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https://www.readbyqxmd.com/read/28916561/succinate-transport-is-not-essential-for-symbiotic-nitrogen-fixation-by-sinorhizobium-meliloti-nor-rhizobium-leguminosarum
#1
Michael J Mitsch, George C diCenzo, Alison Cowie, Turlough M Finan
Symbiotic nitrogen fixation (SNF) is an energetically expensive process performed by bacteria during endosymbiotic relationships with plants. The bacteria require the plant to provide a carbon source for generation of reductant to power SNF. While C4-dicarboxylates (succinate, fumarate, malate) appear to be the primary, if not sole, carbon source provided to the bacteria, the contribution of each C4-dicarboxylate is not known. We address this issue using a genetic and systems-level analyses. Expression of a malate specific transporter (MaeP) in Sinorhizobium meliloti Rm1021 dct mutants unable to transport C4-dicarboxylates resulted in malate import rates up to 30% that of wild type...
September 15, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28905086/identification-and-characterization-of-a-novel-vibo-quercitol-1-dehydrogenase-from-burkholderia-terrae-suitable-for-production-of-vibo-quercitol-from-2-deoxy-scyllo-inosose
#2
Nobuya Itoh, Junji Kurokawa, Hiroshi Toda, Kazunobu Konishi
(-)-vibo-Quercitol is a deoxyinositol (1L-1,2,4/3,5-cyclohexanepentol) that naturally occurs in oak species, honeydew honey, wines aged in oak barrels, and Gymnema sylvestre and is a potential intermediate for pharmaceuticals. We found that (-)-vibo-quercitol is stereoselectively synthesized from 2-deoxy-scyllo-inosose by the reductive reaction of a novel (-)-vibo-quercitol 1-dehydrogenase found in the proteomes of Burkholderia, Pseudomonas, and Arthrobacter. Among them, Burkholderia terrae sp. AKC-020 (40-1) produced a (-)-vibo-quercitol 1-dehydrogenase appropriate for synthesizing (-)-vibo-quercitol with a high diastereomeric excess...
September 13, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28905000/transcriptome-analysis-of-polyhydroxybutyrate-cycle-mutants-reveals-discrete-loci-connecting-nitrogen-utilization-and-carbon-storage-in-sinorhizobium-meliloti
#3
Maya D'Alessio, Ricardo Nordeste, Andrew C Doxey, Trevor C Charles
Polyhydroxybutyrate (PHB) and glycogen polymers are produced by bacteria as carbon storage compounds under unbalanced growth conditions. To gain insights into the transcriptional mechanisms controlling carbon storage in Sinorhizobium meliloti, we investigated the global transcriptomic response to the genetic disruption of key genes in PHB synthesis and degradation and in glycogen synthesis. Under both nitrogen-limited and balanced growth conditions, transcriptomic analysis was performed with genetic mutants deficient in PHB synthesis (phbA, phbB, phbAB, and phbC), PHB degradation (bdhA, phaZ, and acsA2), and glycogen synthesis (glgA1)...
September 2017: MSystems
https://www.readbyqxmd.com/read/28871850/succinoglycan-production-contributes-to-acidic-ph-tolerance-in-sinorhizobium-meliloti-rm1021
#4
Justin P Hawkins, Barney A Geddes, Ivan John Oresnik
In this work, the hypothesis that exopolysaccharide plays a role in the survival of S. meliloti at low pH is addressed. When S. meliloti was grown at pH 5.75 the synthesis of succinoglycan increased, whereas the 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...
September 5, 2017: Molecular Plant-microbe Interactions: MPMI
https://www.readbyqxmd.com/read/28851745/a-key-regulator-of-the-glycolytic-and-gluconeogenic-central-metabolic-pathways-in-sinorhizobium-meliloti
#5
George C diCenzo, Zahed Muhammed, Magne Østerås, Shelley A P O'Brien, Turlough M Finan
The order Rhizobiales contains numerous agriculturally, biotechnologically, and medically important bacteria including the rhizobia, Agrobacterium, Brucella, and Methylobacterium, among others. These organisms tend to be metabolically versatile, but there has been relatively little investigation into the regulation of their central carbon metabolic pathways. Here, RNA-seq and promoter fusion data are presented to show that the PckR protein is a key regulator of central carbon metabolism in Sinorhizobium meliloti; during growth with gluconeogenic substrates, PckR represses expression of the complete Entner-Doudoroff glycolytic pathway and induces expression of the pckA and fbaB gluconeogenic genes...
