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https://www.readbyqxmd.com/read/28533217/transcriptional-control-of-the-lateral-flagellar-genes-of-bradyrhizobium-diazoefficiens
#1
Elías J Mongiardini, J Ignacio Quelas, Carolina Dardis, M Julia Althabegoiti, Aníbal R Lodeiro
Bradyrhizobium diazoefficiens, the 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 those 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 flagella synthesis in Brucella melitensis and Ensifer meliloti, and required for the expression of all the lateral-flagellar genes except lafA2, which locus encodes a single lateral flagellin...
May 22, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28489251/geographically-structured-genetic-variation-in-the-medicago-lupulina-ensifer-mutualism
#2
Tia L Harrison, Corlett W Wood, Katy D Heath, John R Stinchcombe
Gene flow between genetically differentiated populations can maintain variation in species interactions, especially when population structure is congruent between interacting species. However, large-scale empirical comparisons of the population structure of interacting species are rare, particularly in positive interspecific interactions (mutualisms). One agriculturally and ecologically important mutualism is the partnership between legume plants and rhizobia. Through characterizing and comparing the population genomic structure of the legume Medicago lupulina and two rhizobial species (Ensifer medicae and E...
May 10, 2017: Evolution; International Journal of Organic Evolution
https://www.readbyqxmd.com/read/28461447/bacterial-pero-permeases-transport-sulfate-and-related-oxyanions
#3
Marie-Christine Hoffmann, Yvonne Pfänder, Marc Tintel, Bernd Masepohl
Rhodobacter capsulatus synthesizes the high-affinity ABC transporters CysTWA and ModABC to specifically import the chemically related oxyanions sulfate and molybdate, respectively. In addition, R. capsulatus has the low-affinity permease PerO acting as a general oxyanion transporter, whose elimination increases tolerance to molybdate and tungstate. Although widespread in bacteria, the function of PerO-like permeases has not been examined in any other species to date. Here, we present evidence that PerO permeases from the Alphaproteobacteria Agrobacterium tumefaciens, Dinoroseobacter shibae, Rhodobacter sphaeroides, and Sinorhizobium meliloti, and the Gammaproteobacterium Pseudomonas stutzeri functionally substitute for R...
May 1, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28437159/specific-host-responsive-associations-between-medicago-truncatula-accessions-and-sinorhizobium-strains
#4
Théophile Kazmierczak, Marianna Nagymihály, Florian Lamouche, Quentin Barrière, Ibtissem Guefrachi, Benoit Alunni, Mouna Ouadghiri, Jamal Ibijbijen, Éva Kondorosi, Peter Mergaert, Véronique Gruber
Legume plants interact with rhizobia to form nitrogen-fixing root nodules. Legume-rhizobium interactions are specific and only compatible rhizobia and plant species will lead to nodule formation. Even within compatible interactions, the genotype of both the plant and the bacterial symbiont will impact on the efficiency of nodule functioning and nitrogen-fixation activity. The model legume Medicago truncatula forms nodules with several species of the Sinorhizobium genus. However, the efficiency of these bacterial strains is highly variable...
May 2017: Molecular Plant-microbe Interactions: MPMI
https://www.readbyqxmd.com/read/28417169/rational-design-of-substrate-binding-pockets-in-polyphosphate-kinase-for-use-in-cost-effective-atp-dependent-cascade-reactions
#5
Hao Cao, Kaili Nie, Chengcheng Li, Haijun Xu, Fang Wang, Tianwei Tan, Luo Liu
Adenosine-5'-triphosphate (ATP) is the energy equivalent of the living system. Polyphosphate (polyP) is the ancient energy storage equivalent of organisms. Polyphosphate kinases (PPKs) catalyze the polyP formation or ATP formation, to store energy or to regenerate ATP, respectively. However, most PPKs are active only in the presence of long polyPs, which are more difficult and more expensive to generate than the short polyPs. We investigated the PPK preference towards polyPs by site-directed mutagenesis and computational simulation, to understand the mechanism and further design enzymes for effective ATP regeneration using short polyPs for in vitro cascade reactions, which are highly desired for research and applications...
