1
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Bustamante JA, Ceron JS, Gao IT, Ramirez HA, Aviles MV, Bet Adam D, Brice JR, Cuellar RA, Dockery E, Jabagat MK, Karp DG, Lau JKO, Li S, Lopez-Magaña R, Moore RR, Morin BKR, Nzongo J, Rezaeihaghighi Y, Sapienza-Martinez J, Tran TTK, Huang Z, Duthoy AJ, Barnett MJ, Long SR, Chen JC. A protease and a lipoprotein jointly modulate the conserved ExoR-ExoS-ChvI signaling pathway critical in Sinorhizobium meliloti for symbiosis with legume hosts. PLoS Genet 2023; 19:e1010776. [PMID: 37871041 PMCID: PMC10659215 DOI: 10.1371/journal.pgen.1010776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 11/20/2023] [Accepted: 10/11/2023] [Indexed: 10/25/2023] Open
Abstract
Sinorhizobium meliloti is a model alpha-proteobacterium for investigating microbe-host interactions, in particular nitrogen-fixing rhizobium-legume symbioses. Successful infection requires complex coordination between compatible host and endosymbiont, including bacterial production of succinoglycan, also known as exopolysaccharide-I (EPS-I). In S. meliloti EPS-I production is controlled by the conserved ExoS-ChvI two-component system. Periplasmic ExoR associates with the ExoS histidine kinase and negatively regulates ChvI-dependent expression of exo genes, necessary for EPS-I synthesis. We show that two extracytoplasmic proteins, LppA (a lipoprotein) and JspA (a lipoprotein and a metalloprotease), jointly influence EPS-I synthesis by modulating the ExoR-ExoS-ChvI pathway and expression of genes in the ChvI regulon. Deletions of jspA and lppA led to lower EPS-I production and competitive disadvantage during host colonization, for both S. meliloti with Medicago sativa and S. medicae with M. truncatula. Overexpression of jspA reduced steady-state levels of ExoR, suggesting that the JspA protease participates in ExoR degradation. This reduction in ExoR levels is dependent on LppA and can be replicated with ExoR, JspA, and LppA expressed exogenously in Caulobacter crescentus and Escherichia coli. Akin to signaling pathways that sense extracytoplasmic stress in other bacteria, JspA and LppA may monitor periplasmic conditions during interaction with the plant host to adjust accordingly expression of genes that contribute to efficient symbiosis. The molecular mechanisms underlying host colonization in our model system may have parallels in related alpha-proteobacteria.
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Affiliation(s)
- Julian A. Bustamante
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Josue S. Ceron
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Ivan Thomas Gao
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Hector A. Ramirez
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Milo V. Aviles
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Demsin Bet Adam
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Jason R. Brice
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Rodrigo A. Cuellar
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Eva Dockery
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Miguel Karlo Jabagat
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Donna Grace Karp
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Joseph Kin-On Lau
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Suling Li
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Raymondo Lopez-Magaña
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Rebecca R. Moore
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Bethany Kristi R. Morin
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Juliana Nzongo
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Yasha Rezaeihaghighi
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Joseph Sapienza-Martinez
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Tuyet Thi Kim Tran
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Zhenzhong Huang
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Aaron J. Duthoy
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Melanie J. Barnett
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Sharon R. Long
- Department of Biology, Stanford University, Stanford, California, United States of America
| | - Joseph C. Chen
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
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Lv T, Zhan C, Pan Q, Xu H, Fang H, Wang M, Matsumoto H. Plant pathogenesis: Toward multidimensional understanding of the microbiome. IMETA 2023; 2:e129. [PMID: 38867927 PMCID: PMC10989765 DOI: 10.1002/imt2.129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 06/20/2023] [Accepted: 06/26/2023] [Indexed: 06/14/2024]
Abstract
Single pathogen-targeted disease management measure has shown drawbacks in field efficacy under the scenario of global change. An in-depth understanding of plant pathogenesis will provide a promising solution but faces the challenges of the emerging paradigm involving the plant microbiome. While the beneficial impact of the plant microbiome is well characterized, their potential role in facilitating pathological processes has so far remained largely overlooked. To address these unsolved controversies and emerging challenges, we hereby highlight the pathobiome, the disease-assisting portion hidden in the plant microbiome, in the plant pathogenesis paradigm. We review the detrimental actions mediated by the pathobiome at multiple scales and further discuss how natural and human triggers result in the prevalence of the plant pathobiome, which would probably provide a clue to the mitigation of plant disease epidemics. Collectively, the article would advance the current insight into plant pathogenesis and also pave a new way to cope with the upward trends of plant disease by designing the pathobiome-targeted measure.
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Affiliation(s)
- Tianxing Lv
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Laboratory of Molecular Biology of Crop Pathogens and InsectsZhejiang UniversityHangzhouChina
- Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Pesticide and Environmental Toxicology, College of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
| | - Chengfang Zhan
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Laboratory of Molecular Biology of Crop Pathogens and InsectsZhejiang UniversityHangzhouChina
- Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Pesticide and Environmental Toxicology, College of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
| | - Qianqian Pan
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Laboratory of Molecular Biology of Crop Pathogens and InsectsZhejiang UniversityHangzhouChina
- Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Pesticide and Environmental Toxicology, College of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
| | - Haorong Xu
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Laboratory of Molecular Biology of Crop Pathogens and InsectsZhejiang UniversityHangzhouChina
- Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Pesticide and Environmental Toxicology, College of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
| | - Hongda Fang
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Laboratory of Molecular Biology of Crop Pathogens and InsectsZhejiang UniversityHangzhouChina
- Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Pesticide and Environmental Toxicology, College of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
| | - Mengcen Wang
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Laboratory of Molecular Biology of Crop Pathogens and InsectsZhejiang UniversityHangzhouChina
- Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Pesticide and Environmental Toxicology, College of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
- Global Education Program for AgriScience Frontiers, Graduate School of AgricultureHokkaido UniversitySapporoJapan
| | - Haruna Matsumoto
- State Key Laboratory of Rice Biology & Ministry of Agricultural and Rural Affairs Laboratory of Molecular Biology of Crop Pathogens and InsectsZhejiang UniversityHangzhouChina
- Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Institute of Pesticide and Environmental Toxicology, College of Agriculture and BiotechnologyZhejiang UniversityHangzhouChina
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3
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Albicoro FJ, Vacca C, Cafiero JH, Draghi WO, Martini MC, Goulian M, Lagares A, Del Papa MF. Comparative Proteomic Analysis Revealing ActJ-Regulated Proteins in Sinorhizobium meliloti. J Proteome Res 2023; 22:1682-1694. [PMID: 37017314 PMCID: PMC10834056 DOI: 10.1021/acs.jproteome.2c00731] [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] [Indexed: 04/06/2023]
Abstract
To adapt to different environmental conditions, Sinorhizobium meliloti relies on finely tuned regulatory networks, most of which are unexplored to date. We recently demonstrated that deletion of the two-component system ActJK renders an acid-vulnerable phenotype in S. meliloti and negatively impacts bacteroid development and nodule occupancy as well. To fully understand the role of ActJ in acid tolerance, S. meliloti wild-type and S. meliloti ΔactJ proteomes were compared in the presence or absence of acid stress by nanoflow ultrahigh-performance liquid chromatography coupled to mass spectrometry. The analysis demonstrated that proteins involved in the synthesis of exopolysaccharides (EPSs) were notably enriched in ΔactJ cells in acid pH. Total EPS quantification further revealed that although EPS production was augmented at pH 5.6 in both the ΔactJ and the parental strain, the lack of ActJ significantly enhanced this difference. Moreover, several efflux pumps were found to be downregulated in the ΔactJ strain. Promoter fusion assays suggested that ActJ positively modulated its own expression in an acid medium but not at under neutral conditions. The results presented here identify several ActJ-regulated genes in S. meliloti, highlighting key components associated with ActJK regulation that will contribute to a better understanding of rhizobia adaptation to acid stress.
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Affiliation(s)
- Francisco Javier Albicoro
- Instituto de Biotecnología y Biologia Molecular -CONICET CCT La Plata - Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Carolina Vacca
- Instituto de Biotecnología y Biologia Molecular -CONICET CCT La Plata - Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Juan Hilario Cafiero
- Instituto de Biotecnología y Biologia Molecular -CONICET CCT La Plata - Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Walter Omar Draghi
- Instituto de Biotecnología y Biologia Molecular -CONICET CCT La Plata - Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - María Carla Martini
- Instituto de Biotecnología y Biologia Molecular -CONICET CCT La Plata - Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - Mark Goulian
- Department of Biology, University of Pennsylvania, Philadelphia, PA. USA
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA. USA
| | - Antonio Lagares
- Instituto de Biotecnología y Biologia Molecular -CONICET CCT La Plata - Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
| | - María Florencia Del Papa
- Instituto de Biotecnología y Biologia Molecular -CONICET CCT La Plata - Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina
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4
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Calvopina-Chavez DG, Howarth RE, Memmott AK, Pech Gonzalez OH, Hafen CB, Jensen KT, Benedict AB, Altman JD, Burnside BS, Childs JS, Dallon SW, DeMarco AC, Flindt KC, Grover SA, Heninger E, Iverson CS, Johnson AK, Lopez JB, Meinzer MA, Moulder BA, Moulton RI, Russell HS, Scott TM, Shiobara Y, Taylor MD, Tippets KE, Vainerere KM, Von Wallwitz IC, Wagley M, Wiley MS, Young NJ, Griffitts JS. A large-scale genetic screen identifies genes essential for motility in Agrobacterium fabrum. PLoS One 2023; 18:e0279936. [PMID: 36598925 PMCID: PMC9812332 DOI: 10.1371/journal.pone.0279936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Accepted: 12/17/2022] [Indexed: 01/05/2023] Open
Abstract
The genetic and molecular basis of flagellar motility has been investigated for several decades, with innovative research strategies propelling advances at a steady pace. Furthermore, as the phenomenon is examined in diverse bacteria, new taxon-specific regulatory and structural features are being elucidated. Motility is also a straightforward bacterial phenotype that can allow undergraduate researchers to explore the palette of molecular genetic tools available to microbiologists. This study, driven primarily by undergraduate researchers, evaluated hundreds of flagellar motility mutants in the Gram-negative plant-associated bacterium Agrobacterium fabrum. The nearly saturating screen implicates a total of 37 genes in flagellar biosynthesis, including genes of previously unknown function.
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Affiliation(s)
- Diana G. Calvopina-Chavez
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Robyn E. Howarth
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Audrey K. Memmott
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Oscar H. Pech Gonzalez
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Caleb B. Hafen
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kyson T. Jensen
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Alex B. Benedict
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Jessica D. Altman
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Brittany S. Burnside
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Justin S. Childs
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Samuel W. Dallon
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Alexa C. DeMarco
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kirsten C. Flindt
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Sarah A. Grover
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Elizabeth Heninger
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Christina S. Iverson
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Abigail K. Johnson
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Jack B. Lopez
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - McKay A. Meinzer
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Brook A. Moulder
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Rebecca I. Moulton
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Hyrum S. Russell
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Tiana M. Scott
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Yuka Shiobara
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Mason D. Taylor
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kathryn E. Tippets
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Kayla M. Vainerere
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Isabella C. Von Wallwitz
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Madison Wagley
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Megumi S. Wiley
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Naomi J. Young
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
| | - Joel S. Griffitts
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, United States of America
- * E-mail:
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5
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Naoun AA, Raphael I, Forsthuber TG. Immunoregulation via Cell Density and Quorum Sensing-like Mechanisms: An Underexplored Emerging Field with Potential Translational Implications. Cells 2022; 11:cells11152442. [PMID: 35954285 PMCID: PMC9368058 DOI: 10.3390/cells11152442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 07/27/2022] [Accepted: 08/01/2022] [Indexed: 11/16/2022] Open
Abstract
Quorum sensing (QS) was historically described as a mechanism by which bacteria detect and optimize their population density via gene regulation based on dynamic environmental cues. Recently, it was proposed that QS or similar mechanisms may have broader applications across different species and cell types. Indeed, emerging evidence shows that the mammalian immune system can also elicit coordinated responses on a population level to regulate cell density and function, thus suggesting that QS-like mechanisms may also be a beneficial trait of the immune system. In this review, we explore and discuss potential QS-like mechanisms deployed by the immune system to coordinate cellular-level responses, such as T cell responses mediated via the common gamma chain (γc) receptor cytokines and the aryl hydrocarbon receptors (AhRs). We present evidence regarding a novel role of QS as a multifunctional mechanism coordinating CD4+ and CD8+ T cell behavior during steady state and in response to infection, inflammatory diseases, and cancer. Successful clinical therapies such as adoptive cell transfer for cancer treatment may be re-evaluated to harness the effects of the QS mechanism(s) and enhance treatment responsiveness. Moreover, we discuss how signaling threshold perturbations through QS-like mediators may result in disturbances of the complex crosstalk between immune cell populations, undesired T cell responses, and induction of autoimmune pathology. Finally, we discuss the potential therapeutic role of modulating immune-system-related QS as a promising avenue to treat human diseases.
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Affiliation(s)
- Adrian A. Naoun
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - Itay Raphael
- Department of Neurological Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15217, USA
- Correspondence: (I.R.); (T.G.F.)
| | - Thomas G. Forsthuber
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX 78249, USA
- Correspondence: (I.R.); (T.G.F.)
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6
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Bourigault Y, Rodrigues S, Crépin A, Chane A, Taupin L, Bouteiller M, Dupont C, Merieau A, Konto-Ghiorghi Y, Boukerb AM, Turner M, Hamon C, Dufour A, Barbey C, Latour X. Biocontrol of Biofilm Formation: Jamming of Sessile-Associated Rhizobial Communication by Rhodococcal Quorum-Quenching. Int J Mol Sci 2021; 22:ijms22158241. [PMID: 34361010 PMCID: PMC8347015 DOI: 10.3390/ijms22158241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/02/2021] [Accepted: 07/07/2021] [Indexed: 11/16/2022] Open
Abstract
Biofilms are complex structures formed by a community of microbes adhering to a surface and/or to each other through the secretion of an adhesive and protective matrix. The establishment of these structures requires a coordination of action between microorganisms through powerful communication systems such as quorum-sensing. Therefore, auxiliary bacteria capable of interfering with these means of communication could be used to prevent biofilm formation and development. The phytopathogen Rhizobium rhizogenes, which causes hairy root disease and forms large biofilms in hydroponic crops, and the biocontrol agent Rhodococcus erythropolis R138 were used for this study. Changes in biofilm biovolume and structure, as well as interactions between rhizobia and rhodococci, were monitored by confocal laser scanning microscopy with appropriate fluorescent biosensors. We obtained direct visual evidence of an exchange of signals between rhizobia and the jamming of this communication by Rhodococcus within the biofilm. Signaling molecules were characterized as long chain (C14) N-acyl-homoserine lactones. The role of the Qsd quorum-quenching pathway in biofilm alteration was confirmed with an R. erythropolis mutant unable to produce the QsdA lactonase, and by expression of the qsdA gene in a heterologous host, Escherichia coli. Finally, Rhizobium biofilm formation was similarly inhibited by a purified extract of QsdA enzyme.