August 29, 2017: Genetics
https://www.readbyqxmd.com/read/28842338/structure-proteome-and-genome-of-sinorhizobium-meliloti-phage-%C3%AE-m5-a-virus-with-luz24-like-morphology-and-a-highly-mosaic-genome
#6
Matthew C Johnson, Marta Sena-Velez, Brian K Washburn, Georgia N Platt, Stephen Lu, Tess E Brewer, Jason S Lynn, M Elizabeth Stroupe, Kathryn M Jones
Bacteriophages of nitrogen-fixing rhizobial bacteria are revealing a wealth of novel structures, diverse enzyme combinations and genomic features. Here we report the cryo-EM structure of the phage capsid at 4.9-5.7 Å-resolution, the phage particle proteome, and the genome of the Sinorhizobium meliloti-infecting Podovirus ΦM5. This is the first structure of a phage with a capsid and capsid-associated structural proteins related to those of the LUZ24-like viruses that infect Pseudomonas aeruginosa. Like many other Podoviruses, ΦM5 is a T=7 icosahedron with a smooth capsid and short, relatively featureless tail...
August 22, 2017: Journal of Structural Biology
https://www.readbyqxmd.com/read/28827694/a-novel-c-di-gmp-binding-domain-in-glycosyltransferase-bgsa-is-responsible-for-the-synthesis-of-a-mixed-linkage-%C3%AE-glucan
#7
Daniel Pérez-Mendoza, Daniela Bertinetti, Robin Lorenz, María-Trinidad Gallegos, Friedrich W Herberg, Juan Sanjuán
BgsA is the glycosyltransferase (GT) involved in the synthesis of a linear mixed-linkage β-glucan (MLG), a recently described exopolysaccharide activated by c-di-GMP in Sinorhizobium meliloti and other Rhizobiales. Although BgsA displays sequence and structural homology with bacterial cellulose synthases (CS), it does not contain any predictable c-di-GMP binding domain. In this work we demonstrate that the cytoplasmic C-terminal domain of BgsA (C-BgsA) binds c-di-GMP with both high affinity (KD = 0.23 μM) and specificity...
August 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28805544/rna-silencing-in-plant-symbiotic-bacteria-insights-from-a-protein-centric-view
#8
José I Jiménez-Zurdo, Marta Robledo
Extensive work in model enterobacteria has evidenced that the RNA chaperone Hfq and several endoribonucleases, such as RNase E or RNase III, serve pivotal roles in small RNA-mediated post-transcriptional silencing of gene expression. Characterization of these protein hubs commonly provide global functional and mechanistic insights into complex sRNA regulatory networks. The legume endosymbiont Sinorhizobium meliloti is a non-classical model bacterium with a very complex lifestyle in which riboregulation is expected to play important adaptive functions...
August 14, 2017: RNA Biology
https://www.readbyqxmd.com/read/28792680/transcriptomic-basis-of-genome-by-genome-variation-in-a-legume-rhizobia-mutualism
#9
Liana T Burghardt, Joseph Guhlin, Chan Lan Chun, Junqi Liu, Michael J Sadowsky, Robert M Stupar, Nevin D Young, Peter Tiffin
In the legume-rhizobia mutualism, the benefit each partner derives from the other depends on the genetic identity of both host and rhizobial symbiont. To gain insight into the extent of genome x genome interactions on hosts at the molecular level and to identify potential mechanisms responsible for the variation, we examined host gene expression within nodules (the plant organ where the symbiosis occurs) of four genotypes of Medicago truncatula grown with either Ensifer meliloti or E. medicae symbionts. These host x symbiont combinations show significant variation in nodule and biomass phenotypes...
August 9, 2017: Molecular Ecology
https://www.readbyqxmd.com/read/28768212/effects-of-biosolids-from-a-wastewater-treatment-plant-receiving-manufactured-nanomaterials-on-medicago-truncatula-and-associated-soil-microbial-communities-at-low-nanomaterial-concentrations
#10
Chun Chen, Olga V Tsyusko, Dave H McNear, Jonathan Judy, Ricky W Lewis, Jason M Unrine
Concern has grown regarding engineered nanomaterials (ENMs) entering agricultural soils through the application of biosolids and their possible effects on agroecosystems, even though the ENMs are extensively transformed. The effects of exposure to biosolids containing transformation products of these ENMs at low concentrations remain largely unexplored. We examined the responses of Medicago truncatula and its symbiotic rhizobia Sinorhizobium meliloti exposed to soil amended with biosolids from WWTP containing low added concentrations of ENMs (ENM Low), bulk/dissolved metals (bulk/dissolved Low), or no metal additions (control)...
