical studies, including the estimation of 1H and 13C NMR chemical shifts using density functional theory calculations, we confirmed the correctness of the structure of the synthesized compound. These results strongly suggest that the proposed structure of HMCP could be incorrect.
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Affiliation(s)
- Arata Yajima
- Department of Chemistry for Life Sciences and Agriculture, Faculty of Life Sciences, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan
| | - Ryo Katsuta
- Department of Chemistry for Life Sciences and Agriculture, Faculty of Life Sciences, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan
| | - Mikaho Shimura
- Graduate School of Agriculture, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan
| | - Ayaka Yoshihara
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka 599-8531, Japan
| | - Tatsuo Saito
- Department of Chemistry for Life Sciences and Agriculture, Faculty of Life Sciences, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan
| | - Ken Ishigami
- Department of Chemistry for Life Sciences and Agriculture, Faculty of Life Sciences, Tokyo University of Agriculture, Setagaya-ku, Sakuragaoka 1-1-1, Tokyo 156-8502, Japan
| | - Kenji Kai
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka 599-8531, Japan
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Identification of a solo acylhomoserine lactone synthase from the myxobacterium Archangium gephyra. Sci Rep 2021; 11:3018. [PMID: 33542315 PMCID: PMC7862692 DOI: 10.1038/s41598-021-82480-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/20/2021] [Indexed: 12/31/2022] Open
Abstract
Considered a key taxon in soil and marine microbial communities, myxobacteria exist as coordinated swarms that utilize a combination of lytic enzymes and specialized metabolites to facilitate predation of microbes. This capacity to produce specialized metabolites and the associated abundance of biosynthetic pathways contained within their genomes have motivated continued drug discovery efforts from myxobacteria. Of all myxobacterial biosynthetic gene clusters deposited in the antiSMASH database, only one putative acylhomoserine lactone (AHL) synthase, agpI, was observed, in genome data from Archangium gephyra. Without an AHL receptor also apparent in the genome of A. gephyra, we sought to determine if AgpI was an uncommon example of an orphaned AHL synthase. Herein we report the bioinformatic assessment of AgpI and discovery of a second AHL synthase from Vitiosangium sp. During axenic cultivation conditions, no detectible AHL metabolites were observed in A. gephyra extracts. However, heterologous expression of each synthase in Escherichia coli provided detectible quantities of 3 AHL signals including 2 known AHLs, C8-AHL and C9-AHL. These results suggest that A. gephyra AHL production is dormant during axenic cultivation. The functional, orphaned AHL synthase, AgpI, is unique to A. gephyra, and its utility to the predatory myxobacterium remains unknown.
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Modulation of Quorum Sensing as an Adaptation to Nodule Cell Infection during Experimental Evolution of Legume Symbionts. mBio 2020; 11:mBio.03129-19. [PMID: 31992622 PMCID: PMC6989110 DOI: 10.1128/mbio.03129-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Over millions of years, changes have occurred in regulatory circuitries in response to genome reorganization and/or persistent changes in environmental conditions. How bacteria optimize regulatory circuitries is crucial to understand bacterial adaptation. Here, we analyzed the experimental evolution of the plant pathogen Ralstonia solanacearum into legume symbionts after the transfer of a natural plasmid encoding the essential mutualistic genes. We showed that the Phc quorum sensing system required for the virulence of the ancestral bacterium was reconfigured to improve intracellular infection of root nodules induced by evolved Ralstonia A single mutation in either the PhcB autoinducer synthase or the PhcQ regulator of the sensory cascade tuned the kinetics of activation of the central regulator PhcA in response to cell density so that the minimal stimulatory concentration of autoinducers needed for a given response was increased. Yet, a change in the expression of a PhcA target gene was observed in infection threads progressing in root hairs, suggesting early programming for the late accommodation of bacteria in nodule cells. Moreover, this delayed switch to the quorum sensing mode decreased the pathogenicity of the ancestral strain, illustrating the functional plasticity of regulatory systems and showing how a small modulation in signal response can produce drastic changes in bacterial lifestyle.IMPORTANCE Rhizobia are soil bacteria from unrelated genera able to form a mutualistic relationship with legumes. Bacteria induce the formation of root nodules, invade nodule cells, and fix nitrogen to the benefit of the plant. Rhizobial lineages emerged from the horizontal transfer of essential symbiotic genes followed by genome remodeling to activate and/or optimize the acquired symbiotic potential. This evolutionary scenario was replayed in a laboratory evolution experiment in which the plant pathogen Ralstonia solanacearum successively evolved the capacities to nodulate Mimosa pudica and poorly invade, then massively invade, nodule cells. In some lines, the improvement of intracellular infection was achieved by mutations modulating a quorum sensing regulatory system of the ancestral strain. This modulation that affects the activity of a central regulator during the earliest stages of symbiosis has a huge impact on late stages of symbiosis. This work showed that regulatory rewiring is the main driver of this pathogeny-symbiosis transition.
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Ling J, Zhou L, Wu G, Zhao Y, Jiang T, Liu F. The AHL Quorum-Sensing System Negatively Regulates Growth and Autolysis in Lysobacter brunescens. Front Microbiol 2019; 10:2748. [PMID: 31849892 PMCID: PMC6902743 DOI: 10.3389/fmicb.2019.02748] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 11/12/2019] [Indexed: 11/13/2022] Open
Abstract
Lysobacter species are emerging as novel sources of antibiotics, but the regulation of their physiological metabolism is still poorly understood. In this work, we extracted AHL (acyl-homoserine lactone) autoinducers, identified the structures of AHLs and described the AHL quorum-sensing system in Lysobacter brunescens OH23. AHLs were isolated from the supernatant of L. brunescens OH23, and ESI-MS/MS (electrospray ionization mass spectrometry) analysis revealed biosynthesis of three different AHL chemical structures by L. brunescens OH23: N-(3-oxohexanoyl)- homoserine lactone (HSL), 3-OH-C10-HSL and C8-HSL. The growth rate of AHL quorum-sensing knockout mutants was dramatically increased compared to that of wildtype. Sucrose consumptions were also twice as high in AHL quorum-sensing knockout mutants than that in wildtype in early-log phase. Additionally, expression of key genes related to sucrose metabolism α-glucosidase was enhanced in AHL quorum-sensing knockout mutants, which indicated that AHL quorum sensing negatively regulates sucrose uptake and metabolism which further affects the growth rate of L. brunescens. Furthermore, autolysis was strongly induced in AHL quorum-sensing knockout mutants compared to wildtype, suggesting that AHL quorum sensing plays a negative regulatory role in cell autolysis. Moreover, compared to wildtype, XSAC (Xanthomonas-specific antibiotic compound) production was significantly increased in AHL knockout mutants in the early-log and late-log phases, and surface motility capabilities are also enhanced also in AHL knockout mutants; the normalized data of XSAC production and surface motility and expressions of key genes related to these two phenotypes reveal that growth rare and autolysis strongly affects XSAC biosynthesis and surface motility rather than AHL quorum-sensing system. Our results show that the AHL quorum-sensing system negatively regulates cell growth and autolysis, and further maintain nutrition homeostasis and population stability in L. brunescens.