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Affiliation(s)
- Yvann Bourigault
- Laboratory of Microbiology Signals and Microenvironment (LMSM EA 4312), University of Rouen Normandy, F-27000 Evreux, France; (Y.B.); (A.C.); (M.B.); (C.D.); (A.M.); (Y.K.-G.); (A.M.B.); (C.B.)
- Research Federations NORVEGE Fed4277 & NORSEVE, Normandy University, F-76821 Mont-Saint-Aignan, France
| | - Sophie Rodrigues
- Laboratoire de Biotechnologie et Chimie Marines, LBCM IUEM, EA 3884, Université de Bretagne-Sud, F-56100 Lorient, France; (S.R.); (L.T.); (A.D.)
| | - Alexandre Crépin
- Laboratoire Ecologie et Biologie des Interactions, UMR CNRS 7267, F-86073 Poitiers, France;
| | - Andrea Chane
- Laboratory of Microbiology Signals and Microenvironment (LMSM EA 4312), University of Rouen Normandy, F-27000 Evreux, France; (Y.B.); (A.C.); (M.B.); (C.D.); (A.M.); (Y.K.-G.); (A.M.B.); (C.B.)
| | - Laure Taupin
- Laboratoire de Biotechnologie et Chimie Marines, LBCM IUEM, EA 3884, Université de Bretagne-Sud, F-56100 Lorient, France; (S.R.); (L.T.); (A.D.)
| | - Mathilde Bouteiller
- Laboratory of Microbiology Signals and Microenvironment (LMSM EA 4312), University of Rouen Normandy, F-27000 Evreux, France; (Y.B.); (A.C.); (M.B.); (C.D.); (A.M.); (Y.K.-G.); (A.M.B.); (C.B.)
- Research Federations NORVEGE Fed4277 & NORSEVE, Normandy University, F-76821 Mont-Saint-Aignan, France
| | - Charly Dupont
- Laboratory of Microbiology Signals and Microenvironment (LMSM EA 4312), University of Rouen Normandy, F-27000 Evreux, France; (Y.B.); (A.C.); (M.B.); (C.D.); (A.M.); (Y.K.-G.); (A.M.B.); (C.B.)
- Research Federations NORVEGE Fed4277 & NORSEVE, Normandy University, F-76821 Mont-Saint-Aignan, France
| | - Annabelle Merieau
- Laboratory of Microbiology Signals and Microenvironment (LMSM EA 4312), University of Rouen Normandy, F-27000 Evreux, France; (Y.B.); (A.C.); (M.B.); (C.D.); (A.M.); (Y.K.-G.); (A.M.B.); (C.B.)
- Research Federations NORVEGE Fed4277 & NORSEVE, Normandy University, F-76821 Mont-Saint-Aignan, France
| | - Yoan Konto-Ghiorghi
- Laboratory of Microbiology Signals and Microenvironment (LMSM EA 4312), University of Rouen Normandy, F-27000 Evreux, France; (Y.B.); (A.C.); (M.B.); (C.D.); (A.M.); (Y.K.-G.); (A.M.B.); (C.B.)
- Research Federations NORVEGE Fed4277 & NORSEVE, Normandy University, F-76821 Mont-Saint-Aignan, France
| | - Amine M. Boukerb
- Laboratory of Microbiology Signals and Microenvironment (LMSM EA 4312), University of Rouen Normandy, F-27000 Evreux, France; (Y.B.); (A.C.); (M.B.); (C.D.); (A.M.); (Y.K.-G.); (A.M.B.); (C.B.)
| | - Marie Turner
- Vegenov, F-29250 Saint-Pol-de-Léon, France; (M.T.); (C.H.)
- Biocontrol Consortium, F-75007 Paris, France
| | - Céline Hamon
- Vegenov, F-29250 Saint-Pol-de-Léon, France; (M.T.); (C.H.)
| | - Alain Dufour
- Laboratoire de Biotechnologie et Chimie Marines, LBCM IUEM, EA 3884, Université de Bretagne-Sud, F-56100 Lorient, France; (S.R.); (L.T.); (A.D.)
| | - Corinne Barbey
- Laboratory of Microbiology Signals and Microenvironment (LMSM EA 4312), University of Rouen Normandy, F-27000 Evreux, France; (Y.B.); (A.C.); (M.B.); (C.D.); (A.M.); (Y.K.-G.); (A.M.B.); (C.B.)
- Research Federations NORVEGE Fed4277 & NORSEVE, Normandy University, F-76821 Mont-Saint-Aignan, France
| | - Xavier Latour
- Laboratory of Microbiology Signals and Microenvironment (LMSM EA 4312), University of Rouen Normandy, F-27000 Evreux, France; (Y.B.); (A.C.); (M.B.); (C.D.); (A.M.); (Y.K.-G.); (A.M.B.); (C.B.)
- Research Federations NORVEGE Fed4277 & NORSEVE, Normandy University, F-76821 Mont-Saint-Aignan, France
- Biocontrol Consortium, F-75007 Paris, France
- Correspondence: ; +33-235-146-000
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7
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Krol E, Schäper S, Becker A. Cyclic di-GMP signaling controlling the free-living lifestyle of alpha-proteobacterial rhizobia. Biol Chem 2021; 401:1335-1348. [PMID: 32990642 DOI: 10.1515/hsz-2020-0232] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 09/14/2020] [Indexed: 12/12/2022]
Abstract
Cyclic-di-GMP (c-di-GMP) is a ubiquitous bacterial second messenger which has been associated with a motile to sessile lifestyle switch in many bacteria. Here, we review recent insights into c-di-GMP regulated processes related to environmental adaptations in alphaproteobacterial rhizobia, which are diazotrophic bacteria capable of fixing nitrogen in symbiosis with their leguminous host plants. The review centers on Sinorhizobium meliloti, which in the recent years was intensively studied for its c-di-GMP regulatory network.
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Affiliation(s)
- Elizaveta Krol
- Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, D-35032 Marburg, Germany.,Department of Biology, Philipps-Universität Marburg, D-35032 Marburg, Germany
| | - Simon Schäper
- Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, D-35032 Marburg, Germany
| | - Anke Becker
- Center for Synthetic Microbiology (SYNMIKRO), Philipps-Universität Marburg, D-35032 Marburg, Germany.,Department of Biology, Philipps-Universität Marburg, D-35032 Marburg, Germany
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8
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Alencar VC, Silva JDFDS, Vilas Boas RO, Farnézio VM, de Maria YNLF, Aciole Barbosa D, Almeida AT, de Souza EM, Müller-Santos M, Jabes DL, Menegidio FB, Costa de Oliveira R, Rodrigues T, Tersariol ILDS, Walmsley AR, Nunes LR. The Quorum Sensing Auto-Inducer 2 (AI-2) Stimulates Nitrogen Fixation and Favors Ethanol Production over Biomass Accumulation in Zymomonas mobilis. Int J Mol Sci 2021; 22:ijms22115628. [PMID: 34073173 PMCID: PMC8198075 DOI: 10.3390/ijms22115628] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 11/16/2022] Open
Abstract
Autoinducer 2 (or AI-2) is one of the molecules used by bacteria to trigger the Quorum Sensing (QS) response, which activates expression of genes involved in a series of alternative mechanisms, when cells reach high population densities (including bioluminescence, motility, biofilm formation, stress resistance, and production of public goods, or pathogenicity factors, among others). Contrary to most autoinducers, AI-2 can induce QS responses in both Gram-negative and Gram-positive bacteria, and has been suggested to constitute a trans-specific system of bacterial communication, capable of affecting even bacteria that cannot produce this autoinducer. In this work, we demonstrate that the ethanologenic Gram-negative bacterium Zymomonas mobilis (a non-AI-2 producer) responds to exogenous AI-2 by modulating expression of genes involved in mechanisms typically associated with QS in other bacteria, such as motility, DNA repair, and nitrogen fixation. Interestingly, the metabolism of AI-2-induced Z. mobilis cells seems to favor ethanol production over biomass accumulation, probably as an adaptation to the high-energy demand of N2 fixation. This opens the possibility of employing AI-2 during the industrial production of second-generation ethanol, as a way to boost N2 fixation by these bacteria, which could reduce costs associated with the use of nitrogen-based fertilizers, without compromising ethanol production in industrial plants.
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Affiliation(s)
- Valquíria Campos Alencar
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Alameda da Universidade, s/n, São Bernardo do Campo 09606-045, SP, Brazil; (V.C.A.); (J.d.F.d.S.S.); (V.M.F.); (T.R.)
- Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes (UMC), Av. Dr. Cândido Xavier de Almeida Souza, 200, Mogi das Cruzes 08780-911, SP, Brazil; (R.O.V.B.); (Y.N.L.F.d.M.); (D.A.B.); (D.L.J.); (F.B.M.); (R.C.d.O.)
| | - Juliana de Fátima dos Santos Silva
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Alameda da Universidade, s/n, São Bernardo do Campo 09606-045, SP, Brazil; (V.C.A.); (J.d.F.d.S.S.); (V.M.F.); (T.R.)
| | - Renata Ozelami Vilas Boas
- Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes (UMC), Av. Dr. Cândido Xavier de Almeida Souza, 200, Mogi das Cruzes 08780-911, SP, Brazil; (R.O.V.B.); (Y.N.L.F.d.M.); (D.A.B.); (D.L.J.); (F.B.M.); (R.C.d.O.)
| | - Vinícius Manganaro Farnézio
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Alameda da Universidade, s/n, São Bernardo do Campo 09606-045, SP, Brazil; (V.C.A.); (J.d.F.d.S.S.); (V.M.F.); (T.R.)
| | - Yara N. L. F. de Maria
- Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes (UMC), Av. Dr. Cândido Xavier de Almeida Souza, 200, Mogi das Cruzes 08780-911, SP, Brazil; (R.O.V.B.); (Y.N.L.F.d.M.); (D.A.B.); (D.L.J.); (F.B.M.); (R.C.d.O.)
| | - David Aciole Barbosa
- Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes (UMC), Av. Dr. Cândido Xavier de Almeida Souza, 200, Mogi das Cruzes 08780-911, SP, Brazil; (R.O.V.B.); (Y.N.L.F.d.M.); (D.A.B.); (D.L.J.); (F.B.M.); (R.C.d.O.)
| | - Alex Tramontin Almeida
- Setor de Ciências Biológicas-Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná (UFPR), Rua Cel. Francisco H. dos Santos, 100, Curitiba 81531-980, PR, Brazil; (A.T.A.); (E.M.d.S.); (M.M.-S.)
| | - Emanuel Maltempi de Souza
- Setor de Ciências Biológicas-Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná (UFPR), Rua Cel. Francisco H. dos Santos, 100, Curitiba 81531-980, PR, Brazil; (A.T.A.); (E.M.d.S.); (M.M.-S.)
| | - Marcelo Müller-Santos
- Setor de Ciências Biológicas-Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná (UFPR), Rua Cel. Francisco H. dos Santos, 100, Curitiba 81531-980, PR, Brazil; (A.T.A.); (E.M.d.S.); (M.M.-S.)
| | - Daniela L. Jabes
- Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes (UMC), Av. Dr. Cândido Xavier de Almeida Souza, 200, Mogi das Cruzes 08780-911, SP, Brazil; (R.O.V.B.); (Y.N.L.F.d.M.); (D.A.B.); (D.L.J.); (F.B.M.); (R.C.d.O.)
| | - Fabiano B. Menegidio
- Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes (UMC), Av. Dr. Cândido Xavier de Almeida Souza, 200, Mogi das Cruzes 08780-911, SP, Brazil; (R.O.V.B.); (Y.N.L.F.d.M.); (D.A.B.); (D.L.J.); (F.B.M.); (R.C.d.O.)
| | - Regina Costa de Oliveira
- Núcleo Integrado de Biotecnologia, Universidade de Mogi das Cruzes (UMC), Av. Dr. Cândido Xavier de Almeida Souza, 200, Mogi das Cruzes 08780-911, SP, Brazil; (R.O.V.B.); (Y.N.L.F.d.M.); (D.A.B.); (D.L.J.); (F.B.M.); (R.C.d.O.)
| | - Tiago Rodrigues
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Alameda da Universidade, s/n, São Bernardo do Campo 09606-045, SP, Brazil; (V.C.A.); (J.d.F.d.S.S.); (V.M.F.); (T.R.)
| | - Ivarne Luis dos Santos Tersariol
- Departamento de Bioquímica, Universidade Federal de São Paulo (UNIFESP), Rua Três de Maio, 100, São Paulo 04044-020, SP, Brazil;
| | - Adrian R. Walmsley
- Department of Biosciences, Durham University, South Road, Durham DH1 3LE, UK;
| | - Luiz R. Nunes
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Alameda da Universidade, s/n, São Bernardo do Campo 09606-045, SP, Brazil; (V.C.A.); (J.d.F.d.S.S.); (V.M.F.); (T.R.)
