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https://www.readbyqxmd.com/read/27911408/defining-substrate-specificities-for-lipase-and-phospholipase-candidates
#1
Diana X Sahonero-Canavesi, Maritza Zavaleta-Pastor, Lourdes Martínez-Aguilar, Isabel M López-Lara, Otto Geiger
Microorganisms produce a wide spectrum of (phospho)lipases that are secreted in order to make external substrates available for the organism. Alternatively, other (phospho)lipases may be physically associated with the producing organism causing a turnover of intrinsic lipids and frequently giving rise to a remodeling of the cellular membranes. Although potential (phospho)lipases can be predicted with a number of algorithms when the gene/protein sequence is available, experimental proof of the enzyme activities, substrate specificities, and potential physiological functions has frequently not been obtained...
November 23, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/27902438/dna-double-strand-break-repair-is-involved-in-desiccation-resistance-of-sinorhizobium-meliloti-but-is-not-essential-for-its-symbiotic-interaction-with-medicago-truncatula
#2
Pierre Dupuy, Benjamin Gourion, Laurent Sauviac, Claude Bruand
The soil bacterium Sinorhizobium meliloti, a nitrogen-fixing symbiont of legume plants, is exposed to numerous stress conditions in nature, some of which cause the formation of harmful DNA double strand breaks (DSB). In particular, the reactive oxygen (ROS) and nitrogen (RNS) species produced during symbiosis, and the desiccation occurring in dry soils, are conditions which induce DSB. Two major systems of DSB repair are known in S. meliloti: homologous recombination (HR) and non-homologous end-joining (NHEJ)...
November 23, 2016: Microbiology
https://www.readbyqxmd.com/read/27900694/methods-for-the-isolation-of-genes-encoding-novel-pha-metabolism-enzymes-from-complex-microbial-communities
#3
Jiujun Cheng, Ricardo Nordeste, Maria A Trainer, Trevor C Charles
Development of different PHAs as alternatives to petrochemically derived plastics can be facilitated by mining metagenomic libraries for diverse PHA cycle genes that might be useful for synthesis of bio-plastics. The specific phenotypes associated with mutations of the PHA synthesis pathway genes in Sinorhizobium meliloti and Pseudomonas putida, allows the use of powerful selection and screening tools to identify complementing novel PHA synthesis genes. Identification of novel genes through their function rather than sequence facilitates the functional proteins that may otherwise have been excluded through sequence-only screening methodology...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/27864973/the-evolution-of-symbiont-preference-traits-in-the-model-legume-medicago-truncatula
#4
Rebecca T Batstone, Emily M Dutton, Donglin Wang, Molly Yang, Megan E Frederickson
Many hosts preferentially associate with or reward better symbionts, but how these symbiont preference traits evolve is an open question. Legumes often form more nodules with or provide more resources to rhizobia that fix more nitrogen (N), but they also acquire N from soil via root foraging. It is unclear whether root responses to abiotically and symbiotically derived N evolve independently. Here, we measured root foraging and both preferential allocation of root resources to and preferential association with an effective vs an ineffective N-fixing Ensifer meliloti strain in 35 inbred lines of the model legume Medicago truncatula...
November 16, 2016: New Phytologist
https://www.readbyqxmd.com/read/27818838/optical-disassembly-of-cellular-clusters-by-tunable-tug-of-war-tweezers
#5
Anna S Bezryadina, Daryl C Preece, Joseph C Chen, Zhigang Chen
Bacterial biofilms underlie many persistent infections, posing major hurdles in antibiotic treatment. Here we design and demonstrate 'tug-of-war' optical tweezers that can facilitate the assessment of cell-cell adhesion-a key contributing factor to biofilm development, thanks to the combined actions of optical scattering and gradient forces. With a customized optical landscape distinct from that of conventional tweezers, not only can such 'tug-of-war' tweezers stably trap and stretch a rod-shaped bacterium in the observing plane, but, more importantly, they can also impose a tunable lateral force that pulls apart cellular clusters without any tethering or mechanical movement...
2016: Light, Science & Applications
https://www.readbyqxmd.com/read/27795315/negative-regulation-of-ectoine-uptake-and-catabolism-in-sinorhizobium-meliloti-characterization-of-the-ehur-gene
#6
Qinli Yu, Hanlin Cai, Yanfeng Zhang, Yongzhi He, Lincai Chen, Justin Merritt, Shan Zhang, Zhiyang Dong
: Ectoine has osmoprotective effects on Sinorhizobium meliloti that differ from its effects in other bacteria. Ectoine does not accumulate in S. meliloti cells; instead, it is degraded. The products of the ehuABCD-eutABCDE operon were previously discovered to be responsible for the uptake and catabolism of ectoine in S. meliloti However, the mechanism by which ectoine is involved in the regulation of the ehuABCD-eutABCDE operon remains unclear. ehuR, which is upstream of and oriented in the same direction as the ehuABCD-eutABCDE operon, encodes a member of the MocR/GntR family of transcriptional regulators...