December 31, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28765224/genome-wide-sensitivity-analysis-of-the-microsymbiont-sinorhizobium-meliloti-to-symbiotically-important-defensin-like-host-peptides
#11
Markus F F Arnold, Mohammed Shabab, Jon Penterman, Kevin L Boehme, Joel S Griffitts, Graham C Walker
The model legume species Medicago truncatula expresses more than 700 nodule-specific cysteine-rich (NCR) signaling peptides that mediate the differentiation of Sinorhizobium meliloti bacteria into nitrogen-fixing bacteroids. NCR peptides are essential for a successful symbiosis in legume plants of the inverted-repeat-lacking clade (IRLC) and show similarity to mammalian defensins. In addition to signaling functions, many NCR peptides exhibit antimicrobial activity in vitro and in vivo Bacterial resistance to these antimicrobial activities is likely to be important for symbiosis...
August 1, 2017: MBio
https://www.readbyqxmd.com/read/28745538/sinorhizobium-meliloti-chemotaxis-to-multiple-amino-acids-is-mediated-by-the-chemoreceptor-mcpu
#12
Benjamin A Webb, K Karl Compton, Julia S Martin Del Campo, Doris Taylor, Pablo Sobrado, Birgit E Scharf
The legume symbiont Sinorhizobium meliloti is chemoattracted to compounds exuded by germinating seeds of its host alfalfa. This response is mainly mediated by the S. meliloti chemoreceptor McpU. McpU also has a prominent contribution in sensing a synthetic amino acid (aa) mixture mimicking the amounts and composition observed in seed exudate. Here, we used the hydrogel capillary assay to quantify chemotactic responses of S. meliloti to individual aa exuded by germinating alfalfa seeds and to define the role of McpU in this behavior...
July 26, 2017: Molecular Plant-microbe Interactions: MPMI
https://www.readbyqxmd.com/read/28729859/transcriptomic-insight-in-the-control-of-legume-root-secondary-infection-by-the-sinorhizobium-meliloti-transcriptional-regulator-clr
#13
Lan Zou, Amandine Gastebois, Céline Mathieu-Demazière, Fernando Sorroche, Catherine Masson-Boivin, Jacques Batut, Anne-Marie Garnerone
The cAMP-dependent transcriptional regulator Clr of Sinorhizobium meliloti regulates the overall number of infection events on Medicago roots by a so-far unknown mechanism requiring smc02178, a Clr-target gene of unknown function. In order to shed light on the mode of action of Clr on infection and potentially reveal additional biological functions for Clr, we inventoried genomic Clr target genes by transcriptome profiling. We have found that Clr positively controls the synthesis of cAMP-dependent succinoglycan as well as the expression of genes involved in the synthesis of a so-far unknown polysaccharide compound...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28713341/prevalence-host-range-and-comparative-genomic-analysis-of-temperate-ochrobactrum-phages
#14
Claudia Jäckel, Stefan Hertwig, Holger C Scholz, Karsten Nöckler, Jochen Reetz, Jens A Hammerl
Ochrobactrum and Brucella are closely related bacteria that populate different habitats and differ in their pathogenic properties. Only little is known about mobile genetic elements in these genera which might be important for survival and virulence. Previous studies on Brucella lysogeny indicated that active phages are rare in this genus. To gain insight into the presence and nature of prophages in Ochrobactrum, temperate phages were isolated from various species and characterized in detail. In silico analyses disclosed numerous prophages in published Ochrobactrum genomes...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28686606/plant-fed-versus-chemicals-fed-rhizobacteria-of-lucerne-plant-only-teabags-culture-media-not-only-increase-culturability-of-rhizobacteria-but-also-recover-a-previously-uncultured-lysobacter-sp-novosphingobium-sp-and-pedobacter-sp
#15
Nabil A Hegazi, Mohamed S Sarhan, Mohamed Fayez, Sascha Patz, Brian R Murphy, Silke Ruppel
In an effort to axenically culture the previously uncultivable populations of the rhizobacteria of Lucerne (Medicago sativa L.), we propose plant-only teabags culture media to mimic the nutritional matrix available in the rhizosphere. Here, we show that culture media prepared from Lucerne powder teabags substantially increased the cultivability of Lucerne rhizobacteria compared with a standard nutrient agar, where we found that the cultivable populations significantly increased by up to 60% of the total bacterial numbers as estimated by Quantitative Real-time Polymerase Chain Reaction (qRT-PCR)...