- Correspondence: ; Tel.: +55-11-4996-8371 (ext. 4996-3166)
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Rosier A, Beauregard PB, Bais HP. Quorum Quenching Activity of the PGPR Bacillus subtilis UD1022 Alters Nodulation Efficiency of Sinorhizobium meliloti on Medicago truncatula. Front Microbiol 2021; 11:596299. [PMID: 33519732 PMCID: PMC7843924 DOI: 10.3389/fmicb.2020.596299] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 12/15/2020] [Indexed: 12/17/2022] Open
Abstract
Plant growth-promoting rhizobacteria (PGPR) have enormous potential for solving some of the myriad challenges facing our global agricultural system. Intense research efforts are rapidly moving the field forward and illuminating the wide diversity of bacteria and their plant beneficial activities. In the development of better crop solutions using these PGPR, producers are including multiple different species of PGPR in their formulations in a "consortia" approach. While the intention is to emulate more natural rhizomicrobiome systems, the aspect of bacterial interactions has not been properly regarded. By using a tri-trophic model of Medicago truncatula A17 Jemalong, its nitrogen (N)-fixing symbiont Sinorhizobium meliloti Rm8530, and the PGPR Bacillus subtilis UD1022, we demonstrate indirect influences between the bacteria affecting their plant growth-promoting activities. Co-cultures of UD1022 with Rm8530 significantly reduced Rm8530 biofilm formation and downregulated quorum sensing (QS) genes responsible for symbiotically active biofilm production. This work also identifies the presence and activity of a quorum quenching lactonase in UD1022 and proposes this as the mechanism for non-synergistic activity of this model "consortium." These interspecies interactions may be common in the rhizosphere and are critical to understand as we seek to develop new sustainable solutions in agriculture.
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Affiliation(s)
- Amanda Rosier
- Department of Plant and Soil Sciences, University of Delaware, Newark, DE, United States
- Delaware Biotechnology Institute, University of Delaware, Newark, DE, United States
| | | | - Harsh P. Bais
- Department of Plant and Soil Sciences, University of Delaware, Newark, DE, United States
- Delaware Biotechnology Institute, University of Delaware, Newark, DE, United States
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10
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Cai W, Ou F, Staehelin C, Dai W. Bradyrhizobium sp. strain ORS278 promotes rice growth and its quorum sensing system is required for optimal root colonization. ENVIRONMENTAL MICROBIOLOGY REPORTS 2020; 12:656-666. [PMID: 32929871 DOI: 10.1111/1758-2229.12885] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 09/10/2020] [Indexed: 05/25/2023]
Abstract
Many Gram-negative bacteria communicate by using homoserine lactones (HSLs) as quorum sensing (QS) signals in a cell density-dependent manner. In addition to fatty acyl-HSL (acyl-HSL) signals, certain strains, most of them associated with plants, produce non-canonical aryl-HSLs such as cinnamoyl-HSL. However, the role of aryl-HSL in endophytic associations remained elusive. Bradyrhizobium sp. strain ORS278 possesses a LuxI-LuxR type QS system and produces cinnamoyl-HSL as a QS signal. Here, we report that strain ORS278 promotes growth of domesticated rice (Oryza sativa). QS mutants unable to produce cinnamoyl-HSL exhibited reduced plant-growth promoting activity in comparison to the parent strain ORS278. Likewise, the QS mutants were impaired in their ability to colonize rice roots. These findings suggest that genes controlled by cinnamoyl-HSL play an important role in the association between rice and ORS278. However, biofilm production was not visibly altered in these mutants. In conclusion, our study highlights the importance of aryl-HSLs in endophytic plant-bacteria interactions.
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Affiliation(s)
- Wenjie Cai
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510006, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, 510642, China
| | - Fuwen Ou
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510006, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, 510642, China
| | - Christian Staehelin
- State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Bioresources, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510006, China
| | - Weijun Dai
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510006, China
- Guangdong Province Key Laboratory of Microbial Signals and Disease Control, Integrative Microbiology Research Center, South China Agricultural University, Guangzhou, 510642, China
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11
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Primo E, Bogino P, Cossovich S, Foresto E, Nievas F, Giordano W. Exopolysaccharide II Is Relevant for the Survival of Sinorhizobium meliloti under Water Deficiency and Salinity Stress. Molecules 2020; 25:E4876. [PMID: 33105680 PMCID: PMC7659973 DOI: 10.3390/molecules25214876] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 10/12/2020] [Accepted: 10/20/2020] [Indexed: 11/16/2022] Open
Abstract
Sinorhizobium meliloti is a soil bacterium of great agricultural importance because of its ability to fix atmospheric nitrogen in symbiotic association with alfalfa (Medicago sativa) roots. We looked into the involvement of exopolysaccharides (EPS) in its survival when exposed to different environmental stressors, as well as in bacteria-bacteria and bacteria-substrate interactions. The strains used were wild-type Rm8530 and two strains that are defective in the biosynthesis of EPS II: wild-type Rm1021, which has a non-functional expR locus, and mutant Rm8530 expA. Under stress by water deficiency, Rm8530 remained viable and increased in number, whereas Rm1021 and Rm8530 expA did not. These differences could be due to Rm8530's ability to produce EPS II. Survival experiments under saline stress showed that viability was reduced for Rm1021 but not for Rm8530 or Rm8530 expA, which suggests the existence of some regulating mechanism dependent on a functional expR that is absent in Rm1021. The results of salinity-induced stress assays regarding biofilm-forming capacity (BFC) and autoaggregation indicated the protective role of EPS II. As a whole, our observations demonstrate that EPS play major roles in rhizobacterial survival.
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Affiliation(s)
| | | | | | | | | | - Walter Giordano
- Instituto de Biotecnología Ambiental y Salud (INBIAS), CONICET, Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto (UNRC), Río Cuarto X5804BYA, Córdoba, Argentina; (E.P.); (P.B.); (S.C.); (E.F.); (F.N.)
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12
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Shah N, Gislason AS, Becker M, Belmonte MF, Fernando WGD, de Kievit TR. Investigation of the quorum-sensing regulon of the biocontrol bacterium Pseudomonas chlororaphis strain PA23. PLoS One 2020; 15:e0226232. [PMID: 32109244 PMCID: PMC7048289 DOI: 10.1371/journal.pone.0226232] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 02/12/2020] [Indexed: 12/15/2022] Open
Abstract
Pseudomonas chlororaphis strain PA23 is a biocontrol agent capable of protecting canola from stem rot disease caused by the fungal pathogen Sclerotinia sclerotiorum. PA23 produces several inhibitory compounds that are under control of a complex regulatory network. Included in this cascade is the PhzRI quorum sensing (QS) system, which plays an essential role in PA23 biocontrol, as well as CsaRI and AurRI, which have not yet been characterized in PA23. The focus of the current study was to employ RNA sequencing to explore the spectrum of PA23 genes under QS control. In this work, we investigated genes under the control of the main QS transcriptional regulator, PhzR, as well as those differentially expressed in an AHL-deficient strain, PA23-6863, which constitutively expresses an AiiA lactonase, rendering the strain QS defective. Transcriptomic profiling revealed 545 differentially expressed genes (365 downregulated; 180 upregulated) in the phzR mutant and 534 genes (382 downregulated; 152 upregulated) in the AHL-deficient PA23-6863. In both strains, decreased expression of phenazine, pyrrolnitrin, and exoprotease biosynthetic genes was observed. We have previously reported that QS activates expression of these genes and their encoded products. In addition, elevated siderophore and decreased chitinase gene expression was observed in the QS-deficient stains, which was confirmed by phenotypic analysis. Inspection of the promoter regions revealed the presence of "phz-box" sequences in only 58 of the 807 differentially expressed genes, suggesting that much of the QS regulon is indirectly regulated. Consistent with this notion, 41 transcriptional regulators displayed altered expression in one or both of the QS-deficient strains. Collectively, our findings indicate that QS governs expression of approximately 13% of the PA23 genome affecting diverse functions ranging from secondary metabolite production to general metabolism.
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Affiliation(s)
- Nidhi Shah
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - April S. Gislason
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Michael Becker
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Mark F. Belmonte
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | | | - Teresa R. de Kievit
- Department of Microbiology, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
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Gosai J, Anandhan S, Bhattacharjee A, Archana G. Elucidation of quorum sensing components and their role in regulation of symbiotically important traits in Ensifer nodulating pigeon pea. Microbiol Res 2020; 231:126354. [DOI: 10.1016/j.micres.2019.126354] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 09/12/2019] [Accepted: 10/13/2019] [Indexed: 11/15/2022]
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Andrade M, Wang N. The Tad Pilus Apparatus of ' Candidatus Liberibacter asiaticus' and Its Regulation by VisNR. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1175-1187. [PMID: 30925227 DOI: 10.1094/mpmi-02-19-0052-r] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Citrus huanglongbing (HLB) is one of the most destructive diseases affecting citrus plants. 'Candidatus Liberibacter asiaticus', an uncultivated α-proteobacteria, is the most widely spread causal agent of HLB and is transmitted by the Asian citrus psyllid Diaphorina citri. 'Ca. L. asiaticus' attachment to the psyllid midgut is believed to be critical to further infect other organs, including the salivary gland. In this study, the type IVc tight adherence (Tad) pilus locus encoded by 'Ca. L. asiaticus' was characterized. The Tad loci are conserved among members of Rhizobiaceae, including 'Ca. L. asiaticus' and Agrobacterium spp. Ectopic expression of the 'Ca. L. asiaticus' cpaF gene, an ATPase essential for the biogenesis and secretion of the Tad pilus, restored the adherence phenotype in cpaF mutant of A. tumefaciens, indicating CpaF of 'Ca. L. asiaticus' was functional and critical for bacterial adherence mediated by Tad pilus. Quantitative reverse transcription PCR (qRT-PCR) analysis revealed that 'Ca. L. asiaticus' Tad pilus-encoding genes and 'Ca. L. asiaticus' pilin gene flp3 were upregulated in psyllids compared with in planta. A bacterial one-hybrid assay showed that 'Ca. L. asiaticus' VisN and VisR, members of the LuxR transcriptional factor family, were bound to the flp3 promoter. VisNR regulate flp3. Negative regulation of the flp3 promoter by both VisN and VisR was demonstrated using a shuttle strategy, with analysis of the phenotypes and immunoblotting together with quantification of the expression of the flp3 promoter fused to the β-galactosidase reporter gene. Comparative expression analysis confirmed that 'Ca. L. asiaticus' visNR was less expressed in the psyllid than in the plant host. Further, motility and biofilm phenotypes of the visNR mutant of A. tumefaciens were fully complemented by expressing 'Ca. L. asiaticus' visNR together. The physical interaction between VisN and VisR was confirmed by pull-down and stability assays. The interaction of the flp3 promoter with VisR was verified by electrophoretic mobility shift assay. Taken together, the results revealed the contribution of the Tad pilus apparatus in the colonization of the insect vector by 'Ca. L. asiaticus' and shed light on the involvement of VisNR in regulation of the Tad locus.
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Affiliation(s)
- Maxuel Andrade
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850, U.S.A
| | - Nian Wang
- Citrus Research and Education Center (CREC), Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Lake Alfred, FL 33850, U.S.A
- China-USA Citrus Huanglongbing Joint Laboratory (A joint laboratory of the University of Florida Institute of Food and Agricultural Sciences and Gannan Normal University), National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou 341000, China
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15
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Marczak M, Żebracki K, Koper P, Turska-Szewczuk A, Mazur A, Wydrych J, Wójcik M, Skorupska A. Mgl2 Is a Hypothetical Methyltransferase Involved in Exopolysaccharide Production, Biofilm Formation, and Motility in Rhizobium leguminosarum bv. trifolii. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:899-911. [PMID: 30681888 DOI: 10.1094/mpmi-01-19-0026-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this study, functional characterization of the mgl2 gene located near the Pss-I exopolysaccharide biosynthesis region in Rhizobium leguminosarum bv. trifolii TA1 is described. The hypothetical protein encoded by the mgl2 gene was found to be similar to methyltransferases (MTases). Protein homology and template-based modeling facilitated prediction of the Mgl2 structure, which greatly resembled class I MTases with a S-adenosyl-L-methionine-binding cleft. The Mgl2 protein was engaged in exopolysaccharide, but not lipopolysaccharide, synthesis. The mgl2 deletion mutant produced exopolysaccharide comprised of only low molecular weight fractions, while overexpression of mgl2 caused overproduction of exopolysaccharide with a normal low to high molecular weight ratio. The deletion of the mgl2 gene resulted in disturbances in biofilm formation and a slight increase in motility in minimal medium. Red clover (Trifolium pratense) inoculated with the mgl2 mutant formed effective nodules, and the appearance of the plants indicated active nitrogen fixation. The mgl2 gene was preceded by an active and strong promoter. Mgl2 was defined as an integral membrane protein and formed homodimers in vivo; however, it did not interact with Pss proteins encoded within the Pss-I region. The results are discussed in the context of the possible involvement of the newly described potential MTase in various metabolic traits, such as the exopolysaccharide synthesis and motility that are important for rhizobial saprophytic and symbiotic relationships.
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Affiliation(s)
- Małgorzata Marczak
- 1 Department of Genetics and Microbiology, Institute of Microbiology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19 St, 20-033 Lublin, Poland
| | - Kamil Żebracki
- 1 Department of Genetics and Microbiology, Institute of Microbiology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19 St, 20-033 Lublin, Poland
| | - Piotr Koper
- 1 Department of Genetics and Microbiology, Institute of Microbiology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19 St, 20-033 Lublin, Poland
| | - Anna Turska-Szewczuk
- 1 Department of Genetics and Microbiology, Institute of Microbiology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19 St, 20-033 Lublin, Poland
| | - Andrzej Mazur
- 1 Department of Genetics and Microbiology, Institute of Microbiology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19 St, 20-033 Lublin, Poland
| | - Jerzy Wydrych
- 2 Department of Comparative Anatomy and Anthropology, Institute of Biology, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University
| | - Magdalena Wójcik
- 1 Department of Genetics and Microbiology, Institute of Microbiology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19 St, 20-033 Lublin, Poland
| | - Anna Skorupska
- 1 Department of Genetics and Microbiology, Institute of Microbiology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19 St, 20-033 Lublin, Poland
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Antunes J, Leão P, Vasconcelos V. Marine biofilms: diversity of communities and of chemical cues. ENVIRONMENTAL MICROBIOLOGY REPORTS 2019; 11:287-305. [PMID: 30246474 DOI: 10.1111/1758-2229.12694] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 09/14/2018] [Indexed: 06/08/2023]
Abstract
Surfaces immersed in seawater are rapidly colonized by various microorganisms, resulting in the formation of heterogenic marine biofilms. These communities are known to influence the settlement of algae spores and invertebrate larvae, triggering a succession of fouling events, with significant environmental and economic impacts. This review covers recent research regarding the differences in composition of biofilms isolated from different artificial surface types and the influence of environmental factors on their formation. One particular phenomenon - bacterial quorum sensing (QS) - allows bacteria to coordinate swarming, biofilm formation among other phenomena. Some other marine biofilm chemical cues are believed to modulate the settlement and the succession of macrofouling organisms, and they are also reviewed here. Finally, since the formation of a marine biofilm is considered to be an initial, QS-dependent step in the development of marine fouling events, QS inhibition is discussed on its potential as a tool for antibiofouling control in marine settings.