October 17, 2016: Journal of Bacteriology
https://www.readbyqxmd.com/read/27748981/sinorhizobium-meliloti-chemotaxis-to-quaternary-ammonium-compounds-is-mediated-by-the-chemoreceptor-mcpx
#7
Benjamin A Webb, K Karl Compton, Rafael Castañeda Saldaña, Timofey Arapov, W Keith Ray, Richard F Helm, Birgit E Scharf
The bacterium Sinorhizobium meliloti is attracted to seed exudates of its host plant alfalfa (Medicago sativa). Since quaternary ammonium compounds (QACs) are exuded by germinating seeds, we assayed chemotaxis of S. meliloti towards betonicine, choline, glycine betaine, stachydrine, and trigonelline. The wild type displayed a positive response to all QACs. Using LC-MS, we determined that each germinating alfalfa seed exuded QACs in the nanogram range. Compared to the closely related non-host species, spotted medic (Medicago arabica), unique profiles were released...
October 17, 2016: Molecular Microbiology
https://www.readbyqxmd.com/read/27748755/a-proteomic-atlas-of-the-legume-medicago-truncatula-and-its-nitrogen-fixing-endosymbiont-sinorhizobium-meliloti
#8
Harald Marx, Catherine E Minogue, Dhileepkumar Jayaraman, Alicia L Richards, Nicholas W Kwiecien, Alireza F Sihapirani, Shanmugam Rajasekar, Junko Maeda, Kevin Garcia, Angel R Del Valle-Echevarria, Jeremy D Volkening, Michael S Westphall, Sushmita Roy, Michael R Sussman, Jean-Michel Ané, Joshua J Coon
Legumes are essential components of agricultural systems because they enrich the soil in nitrogen and require little environmentally deleterious fertilizers. A complex symbiotic association between legumes and nitrogen-fixing soil bacteria called rhizobia culminates in the development of root nodules, where rhizobia fix atmospheric nitrogen and transfer it to their plant host. Here we describe a quantitative proteomic atlas of the model legume Medicago truncatula and its rhizobial symbiont Sinorhizobium meliloti, which includes more than 23,000 proteins, 20,000 phosphorylation sites, and 700 lysine acetylation sites...
October 17, 2016: Nature Biotechnology
https://www.readbyqxmd.com/read/27739645/interkingdom-responses-to-bacterial-quorum-sensing-signals-regulate-frequency-and-rate-of-nodulation-in-legume-rhizobia-symbiosis
#9
Andrew G Palmer, Arijit Mukherjee, Danielle M Stacy, Stephen Lazar, Jean-Michel Ané, Helen E Blackwell
Density-dependent phenotypic switching in bacteria, the phenomenon of quorum sensing (QS), is instrumental in many pathogenic and mutualistic behaviors. In many Gram-negative bacteria, QS is regulated by N-acylated-l-homoserine lactones (AHLs). Synthetic analogues of these AHLs hold significant promise for regulating QS at the host-symbiont interface. Regulation depends on refined temporal and spatial models of quorums under native conditions. Critical to this is an understanding of how the presence of these signals may affect a prospective host...
October 14, 2016: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/27730127/functionality-of-in-vitro-reconstituted-group-ii-intron-rmint1-derived-ribonucleoprotein-particles
#10
Maria D Molina-Sánchez, Fernando M García-Rodríguez, Nicolás Toro
The functional unit of mobile group II introns is a ribonucleoprotein particle (RNP) consisting of the intron-encoded protein (IEP) and the excised intron RNA. The IEP has reverse transcriptase activity but also promotes RNA splicing, and the RNA-protein complex triggers site-specific DNA insertion by reverse splicing, in a process called retrohoming. In vitro reconstituted ribonucleoprotein complexes from the Lactococcus lactis group II intron Ll.LtrB, which produce a double strand break, have recently been studied as a means of developing group II intron-based gene targeting methods for higher organisms...