April 18, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28416708/phou-allows-rapid-adaptation-to-high-phosphate-concentrations-by-modulating-pstscab-transport-rate-in-sinorhizobium-meliloti
#6
George C diCenzo, Harsh Sharthiya, Anish Nanda, Maryam Zamani, Turlough M Finan
Maintenance of cellular phosphate homeostasis is essential for cellular life. The PhoU protein has emerged as a key regulator of this process in bacteria and it is suggested to modulate phosphate import by PstSCAB and control activation of the phosphate limitation response by the PhoR-PhoB two-component system. However, a proper understanding of PhoU has remained elusive due to numerous complications of mutating phoU, including loss of viability and genetic instability of the mutants. Here, we developed two sets of strains of Sinorhizobium meliloti that overcame these limitations and allowed for a more detailed and comprehensive analysis of the biological and molecular activities of PhoU...
April 17, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28401641/a-conserved-%C3%AE-proteobacterial-small-rna-contributes-to-osmoadaptation-and-symbiotic-efficiency-of-rhizobia-on-legume-roots
#7
Marta Robledo, Alexandra Peregrina, Vicenta Millán, Natalia I García-Tomsig, Omar Torres-Quesada, Pedro F Mateos, Anke Becker, José I Jiménez-Zurdo
Small non-coding RNAs (sRNAs) are expected to have pivotal roles in the adaptive responses underlying symbiosis of nitrogen-fixing rhizobia with legumes. Here, we provide primary insights into the function and activity mechanism of the Sinorhizobium meliloti trans-sRNA NfeR1 (Nodule Formation Efficiency RNA). Northern blot probing and transcription tracking with fluorescent promoter-reporter fusions unveiled high nfeR1 expression in response to salt stress and throughout the symbiotic interaction. The strength and differential regulation of nfeR1 transcription are conferred by a motif, which is conserved in nfeR1 promoter regions in α-proteobacteria...
April 12, 2017: Environmental Microbiology
https://www.readbyqxmd.com/read/28398840/the-ntry-ntrx-system-of-sinorhizobium-meliloti-gr4-regulates-motility-eps-i-production-and-nitrogen-metabolism-but-is-dispensable-for-symbiotic-nitrogen-fixation
#8
Nieves Calatrava-Morales, Joaquina Nogales, Kinia Ameztoy, Bart van Steenbergen, María José Soto
Sinorhizobium meliloti can translocate over surfaces. However, little is known about the regulatory mechanisms that control this trait and its relevance for establishing symbiosis with alfalfa plants. To gain insights into this field, we isolated Tn5 mutants of S. meliloti GR4 with impaired surface motility. In mutant strain GRS577, the transposon interrupted the ntrY gene encoding the sensor kinase of the NtrY/NtrX two-component regulatory system. GRS577 is impaired in flagella synthesis, and overproduces succinoglycan which is responsible for increased biofilm formation...
April 11, 2017: Molecular Plant-microbe Interactions: MPMI
https://www.readbyqxmd.com/read/28398123/heterologous-complementation-reveals-a-specialized-activity-for-baca-in-the-medicago-sinorhizobium-meliloti-symbiosis
#9
George C diCenzo, Maryam Zamani, Hannah N Ludwig, Turlough M Finan
The bacterium Sinorhizobium meliloti Rm2011 forms N2-fixing root nodules on alfalfa and other leguminous plants. The pSymB chromid contains a 110-kb region (the ETR region) showing high synteny to a chromosomally located region in Sinorhizobium fredii NGR234 and related rhizobia. We recently introduced the ETR region from S. fredii NGR234 into the S. meliloti chromosome. Here, we report that, unexpectedly, the S. fredii NGR234 ETR region did not complement deletion of the S. meliloti ETR region in symbiosis with Medicago sativa...
April 2017: Molecular Plant-microbe Interactions: MPMI
https://www.readbyqxmd.com/read/28394919/correction-quantitative-proteomic-analysis-of-the-hfq-regulon-in-sinorhizobium-meliloti-2011
#10
Patricio Sobrero, Jan-Philip Schlüter, Ulrike Lanner, Andreas Schlosser, Anke Becker, Claudio Valverde
[This corrects the article DOI: 10.1371/journal.pone.0048494.].