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Affiliation(s)
- Jun Ling
- Jiangsu Key Laboratory for Food Quality and Safety, State Key Laboratory Cultivation Base of Ministry of Science and Technology, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Lan Zhou
- Academy of Agricultural Sciences of Yanbian, Longjing, China
| | - Guichun Wu
- Jiangsu Key Laboratory for Food Quality and Safety, State Key Laboratory Cultivation Base of Ministry of Science and Technology, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Yancun Zhao
- Jiangsu Key Laboratory for Food Quality and Safety, State Key Laboratory Cultivation Base of Ministry of Science and Technology, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Tianping Jiang
- Jiangsu Key Laboratory for Food Quality and Safety, State Key Laboratory Cultivation Base of Ministry of Science and Technology, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China
| | - Fengquan Liu
- Jiangsu Key Laboratory for Food Quality and Safety, State Key Laboratory Cultivation Base of Ministry of Science and Technology, Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Nanjing, China.,School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China
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9
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Xu YY, Yang JS, Liu C, Wang ET, Wang RN, Qiu XQ, Li BZ, Chen WF, Yuan HL. Water-Soluble Humic Materials Regulate Quorum Sensing in Sinorhizobium meliloti Through a Novel Repressor of expR. Front Microbiol 2018; 9:3194. [PMID: 30627123 PMCID: PMC6309736 DOI: 10.3389/fmicb.2018.03194] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 12/10/2018] [Indexed: 11/23/2022] Open
Abstract
Quorum sensing (QS) plays an important role in the growth, nodulation, and nitrogen fixation of rhizobia. In this study, we show that water-soluble humic materials (WSHM) repress the expression of the QS related genes sinI, sinR, and expR in Sinorhizobium meliloti. This decreased the production of N-acetyl homoserine lactones (AHL) and exopolysaccharides (EPS), and ultimately increased S. meliloti cell density. We also identified a novel regulator, SMc03890 (renamed QsrR), which binds directly to the expR promoter. Deletion of qsrR increased expR expression. WSHM repressed the expression of expR by augmenting the interaction between QsrR and the expR promoter; this was determined by a bacterial-one-hybrid assay. These effects of WSHM on the QS system in S. meliloti may be the underlying mechanism by which WSHM increase the symbiotic nitrogen fixation of Medicago sativa inoculated with S. meliloti. This study provides the first evidence that humic acids regulate the QS of rhizobia and suggests that WSHM could be used as fertilizers to improve the efficiency of symbiotic nitrogen fixation.
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Affiliation(s)
- Yuan-Yuan Xu
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jin-Shui Yang
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Cong Liu
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - En-Tao Wang
- Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Ruo-Nan Wang
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xiao-Qian Qiu
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Bao-Zhen Li
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Wen-Feng Chen
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Hong-Li Yuan
- State Key Laboratory of Agrobiotechnology and Key Laboratory of Soil Microbial, Ministry of Agriculture, College of Biological Sciences, China Agricultural University, Beijing, China
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10
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Environmental Adaptability and Quorum Sensing: Iron Uptake Regulation during Biofilm Formation by Paracoccus denitrificans. Appl Environ Microbiol 2018; 84:AEM.00865-18. [PMID: 29776923 DOI: 10.1128/aem.00865-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 05/07/2018] [Indexed: 11/20/2022] Open
Abstract
Paracoccus denitrificans is a valuable model organism due to its versatile respiration capability and bioenergetic flexibility, both of which are critical to its survival in different environments. Quorum sensing (QS) plays a crucial role in the regulation of many cell functions; however, whether QS systems play a role in P. denitrificans is unknown. In this study, we demonstrated that iron uptake systems in P. denitrificans were directly regulated by a newly identified QS system. Genes coding for TonB-dependent systems, which transport chelated iron, were transcribed at higher levels in the QS-defective mutants. In contrast, genes coding for the Fbp system, which is TonB independent and transports unchelated ferric iron, were downregulated in the mutants. In brief, QS in P. denitrificans triggers a switch in iron uptake from TonB-dependent to TonB-independent transport during biofilm formation as higher concentrations of iron accumulate in the exopolysaccharide (EPS). Switching from TonB-dependent iron uptake systems to TonB-independent systems not only prevents cells from absorbing excess iron but also conserves energy. Our data suggest that iron uptake strategies are directly regulated by QS in Paracoccus denitrificans to support their survival in available ecological niches.IMPORTANCE As iron is an important trace metal for most organisms, its absorption is highly regulated. Fur has been reported as a prevalent regulator of iron acquisition. In addition, there is a relationship between QS and iron acquisition in pathogenic microbes. However, there have been few studies on the iron uptake strategies of nonpathogenic bacteria. In this study, we demonstrated that iron uptake systems in Paracoccus denitrificans PD1222 were regulated by a newly identified PdeR/PdeI QS system during biofilm formation, and we put forward a hypothesis that QS-dependent iron uptake systems benefit the stability of biofilms. This report elaborates the correlation among QS, iron uptake, and biofilm formation and thus contributes to an understanding of the ecological behavior of environmental bacteria.