2016: Frontiers in Molecular Biosciences
https://www.readbyqxmd.com/read/27727485/a-putative-3-hydroxyisobutyryl-coa-hydrolase-is-required-for-efficient-symbiotic-nitrogen-fixation-in-sinorhizobium-meliloti-and-sinorhizobium-fredii-ngr234
#11
Maryam Zamani, George C diCenzo, Branislava Milunovic, Turlough M Finan
We report that the smb20752 gene of the alfalfa symbiont Sinorhizobium meliloti is a novel symbiotic gene required for full N2 -fixation. Deletion of smb20752 resulted in lower nitrogenase activity and smaller nodules without impacting overall nodule morphology. Orthologs of smb20752 were present in all alpha and beta rhizobia, including the ngr_b20860 gene of Sinorhizobium fredii NGR234. A ngr_b20860 mutant formed Fix(-) determinate nodules that developed normally to a late stage of the symbiosis on the host plants Macroptillium atropurpureum and Vigna unguiculata...
October 11, 2016: Environmental Microbiology
https://www.readbyqxmd.com/read/27712144/regulation-of-fixlj-by-hfq-controls-symbiotically-important-genes-in-sinorhizobium-meliloti
#12
Mengsheng Gao, Hahn Nguyen, Isai Salas González, Max Teplitski
The RNA-binding chaperone Hfq plays critical roles in the establishment and functionality of the symbiosis between Sinorhizobium meliloti and its legume hosts. A mutation in hfq reduces symbiotic efficiency resulting in a Fix(-) phenotype, characterized by the inability of the bacterium to fix nitrogen. At least in part, this is due to the ability of Hfq to regulate the fixLJ operon, which encodes a sensor kinase-response regulator pair that controls expression of the nitrogenase genes. The ability of Hfq to bind fixLJ in vitro and in planta was demonstrated with gel shift and coimmunoprecipitation experiments...
November 18, 2016: Molecular Plant-microbe Interactions: MPMI
https://www.readbyqxmd.com/read/27679491/structures-of-proline-utilization-a-puta-reveal-the-fold-and-functions-of-the-aldehyde-dehydrogenase-superfamily-domain-of-unknown-function
#13
Min Luo, Thameesha T Gamage, Benjamin W Arentson, Katherine N Schlasner, Donald F Becker, John J Tanner
Aldehyde dehydrogenases (ALDHs) catalyze the NAD(P)(+)-dependent oxidation of aldehydes to carboxylic acids and are important for metabolism and detoxification. Although the ALDH superfamily fold is well established, some ALDHs contain an uncharacterized domain of unknown function (DUF) near the C terminus of the polypeptide chain. Herein, we report the first structure of a protein containing the ALDH superfamily DUF. Proline utilization A from Sinorhizobium meliloti (SmPutA) is a 1233-residue bifunctional enzyme that contains the DUF in addition to proline dehydrogenase and l-glutamate-γ-semialdehyde dehydrogenase catalytic modules...
November 11, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/27597170/ensifer-meliloti-overexpressing-escherichia-coli-phytase-gene-appa-improves-phosphorus-p-acquisition-in-maize-plants
#14
Vikas Sharma, Ajit Kumar, G Archana, G Naresh Kumar
The Escherichia coli phytase gene appA encoding enzyme AppA was cloned in a broad host range plasmid pBBR1MCS2 (lac promoter), termed pVA1, and transformed into the Ensifer meliloti 1020. Transformation of pVA1 in Ensifer meliloti {E. m (pVA1)} increased its phosphatase and phytase activity by ∼9- and ∼50-fold, respectively, compared to the transformants containing empty plasmid as control {E. m (pBBR1MCS2)}. The western blot experiments using rabbit anti-AppA antibody showed that AppA is translocated into the periplasm of the host after its expression...
October 2016: Die Naturwissenschaften
https://www.readbyqxmd.com/read/27588750/host-factors-influencing-the-retrohoming-pathway-of-group-ii-intron-rmint1-which-has-an-intron-encoded-protein-naturally-devoid-of-endonuclease-activity
#15
Rafael Nisa-Martínez, María Dolores Molina-Sánchez, Nicolás Toro
Bacterial group II introns are self-splicing catalytic RNAs and mobile retroelements that have an open reading frame encoding an intron-encoded protein (IEP) with reverse transcriptase (RT) and RNA splicing or maturase activity. Some IEPs carry a DNA endonuclease (En) domain, which is required to cleave the bottom strand downstream from the intron-insertion site for target DNA-primed reverse transcription (TPRT) of the inserted intron RNA. Host factors complete the insertion of the intron. By contrast, the major retrohoming pathway of introns with IEPs naturally lacking endonuclease activity, like the Sinorhizobium meliloti intron RmInt1, is thought to involve insertion of the intron RNA into the template for lagging strand DNA synthesis ahead of the replication fork, with possible use of the nascent strand to prime reverse transcription of the intron RNA...