2017: PloS One
https://www.readbyqxmd.com/read/28386109/the-underlying-process-of-early-ecological-and-genetic-differentiation-in-a-facultative-mutualistic-sinorhizobium-meliloti-population
#11
Nicolás Toro, Pablo J Villadas, María Dolores Molina-Sánchez, Pilar Navarro-Gómez, José M Vinardell, Lidia Cuesta-Berrio, Miguel A Rodríguez-Carvajal
The question of how genotypic and ecological units arise and spread in natural microbial populations remains controversial in the field of evolutionary biology. Here, we investigated the early stages of ecological and genetic differentiation in a highly clonal sympatric Sinorhizobium meliloti population. Whole-genome sequencing revealed that a large DNA region of the symbiotic plasmid pSymB was replaced in some isolates with a similar synteny block carrying densely clustered SNPs and displaying gene acquisition and loss...
April 6, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28346361/specificity-in-legume-rhizobia-symbioses
#12
REVIEW
Mitchell Andrews, Morag E Andrews
Most species in the Leguminosae (legume family) can fix atmospheric nitrogen (N₂) via symbiotic bacteria (rhizobia) in root nodules. Here, the literature on legume-rhizobia symbioses in field soils was reviewed and genotypically characterised rhizobia related to the taxonomy of the legumes from which they were isolated. The Leguminosae was divided into three sub-families, the Caesalpinioideae, Mimosoideae and Papilionoideae. Bradyrhizobium spp. were the exclusive rhizobial symbionts of species in the Caesalpinioideae, but data are limited...
March 26, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28333317/characterisation-of-a-gene-encoding-a-membrane-protein-that-affects-exopolysaccharide-production-and-intracellular-mg2-concentrations-in-ensifer-meliloti
#13
Justin P Hawkins, Ivan J Oresnik
Exopolysaccharides play an important role in the physiology of a bacterial cell. Ensifer meliloti is capable of producing at least two types of exopolysaccharides (EPS): succinoglycan and galactoglucan. In E. meliloti, EPS are best known for their role in mediating interaction with its symbiotic hosts. It was previously shown that high concentrations of Mg2+ or K+ were capable of suppressing the mucoid phenotype associated with galactoglucan production in an expR+ derivative of Rm1021. In an attempt to determine how Mg2+ regulates galactoglucan production, SRmD363 was mutagenised and screened for mutants which were visibly mucoid at high concentrations of magnesium...
April 1, 2017: FEMS Microbiology Letters
https://www.readbyqxmd.com/read/28314132/rhizobial-symbiosis-alleviates-polychlorinated-biphenyls-induced-systematic-oxidative-stress-via-brassinosteroids-signaling-in-alfalfa
#14
Xiaomi Wang, Ying Teng, Ning Zhang, Peter Christie, Zhengao Li, Yongming Luo, Jun Wang
The role of symbiotic rhizobia in the alleviation of polychlorinated biphenyl (PCB)-induced phytotoxicity in alfalfa and the brassinosteroid (BR) hormone signaling involved were investigated during phytoremediation. The association between alfalfa and Sinorhizobium meliloti was adopted as a remediation model. Phytotoxicity due to PCB 77 (3,3',4,4'-tetrachlorobiphenyl) exerted adverse impacts on plant performance (biomass accumulation and photosynthesis) and elicited cellular oxidative stress (overproduction of reactive oxygen species, lipid peroxidation, and cell necrosis) which was largely attenuated by pre-inoculation with S...
March 14, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28285657/two-component-regulatory-system-acts-actr-is-required-for-sinorhizobium-meliloti-adaptation-to-oxidative-stress
#15
Guirong Tang, Sunjun Wang, Dawei Lu, Leqi Huang, Ningning Li, Li Luo
The two-component system ActS/ActR plays important roles in bacterial adaptation to abiotic stress, including acid tolerance and oxidant resistance. However, the underlying regulatory mechanism is not clear. In this study, we found that the ActS/ActR system is required for adaptation to oxidative stress by regulating the transcription of the genes actR, katB, gshA and gshB1. The actS and actR mutants were sensitive to low pH and oxidants such as H2O2, oxidized glutathione (GSSG) and sodium nitroprusside (SNP)...