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Calatrava-Morales N, McIntosh M, Soto MJ. Regulation Mediated by N-Acyl Homoserine Lactone Quorum Sensing Signals in the Rhizobium-Legume Symbiosis. Genes (Basel) 2018; 9:genes9050263. [PMID: 29783703 PMCID: PMC5977203 DOI: 10.3390/genes9050263] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Revised: 05/15/2018] [Accepted: 05/15/2018] [Indexed: 02/06/2023] Open
Abstract
Soil-dwelling bacteria collectively referred to as rhizobia synthesize and perceive N-acyl-homoserine lactone (AHL) signals to regulate gene expression in a population density-dependent manner. AHL-mediated signaling in these bacteria regulates several functions which are important for the establishment of nitrogen-fixing symbiosis with legume plants. Moreover, rhizobial AHL act as interkingdom signals triggering plant responses that impact the plant-bacteria interaction. Both the regulatory mechanisms that control AHL synthesis in rhizobia and the set of bacterial genes and associated traits under quorum sensing (QS) control vary greatly among the rhizobial species. In this article, we focus on the well-known QS system of the alfalfa symbiont Sinorhizobium(Ensifer)meliloti. Bacterial genes, environmental factors and transcriptional and posttranscriptional regulatory mechanisms that control AHL production in this Rhizobium, as well as the effects of the signaling molecule on bacterial phenotypes and plant responses will be reviewed. Current knowledge of S. meliloti QS will be compared with that of other rhizobia. Finally, participation of the legume host in QS by interfering with rhizobial AHL perception through the production of molecular mimics will also be addressed.
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Affiliation(s)
- Nieves Calatrava-Morales
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC; Granada 18008, Spain.
| | - Matthew McIntosh
- Institut für Mikrobiologie und Molekularbiologie, Universität Giessen, 35392 Giessen, Germany.
| | - María J Soto
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC; Granada 18008, Spain.
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Membrane fouling induced by AHL-mediated soluble microbial product (SMP) formation by fouling-causing bacteria co-cultured with fouling-enhancing bacteria. Sci Rep 2017; 7:8482. [PMID: 28814755 PMCID: PMC5559553 DOI: 10.1038/s41598-017-09023-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 07/14/2017] [Indexed: 11/24/2022] Open
Abstract
Membrane fouling still remains a major obstacle for wider applications of membrane bioreactor (MBR), which is mainly caused by soluble microbial products (SMP). Identification of key bacteria responsible for SMP production is essential for mitigation of membrane fouling. Here, we investigated the effect of microbial interaction on membrane fouling. We measured the membrane fouling potentials of 13 bacterial strains isolated from a pilot-scale MBR treating domestic wastewater when they were cultivated as single-culture and co-culture. We found that fouling-causing bacteria (FCB) displayed much higher fouling potential when co-cultured even with non-FCB and mixed population (activated sludge). In particular, the fouling potential of strain S26, one of FCB, increased 26.8 times when cultivated with strain S22 (fouling-enhancing bacteria, FEB). The secretion of N-octanoyl-L-homoserine lactone (C8-HSL) was increased by co-cultivating S22 and S26 as compared with cultivating as single culture, which stimulated the production of fouling-causing SMP by S26 and consequently resulted in severe membrane fouling. This result suggests that AHL-mediated quorum-sensing (QS) regulatory system was involved in secretion of fouling-causing SMP.
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Onishchuk OP, Vorobyov NI, Provorov NA. Nodulation competitiveness of nodule bacteria: Genetic control and adaptive significance: Review. APPL BIOCHEM MICRO+ 2017. [DOI: 10.1134/s0003683817020132] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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14
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Reyes-Pérez A, Vargas MDC, Hernández M, Aguirre-von-Wobeser E, Pérez-Rueda E, Encarnacion S. Transcriptomic analysis of the process of biofilm formation in Rhizobium etli CFN42. Arch Microbiol 2016; 198:847-60. [PMID: 27226009 DOI: 10.1007/s00203-016-1241-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 03/17/2016] [Accepted: 05/06/2016] [Indexed: 12/19/2022]
Abstract
Organisms belonging to the genus Rhizobium colonize leguminous plant roots and establish a mutually beneficial symbiosis. Biofilms are structured ecosystems in which microbes are embedded in a matrix of extracellular polymeric substances, and their development is a multistep process. The biofilm formation processes of R. etli CFN42 were analyzed at an early (24-h incubation) and mature stage (72 h), comparing cells in the biofilm with cells remaining in the planktonic stage. A genome-wide microarray analysis identified 498 differentially regulated genes, implying that expression of ~8.3 % of the total R. etli gene content was altered during biofilm formation. In biofilms-attached cells, genes encoding proteins with diverse functions were overexpressed including genes involved in membrane synthesis, transport and chemotaxis, repression of flagellin synthesis, as well as surface components (particularly exopolysaccharides and lipopolysaccharides), in combination with the presence of activators or stimulators of N-acyl-homoserine lactone synthesis This suggests that R. etli is able to sense surrounding environmental conditions and accordingly regulate the transition from planktonic and biofilm growth. In contrast, planktonic cells differentially expressed genes associated with transport, motility (flagellar and twitching) and inhibition of exopolysaccharide synthesis. To our knowledge, this is the first report of nodulation and nitrogen assimilation-related genes being involved in biofilm formation in R. etli. These results contribute to the understanding of the physiological changes involved in biofilm formation by bacteria.
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Affiliation(s)
- Agustín Reyes-Pérez
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apartado Postal 565-A, Cuernavaca, Morelos, Mexico.,Facultad de Ciencias, Posgrado en Ciencias Biológicas, Universidad Nacional Autónoma de México, Apartado Postal 70-153, C.P. 0415, Cuernavaca, D.F., Mexico.,Centro de Investigación en Dinámica Celular, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, Cuernavaca, Morelos, 62209, Mexico
| | - María Del Carmen Vargas
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apartado Postal 565-A, Cuernavaca, Morelos, Mexico
| | - Magdalena Hernández
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apartado Postal 565-A, Cuernavaca, Morelos, Mexico
| | - Eneas Aguirre-von-Wobeser
- Red de Estudios Moleculares Avanzados, Instituto de Ecología, A. C. Coatepec 351, El Haya, Xalapa, Veracruz, Mexico
| | - Ernesto Pérez-Rueda
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, UNAM, Av. Universidad s/n, Col. Chamilpa, Cuernavaca, Morelos, Mexico
| | - Sergio Encarnacion
- Programa de Genómica Funcional de Procariotes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apartado Postal 565-A, Cuernavaca, Morelos, Mexico.