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Affiliation(s)
- Jorge Antunes
- CIIMAR/CIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Av. General Norton de Matos, s/n 4450-208, Matosinhos, Portugal
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre 4069-007, Porto, Portugal
| | - Pedro Leão
- CIIMAR/CIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Av. General Norton de Matos, s/n 4450-208, Matosinhos, Portugal
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre 4069-007, Porto, Portugal
| | - Vitor Vasconcelos
- CIIMAR/CIMAR - Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Av. General Norton de Matos, s/n 4450-208, Matosinhos, Portugal
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre 4069-007, Porto, Portugal
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An Osmoregulatory Mechanism Operating through OmpR and LrhA Controls the Motile-Sessile Switch in the Plant Growth-Promoting Bacterium Pantoea alhagi. Appl Environ Microbiol 2019; 85:AEM.00077-19. [PMID: 30902852 DOI: 10.1128/aem.00077-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 03/14/2019] [Indexed: 11/20/2022] Open
Abstract
Adaptation to osmotic stress is crucial for bacterial growth and survival in changing environments. Although a large number of osmotic stress response genes have been identified in various bacterial species, how osmotic changes affect bacterial motility, biofilm formation, and colonization of host niches remains largely unknown. In this study, we report that the LrhA regulator is an osmoregulated transcription factor that directly binds to the promoters of the flhDC, eps, and opgGH operons and differentially regulates their expression, thus inhibiting motility and promoting exopolysaccharide (EPS) production, synthesis of osmoregulated periplasmic glucans (OPGs), biofilm formation, and root colonization of the plant growth-promoting bacterium Pantoea alhagi LTYR-11Z. Further, we observed that the LrhA-regulated OPGs control RcsCD-RcsB activation in a concentration-dependent manner, and a high concentration of OPGs induced by increased medium osmolarity is maintained to achieve the high level of activation of the Rcs phosphorelay, which results in enhanced EPS synthesis and decreased motility in P. alhagi Moreover, we showed that the osmosensing regulator OmpR directly binds to the promoter of lrhA and promotes its expression, while lrhA expression is feedback inhibited by the activated Rcs phosphorelay system. Overall, our data support a model whereby P. alhagi senses environmental osmolarity changes through the EnvZ-OmpR two-component system and LrhA to regulate the synthesis of OPGs, EPS production, and flagellum-dependent motility, thereby employing a hierarchical signaling cascade to control the transition between a motile lifestyle and a biofilm lifestyle.IMPORTANCE Many motile bacterial populations form surface-attached biofilms in response to specific environmental cues, including osmotic stress in a range of natural and host-related systems. However, cross talk between bacterial osmosensing, swimming, and biofilm formation regulatory networks is not fully understood. Here, we report that the pleiotropic regulator LrhA in Pantoea alhagi is involved in the regulation of flagellar motility, biofilm formation, and host colonization and responds to osmotic upshift. We further show that this sensing relies on the EnvZ-OmpR two-component system that was known to detect changes in external osmotic stress. The EnvZ-OmpR-LrhA osmosensing signal transduction cascade is proposed to increase bacterial fitness under hyperosmotic conditions inside the host. Our work proposes a novel regulatory mechanism that links osmosensing and motile-sessile lifestyle transitions, which may provide new approaches to prevent or promote the formation of biofilms and host colonization in P. alhagi and other bacteria possessing a similar osmoregulatory mechanism.
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The Catabolite Repressor/Activator Cra Is a Bridge Connecting Carbon Metabolism and Host Colonization in the Plant Drought Resistance-Promoting Bacterium Pantoea alhagi LTYR-11Z. Appl Environ Microbiol 2018; 84:AEM.00054-18. [PMID: 29703735 DOI: 10.1128/aem.00054-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 04/20/2018] [Indexed: 12/22/2022] Open
Abstract
Efficient root colonization is a prerequisite for application of plant growth-promoting (PGP) bacteria in improving health and yield of agricultural crops. We have recently identified an endophytic bacterium, Pantoea alhagi LTYR-11Z, with multiple PGP properties that effectively colonizes the root system of wheat and improves its growth and drought tolerance. To identify novel regulatory genes required for wheat colonization, we screened an LTYR-11Z transposon (Tn) insertion library and found cra to be a colonization-related gene. By using transcriptome (RNA-seq) analysis, we found that transcriptional levels of an eps operon, the ydiV gene encoding an anti-FlhD4C2 factor, and the yedQ gene encoding an enzyme for synthesis of cyclic dimeric GMP (c-di-GMP) were significantly downregulated in the Δcra mutant. Further studies demonstrated that Cra directly binds to the promoters of the eps operon, ydiV, and yedQ and activates their expression, thus inhibiting motility and promoting exopolysaccharide (EPS) production and biofilm formation. Consistent with previous findings that Cra plays a role in transcriptional regulation in response to carbon source availability, the activating effects of Cra were much more pronounced when LTYR-11Z was grown within a gluconeogenic environment than when it was grown within a glycolytic environment. We further demonstrate that the ability of LTYR-11Z to colonize wheat roots is modulated by the availability of carbon sources. Altogether, these results uncover a novel strategy utilized by LTYR-11Z to achieve host colonization in response to carbon nutrition in the environment, in which Cra bridges a connection between carbon metabolism and colonization capacity of LTYR-11Z.IMPORTANCE Rapid and appropriate response to environmental signals is crucial for bacteria to adapt to competitive environments and to establish interactions with their hosts. Efficient colonization and persistence within the host are controlled by various regulatory factors that respond to specific environmental cues. The most common is nutrient availability. In this work, we unraveled the pivotal role of Cra in regulation of colonization ability of Pantoea alhagi LTYR-11Z in response to carbon source availability. Moreover, we identified three novel members of the Cra regulon involved in EPS synthesis, regulation of flagellar biosynthesis, and synthesis of c-di-GMP and propose a working model to explain the Cra-mediated regulatory mechanism that links carbon metabolism to host colonization. This study elucidates the regulatory role of Cra in bacterial attachment and colonization of plants, which raises the possibility of extending our studies to other bacteria associated with plant and human health.
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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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20
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Cellular Stoichiometry of Methyl-Accepting Chemotaxis Proteins in Sinorhizobium meliloti. J Bacteriol 2018; 200:JB.00614-17. [PMID: 29263102 DOI: 10.1128/jb.00614-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 12/15/2017] [Indexed: 12/29/2022] Open
Abstract
The chemosensory system in Sinorhizobium meliloti has several important deviations from the widely studied enterobacterial paradigm. To better understand the differences between the two systems and how they are optimally tuned, we determined the cellular stoichiometry of the methyl-accepting chemotaxis proteins (MCPs) and the histidine kinase CheA in S. meliloti Quantitative immunoblotting was used to determine the total amount of MCPs and CheA per cell in S. meliloti The MCPs are present in the cell in high abundance (McpV), low abundance (IcpA, McpU, McpX, and McpW), and very low abundance (McpY and McpZ), whereas McpT was below the detection limit. The approximate cellular ratio of these three receptor groups is 300:30:1. The chemoreceptor-to-CheA ratio is 23.5:1, highly similar to that seen in Bacillus subtilis (23:1) and about 10 times higher than that in Escherichia coli (3.4:1). Different from E. coli, the high-abundance receptors in S. meliloti are lacking the carboxy-terminal NWETF pentapeptide that binds the CheR methyltransferase and CheB methylesterase. Using transcriptional lacZ fusions, we showed that chemoreceptors are positively controlled by the master regulators of motility, VisNR and Rem. In addition, FlbT, a class IIA transcriptional regulator of flagellins, also positively regulates the expression of most chemoreceptors except for McpT and McpY, identifying chemoreceptors as class III genes. Taken together, these results demonstrate that the chemosensory complex and the adaptation system in S. meliloti deviates significantly from the established enterobacterial paradigm but shares some similarities with B. subtilisIMPORTANCE The symbiotic soil bacterium Sinorhizobium meliloti is of great agricultural importance because of its nitrogen-fixing properties, which enhances growth of its plant symbiont, alfalfa. Chemotaxis provides a competitive advantage for bacteria to sense their environment and interact with their eukaryotic hosts. For a better understanding of the role of chemotaxis in these processes, detailed knowledge on the regulation and composition of the chemosensory machinery is essential. Here, we show that chemoreceptor gene expression in S. meliloti is controlled through the main transcriptional regulators of motility. Chemoreceptor abundance is much lower in S. meliloti than in Escherichia coli and Bacillus subtilis Moreover, the chemoreceptor-to-kinase CheA ratio is different from that of E. coli but similar to that of B. subtilis.
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21
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Novel Genes and Regulators That Influence Production of Cell Surface Exopolysaccharides in Sinorhizobium meliloti. J Bacteriol 2018; 200:JB.00501-17. [PMID: 29158240 DOI: 10.1128/jb.00501-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 11/10/2017] [Indexed: 12/21/2022] Open
Abstract
Sinorhizobium meliloti is a soil-dwelling alphaproteobacterium that engages in a nitrogen-fixing root nodule symbiosis with leguminous plants. Cell surface polysaccharides are important both for adapting to stresses in the soil and for the development of an effective symbiotic interaction. Among the polysaccharides characterized to date, the acidic exopolysaccharides I (EPS-I; succinoglycan) and II (EPS-II; galactoglucan) are particularly important for protection from abiotic stresses, biofilm formation, root colonization, and infection of plant roots. Previous genetic screens discovered mutants with impaired EPS production, allowing the delineation of EPS biosynthetic pathways. Here we report on a genetic screen to isolate mutants with mucoid colonial morphologies that suggest EPS overproduction. Screening with Tn5-110, which allows the recovery of both null and upregulation mutants, yielded 47 mucoid mutants, most of which overproduce EPS-I; among the 30 unique genes and intergenic regions identified, 14 have not been associated with EPS production previously. We identified a new protein-coding gene, emmD, which may be involved in the regulation of EPS-I production as part of the EmmABC three-component regulatory circuit. We also identified a mutant defective in EPS-I production, motility, and symbiosis, where Tn5-110 was not responsible for the mutant phenotypes; these phenotypes result from a missense mutation in rpoA corresponding to the domain of the RNA polymerase alpha subunit known to interact with transcription regulators.IMPORTANCE The alphaproteobacterium Sinorhizobium meliloti converts dinitrogen to ammonium while inhabiting specialized plant organs termed root nodules. The transformation of S. meliloti from a free-living soil bacterium to a nitrogen-fixing plant symbiont is a complex developmental process requiring close interaction between the two partners. As the interface between the bacterium and its environment, the S. meliloti cell surface plays a critical role in adaptation to varied soil environments and in interaction with plant hosts. We isolated and characterized S. meliloti mutants with increased production of exopolysaccharides, key cell surface components. Our diverse set of mutants suggests roles for exopolysaccharide production in growth, metabolism, cell division, envelope homeostasis, biofilm formation, stress response, motility, and symbiosis.
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Hawkins JP, Geddes BA, Oresnik IJ. Succinoglycan Production Contributes to Acidic pH Tolerance in Sinorhizobium meliloti Rm1021. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:1009-1019. [PMID: 28871850 DOI: 10.1094/mpmi-07-17-0176-r] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In this work, the hypothesis that exopolysaccharide plays a role in the survival of Sinorhizobium meliloti at low pH levels is addressed. When S. meliloti was grown at pH 5.75, synthesis of succinoglycan increased, whereas synthesis of galactoglucan decreased. Succinoglycan that was isolated from cultures grown at low pH had a lower degree of polymerization relative to that which was isolated from cultures grown at neutral pH, suggesting that low-molecular weight (LMW) succinoglycan might play a role in adaptation to low pH. Mutants unable to produce succinoglycan or only able to produce high-molecular weight polysaccharide were found to be sensitive to low pH. However, strains unable to produce LMW polysaccharide were 10-fold more sensitive. In response to low pH, transcription of genes encoding proteins for succinoglycan, glycogen, and cyclic β(1-2) glucans biosynthesis increased, while those encoding proteins necessary for the biosynthesis of galactoglucan decreased. While changes in pH did not affect the production of glycogen or cyclic β(1-2) glucan, it was found that the inability to produce cyclic β(1-2) glucan did contribute to pH tolerance in the absence of succinoglycan. Finally, in addition to being sensitive to low pH, a strain carrying mutations in exoK and exsH, which encode the glycanases responsible for the cleavage of succinoglycan to LMW succinoglycan, exhibited a delay in nodulation and was uncompetitive for nodule occupancy. Taken together, the data suggest that the role for LMW succinoglycan in nodule development may be to enhance survival in the colonized curled root hair.
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Affiliation(s)
- Justin P Hawkins
- Dept. of Microbiology, University of Manitoba, Winnipeg, R3T 2N2, Canada
| | - Barney A Geddes
- Dept. of Microbiology, University of Manitoba, Winnipeg, R3T 2N2, Canada
| | - Ivan J Oresnik
- Dept. of Microbiology, University of Manitoba, Winnipeg, R3T 2N2, Canada
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23
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Mongiardini EJ, Quelas JI, Dardis C, Althabegoiti MJ, Lodeiro AR. Transcriptional Control of the Lateral-Flagellar Genes of Bradyrhizobium diazoefficiens. J Bacteriol 2017; 199:e00253-17. [PMID: 28533217 PMCID: PMC5512216 DOI: 10.1128/jb.00253-17] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Accepted: 05/16/2017] [Indexed: 11/20/2022] Open
Abstract
Bradyrhizobium diazoefficiens, a soybean N2-fixing symbiont, possesses a dual flagellar system comprising a constitutive subpolar flagellum and inducible lateral flagella. Here, we analyzed the genomic organization and biosynthetic regulation of the lateral-flagellar genes. We found that these genes are located in a single genomic cluster, organized in two monocistronic transcriptional units and three operons, one possibly containing an internal transcription start site. Among the monocistronic units is blr6846, homologous to the class IB master regulators of flagellum synthesis in Brucella melitensis and Ensifer meliloti and required for the expression of all the lateral-flagellar genes except lafA2, whose locus encodes a single lateral flagellin. We therefore named blr6846 lafR (lateral-flagellar regulator). Despite its similarity to two-component response regulators and its possession of a phosphorylatable Asp residue, lafR behaved as an orphan response regulator by not requiring phosphorylation at this site. Among the genes induced by lafR is flbTL , a class III regulator. We observed different requirements for FlbTL in the synthesis of each flagellin subunit. Although the accumulation of lafA1, but not lafA2, transcripts required FlbTL, the production of both flagellin polypeptides required FlbTL Moreover, the regulation cascade of this lateral-flagellar regulon appeared to be not as strictly ordered as those found in other bacterial species.IMPORTANCE Bacterial motility seems essential for the free-living style in the environment, and therefore these microorganisms allocate a great deal of their energetic resources to the biosynthesis and functioning of flagella. Despite energetic costs, some bacterial species possess dual flagellar systems, one of which is a primary system normally polar or subpolar, and the other is a secondary, lateral system that is produced only under special circumstances. Bradyrhizobium diazoefficiens, an N2-fixing symbiont of soybean plants, possesses dual flagellar systems, including the lateral system that contributes to swimming in wet soil and competition for nodulation and is expressed under high energy availability, as well as under requirement for high torque by the flagella. The structural organization and transcriptional regulation of the 41 genes that comprise this secondary flagellar system seem adapted to adjust bacterial energy expenditures for motility to the soil's environmental dynamics.