May 2017: Microbiological Research
https://www.readbyqxmd.com/read/28284052/high-yield-production-of-rhizobium-nodb-chitin-deacetylase-and-its-use-for-in%C3%A2-vitro-synthesis-of-lipo-chitinoligosaccharide-precursors
#16
Rémi Chambon, Stéphanie Pradeau, Sébastien Fort, Sylvain Cottaz, Sylvie Armand
Lipo-chitinoligosaccharides (LCOs) are key molecules for the establishment of plant-microorganisms symbiosis. Interactions of leguminous crops with nitrogen-fixing rhizobial bacteria involve Nod factors, while Myc-LCOs improve the association of most plants with arbuscular mycorrhizal fungi. Both Nod factors and Myc-LCOs are composed of a chitinoligosaccharide fatty acylated at the non-reducing end accompanied with various substituting groups. One straightforward way to access LCOs is starting from chitin hydrolysate, an abundant polysaccharide found in crustacean shells, followed by regioselective enzymatic cleavage of an acetyl group from the non-reducing end of chitin tetra- or pentaose, and subsequent chemical introduction of N-acyl group...
April 10, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28283520/biogeography-of-a-novel-ensifer-meliloti-clade-associated-with-the-australian-legume-trigonella-suavissima
#17
Bertrand Eardly, Patrick Elia, John Brockwell, Daniel Golemboski, Peter van Berkum
Here, we describe a novel clade within Ensifer meliloti and consider how geographic and ecological isolation contributed to the limited distribution of this group. Members of the genus Ensifer are best known for their ability to form nitrogen-fixing symbioses with forage legumes of three related genera, Medicago L., Melilotus Mill., and Trigonella L., which are members of the tribe Trifolieae. These legumes have a natural distribution extending from the Mediterranean Basin through western Asia, where there is an unsurpassed number of species belonging to these genera...
May 15, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28273103/functional-metagenomics-reveals-novel-%C3%AE-galactosidases-not-predictable-from-gene-sequences
#18
Jiujun Cheng, Tatyana Romantsov, Katja Engel, Andrew C Doxey, David R Rose, Josh D Neufeld, Trevor C Charles
The techniques of metagenomics have allowed researchers to access the genomic potential of uncultivated microbes, but there remain significant barriers to determination of gene function based on DNA sequence alone. Functional metagenomics, in which DNA is cloned and expressed in surrogate hosts, can overcome these barriers, and make important contributions to the discovery of novel enzymes. In this study, a soil metagenomic library carried in an IncP cosmid was used for functional complementation for β-galactosidase activity in both Sinorhizobium meliloti (α-Proteobacteria) and Escherichia coli (γ-Proteobacteria) backgrounds...
2017: PloS One
https://www.readbyqxmd.com/read/28264559/a-family-of-single-copy-repabc-type-shuttle-vectors-stably-maintained-in-the-alpha-proteobacterium-sinorhizobium-meliloti
#19
Johannes Döhlemann, Marcel Wagner, Carina Happel, Martina Carrillo, Patrick Sobetzko, Tobias J Erb, Martin Thanbichler, Anke Becker
A considerable share of bacterial species maintains segmented genomes. Plant symbiotic α-proteobacterial rhizobia contain up to six repABC-type replicons in addition to the primary chromosome. These low or unit-copy replicons, classified as secondary chromosomes, chromids, or megaplasmids, are exclusively found in α-proteobacteria. Replication and faithful partitioning of these replicons to the daughter cells is mediated by the repABC region. The importance of α-rhizobial symbiotic nitrogen fixation for sustainable agriculture and Agrobacterium-mediated plant transformation as a tool in plant sciences has increasingly moved biological engineering of these organisms into focus...
March 20, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28235609/massive-parallel-insertion-site-sequencing-of-an-arrayed-sinorhizobium-meliloti-signature-tagged-mini-tn-5-transposon-mutant-library
#20
Javier Serrania, Tobias Johner, Oliver Rupp, Alexander Goesmann, Anke Becker
Transposon mutagenesis in conjunction with identification of genomic transposon insertion sites is a powerful tool for gene function studies. We have implemented a protocol for parallel determination of transposon insertion sites by Illumina sequencing involving a hierarchical barcoding method that allowed for tracking back insertion sites to individual clones of an arrayed signature-tagged transposon mutant library. This protocol was applied to further characterize a signature-tagged mini-Tn 5 mutant library comprising about 12,000 mutants of the symbiotic nitrogen-fixing alphaproteobacterium Sinorhizobium meliloti (Pobigaylo et al...
February 21, 2017: Journal of Biotechnology
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