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15
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Function of MsiR on canavanine-mediated repression in Mesorhizobium tianshanense. Arch Microbiol 2015; 197:729-35. [PMID: 25854984 DOI: 10.1007/s00203-015-1106-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 09/16/2014] [Accepted: 03/16/2015] [Indexed: 10/23/2022]
Abstract
Mesorhizobium tianshanense employs MsiA as canavanine exporter, which is upregulated by MsiR, to successfully form a symbiosis with the legume Glycyrrhiza uralensis. In this research, through gel-shift and bacterial two-hybrid examination, MsiR was found to spontaneously form dimers and bind to msiA promoter without additional canavanine. Six truncated forms of MsiR were constructed, and the conserved helix-turn-helix (HTH), substrate-binding, and surface-loop domains were found essential for MsiR functions. Random mutagenesis was used to study the functional sites of MsiR. Seven point mutants were selected, in which three mutants constitutively induced msiA expression without additional canavanine, two mutants partially changed substrate specificity, and the other two were almost null mutants. Results from the site mutation show that the functional subunits (HTH domain, dimerization interface domains, and C-terminal) are important in the conformation and induction ability of MsiR.
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16
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Zheng H, Mao Y, Teng J, Zhu Q, Ling J, Zhong Z. Flagellar-dependent motility in Mesorhizobium tianshanense is involved in the early stage of plant host interaction: study of an flgE mutant. Curr Microbiol 2014; 70:219-27. [PMID: 25287045 DOI: 10.1007/s00284-014-0701-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 08/17/2014] [Indexed: 11/26/2022]
Abstract
Bacterial motility is most likely a critical factor for rhizobium to chemotactically colonize on the root surface prior to infecting leguminous plant hosts. Several studies of the rhizobium flagellar filament have been reported, but little is known about the rhizobium flagellum hook. To investigate the roles of the hook protein in flagellum synthesis in Mesorhizobium tianshanense, the hook protein-encoding gene flgE of M. tianshanense was amplified by PCR and sequenced. Comparison of the deduced amino acid sequences revealed pronounced similarities in Domain 1 and lower similarities in Domain 2, which are supposed to be related to hook structure assembly and antigenic diversity, respectively. The level of transcription of flgE increased along with the cell growth and reached its maximum at the middle log phase. Disruption of the flgE gene caused a flagellar-less phenotype, thereby causing complete loss of swimming ability, modified nutrient-related swarming ability and biofilm formation. Moreover, the absence of flagellar caused decreased bacterial attachment on the root hair, suggesting that flagellar is involved in the early stage of symbiosis process.
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Affiliation(s)
- Huiming Zheng
- Department of Microbiology, Nanjing Agricultural University, Nanjing, China,
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17
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Yunos NYM, Tan WS, Mohamad NI, Tan PW, Adrian TGS, Yin WF, Chan KG. Quorum sensing activity of a Kluyvera sp. isolated from a Malaysian waterfall. SENSORS 2014; 14:8305-12. [PMID: 24815680 PMCID: PMC4063027 DOI: 10.3390/s140508305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 04/30/2014] [Accepted: 05/04/2014] [Indexed: 01/19/2023]
Abstract
In many species of bacteria, the quorum sensing mechanism is used as a unique communication system which allows them to regulate gene expression and behavior in accordance with their population density. N-Acylhomoserine lactones (AHLs) are known as diffusible autoinducer molecules involved in this communication network. This finding aimed to characterize the production of AHL of a bacterial strain ND04 isolated from a Malaysian waterfall. Strain ND04 was identified as Kluyvera sp. as confirmed by molecular analysis of its 16S ribosomal RNA gene sequence. Kluyvera sp. is closely related to the Enterobacteriaceae family. Chromobacterium violaceum CV026 was used as a biosensor to detect the production of AHL by strain ND04. High resolution triple quadrupole liquid chromatography-mass spectrometry analysis of strain ND04 showed our isolate produced two AHLs which are N-(3-oxohexanoyl)homoserine lactone (3-oxo-C6 HSL) and N-3-oxo-octanoyl-L-homoserine lactone (3-oxo-C8 HSL).
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Affiliation(s)
- Nina Yusrina Muhamad Yunos
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
| | - Wen-Si Tan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
| | - Nur Izzati Mohamad
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
| | - Pui-Wan Tan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
| | - Tan-Guan-Sheng Adrian
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
| | - Wai-Fong Yin
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia.
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18
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Sieira R. Regulation of virulence in Brucella: an eclectic repertoire of transcription factors defines the complex architecture of the virB promoter. Future Microbiol 2013; 8:1193-208. [DOI: 10.2217/fmb.13.83] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Many intracellular bacterial pathogens use type IV secretion systems to deliver effector molecules and subvert the eukaryotic host cell defenses. The genus Brucella comprises facultative intracellular bacteria that cause brucellosis, a disease affecting a wide range of mammals including humans. The virB operon codes for a type IV secretion system that plays a central role in intracellular survival and replication of Brucella within the host. Expression of the virB genes is under the control of various transcription factors that allow this system to respond to different types of environmental signals, and display binding site structures and arrangements that define the intrinsic complexity of the virB promoter. This review focuses on summarizing the current state of research concerning regulation of the Brucella virB operon, with special emphasis on describing the nature and function of the implicated regulatory elements and examining the involved protein–DNA interactions.
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Affiliation(s)
- Rodrigo Sieira
- Fundación Instituto Leloir-IIBBA-CONICET, Av. Patricias Argentinas 435, Buenos Aires C1405BWE, Argentina
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19
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Mahmoudi E, Naderi D, Venturi V. AiiA lactonase disrupts N-acylhomoserine lactone and attenuates quorum-sensing-related virulence in Pectobacterium carotovorum EMPCC. ANN MICROBIOL 2012. [DOI: 10.1007/s13213-012-0521-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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20
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Tahrioui A, Quesada E, Llamas I. The hanR/hanI quorum-sensing system of Halomonas anticariensis, a moderately halophilic bacterium. Microbiology (Reading) 2011; 157:3378-3387. [DOI: 10.1099/mic.0.052167-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Quorum sensing is a cell density-dependent gene expression mechanism found in many Gram-negative bacteria which involves the production of signal molecules such as N-acylhomoserine lactones (AHLs). One significant group of micro-organisms in which quorum sensing has not been previously studied, however, are the moderate halophiles. We describe here the results of our studies of the quorum-sensing system in Halomonas anticariensis FP35T, which is composed of luxR/luxI homologues: hanR (the putative transcriptional regulator gene) and hanI (the autoinducer synthase gene). To understand how the hanR/hanI system is organized and regulated we conducted RT-PCR and quantitative real-time PCR assays. Transcriptional analysis indicated that the hanR and hanI genes are on the same transcript and that their transcription is growth phase-dependent. HanI seems to be the only autoinducer synthase responsible for the synthesis of AHLs by the bacterium, since the inactivation of hanI resulted in the complete loss of its AHLs. We also found that the hanI gene appears to be transcribed from its own promoter and that its expression does not depend upon HanR. This finding was supported by the fact that the FP35hanR mutant showed AHL-producing activity and hanI expression similar to that of the wild-type strain, the latter being measured by RT-PCR. Moreover, hanR is expressed from its own promoter and appears to be independent of the AHL signalling molecules produced by HanI.