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Affiliation(s)
- Elías J Mongiardini
- Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata y CCT-La Plata, CONICET, La Plata, Argentina
| | - J Ignacio Quelas
- Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata y CCT-La Plata, CONICET, La Plata, Argentina
| | - Carolina Dardis
- Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata y CCT-La Plata, CONICET, La Plata, Argentina
| | - M Julia Althabegoiti
- Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata y CCT-La Plata, CONICET, La Plata, Argentina
| | - Aníbal R Lodeiro
- Instituto de Biotecnología y Biología Molecular, Facultad de Ciencias Exactas, Universidad Nacional de La Plata y CCT-La Plata, CONICET, La Plata, Argentina
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24
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Baumgardt K, Melior H, Madhugiri R, Thalmann S, Schikora A, McIntosh M, Becker A, Evguenieva-Hackenberg E. RNase E and RNase J are needed for S-adenosylmethionine homeostasis in Sinorhizobium meliloti. MICROBIOLOGY-SGM 2017; 163:570-583. [PMID: 28141492 DOI: 10.1099/mic.0.000442] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The ribonucleases (RNases) E and J play major roles in E. coli and Bacillus subtilis, respectively, and co-exist in Sinorhizobium meliloti. We analysed S. meliloti 2011 mutants with mini-Tn5 insertions in the corresponding genes rne and rnj and found many overlapping effects. We observed similar changes in mRNA levels, including lower mRNA levels of the motility and chemotaxis related genes flaA, flgB and cheR and higher levels of ndvA (important for glucan export). The acyl-homoserine lactone (AHL) levels were also higher during exponential growth in both RNase mutants, despite no increase in the expression of the sinI AHL synthase gene. Furthermore, several RNAs from both mutants migrated aberrantly in denaturing gels at 300 V but not under stronger denaturing conditions at 1300 V. The similarities between the two mutants could be explained by increased levels of the key methyl donor S-adenosylmethionine (SAM), since this may result in faster AHL synthesis leading to higher AHL accumulation as well as in uncontrolled methylation of macromolecules including RNA, which may strengthen RNA secondary structures. Indeed, we found that in both mutants the N6-methyladenosine content was increased almost threefold and the SAM level was increased at least sevenfold. Complementation by induced ectopic expression of the respective RNase restored the AHL and SAM levels in each of the mutants. In summary, our data show that both RNase E and RNase J are needed for SAM homeostasis in S. meliloti.
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Affiliation(s)
- Kathrin Baumgardt
- Institute of Microbiology and Molecular Biology, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany.,Present address: CNRS, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Hendrik Melior
- Institute of Microbiology and Molecular Biology, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany
| | - Ramakanth Madhugiri
- Institute of Microbiology and Molecular Biology, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany.,Present address: Institute of Medical Virology, Biomedical Research Center, Justus Liebig University, Schubertstr. 81, D 35392 Giessen, Germany
| | - Sebastian Thalmann
- Institute of Microbiology and Molecular Biology, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany
| | - Adam Schikora
- Institute of Phytopathology and Applied Zoology, Heinrich-Buff-Ring 26-32, D-35392 Giessen, Germany.,Present address: Julius Kühn-Institut, Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Messeweg 11/12, 38104, Brunswick, Germany
| | - Matthew McIntosh
- Centre of Synthetic Microbiology, Hans-Meerwein-Straße 6, D-35043 Marburg, Germany
| | - Anke Becker
- Centre of Synthetic Microbiology, Hans-Meerwein-Straße 6, D-35043 Marburg, Germany
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25
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Torres M, Uroz S, Salto R, Fauchery L, Quesada E, Llamas I. HqiA, a novel quorum-quenching enzyme which expands the AHL lactonase family. Sci Rep 2017; 7:943. [PMID: 28424524 PMCID: PMC5430456 DOI: 10.1038/s41598-017-01176-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 03/22/2017] [Indexed: 11/09/2022] Open
Abstract
The screening of a metagenomic library of 250,000 clones generated from a hypersaline soil (Spain) allowed us to identify a single positive clone which confers the ability to degrade N-acyl homoserine lactones (AHLs). The sequencing of the fosmid revealed a 42,318 bp environmental insert characterized by 46 ORFs. The subcloning of these ORFs demonstrated that a single gene (hqiA) allowed AHL degradation. Enzymatic analysis using purified HqiA and HPLC/MS revealed that this protein has lactonase activity on a broad range of AHLs. The introduction of hqiA in the plant pathogen Pectobacterium carotovorum efficiently interfered with both the synthesis of AHLs and quorum-sensing regulated functions, such as swarming motility and the production of maceration enzymes. Bioinformatic analyses highlighted that HqiA showed no sequence homology with the known prototypic AHL lactonases or acylases, thus expanding the AHL-degrading enzymes with a new family related to the cysteine hydrolase (CHase) group. The complete sequence analysis of the fosmid showed that 31 ORFs out of the 46 identified were related to Deltaproteobacteria, whilst many intercalated ORFs presented high homology with other taxa. In this sense, hqiA appeared to be assigned to the Hyphomonas genus (Alphaproteobacteria), suggesting that horizontal gene transfer had occurred.
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Affiliation(s)
- Marta Torres
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Granada, Spain.,Institute of Biotechnology, Biomedical Research Center (CIBM), University of Granada, Granada, Spain
| | - Stéphane Uroz
- UMR 1136 INRA-Université de Lorraine Interactions Arbres-Microorganismes, Centre INRA de Nancy, Champenoux, France
| | - Rafael Salto
- Department of Biochemistry and Molecular Biology II, Faculty of Pharmacy, University of Granada, Granada, Spain
| | - Laure Fauchery
- UMR 1136 INRA-Université de Lorraine Interactions Arbres-Microorganismes, Centre INRA de Nancy, Champenoux, France
| | - Emilia Quesada
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Granada, Spain.,Institute of Biotechnology, Biomedical Research Center (CIBM), University of Granada, Granada, Spain
| | - Inmaculada Llamas
- Department of Microbiology, Faculty of Pharmacy, University of Granada, Granada, Spain. .,Institute of Biotechnology, Biomedical Research Center (CIBM), University of Granada, Granada, Spain.
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26
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Beyersmann PG, Tomasch J, Son K, Stocker R, Göker M, Wagner-Döbler I, Simon M, Brinkhoff T. Dual function of tropodithietic acid as antibiotic and signaling molecule in global gene regulation of the probiotic bacterium Phaeobacter inhibens. Sci Rep 2017; 7:730. [PMID: 28389641 PMCID: PMC5429656 DOI: 10.1038/s41598-017-00784-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 03/13/2017] [Indexed: 01/12/2023] Open
Abstract
Antibiotics are typically regarded as microbial weapons, but whereas their function at concentrations lethal for bacteria is often well characterized, the role of antibiotics at much lower concentrations as possibly found under natural conditions remains poorly understood. By using whole-transcriptome analyses and phenotypic screenings of the marine bacterium Phaeobacter inhibens we found that the broad-spectrum antibiotic tropodithietic acid (TDA) causes the same regulatory effects in quorum sensing (QS) as the common signaling molecule N-acyl-homoserine lactone (AHL) at concentrations 100-fold lower than the minimal inhibitory concentration against bacteria. Our results show that TDA has a significant impact on the expression of ~10% of the total genes of P. inhibens, in the same manner as the AHL. Furthermore, TDA needs the AHL associated LuxR-type transcriptional regulator, just as the AHL molecule. Low concentrations of antibiotics can obviously have a strong influence on the global gene expression of the bacterium that produces it and drastically change the metabolism and behaviour of the bacterium. For P. inhibens this includes motility, biofilm formation and antibiotic production, all important for settlement on new host-associated surfaces. Our results demonstrate that bacteria can produce antibiotics not only to antagonise other bacteria, but also to mediate QS like endogenous AHL molecules.
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Affiliation(s)
- Paul G Beyersmann
- Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, 26129, Oldenburg, Germany
| | - Jürgen Tomasch
- Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Kwangmin Son
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Roman Stocker
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Institute for Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, Eidgenössische Technische Hochschule (ETH) Zürich, Zurich, 8093, Switzerland
| | - Markus Göker
- Leibniz-Institute DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, 38124, Braunschweig, Germany
| | | | - Meinhard Simon
- Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, 26129, Oldenburg, Germany
| | - Thorsten Brinkhoff
- Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, 26129, Oldenburg, Germany.
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27
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Vu TQ, de Castro RMB, Qin L. Bridging the gap: microfluidic devices for short and long distance cell-cell communication. LAB ON A CHIP 2017; 17:1009-1023. [PMID: 28205652 PMCID: PMC5473339 DOI: 10.1039/c6lc01367h] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Cell-cell communication is a crucial component of many biological functions. For example, understanding how immune cells and cancer cells interact, both at the immunological synapse and through cytokine secretion, can help us understand and improve cancer immunotherapy. The study of how cells communicate and form synaptic connections is important in neuroscience, ophthalmology, and cancer research. But in order to increase our understanding of these cellular phenomena, better tools need to be developed that allow us to study cell-cell communication in a highly controlled manner. Some technical requirements for better communication studies include manipulating cells spatiotemporally, high resolution imaging, and integrating sensors. Microfluidics is a powerful platform that has the ability to address these requirements and other current limitations. In this review, we describe some new advances in microfluidic technologies that have provided researchers with novel methods to study intercellular communication. The advantages of microfluidics have allowed for new capabilities in both single cell-cell communication and population-based communication. This review highlights microfluidic communication devices categorized as "short distance", or primarily at the single cell level, and "long distance", which mostly encompasses population level studies. Future directions and translation/commercialization will also be discussed.
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Affiliation(s)
- Timothy Quang Vu
- Department of Bioengineering, Rice University, Houston, TX 77030, USA and Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA.
| | - Ricardo Miguel Bessa de Castro
- College of Engineering, Swansea University Singleton Park, Swansea, UK and Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA.
| | - Lidong Qin
- Department of Nanomedicine, Houston Methodist Research Institute, Houston, TX 77030, USA. and Department of Cell and Developmental Biology, Weill Cornell Medical College, New York, NY 10065, USA
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Scharf BE, Hynes MF, Alexandre GM. Chemotaxis signaling systems in model beneficial plant-bacteria associations. PLANT MOLECULAR BIOLOGY 2016; 90:549-59. [PMID: 26797793 DOI: 10.1007/s11103-016-0432-4] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 01/04/2016] [Indexed: 05/07/2023]
Abstract
Beneficial plant-microbe associations play critical roles in plant health. Bacterial chemotaxis provides a competitive advantage to motile flagellated bacteria in colonization of plant root surfaces, which is a prerequisite for the establishment of beneficial associations. Chemotaxis signaling enables motile soil bacteria to sense and respond to gradients of chemical compounds released by plant roots. This process allows bacteria to actively swim towards plant roots and is thus critical for competitive root surface colonization. The complete genome sequences of several plant-associated bacterial species indicate the presence of multiple chemotaxis systems and a large number of chemoreceptors. Further, most soil bacteria are motile and capable of chemotaxis, and chemotaxis-encoding genes are enriched in the bacteria found in the rhizosphere compared to the bulk soil. This review compares the architecture and diversity of chemotaxis signaling systems in model beneficial plant-associated bacteria and discusses their relevance to the rhizosphere lifestyle. While it is unclear how controlling chemotaxis via multiple parallel chemotaxis systems provides a competitive advantage to certain bacterial species, the presence of a larger number of chemoreceptors is likely to contribute to the ability of motile bacteria to survive in the soil and to compete for root surface colonization.
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Affiliation(s)
- Birgit E Scharf
- Department of Biological Sciences, Life Sciences I, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA
| | - Michael F Hynes
- Department of Biological Sciences, University of Calgary, Calgary, AB, T2N 1N4, Canada
| | - Gladys M Alexandre
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA.
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Gao R, Krysciak D, Petersen K, Utpatel C, Knapp A, Schmeisser C, Daniel R, Voget S, Jaeger KE, Streit WR. Genome-wide RNA sequencing analysis of quorum sensing-controlled regulons in the plant-associated Burkholderia glumae PG1 strain. Appl Environ Microbiol 2015; 81:7993-8007. [PMID: 26362987 PMCID: PMC4651095 DOI: 10.1128/aem.01043-15] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 09/01/2015] [Indexed: 01/16/2023] Open
Abstract
Burkholderia glumae PG1 is a soil-associated motile plant-pathogenic bacterium possessing a cell density-dependent regulation system called quorum sensing (QS). Its genome contains three genes, here designated bgaI1 to bgaI3, encoding distinct autoinducer-1 (AI-1) synthases, which are capable of synthesizing QS signaling molecules. Here, we report on the construction of B. glumae PG1 ΔbgaI1, ΔbgaI2, and ΔbgaI3 mutants, their phenotypic characterization, and genome-wide transcriptome analysis using RNA sequencing (RNA-seq) technology. Knockout of each of these bgaI genes resulted in strongly decreased motility, reduced extracellular lipase activity, a reduced ability to cause plant tissue maceration, and decreased pathogenicity. RNA-seq analysis of all three B. glumae PG1 AI-1 synthase mutants performed in the transition from exponential to stationary growth phase revealed differential expression of a significant number of predicted genes. In comparison with the levels of gene expression by wild-type strain B. glumae PG1, 481 genes were differentially expressed in the ΔbgaI1 mutant, 213 were differentially expressed in the ΔbgaI2 mutant, and 367 were differentially expressed in the ΔbgaI3 mutant. Interestingly, only a minor set of 78 genes was coregulated in all three mutants. The majority of the QS-regulated genes were linked to metabolic activities, and the most pronounced regulation was observed for genes involved in rhamnolipid and Flp pilus biosynthesis and the type VI secretion system and genes linked to a clustered regularly interspaced short palindromic repeat (CRISPR)-cas gene cluster.