2016: PloS One
https://www.readbyqxmd.com/read/27551097/disulfide-cross-linking-influences-symbiotic-activities-of-nodule-peptide-ncr247
#16
Mohammed Shabab, Markus F F Arnold, Jon Penterman, Andrew J Wommack, Hartmut T Bocker, Paul A Price, Joel S Griffitts, Elizabeth M Nolan, Graham C Walker
Interactions of rhizobia with legumes establish the chronic intracellular infection that underlies symbiosis. Within nodules of inverted repeat-lacking clade (IRLC) legumes, rhizobia differentiate into nitrogen-fixing bacteroids. This terminal differentiation is driven by host nodule-specific cysteine-rich (NCR) peptides that orchestrate the adaptation of free-living bacteria into intracellular residents. Medicago truncatula encodes a family of >700 NCR peptides that have conserved cysteine motifs. NCR247 is a cationic peptide with four cysteines that can form two intramolecular disulfide bonds in the oxidized forms...
September 6, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27535558/cyclic-mononucleotide-and-clr-dependent-gene-regulation-in-sinorhizobium-meliloti
#17
Elizaveta Krol, Christina Klaner, Petra Gnau, Volkhard Kaever, Lars-Oliver Essen, Anke Becker
To identify physiological processes affected by cAMP in the plant-symbiotic nitrogen-fixing α-proteobacterium Sinorhizobium meliloti Rm2011, cAMP levels were artificially increased by overexpression of its cognate adenylate/guanylate cyclase gene cyaJ. This resulted in high accumulation of cAMP in the culture supernatant, decreased swimming motility and increased production of succinoglycan, an exopolysaccharide involved in host invasion. Weaker, similar phenotypic changes were induced by overexpression of cyaB and cyaG1...
October 2016: Microbiology
https://www.readbyqxmd.com/read/27508354/rhizobial-strains-exert-a-major-effect-on-the-amino-acid-composition-of-alfalfa-nodules-under-nacl-stress
#18
Annick Bertrand, Marie Bipfubusa, Catherine Dhont, François-P Chalifour, Pascal Drouin, Chantal J Beauchamp
Specific amino acids have protective functions in plants under stress conditions. This study assessed the effects of rhizobial strains on the amino acid composition in alfalfa under salt stress. Two alfalfa cultivars (Medicago sativa L. cv Apica and salt-tolerant cv Halo) in association with two Sinorhizobium meliloti strains with contrasting growth under salt stress (strain A2 and salt-tolerant strain Rm1521) were exposed to different levels of NaCl (0, 20, 40, 80 or 160 mM NaCl) under controlled conditions...
August 3, 2016: Plant Physiology and Biochemistry: PPB
https://www.readbyqxmd.com/read/27495742/the-early-events-underlying-genome-evolution-in-a-localized-sinorhizobium-meliloti-population
#19
Nicolás Toro, Francisco Martínez-Abarca, Manuel Fernández-López
BACKGROUND: Population genetic analyses based on genome-wide sequencing data have been carried out for Sinorhizobium medicae and S. meliloti, two closely related bacterial species forming nitrogen-fixing symbioses with plants of the genus Medicago. However, genome coverage was low or the isolates had a broad geographic distribution, making it difficult to interpret the estimated diversity and to unravel the early events underlying population genetic variations and ecological differentiation...
2016: BMC Genomics
https://www.readbyqxmd.com/read/27465344/antimicrobial-nodule-specific-cysteine-rich-peptides-disturb-the-integrity-of-bacterial-outer-and-inner-membranes-and-cause-loss-of-membrane-potential
#20
Kata R Mikuláss, Krisztina Nagy, Balázs Bogos, Zsolt Szegletes, Etelka Kovács, Attila Farkas, György Váró, Éva Kondorosi, Attila Kereszt
BACKGROUND: Certain legume plants produce a plethora of AMP-like peptides in their symbiotic cells. The cationic subgroup of the nodule-specific cysteine-rich (NCR) peptides has potent antimicrobial activity against gram-negative and gram-positive bacteria as well as unicellular and filamentous fungi. FINDINGS: It was shown by scanning and atomic force microscopies that the cationic peptides NCR335, NCR247 and Polymyxin B (PMB) affect differentially on the surfaces of Sinorhizobium meliloti bacteria...
2016: Annals of Clinical Microbiology and Antimicrobials
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