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Affiliation(s)
- Ali Tahrioui
- Microbial Exopolysaccharide Research Group, Department of Microbiology, Faculty of Pharmacy, Cartuja Campus, University of Granada, 18071 Granada, Spain
| | - Emilia Quesada
- Microbial Exopolysaccharide Research Group, Department of Microbiology, Faculty of Pharmacy, Cartuja Campus, University of Granada, 18071 Granada, Spain
| | - Inmaculada Llamas
- Microbial Exopolysaccharide Research Group, Department of Microbiology, Faculty of Pharmacy, Cartuja Campus, University of Granada, 18071 Granada, Spain
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21
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Abstract
Many bacteria use 'quorum sensing' (QS) as a mechanism to regulate gene induction in a population-dependent manner. In its simplest sense this involves the accumulation of a signaling metabolite during growth; the binding of this metabolite to a regulator or multiple regulators activates induction or repression of gene expression. However QS regulation is seldom this simple, because other inputs are usually involved. In this review we have focussed on how those other inputs influence QS regulation and as implied by the title, this often occurs by environmental or physiological effects regulating the expression or activity of the QS regulators. The rationale of this review is to briefly introduce the main QS signals used in Gram-negative bacteria and then introduce one of the earliest understood mechanisms of regulation of the regulator, namely the plant-mediated control of expression of the TraR QS regulator in Agrobacterium tumefaciens. We then describe how in several species, multiple QS regulatory systems can act as integrated hierarchical regulatory networks and usually this involves the regulation of QS regulators. Such networks can be influenced by many different physiological and environmental inputs and we describe diverse examples of these. In the final section, we describe different examples of how eukaryotes can influence QS regulation in Gram-negative bacteria.
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Affiliation(s)
- Marijke Frederix
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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22
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Ryan RP, Vorhölter FJ, Potnis N, Jones JB, Van Sluys MA, Bogdanove AJ, Dow JM. Pathogenomics of Xanthomonas: understanding bacterium-plant interactions. Nat Rev Microbiol 2011; 9:344-55. [PMID: 21478901 DOI: 10.1038/nrmicro2558] [Citation(s) in RCA: 303] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Xanthomonas is a large genus of Gram-negative bacteria that cause disease in hundreds of plant hosts, including many economically important crops. Pathogenic species and pathovars within species show a high degree of host plant specificity and many exhibit tissue specificity, invading either the vascular system or the mesophyll tissue of the host. In this Review, we discuss the insights that functional and comparative genomic studies are providing into the adaptation of this group of bacteria to exploit the extraordinary diversity of plant hosts and different host tissues.
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Affiliation(s)
- Robert P Ryan
- BIOMERIT Research Centre, Department of Microbiology, BioSciences Institute, University College Cork, Ireland
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23
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Aryl-homoserine lactone quorum sensing in stem-nodulating photosynthetic bradyrhizobia. Proc Natl Acad Sci U S A 2011; 108:7183-8. [PMID: 21471459 DOI: 10.1073/pnas.1103821108] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Many Proteobacteria possess LuxI-LuxR-type quorum-sensing systems that produce and detect fatty acyl-homoserine lactone (HSL) signals. The photoheterotroph Rhodopseudomonas palustris is unusual in that it produces and detects an aryl-HSL, p-coumaroyl-HSL, and signal production requires an exogenous source of p-coumarate. A photosynthetic stem-nodulating member of the genus Bradyrhizobium produces a small molecule signal that elicits an R. palustris quorum-sensing response. Here, we show that this signal is cinnamoyl-HSL and that cinnamoyl-HSL is produced by the LuxI homolog BraI and detected by BraR. Cinnamoyl-HSL reaches concentrations on the order of 50 nM in cultures of stem-nodulating bradyrhizobia grown in the presence or absence of cinnamate. Acyl-HSLs often reach concentrations of 0.1-30 μM in bacterial cultures, and generally, LuxR-type receptors respond to signals in a concentration range from 5 to a few hundred nanomolar. Our stem-nodulating Bradyrhizobium strain responds to picomolar concentrations of cinnamoyl-HSL and thus, produces cinnamoyl-HSL in excess of the levels required for a signal response without an exogenous source of cinnamate. The ability of Bradyrhizobium to produce and respond to cinnamoyl-HSL shows that aryl-HSL production is not unique to R. palustris, that the aromatic acid substrate for aryl-HSL synthesis does not have to be supplied exogenously, and that some acyl-HSL quorum-sensing systems may function at very low signal production and response levels.
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Fan J, Qian G, Chen T, Zhao Y, Liu F, Walcott RR, Hu B. The acyl-homoserine lactone (AHL)-type quorum sensing system affects growth rate, swimming motility and virulence in Acidovorax avenae subsp. citrulli. World J Microbiol Biotechnol 2010. [DOI: 10.1007/s11274-010-0562-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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25
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Downie JA. The roles of extracellular proteins, polysaccharides and signals in the interactions of rhizobia with legume roots. FEMS Microbiol Rev 2009; 34:150-70. [PMID: 20070373 DOI: 10.1111/j.1574-6976.2009.00205.x] [Citation(s) in RCA: 219] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Rhizobia adopt many different lifestyles including survival in soil, growth in the rhizosphere, attachment to root hairs and infection and growth within legume roots, both in infection threads and in nodules where they fix nitrogen. They are actively involved in extracellular signalling to their host legumes to initiate infection and nodule morphogenesis. Rhizobia also use quorum-sensing gene regulation via N-acyl-homoserine lactone signals and this can enhance their interaction with legumes as well as their survival under stress and their ability to induce conjugation of plasmids and symbiotic islands, thereby spreading their symbiotic capacity. They produce several surface polysaccharides that are critical for attachment and biofilm formation; some of these polysaccharides are specific for their growth on root hairs and can considerably enhance their ability to infect their host legumes. Different rhizobia use several different types of protein secretion mechanisms (Types I, III, IV, V and VI), and many of the secreted proteins play an important role in their interaction with plants. This review summarizes many of the aspects of the extracellular biology of rhizobia, in particular in relation to their symbiotic interaction with legumes.