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Affiliation(s)
- Rong Gao
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Dagmar Krysciak
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Katrin Petersen
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Christian Utpatel
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Andreas Knapp
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany
| | - Christel Schmeisser
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Rolf Daniel
- Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg August University Göttingen, Göttingen, Germany
| | - Sonja Voget
- Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg August University Göttingen, Göttingen, Germany
| | - Karl-Erich Jaeger
- Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Forschungszentrum Jülich, Jülich, Germany Institute of Bio- and Geosciences IBG-1: Biotechnology, Forschungszentrum Jülich, Jülich, Germany
| | - Wolfgang R Streit
- Biocenter Klein Flottbek, Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
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Galardini M, Brilli M, Spini G, Rossi M, Roncaglia B, Bani A, Chiancianesi M, Moretto M, Engelen K, Bacci G, Pini F, Biondi EG, Bazzicalupo M, Mengoni A. Evolution of Intra-specific Regulatory Networks in a Multipartite Bacterial Genome. PLoS Comput Biol 2015; 11:e1004478. [PMID: 26340565 PMCID: PMC4560400 DOI: 10.1371/journal.pcbi.1004478] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 07/24/2015] [Indexed: 11/21/2022] Open
Abstract
Reconstruction of the regulatory network is an important step in understanding how organisms control the expression of gene products and therefore phenotypes. Recent studies have pointed out the importance of regulatory network plasticity in bacterial adaptation and evolution. The evolution of such networks within and outside the species boundary is however still obscure. Sinorhizobium meliloti is an ideal species for such study, having three large replicons, many genomes available and a significant knowledge of its transcription factors (TF). Each replicon has a specific functional and evolutionary mark; which might also emerge from the analysis of their regulatory signatures. Here we have studied the plasticity of the regulatory network within and outside the S. meliloti species, looking for the presence of 41 TFs binding motifs in 51 strains and 5 related rhizobial species. We have detected a preference of several TFs for one of the three replicons, and the function of regulated genes was found to be in accordance with the overall replicon functional signature: house-keeping functions for the chromosome, metabolism for the chromid, symbiosis for the megaplasmid. This therefore suggests a replicon-specific wiring of the regulatory network in the S. meliloti species. At the same time a significant part of the predicted regulatory network is shared between the chromosome and the chromid, thus adding an additional layer by which the chromid integrates itself in the core genome. Furthermore, the regulatory network distance was found to be correlated with both promoter regions and accessory genome evolution inside the species, indicating that both pangenome compartments are involved in the regulatory network evolution. We also observed that genes which are not included in the species regulatory network are more likely to belong to the accessory genome, indicating that regulatory interactions should also be considered to predict gene conservation in bacterial pangenomes. The influence of transcriptional regulatory networks on the evolution of bacterial pangenomes has not yet been elucidated, even though the role of transcriptional regulation is widely recognized. Using the model symbiont Sinorhizobium meliloti we have predicted the regulatory targets of 41 transcription factors in 51 strains and 5 other rhizobial species, showing a correlation between regulon diversity and pangenome evolution, through upstream sequence diversity and accessory genome composition. We have also shown that genes not wired to the regulatory network are more likely to belong to the accessory genome, thus suggesting that inclusion in the regulatory circuits may be an indicator of gene conservation. We have also highlighted a series of transcription factors that preferentially regulate genes belonging to one of the three replicons of this species, indicating the presence of replicon-specific regulatory modules, with peculiar functional signatures. At the same time the chromid shares a significant part of the regulatory network with the chromosome, indicating an additional way by which this replicon integrates itself in the pangenome.
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Affiliation(s)
- Marco Galardini
- Department of Biology, University of Florence, Florence, Italy
| | - Matteo Brilli
- Department of Genomics and Biology of Fruit Crops, Research and Innovation Centre, Fondazione Edmund Mach (FEM), San Michele all’Adige, Italy
| | - Giulia Spini
- Dipartimento di Biotecnologie Agrarie, Sezione di Microbiologia, University of Florence, Florence, Italy
| | - Matteo Rossi
- Department of Biology, University of Florence, Florence, Italy
| | | | - Alessia Bani
- Department of Biology, University of Florence, Florence, Italy
| | | | - Marco Moretto
- Department of Computational Biology, Research and Innovation Centre, Fondazione Edmund Mach (FEM), San Michele all’Adige, Italy
| | - Kristof Engelen
- Department of Computational Biology, Research and Innovation Centre, Fondazione Edmund Mach (FEM), San Michele all’Adige, Italy
| | - Giovanni Bacci
- Department of Biology, University of Florence, Florence, Italy
- Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Centro di Ricerca per lo Studio delle Relazioni tra Pianta e Suolo (CRA-RPS), Rome, Italy
| | - Francesco Pini
- Interdisciplinary Research Institute USR3078, CNRS-Universit Lille Nord de France, Villeneuve d’Ascq, France
| | - Emanuele G. Biondi
- Interdisciplinary Research Institute USR3078, CNRS-Universit Lille Nord de France, Villeneuve d’Ascq, France
| | | | - Alessio Mengoni
- Department of Biology, University of Florence, Florence, Italy
- * E-mail:
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Molina-Sánchez MD, López-Contreras JA, Toro N, Fernández-López M. Genomic characterization of Sinorhizobium meliloti AK21, a wild isolate from the Aral Sea Region. SPRINGERPLUS 2015; 4:259. [PMID: 26090306 PMCID: PMC4468178 DOI: 10.1186/s40064-015-1062-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 05/26/2015] [Indexed: 11/10/2022]
Abstract
The symbiotic, nitrogen-fixing bacterium Sinorhizobium meliloti has been widely studied due to its ability to improve crop yields through direct interactions with leguminous plants. S. meliloti AK21 is a wild type strain that forms nodules on Medicago plants in saline and drought conditions in the Aral Sea Region. The aim of this work was to establish the genetic similarities and differences between S. meliloti AK21 and the reference strain S. meliloti 1021. Comparative genome hybridization with the model reference strain S. meliloti 1021 yielded 365 variable genes, grouped into 11 regions in the three main replicons in S. meliloti AK21. The most extensive regions of variability were found in the symbiotic plasmid pSymA, which also contained the largest number of orthologous and polymorphic sequences identified by suppression subtractive hybridization. This procedure identified a large number of divergent sequences and others without homology in the databases, the further investigation of which could provide new insight into the alternative metabolic pathways present in S. meliloti AK21. We identified a plasmid replication module from the repABC replicon family, together with plasmid mobilization-related genes (traG and a VirB9-like protein), which suggest that this indigenous isolate harbors an accessory plasmid. Furthermore, the transcriptomic profiles reflected differences in gene content and regulation between S. meliloti AK21 and S. meliloti 1021 (ExpR and PhoB regulons), but provided evidence for an as yet unknown, alternative mechanism involving activation of the cbb3 terminal oxidase. Finally, phenotypic microarrays characterization revealed a greater versatility of substrate use and chemical degradation than for S. meliloti 1021.
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Affiliation(s)
- María Dolores Molina-Sánchez
- Grupo de Ecología Genética, Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Calle Profesor Albareda 1, 18008 Granada, Spain
| | - José Antonio López-Contreras
- Grupo de Ecología Genética, Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Calle Profesor Albareda 1, 18008 Granada, Spain
| | - Nicolás Toro
- Grupo de Ecología Genética, Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Calle Profesor Albareda 1, 18008 Granada, Spain
| | - Manuel Fernández-López
- Grupo de Ecología Genética, Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, Calle Profesor Albareda 1, 18008 Granada, Spain
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32
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Charoenpanich P, Soto MJ, Becker A, McIntosh M. Quorum sensing restrains growth and is rapidly inactivated during domestication of Sinorhizobium meliloti. ENVIRONMENTAL MICROBIOLOGY REPORTS 2015; 7:373-382. [PMID: 25534533 DOI: 10.1111/1758-2229.12262] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 12/11/2014] [Indexed: 06/04/2023]
Abstract
Microbial cooperative behaviours, such as quorum sensing (QS), improve survival and this explains their prevalence throughout the microbial world. However, relatively little is known about the mechanisms by which cooperation promotes survival. Furthermore, cooperation typically requires costly contributions, e.g. exopolysaccharides, which are produced from limited resources. Inevitably, cooperation is vulnerable to damaging mutations which results in mutants that are relieved of the burden of contributing but nonetheless benefit from the contributions of their parent. Unless somehow prevented, such mutants may outcompete and replace the parent. The bacterium Sinorhizobium meliloti uses QS to activate the production of copious levels of exopolysaccharide (EPS). Domestication of this bacterium is typified by the appearance of spontaneous mutants incapable of EPS production, which take advantage of EPS production by the parent and outcompete the parent. We found that all of the mutants were defect in QS, implying that loss of QS is a typical consequence of the domestication of this bacterium. This instability was traced to several QS-regulated processes, including a QS-dependent restraint of growth, providing the mutant with a significant growth advantage. A model is proposed whereby QS restrains population growth to prevent overcrowding and prepares the population for the survival of severe conditions.
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Affiliation(s)
- Pornsri Charoenpanich
- LOEWE Center for Synthetic Microbiology, Faculty of Biology, University of Marburg, Marburg, Germany
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Raut N, Joel S, Pasini P, Daunert S. Bacterial autoinducer-2 detection via an engineered quorum sensing protein. Anal Chem 2015; 87:2608-14. [PMID: 25654248 DOI: 10.1021/ac504172f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Autoinducer-2 (AI-2) is a Quorum Sensing (QS) molecule utilized by bacteria in interspecies communication. More recently, it is identified to be vital in regulating QS pathways in a number of human and foodborne pathogens. Methods to detect AI-2 in a rapid and highly sensitive manner can help in the early detection of bacterial infections. Herein, we describe a rapid, selective, and highly sensitive protein based biosensing system employing the Fluorescence Resonance Energy Transfer (FRET) between a protein fusion LuxP-EGFP and 7-diethylamino-3-[N-(2-maleimidoethyl)carbamoyl]coumarin (MDCC). The developed biosensing system, which can detect AI-2 at subnanomolar levels, was successfully applied to detect AI-2 in clinical samples such as saliva and blood serum.
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Affiliation(s)
- Nilesh Raut
- Department of Chemistry, University of Kentucky , Lexington, Kentucky 40506, United States
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34
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Geddes BA, González JE, Oresnik IJ. Exopolysaccharide production in response to medium acidification is correlated with an increase in competition for nodule occupancy. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:1307-17. [PMID: 25387133 DOI: 10.1094/mpmi-06-14-0168-r] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Sinorhizobium meliloti strains unable to utilize galactose as a sole carbon source, due to mutations in the De-Ley Doudoroff pathway (dgoK), were previously shown to be more competitive for nodule occupancy. In this work, we show that strains carrying this mutation have galactose-dependent exopolysaccharide (EPS) phenotypes that were manifested as aberrant Calcofluor staining as well as decreased mucoidy when in an expR(+) genetic background. The aberrant Calcofluor staining was correlated with changes in the pH of the growth medium. Strains carrying dgoK mutations were subsequently demonstrated to show earlier acidification of their growth medium that was correlated with an increase expression of genes associated with succinoglycan biosynthesis as well as increased accumulation of high and low molecular weight EPS in the medium. In addition, it was shown that the acidification of the medium was dependent on the inability of S. meliloti strains to initiate the catabolism of galactose. To more fully understand why strains carrying the dgoK allele were more competitive for nodule occupancy, early nodulation phenotypes were investigated. It was found that strains carrying the dgoK allele had a faster rate of nodulation. In addition, nodule competition experiments using genetic backgrounds unable to synthesize either succinoglycan or EPSII were consistent with the hypothesis that the increased competition phenotype was dependent upon the synthesis of succinoglycan. Fluorescent microscopy experiments on infected root-hair cells, using the acidotropic dye Lysotracker Red DND-99, provide evidence that the colonized curled root hair is an acidic compartment.
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35
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Krol E, Becker A. Rhizobial homologs of the fatty acid transporter FadL facilitate perception of long-chain acyl-homoserine lactone signals. Proc Natl Acad Sci U S A 2014; 111:10702-7. [PMID: 25002473 PMCID: PMC4115515 DOI: 10.1073/pnas.1404929111] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Quorum sensing (QS) using N-acyl homoserine lactones (AHLs) as signal molecules is a common strategy used by diverse Gram-negative bacteria. A widespread mechanism of AHL sensing involves binding of these molecules by cytosolic LuxR-type transcriptional regulators, which requires uptake of external AHLs. The outer membrane is supposed to be an efficient barrier for diffusion of long-chain AHLs. Here we report evidence that in Sinorhizobium meliloti, sensing of AHLs with acyl chains composed of 14 or more carbons is facilitated by the outer membrane protein FadLSm, a homolog of the Escherichia coli FadLEc long-chain fatty acid transporter. The effect of fadLSm on AHL sensing was more prominent for longer and more hydrophobic signal molecules. Using reporter gene fusions to QS target genes, we found that fadLSm increased AHL sensitivity and accelerated the course of QS. In contrast to FadLEc, FadLSm did not support uptake of oleic acid, but did contribute to growth on palmitoleic acid. FadLSm homologs from related symbiotic α-rhizobia and the plant pathogen Agrobacterium tumefaciens differed in their ability to facilitate long-chain AHL sensing or to support growth on oleic acid. FadLAt was found to be ineffective toward long-chain AHLs. We obtained evidence that the predicted extracellular loop 5 of FadLSm and further α-rhizobial FadL proteins contains determinants of specificity to long-chain AHLs. Replacement of a part of loop 5 by the corresponding region from α-rhizobial FadL proteins transferred sensitivity for long-chain AHLs to FadLAt.