2017: PloS One
https://www.readbyqxmd.com/read/28649348/no-evidence-for-adaptation-to-local-rhizobial-mutualists-in-the-legume-medicago-lupulina
#16
Tia L Harrison, Corlett W Wood, Isabela L Borges, John R Stinchcombe
Local adaptation is a common but not ubiquitous feature of species interactions, and understanding the circumstances under which it evolves illuminates the factors that influence adaptive population divergence. Antagonistic species interactions dominate the local adaptation literature relative to mutualistic ones, preventing an overall assessment of adaptation within interspecific interactions. Here, we tested whether the legume Medicago lupulina is adapted to the locally abundant species of mutualistic nitrogen-fixing rhizobial bacteria that vary in frequency across its eastern North American range...
June 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28625986/the-irr-and-rira-proteins-participate-in-a-complex-regulatory-circuit-and-act-in-concert-to-modulate-bacterioferritin-expression-in-ensifer-meliloti-1021
#17
Daniela Costa, Vanesa Amarelle, Claudio Valverde, Mark R O'Brian, Elena Fabiano
In this work we found that the bfr gene of the rhizobial species Ensifer meliloti, encoding a bacterioferritin iron storage protein, is involved in iron homeostasis and the oxidative stress response. This gene is located downstream of and overlapping the smc03787 open reading frame (ORF). No well-predicted RirA or Irr boxes were found in the region immediately upstream of the bfr gene although two presumptive RirA boxes and one presumptive Irr box were present in the putative promoter of smc03787 We demonstrate that bfr gene expression is enhanced under iron-sufficient conditions and that Irr and RirA modulate this expression...
August 15, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28618121/specificity-traits-consistent-with-legume-rhizobia-coevolution-displayed-by-ensifer-meliloti-rhizosphere-colonization
#18
María Eugenia Salas, Mauricio Javier Lozano, José Luis López, Walter Omar Draghi, Javier Serrania, Gonzalo Arturo Torres Tejerizo, Francisco Javier Albicoro, Juliet Fernanda Nilsson, Mariano Pistorio, María Florencia Del Papa, Gustavo Parisi, Anke Becker, Antonio Lagares
Rhizobia are α- and ß-proteobacteria that associate with legumes in symbiosis to fix atmospheric nitrogen. The chemical communication between roots and rhizobia begins in the rhizosphere. Using signature-tagged-Tn5 mutagenesis (STM) we performed a genome-wide screening for Ensifer meliloti genes that participate in colonizing the rhizospheres of alfalfa and other legumes. The analysis of ca. 6,000 mutants indicated that genes relevant for rhizosphere colonization account for nearly 2% of the rhizobial genome and that most (ca...
June 15, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/28611764/interplay-of-pathogen-induced-defense-responses-and-symbiotic-establishment-in-medicago-truncatula
#19
Tao Chen, Liujian Duan, Bo Zhou, Haixiang Yu, Hui Zhu, Yangrong Cao, Zhongming Zhang
Suppression of host innate immunity appears to be required for the establishment of symbiosis between rhizobia and host plants. In this study, we established a system that included a host plant, a bacterial pathogen and a symbiotic rhizobium to study the role of innate immunity during symbiotic interactions. A pathogenic bacterium, Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000), was shown to cause chlorosis in Medicago truncatula A17. Sinorhizobium meliloti strain Sm2011 (Sm2011) and Pst DC3000 strain alone induced similar defense responses in M...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28607058/host-secreted-antimicrobial-peptide-enforces-symbiotic-selectivity-in-medicago-truncatula
#20
Qi Wang, Shengming Yang, Jinge Liu, Kata Terecskei, Edit Ábrahám, Anikó Gombár, Ágota Domonkos, Attila Szűcs, Péter Körmöczi, Ting Wang, Lili Fodor, Linyong Mao, Zhangjun Fei, Éva Kondorosi, Péter Kaló, Attila Kereszt, Hongyan Zhu
Legumes engage in root nodule symbioses with nitrogen-fixing soil bacteria known as rhizobia. In nodule cells, bacteria are enclosed in membrane-bound vesicles called symbiosomes and differentiate into bacteroids that are capable of converting atmospheric nitrogen into ammonia. Bacteroid differentiation and prolonged intracellular survival are essential for development of functional nodules. However, in the Medicago truncatula-Sinorhizobium meliloti symbiosis, incompatibility between symbiotic partners frequently occurs, leading to the formation of infected nodules defective in nitrogen fixation (Fix(-))...
June 27, 2017: Proceedings of the National Academy of Sciences of the United States of America
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