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Abstract
Biofilms are bacterial communities enclosed within an extracellular matrix of polysaccharides produced by the bacteria, which adhere to a living or an inert macrosurface. In nature, biofilms constitute a protected growth modality allowing bacteria to survive in hostile environments. Studies of environmental isolates have revealed a highly ordered, three-dimensional organization of the extracellular matrix, which has important implications for biofilm physiology. The zone of soil immediately surrounding a plant root where complex biological and ecological processes occur, termed rhizosphere, forms an environment that fulfills the requirements for biofilm formation, including sufficient moisture and supply of nutrients, which are provided by the plant. Biofilm formation on plants appears to be associated with symbiotic and pathogenic responses, but it is unclear how plants regulate the association. Biofilms function as structures resistant against stress factors such as desiccation, UV radiation, predation, and antibiosis, which help create protective niches for rhizobia. However, the role of biofilms in rhizobial-legume symbiosis remains to be clarified. Here, the mechanisms involved in bacterial biofilm formation and attachment on plant roots, and the relation of these mechanisms to rhizobial function and survival are reviewed.
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Affiliation(s)
- Luciana V Rinaudi
- Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina
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27
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Badri DV, Weir TL, van der Lelie D, Vivanco JM. Rhizosphere chemical dialogues: plant-microbe interactions. Curr Opin Biotechnol 2009; 20:642-50. [PMID: 19875278 DOI: 10.1016/j.copbio.2009.09.014] [Citation(s) in RCA: 218] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2009] [Revised: 09/18/2009] [Accepted: 09/25/2009] [Indexed: 11/16/2022]
Abstract
Every organism on earth relies on associations with its neighbors to sustain life. For example, plants form associations with neighboring plants, microflora, and microfauna, while humans maintain symbiotic associations with intestinal microbial flora, which is indispensable for nutrient assimilation and development of the innate immune system. Most of these associations are facilitated by chemical cues exchanged between the host and the symbionts. In the rhizosphere, which includes plant roots and the surrounding area of soil influenced by the roots, plants exude chemicals to effectively communicate with their neighboring soil organisms. Here we review the current literature pertaining to the chemical communication that exists between plants and microorganisms and the biological processes they sustain.
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Affiliation(s)
- Dayakar V Badri
- Center for Rhizosphere Biology and Department of Horticulture & LA, Colorado State University, Fort Collins, CO 80523, USA
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28
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Hao Y, Winans SC, Glick BR, Charles TC. Identification and characterization of new LuxR/LuxI-type quorum sensing systems from metagenomic libraries. Environ Microbiol 2009; 12:105-17. [PMID: 19735279 DOI: 10.1111/j.1462-2920.2009.02049.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Quorum sensing (QS) cell-cell communication systems are utilized by bacteria to coordinate their behaviour according to cell density. Several different types of QS signal molecules have been identified, among which acyl-homoserine lactones (AHLs) produced by Proteobacteria have been studied to the greatest extent. Although QS has been studied extensively in cultured microorganisms, little is known about the QS systems of uncultured microorganisms and the roles of these systems in microbial communities. To extend our knowledge of QS systems and to better understand the signalling that takes place in the natural environment, metagenomic libraries constructed using DNA from activated sludge and soil were screened, using an Agrobacterium biosensor strain, for novel QS synthase genes. Three cosmids (QS6-1, QS10-1 and QS10-2) that encode the production of QS signals were identified and DNA sequence analysis revealed that all three clones encode a novel luxI family AHL synthase and a luxR family transcriptional regulator. Thin layer chromatography revealed that these LuxI homologue proteins are able to synthesize multiple AHL signals. Tandem mass spectrometry analysis revealed that LuxI(QS6-1) directs the synthesis of at least three AHLs, 3-O-C14:1 HSL, 3-O-C16:1 HSL and 3-O-C14 HSL; LuxI(QS10-1) directs the synthesis of at least 3-O-C12 HSL and 3-O-C14 HSL; while LuxI(QS10-2) directs the synthesis of at least C8 HSL and C10 HSL. Two possible new AHLs, C14:3 HSL and (?)-hydroxymethyl-3-O-C14 HSL, were also found to be synthesized by LuxI(QS6-1).
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Affiliation(s)
- Youai Hao
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
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Cai T, Cai W, Zhang J, Zheng H, Tsou AM, Xiao L, Zhong Z, Zhu J. Host legume-exuded antimetabolites optimize the symbiotic rhizosphere. Mol Microbiol 2009; 73:507-17. [PMID: 19602148 DOI: 10.1111/j.1365-2958.2009.06790.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Rhizobia form symbiotic nodules on host legumes and fix nitrogen for their hosts in exchange for nutrients. In order to establish this mutually beneficial relationship, rhizobia must compete with other soil bacteria in the host legume rhizosphere to colonize plant roots efficiently. A promoter-trap transposon screen in Mesorhizobium tianshanense, a Rhizobium that forms nodules on licorice (Glycyrrhiza uralensis) plants revealed that the expression of msiA, which encodes a putative exporter protein belonging to the LysE family of translocators, is activated by both legume exudates and MsiR, a LysR family transcriptional regulator. Chemical analysis suggests that the msiA-inducing signal in exudates is canavanine, an anti-metabolite present in the seeds and exudates of a variety of legume plants. We show that MsiA serves as a canavanine exporter that is indispensable for canavanine resistance in M. tianshanense. We also show that the expression of MsiA homologues in other rhizobial species is induced by canavanine and is critical for canavanine resistance. Furthermore, rhizobial canavanine resistance is important for root hair adherence as well as for survival in a canavanine-producing legume rhizosphere. Together, these data suggest that host legumes may exude specific antimetabolites into their surroundings to optimize the bacterial population in order to have successful symbiotic events with rhizobia.