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Affiliation(s)
- Elizaveta Krol
- LOEWE Center for Synthetic Microbiology, Department of Biology, Philipps-University Marburg, 35032 Marburg, Germany
| | - Anke Becker
- LOEWE Center for Synthetic Microbiology, Department of Biology, Philipps-University Marburg, 35032 Marburg, Germany
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RNA sequencing analysis of the broad-host-range strain Sinorhizobium fredii NGR234 identifies a large set of genes linked to quorum sensing-dependent regulation in the background of a traI and ngrI deletion mutant. Appl Environ Microbiol 2014; 80:5655-71. [PMID: 25002423 DOI: 10.1128/aem.01835-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The alphaproteobacterium Sinorhizobium fredii NGR234 has an exceptionally wide host range, as it forms nitrogen-fixing nodules with more legumes than any other known microsymbiont. Within its 6.9-Mbp genome, it encodes two N-acyl-homoserine-lactone synthase genes (i.e., traI and ngrI) involved in the biosynthesis of two distinct autoinducer I-type molecules. Here, we report on the construction of an NGR234-ΔtraI and an NGR234-ΔngrI mutant and their genome-wide transcriptome analysis. A high-resolution RNA sequencing (RNA-seq) analysis of early-stationary-phase cultures in the NGR234-ΔtraI background suggested that up to 316 genes were differentially expressed in the NGR234-ΔtraI mutant versus the parent strain. Similarly, in the background of NGR234-ΔngrI 466 differentially regulated genes were identified. Accordingly, a common set of 186 genes was regulated by the TraI/R and NgrI/R regulon. Coregulated genes included 42 flagellar biosynthesis genes and 22 genes linked to exopolysaccharide (EPS) biosynthesis. Among the genes and open reading frames (ORFs) that were differentially regulated in NGR234-ΔtraI were those linked to replication of the pNGR234a symbiotic plasmid and cytochrome c oxidases. Biotin and pyrroloquinoline quinone biosynthesis genes were differentially expressed in the NGR234-ΔngrI mutant as well as the entire cluster of 21 genes linked to assembly of the NGR234 type III secretion system (T3SS-II). Further, we also discovered that genes responsible for rhizopine catabolism in NGR234 were strongly repressed in the presence of high levels of N-acyl-homoserine-lactones. Together with nodulation assays, the RNA-seq-based findings suggested that quorum sensing (QS)-dependent gene regulation appears to be of higher relevance during nonsymbiotic growth rather than for life within root nodules.
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Pérez J, Jiménez-Zurdo JI, Martínez-Abarca F, Millán V, Shimkets LJ, Muñoz-Dorado J. Rhizobial galactoglucan determines the predatory pattern of Myxococcus xanthus and protects Sinorhizobium meliloti from predation. Environ Microbiol 2014; 16:2341-50. [PMID: 24707988 PMCID: PMC4079745 DOI: 10.1111/1462-2920.12477] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 03/17/2014] [Accepted: 03/31/2014] [Indexed: 11/29/2022]
Abstract
Myxococcus xanthus is a social bacterium that preys on prokaryotic and eukaryotic microorganisms. Co-culture of M. xanthus with reference laboratory strains and field isolates of the legume symbiont Sinorhizobium meliloti revealed two different predatory patterns that resemble frontal and wolf-pack attacks. Use of mutants impaired in the two types of M. xanthus surface motility (A or adventurous and S or social motility) and a csgA mutant, which is unable to form macroscopic travelling waves known as ripples, has demonstrated that both motility systems but not rippling are required for efficient predation. To avoid frontal attack and reduce killing rates, rhizobial cells require a functional expR gene. ExpR regulates expression of genes involved in a variety of functions. The use of S. meliloti mutants impaired in several of these functions revealed that the exopolysaccharide galactoglucan (EPS II) is the major determinant of the M. xanthus predatory pattern. The data also suggest that this biopolymer confers an ecological advantage to rhizobial survival in soil, which may have broad environmental implications.
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Affiliation(s)
- Juana Pérez
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n E-18071, Granada, Spain
| | - José I. Jiménez-Zurdo
- Grupo de Ecología Genética de la Rizosfera. Estación Experimental del Zaidín. Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Francisco Martínez-Abarca
- Grupo de Ecología Genética de la Rizosfera. Estación Experimental del Zaidín. Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Vicenta Millán
- Grupo de Ecología Genética de la Rizosfera. Estación Experimental del Zaidín. Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | | | - José Muñoz-Dorado
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva s/n E-18071, Granada, Spain
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Agrobacterium tumefaciens exoR controls acid response genes and impacts exopolysaccharide synthesis, horizontal gene transfer, and virulence gene expression. J Bacteriol 2014; 196:3221-33. [PMID: 24982308 DOI: 10.1128/jb.01751-14] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Agrobacterium tumefaciens is a facultative plant pathogen and the causative agent of crown gall disease. The initial stage of infection involves attachment to plant tissues, and subsequently, biofilms may form at these sites. This study focuses on the periplasmic ExoR regulator, which was identified based on the severe biofilm deficiency of A. tumefaciens exoR mutants. Genome-wide expression analysis was performed to elucidate the complete ExoR regulon. Overproduction of the exopolysaccharide succinoglycan is a dramatic phenotype of exoR mutants. Comparative expression analyses revealed that the core ExoR regulon is unaffected by succinoglycan synthesis. Several findings are consistent with previous observations: genes involved in succinoglycan biosynthesis, motility, and type VI secretion are differentially expressed in the ΔexoR mutant. In addition, these studies revealed new functional categories regulated by ExoR, including genes related to virulence, conjugation of the pAtC58 megaplasmid, ABC transporters, and cell envelope architecture. To address how ExoR exerts a broad impact on gene expression from its periplasmic location, a genetic screen was performed to isolate suppressor mutants that mitigate the exoR motility phenotype and identify downstream components of the ExoR regulatory pathway. This suppression analysis identified the acid-sensing two-component system ChvG-ChvI, and the suppressor mutant phenotypes suggest that all or most of the characteristic exoR properties are mediated through ChvG-ChvI. Subsequent analysis indicates that exoR mutants are simulating a response to acidic conditions, even in neutral media. This work expands the model for ExoR regulation in A. tumefaciens and underscores the global role that this regulator plays on gene expression.
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Stasiak G, Mazur A, Wielbo J, Marczak M, Zebracki K, Koper P, Skorupska A. Functional relationships between plasmids and their significance for metabolism and symbiotic performance of Rhizobium leguminosarum bv. trifolii. J Appl Genet 2014; 55:515-27. [PMID: 24839164 PMCID: PMC4185100 DOI: 10.1007/s13353-014-0220-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 04/11/2014] [Accepted: 04/30/2014] [Indexed: 12/31/2022]
Abstract
Rhizobium leguminosarum bv. trifolii TA1 (RtTA1) is a soil bacterium establishing a highly specific symbiotic relationship with clover, which is based on the exchange of molecular signals between the host plant and the microsymbiont. The RtTA1 genome is large and multipartite, composed of a chromosome and four plasmids, which comprise approximately 65 % and 35 % of the total genome, respectively. Extrachromosomal replicons were previously shown to confer significant metabolic versatility to bacteria, which is important for their adaptation in the soil and nodulation competitiveness. To investigate the contribution of individual RtTA1 plasmids to the overall cell phenotype, metabolic properties and symbiotic performance, a transposon-based elimination strategy was employed. RtTA1 derivatives cured of pRleTA1b or pRleTA1d and deleted in pRleTA1a were obtained. In contrast to the in silico predictions of pRleTA1b and pRleTA1d, which were described as chromid-like replicons, both appeared to be completely curable. On the other hand, for pRleTA1a (symbiotic plasmid) and pRleTA1c, which were proposed to be unessential for RtTA1 viability, it was not possible to eliminate them at all (pRleTA1c) or entirely (pRleTA1a). Analyses of the phenotypic traits of the RtTA1 derivatives obtained revealed the functional significance of individual plasmids and their indispensability for growth, certain metabolic pathways, production of surface polysaccharides, autoaggregation, biofilm formation, motility and symbiotic performance. Moreover, the results allow us to suggest broad functional cooperation among the plasmids in shaping the phenotypic properties and symbiotic capabilities of rhizobia.
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Affiliation(s)
- Grażyna Stasiak
- Department of Genetics and Microbiology, Maria-Curie Skłodowska University, 19 Akademicka St., 20-033, Lublin, Poland
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ExpR coordinates the expression of symbiotically important, bundle-forming Flp pili with quorum sensing in Sinorhizobium meliloti. Appl Environ Microbiol 2014; 80:2429-39. [PMID: 24509921 DOI: 10.1128/aem.04088-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Type IVb pili in enteropathogenic bacteria function as a host colonization factor by mediating tight adherence to host cells, but their role in bacterium-plant symbiosis is currently unknown. The genome of the symbiotic soil bacterium Sinorhizobium meliloti contains two clusters encoding proteins for type IVb pili of the Flp (fimbrial low-molecular-weight protein) subfamily. To establish the role of Flp pili in the symbiotic interaction of S. meliloti and its host, Medicago sativa, we deleted pilA1, which encodes the putative pilin subunit in the chromosomal flp-1 cluster and conducted competitive nodulation assays. The pilA1 deletion strain formed 27% fewer nodules than the wild type. Transmission electron microscopy revealed the presence of bundle-forming pili protruding from the polar and lateral region of S. meliloti wild-type cells. The putative pilus assembly ATPase CpaE1 fused to mCherry showed a predominantly unilateral localization. Transcriptional reporter gene assays demonstrated that expression of pilA1 peaks in early stationary phase and is repressed by the quorum-sensing regulator ExpR, which also controls production of exopolysaccharides and motility. Binding of acyl homoserine lactone-activated ExpR to the pilA1 promoter was confirmed with electrophoretic mobility shift assays. A 17-bp consensus sequence for ExpR binding was identified within the 28-bp protected region by DNase I footprinting analyses. Our results show that Flp pili are important for efficient symbiosis of S. meliloti with its plant host. The temporal inverse regulation of exopolysaccharides and pili by ExpR enables S. meliloti to achieve a coordinated expression of cellular processes during early stages of host interaction.
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Global analysis of cell cycle gene expression of the legume symbiont Sinorhizobium meliloti. Proc Natl Acad Sci U S A 2014; 111:3217-24. [PMID: 24501121 DOI: 10.1073/pnas.1400421111] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In α-proteobacteria, strict regulation of cell cycle progression is necessary for the specific cellular differentiation required for adaptation to diverse environmental niches. The symbiotic lifestyle of Sinorhizobium meliloti requires a drastic cellular differentiation that includes genome amplification. To achieve polyploidy, the S. meliloti cell cycle program must be altered to uncouple DNA replication from cell division. In the α-proteobacterium Caulobacter crescentus, cell cycle-regulated transcription plays an important role in the control of cell cycle progression but this has not been demonstrated in other α-proteobacteria. Here we describe a robust method for synchronizing cell growth that enabled global analysis of S. meliloti cell cycle-regulated gene expression. This analysis identified 462 genes with cell cycle-regulated transcripts, including several key cell cycle regulators, and genes involved in motility, attachment, and cell division. Only 28% of the 462 S. meliloti cell cycle-regulated genes were also transcriptionally cell cycle-regulated in C. crescentus. Furthermore, CtrA- and DnaA-binding motif analysis revealed little overlap between the cell cycle-dependent regulons of CtrA and DnaA in S. meliloti and C. crescentus. The predicted S. meliloti cell cycle regulon of CtrA, but not that of DnaA, was strongly conserved in more closely related α-proteobacteria with similar ecological niches as S. meliloti, suggesting that the CtrA cell cycle regulatory network may control functions of central importance to the specific lifestyles of α-proteobacteria.
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RNase E affects the expression of the acyl-homoserine lactone synthase gene sinI in Sinorhizobium meliloti. J Bacteriol 2014; 196:1435-47. [PMID: 24488310 DOI: 10.1128/jb.01471-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Quorum sensing of Sinorhizobium meliloti relies on N-acyl-homoserine lactones (AHLs) as autoinducers. AHL production increases at high population density, and this depends on the AHL synthase SinI and two transcriptional regulators, SinR and ExpR. Our study demonstrates that ectopic expression of the gene rne, coding for RNase E, an endoribonuclease that is probably essential for growth, prevents the accumulation of AHLs at detectable levels. The ectopic rne expression led to a higher level of rne mRNA and a lower level of sinI mRNA independently of the presence of ExpR, the AHL receptor, and AHLs. In line with this, IPTG (isopropyl-β-D-thiogalactopyranoside)-induced overexpression of rne resulted in a shorter half-life of sinI mRNA and a strong reduction of AHL accumulation. Moreover, using translational sinI-egfp fusions, we found that sinI expression is specifically decreased upon induced overexpression of rne, independently of the presence of the global posttranscriptional regulator Hfq. The 28-nucleotide 5' untranslated region (UTR) of sinI mRNA was sufficient for this effect. Random amplification of 5' cDNA ends (5'-RACE) analyses revealed a potential RNase E cleavage site at position +24 between the Shine-Dalgarno site and the translation start site. We postulate therefore that RNase E-dependent degradation of sinI mRNA from the 5' end is one of the steps mediating a high turnover of sinI mRNA, which allows the Sin quorum-sensing system to respond rapidly to changes in transcriptional control of AHL production.
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Jang MS, Goo E, An JH, Kim J, Hwang I. Quorum sensing controls flagellar morphogenesis in Burkholderia glumae. PLoS One 2014; 9:e84831. [PMID: 24416296 PMCID: PMC3885665 DOI: 10.1371/journal.pone.0084831] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 11/19/2013] [Indexed: 12/30/2022] Open
Abstract
Burkholderia glumae is a motile plant pathogenic bacterium that has multiple polar flagella and one LuxR/LuxI-type quorum sensing (QS) system, TofR/TofI. A QS-dependent transcriptional regulator, QsmR, activates flagellar master regulator flhDC genes. FlhDC subsequently activates flagellar gene expression in B. glumae at 37°C. Here, we confirm that the interplay between QS and temperature is critical for normal polar flagellar morphogenesis in B. glumae. In the wild-type bacterium, flagellar gene expression and flagellar number were greater at 28°C compared to 37°C. The QS-dependent flhC gene was significantly expressed at 28°C in two QS-defective (tofI::Ω and qsmR::Ω) mutants. Thus, flagella were present in both tofI::Ω and qsmR::Ω mutants at 28°C, but were absent at 37°C. Most tofI::Ω and qsmR::Ω mutant cells possessed polar or nonpolar flagella at 28°C. Nonpolarly flagellated cells processing flagella around cell surface of both tofI::Ω and qsmR::Ω mutants exhibited tumbling and spinning movements. The flhF gene encoding GTPase involved in regulating the correct placement of flagella in other bacteria was expressed in QS mutants in a FlhDC-dependent manner at 28°C. However, FlhF was mislocalized in QS mutants, and was associated with nonpolar flagellar formation in QS mutants at 28°C. These results indicate that QS-independent expression of flagellar genes at 28°C allows flagellar biogenesis, but is not sufficient for normal polar flagellar morphogenesis in B. glumae. Our findings demonstrate that QS functions together with temperature to control flagellar morphogenesis in B. glumae.