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Affiliation(s)
- Tao Cai
- Department of Microbiology, MOA Key Laboratory of Microbiological Engineering of Agricultural Environment, Nanjing Agricultural University, Nanjing, China
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30
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Yang M, Sun K, Zhou L, Yang R, Zhong Z, Zhu J. Functional analysis of three AHL autoinducer synthase genes in Mesorhizobium loti reveals the important role of quorum sensing in symbiotic nodulation. Can J Microbiol 2009; 55:210-4. [DOI: 10.1139/w08-128] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
One of the most important signal transduction pathways in bacteria, quorum sensing, is involved in many regulatory circuits in rhizobia, especially in the control of communication between rhizobia and their plant hosts. In this study, we identified 3 autoinducer synthase genes — mrlI1, mrlI2, and mrlI3 — in Mesorhizobium loti NZP 2213. We found that MrlI1 and MrlI2 could synthesize distinct N-acyl homoserine lactone (AHL) autoinducers in rich medium cultures, and the expression of mrlI1 was shown to be growth-phase-dependent. MrlI3 did not produce any detectable AHL molecules under the culture conditions tested. To investigate whether these AHL synthases affect nodulation, we examined the nodulation of AHL-deficient mutants on their native plant host Lotus corniculatus and found that the efficiency of nodulation of bacteria with mutations of any of these 3 synthase genes was reduced, suggesting that quorum sensing systems in M. loti may play an important role in successful establishment of rhizobium–legume symbiosis.
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Affiliation(s)
- Menghua Yang
- Department of Microbiology, MOA Key Laboratory of Microbiological Engineering of Agricultural Environment, Nanjing Agricultural University, Nanjing, China
- Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China
- The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, China
| | - Kejing Sun
- Department of Microbiology, MOA Key Laboratory of Microbiological Engineering of Agricultural Environment, Nanjing Agricultural University, Nanjing, China
- Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China
- The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, China
| | - Lei Zhou
- Department of Microbiology, MOA Key Laboratory of Microbiological Engineering of Agricultural Environment, Nanjing Agricultural University, Nanjing, China
- Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China
- The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, China
| | - Ruifu Yang
- Department of Microbiology, MOA Key Laboratory of Microbiological Engineering of Agricultural Environment, Nanjing Agricultural University, Nanjing, China
- Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China
- The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, China
| | - Zengtao Zhong
- Department of Microbiology, MOA Key Laboratory of Microbiological Engineering of Agricultural Environment, Nanjing Agricultural University, Nanjing, China
- Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China
- The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, China
| | - Jun Zhu
- Department of Microbiology, MOA Key Laboratory of Microbiological Engineering of Agricultural Environment, Nanjing Agricultural University, Nanjing, China
- Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China
- The State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, Nanjing, China
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31
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Complex quorum-sensing regulatory systems regulate bacterial growth and symbiotic nodulation in Mesorhizobium tianshanense. Arch Microbiol 2008; 191:283-9. [DOI: 10.1007/s00203-008-0454-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 12/11/2008] [Accepted: 12/16/2008] [Indexed: 11/27/2022]
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Santos CL, Tavares F, Thioulouse J, Normand P. A phylogenomic analysis of bacterial helix-turn-helix transcription factors. FEMS Microbiol Rev 2008; 33:411-29. [PMID: 19076237 DOI: 10.1111/j.1574-6976.2008.00154.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Perception by each individual organism of its environment's parameters is a key factor for survival. In a constantly changing environment, the ability to assess nutrient sources and potentially stressful situations constitutes the main basis for ecological adaptability. Transcription regulators are key decision-making proteins that mediate the communication between environmental conditions and DNA transcription through a multifaceted network. The parallel study of these regulators across microbial organisms adapted to contrasting biotopes constitutes an unexplored approach to understand the evolution of genome plasticity and cell function. We present here a reassessment of bacterial helix-turn-helix regulator diversity in different organisms from a multidisciplinary perspective, on the interface that links metabolism, ecology and phylogeny, further sustained by a statistically based approach. The present revision brought to light evidence of patterns among families of regulators, suggesting that multiple selective forces modulate the number and kind of regulators present in a given genome. Besides being an important step towards understanding the adaptive traits that influence the microbial responses to the varying environment on the very first and most prevalent line of reaction, the transcription of DNA, this approach is a promising tool to extract biological trends from genomic databases.
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Affiliation(s)
- Catarina L Santos
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.
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33
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Abstract
This review describes secondary metabolites that have been shown to be synthesized by symbiotic bacteria, or for which this possibility has been discussed. It includes 365 references.
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Affiliation(s)
- Jörn Piel
- Kekulé-Institute of Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Str. 1, 53121 Bonn, Germany.
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34
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The LuxR family quorum-sensing activator MrtR requires its cognate autoinducer for dimerization and activation but not for protein folding. J Bacteriol 2008; 191:434-8. [PMID: 18978063 DOI: 10.1128/jb.01247-08] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
MrtR, a LuxR homolog in Mesorhizobium tianshanense, is important for symbiosis. We found that MrtR requires its cognate N-acylhomoserine lactone for forming dimers, binding to a single DNA site and activating the downstream promoter. However, MrtR is able to fold independently of its ligand.
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Joelsson AC, Zhu J. LacZ-based detection of acyl-homoserine lactone quorum-sensing signals. ACTA ACUST UNITED AC 2008; Chapter 1:Unit 1C.2. [PMID: 18770574 DOI: 10.1002/9780471729259.mc01c02s3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Many bacteria use quorum-sensing regulatory systems to monitor their population density and to coordinate their genetic expression under certain conditions. Acyl-homoserine lactones are often produced by many Gram-negative bacteria and serve as quorum-sensing signal molecules. This unit describes two commonly used methods to detect acyl-homoserine lactones from laboratory or environmental bacterial cultures.
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Affiliation(s)
- Adam C Joelsson
- University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA
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36
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Ortíz-Castro R, Martínez-Trujillo M, López-Bucio J. N-acyl-L-homoserine lactones: a class of bacterial quorum-sensing signals alter post-embryonic root development in Arabidopsis thaliana. PLANT, CELL & ENVIRONMENT 2008; 31:1497-509. [PMID: 18657054 DOI: 10.1111/j.1365-3040.2008.01863.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
N-acyl-homoserine lactones (AHLs) belong to a class of bacterial quorum-sensing signals important for bacterial cell-to-cell communication. We evaluated Arabidopsis thaliana growth responses to a variety of AHLs ranging from 4 to 14 carbons in length, focusing on alterations in post-embryonic root development as a way to determine the biological activity of these signals. The compounds affected primary root growth, lateral root formation and root hair development, and in particular, N-decanoyl-HL (C10-HL) was found to be the most active AHL in altering root system architecture. Developmental changes elicited by C10-HL were related to altered expression of cell division and differentiation marker lines pPRZ1:uidA, CycB1:uidA and pAtEXP7:uidA in Arabidopsis roots. Although the effects of C10-HL were similar to those produced by auxins in modulating root system architecture, the primary and lateral root response to this compound was found to be independent of auxin signalling. Furthermore, we show that mutant and overexpressor lines for an Arabidopsis fatty acid amide hydrolase gene (AtFAAH) sustained altered growth response to C10-HL. All together, our results suggest that AHLs alter root development in Arabidopsis and that plants posses the enzymatic machinery to metabolize these compounds.
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Affiliation(s)
- Randy Ortíz-Castro
- Instituto de Investigaciones Químico-Biológicas, Edificio B3, Cuidad Universitaria, Morelia, Michoacán, Mexico
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37
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Exopolysaccharide biosynthesis is important for Mesorhizobium tianshanense: plant host interaction. Arch Microbiol 2008; 189:525-30. [DOI: 10.1007/s00203-007-0345-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 11/14/2007] [Accepted: 12/11/2007] [Indexed: 10/22/2022]
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38
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39
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Yuan ZC, Edlind MP, Liu P, Saenkham P, Banta LM, Wise AA, Ronzone E, Binns AN, Kerr K, Nester EW. The plant signal salicylic acid shuts down expression of the vir regulon and activates quormone-quenching genes in Agrobacterium. Proc Natl Acad Sci U S A 2007; 104:11790-5. [PMID: 17606909 PMCID: PMC1905925 DOI: 10.1073/pnas.0704866104] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Indexed: 11/18/2022] Open
Abstract
Agrobacterium tumefaciens is capable of transferring and integrating an oncogenic T-DNA (transferred DNA) from its tumor-inducing (Ti) plasmid into dicotyledonous plants. This transfer requires that the virulence genes (vir regulon) be induced by plant signals such as acetosyringone in an acidic environment. Salicylic acid (SA) is a key signal molecule in regulating plant defense against pathogens. However, how SA influences Agrobacterium and its interactions with plants is poorly understood. Here we show that SA can directly shut down the expression of the vir regulon. SA specifically inhibited the expression of the Agrobacterium virA/G two-component regulatory system that tightly controls the expression of the vir regulon including the repABC operon on the Ti plasmid. We provide evidence suggesting that SA attenuates the function of the VirA kinase domain. Independent of its effect on the vir regulon, SA up-regulated the attKLM operon, which functions in degrading the bacterial quormone N-acylhomoserine lactone. Plants defective in SA accumulation were more susceptible to Agrobacterium infection, whereas plants overproducing SA were relatively recalcitrant to tumor formation. Our results illustrate that SA, besides its well known function in regulating plant defense, can also interfere directly with several aspects of the Agrobacterium infection process.
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Affiliation(s)
| | - Merritt P. Edlind
- Department of Biology, Williams College, Williamstown, MA 01267; and
| | - Pu Liu
- Departments of *Microbiology and
| | | | - Lois M. Banta
- Department of Biology, Williams College, Williamstown, MA 01267; and
| | - Arlene A. Wise
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018
| | - Erik Ronzone
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018
| | - Andrew N. Binns
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018
| | - Kathleen Kerr
- Biostatistics, University of Washington, Seattle, WA 98195
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40
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Gao M, Chen H, Eberhard A, Gronquist MR, Robinson JB, Connolly M, Teplitski M, Rolfe BG, Bauer WD. Effects of AiiA-mediated quorum quenching in Sinorhizobium meliloti on quorum-sensing signals, proteome patterns, and symbiotic interactions. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2007; 20:843-56. [PMID: 17601171 DOI: 10.1094/mpmi-20-7-0843] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Many behaviors in bacteria, including behaviors important to pathogenic and symbiotic interactions with eukaryotic hosts, are regulated by a mechanism called quorum sensing (QS). A "quorum-quenching" approach was used here to identify QS-regulated behaviors in the N-fixing bacterial symbiont Sinorhizobium meliloti. The AiiA lactonase from Bacillus produced in S. meliloti was shown to enzymatically inactivate S. meliloti's N-acyl homoserine lactone (AHL) QS signals, thereby disrupting normal QS regulation. Sixty proteins were differentially accumulated in the AiiA-producing strain versus the control in early log or early stationary phase cultures. Fifty-two of these QS-regulated proteins, with putative functions that include cell division, protein processing and translation, metabolite transport, oxidative stress, and amino acid metabolism, were identified by peptide mass fingerprinting. Transcription of representative genes was reduced significantly in the AiiA-producing strain, although the effects of AiiA on protein accumulation did not always correspond to effects on transcription. The QS signal-deficient strain was reduced significantly in nodule initiation during the first 12 h after inoculation onto Medicago truncatula host plants. The AiiA lactonase also was found to substantially inactivate two of the AHL mimic compounds secreted by M. truncatula. This suggests some structural similarity between bacterial AHLs and these mimic compounds. It also indicates that quorum quenching could be useful in identifying Sinorhizobium genes that are affected by such host QS mimics in planta.
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Affiliation(s)
- Mengsheng Gao
- Department of Soil and Water Sciences, 2159 McCarty Hall A, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Gainesville 32611-0290, USA
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41
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Soto MJ, Sanjuán J, Olivares J. Rhizobia and plant-pathogenic bacteria: common infection weapons. MICROBIOLOGY-SGM 2007; 152:3167-3174. [PMID: 17074888 DOI: 10.1099/mic.0.29112-0] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Plant-interacting micro-organisms can establish either mutualistic or pathogenic associations. Although the outcome is completely different, common molecular mechanisms that mediate communication between the interacting partners seem to be involved. Specifically, nitrogen-fixing bacterial symbionts of legume plants, collectively termed rhizobia, and phytopathogenic bacteria have adopted similar strategies and genetic traits to colonize, invade and establish a chronic infection in the plant host. Quorum-sensing signals and identical two-component regulatory systems are used by these bacteria to coordinate, in a cell density-dependent manner or in response to changing environmental conditions, the expression of important factors for host colonization and infection. The success of invasion and survival within the host also requires that rhizobia and pathogens suppress and/or overcome plant defence responses triggered after microbial recognition, a process in which surface polysaccharides, antioxidant systems, ethylene biosynthesis inhibitors and virulence genes are involved.
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Affiliation(s)
- María J Soto
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Profesor Albareda 1, 18008 Granada, Spain
| | - Juan Sanjuán
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Profesor Albareda 1, 18008 Granada, Spain
| | - José Olivares
- Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Profesor Albareda 1, 18008 Granada, Spain
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