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Affiliation(s)
- Moon Sun Jang
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Eunhye Goo
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Jae Hyung An
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
| | - Jinwoo Kim
- Division of Applied Life Science and Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju, Republic of Korea
| | - Ingyu Hwang
- Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea
- * E-mail:
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The Sinorhizobium meliloti ntrX gene is involved in succinoglycan production, motility, and symbiotic nodulation on alfalfa. Appl Environ Microbiol 2013; 79:7150-9. [PMID: 24038694 DOI: 10.1128/aem.02225-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Rhizobia establish a symbiotic relationship with their host legumes to induce the formation of nitrogen-fixing nodules. This process is regulated by many rhizobium regulators, including some two-component regulatory systems (TCSs). NtrY/NtrX, a TCS that was first identified in Azorhizobium caulinodans, is required for free-living nitrogen metabolism and symbiotic nodulation on Sesbania rostrata. However, its functions in a typical rhizobium such as Sinorhizobium meliloti remain unclear. Here we found that the S. meliloti response regulator NtrX but not the histidine kinase NtrY is involved in the regulation of exopolysaccharide production, motility, and symbiosis with alfalfa. A plasmid insertion mutant of ntrX formed mucous colonies, which overproduced succinoglycan, an exopolysaccharide, by upregulating its biosynthesis genes. This mutant also exhibited motility defects due to reduced flagella and decreased expression of flagellins and regulatory genes. The regulation is independent of the known regulatory systems of ExoR/ExoS/ChvI, EmmABC, and ExpR. Alfalfa plants inoculated with the ntrX mutant were small and displayed symptoms of nitrogen starvation. Interestingly, the deletion mutant of ntrY showed a phenotype similar to that of the parent strain. These findings demonstrate that the S. meliloti NtrX is a new regulator of succinoglycan production and motility that is not genetically coupled with NtrY.
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Zhuang X, Gao J, Ma A, Fu S, Zhuang G. Bioactive molecules in soil ecosystems: masters of the underground. Int J Mol Sci 2013; 14:8841-68. [PMID: 23615474 PMCID: PMC3676760 DOI: 10.3390/ijms14058841] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 04/10/2013] [Accepted: 04/12/2013] [Indexed: 11/17/2022] Open
Abstract
Complex biological and ecological processes occur in the rhizosphere through ecosystem-level interactions between roots, microorganisms and soil fauna. Over the past decade, studies of the rhizosphere have revealed that when roots, microorganisms and soil fauna physically contact one another, bioactive molecular exchanges often mediate these interactions as intercellular signal, which prepare the partners for successful interactions. Despite the importance of bioactive molecules in sustainable agriculture, little is known of their numerous functions, and improving plant health and productivity by altering ecological processes remains difficult. In this review, we describe the major bioactive molecules present in below-ground ecosystems (i.e., flavonoids, exopolysaccharides, antibiotics and quorum-sensing signals), and we discuss how these molecules affect microbial communities, nutrient availability and plant defense responses.
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Affiliation(s)
- Xuliang Zhuang
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; E-Mails: (J.G.); (A.M.); (G.Z.)
| | - Jie Gao
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; E-Mails: (J.G.); (A.M.); (G.Z.)
| | - Anzhou Ma
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; E-Mails: (J.G.); (A.M.); (G.Z.)
| | - Shenglei Fu
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China; E-Mail:
| | - Guoqiang Zhuang
- Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; E-Mails: (J.G.); (A.M.); (G.Z.)
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Guttenplan SB, Kearns DB. Regulation of flagellar motility during biofilm formation. FEMS Microbiol Rev 2013; 37:849-71. [PMID: 23480406 DOI: 10.1111/1574-6976.12018] [Citation(s) in RCA: 360] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 01/07/2013] [Accepted: 02/07/2013] [Indexed: 11/30/2022] Open
Abstract
Many bacteria swim in liquid or swarm over solid surfaces by synthesizing rotary flagella. The same bacteria that are motile also commonly form nonmotile multicellular aggregates called biofilms. Biofilms are an important part of the lifestyle of pathogenic bacteria, and it is assumed that there is a motility-to-biofilm transition wherein the inhibition of motility promotes biofilm formation. The transition is largely inferred from regulatory mutants that reveal the opposite regulation of the two phenotypes. Here, we review the regulation of motility during biofilm formation in Bacillus, Pseudomonas, Vibrio, and Escherichia, and we conclude that the motility-to-biofilm transition, if necessary, likely involves two steps. In the short term, flagella are functionally regulated to either inhibit rotation or modulate the basal flagellar reversal frequency. Over the long term, flagellar gene transcription is inhibited and in the absence of de novo synthesis, flagella are diluted to extinction through growth. Both short-term and long-term motility inhibition is likely important to stabilize cell aggregates and optimize resource investment. We emphasize the newly discovered flagellar functional regulators and speculate that others await discovery in the context of biofilm formation.
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Mitter B, Petric A, Shin MW, Chain PSG, Hauberg-Lotte L, Reinhold-Hurek B, Nowak J, Sessitsch A. Comparative genome analysis of Burkholderia phytofirmans PsJN reveals a wide spectrum of endophytic lifestyles based on interaction strategies with host plants. FRONTIERS IN PLANT SCIENCE 2013; 4:120. [PMID: 23641251 PMCID: PMC3639386 DOI: 10.3389/fpls.2013.00120] [Citation(s) in RCA: 133] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 04/16/2013] [Indexed: 05/20/2023]
Abstract
Burkholderia phytofirmans PsJN is a naturally occurring plant-associated bacterial endophyte that effectively colonizes a wide range of plants and stimulates their growth and vitality. Here we analyze whole genomes, of PsJN and of eight other endophytic bacteria. This study illustrates that a wide spectrum of endophytic life styles exists. Although we postulate the existence of typical endophytic traits, no unique gene cluster could be exclusively linked to the endophytic lifestyle. Furthermore, our study revealed a high genetic diversity among bacterial endophytes as reflected in their genotypic and phenotypic features. B. phytofirmans PsJN is in many aspects outstanding among the selected endophytes. It has the biggest genome consisting of two chromosomes and one plasmid, well-equipped with genes for the degradation of complex organic compounds and detoxification, e.g., 24 glutathione-S-transferase (GST) genes. Furthermore, strain PsJN has a high number of cell surface signaling and secretion systems and harbors the 3-OH-PAME quorum-sensing system that coordinates the switch of free-living to the symbiotic lifestyle in the plant-pathogen R. solanacearum. The ability of B. phytofirmans PsJN to successfully colonize such a wide variety of plant species might be based on its large genome harboring a broad range of physiological functions.
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Affiliation(s)
- Birgit Mitter
- Department of Health and Environment, Bioresources Unit, Austrian Institute of Technology GmbHTulln, Austria
- *Correspondence: Birgit Mitter, Bioresources Unit, Austrian Institute of Technology Gmbh, Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria. e-mail:
| | - Alexandra Petric
- Department of Health and Environment, Bioresources Unit, Austrian Institute of Technology GmbHTulln, Austria
| | - Maria W. Shin
- Department of Energy, Joint Genome InstituteWalnut Creek, CA, USA
| | | | | | | | - Jerzy Nowak
- Department of Agriculture and Life Sciences, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA
| | - Angela Sessitsch
- Department of Health and Environment, Bioresources Unit, Austrian Institute of Technology GmbHTulln, Austria
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Zan J, Cicirelli EM, Mohamed NM, Sibhatu H, Kroll S, Choi O, Choi O, Uhlson CL, Wysoczynski CL, Wysoczinski CL, Murphy RC, Churchill MEA, Hill RT, Fuqua C. A complex LuxR-LuxI type quorum sensing network in a roseobacterial marine sponge symbiont activates flagellar motility and inhibits biofilm formation. Mol Microbiol 2012; 85:916-33. [PMID: 22742196 DOI: 10.1111/j.1365-2958.2012.08149.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Bacteria isolated from marine sponges, including the Silicibacter-Ruegeria (SR) subgroup of the Roseobacter clade, produce N-acylhomoserine lactone (AHL) quorum sensing signal molecules. This study is the first detailed analysis of AHL quorum sensing in sponge-associated bacteria, specifically Ruegeria sp. KLH11, from the sponge Mycale laxissima. Two pairs of luxR and luxI homologues and one solo luxI homologue were identified and designated ssaRI, ssbRI and sscI (sponge-associated symbiont locus A, B and C, luxR or luxI homologue). SsaI produced predominantly long-chain 3-oxo-AHLs and both SsbI and SscI specified 3-OH-AHLs. Addition of exogenous AHLs to KLH11 increased the expression of ssaI but not ssaR, ssbI or ssbR, and genetic analyses revealed a complex interconnected arrangement between SsaRI and SsbRI systems. Interestingly, flagellar motility was abolished in the ssaI and ssaR mutants, with the flagellar biosynthesis genes under strict SsaRI control, and active motility only at high culture density. Conversely, ssaI and ssaR mutants formed more robust biofilms than wild-type KLH11. AHLs and the ssaI transcript were detected in M. laxissima extracts, suggesting that AHL signalling contributes to the decision between motility and sessility and that it may also facilitate acclimation to different environments that include the sponge host.
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Affiliation(s)
- Jindong Zan
- Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, Baltimore, MD 21202, USA
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Fields AT, Navarrete CS, Zare AZ, Huang Z, Mostafavi M, Lewis JC, Rezaeihaghighi Y, Brezler BJ, Ray S, Rizzacasa AL, Barnett MJ, Long SR, Chen EJ, Chen JC. The conserved polarity factor podJ1 impacts multiple cell envelope-associated functions in Sinorhizobium meliloti. Mol Microbiol 2012; 84:892-920. [PMID: 22553970 DOI: 10.1111/j.1365-2958.2012.08064.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Although diminutive in size, bacteria possess highly diverse and spatially confined cellular structures. Two related alphaproteobacteria, Sinorhizobium meliloti and Caulobacter crescentus, serve as models for investigating the genetic basis of morphological variations. S. meliloti, a symbiont of leguminous plants, synthesizes multiple flagella and no prosthecae, whereas C. crescentus, a freshwater bacterium, has a single polar flagellum and stalk. The podJ gene, originally identified in C. crescentus for its role in polar organelle development, is split into two adjacent open reading frames, podJ1 and podJ2, in S. meliloti. Deletion of podJ1 interferes with flagellar motility, exopolysaccharide production, cell envelope integrity, cell division and normal morphology, but not symbiosis. As in C. crescentus, the S. meliloti PodJ1 protein appears to act as a polarity beacon and localizes to the newer cell pole. Microarray analysis indicates that podJ1 affects the expression of at least 129 genes, the majority of which correspond to observed mutant phenotypes. Together, phenotypic characterization, microarray analysis and suppressor identification suggest that PodJ1 controls a core set of conserved elements, including flagellar and pili genes, the signalling proteins PleC and DivK, and the transcriptional activator TacA, while alternative downstream targets have evolved to suit the distinct lifestyles of individual species.
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Affiliation(s)
- Alexander T Fields
- Department of Biology, San Francisco State University, San Francisco, CA 94132, USA
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Nievas F, Bogino P, Sorroche F, Giordano W. Detection, characterization, and biological effect of quorum-sensing signaling molecules in peanut-nodulating bradyrhizobia. SENSORS 2012; 12:2851-73. [PMID: 22736981 PMCID: PMC3376631 DOI: 10.3390/s120302851] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2012] [Revised: 02/23/2012] [Accepted: 02/23/2012] [Indexed: 11/16/2022]
Abstract
Bacteria of the genus Bradyrhizobium are able to establish a symbiotic relationship with peanut (Arachis hypogaea) root cells and to fix atmospheric nitrogen by converting it to nitrogenous compounds. Quorum sensing (QS) is a cell-cell communication mechanism employed by a variety of bacterial species to coordinate behavior at a community level through regulation of gene expression. The QS process depends on bacterial production of various signaling molecules, among which the N-acylhomoserine lactones (AHLs) are most commonly used by Gram-negative bacteria. Some previous reports have shown the production of QS signaling molecules by various rhizobia, but little is known regarding mechanisms of communication among peanut-nodulating strains. The aims of this study were to identify and characterize QS signals produced by peanut-nodulating bradyrhizobial strains and to evaluate their effects on processes related to cell interaction. Detection of AHLs in 53 rhizobial strains was performed using the biosensor strains Agrobacterium tumefaciens NTL4 (pZLR4) and Chromobacterium violaceum CV026 for AHLs with long and short acyl chains, respectively. None of the strains screened were found to produce AHLs with short acyl chains, but 14 strains produced AHLs with long acyl chains. These 14 AHL-producing strains were further studied by quantification of β-galactosidase activity levels (AHL-like inducer activity) in NTL4 (pZLR4). Strains displaying moderate to high levels of AHL-like inducer activity were subjected to chemical identification of signaling molecules by high-performance liquid chromatography coupled to mass spectrometry (LC-MS/MS). For each AHL-producing strain, we found at least four different AHLs, corresponding to N-hexanoyl-dl-homoserine lactone (C6), N-(3-oxodecanoyl)-l-homoserine lactone (3OC10), N-(3-oxododecanoyl)-l-homoserine lactone (3OC12), and N-(3-oxotetradecanoyl)-l-homoserine lactone (3OC14). Biological roles of 3OC10, 3OC12, and 3OC14 AHLs were evaluated in both AHL-producing and -non-producing peanut-nodulating strains. Bacterial processes related to survival and nodulation, including motility, biofilm formation, and cell aggregation, were affected or modified by the exogenous addition of increasing concentrations of synthetic AHLs. Our results clearly demonstrate the existence of cell communication mechanisms among bradyrhizobial strains symbiotic of peanut. AHLs with long acyl chains appear to be signaling molecules regulating important QS physiological processes in these bacteria.
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Affiliation(s)
- Fiorela Nievas
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina.
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