A5000015314- Legume Nitrogen Fixing Symbiosis
- Plant nutrient uptake and metabolism
- Wastewater Treatment and Nitrogen Removal
- Genomics and Phylogenetic Studies
- Microbial Community Ecology and Physiology
- Plant Micronutrient Interactions and Effects
- Coastal wetland ecosystem dynamics
- Cassava research and cyanide
- Plant Pathogenic Bacteria Studies
- Agronomic Practices and Intercropping Systems
- Microbial Fuel Cells and Bioremediation
- Bacterial Genetics and Biotechnology
- Ammonia Synthesis and Nitrogen Reduction
- Plant-Microbe Interactions and Immunity
- Amino Acid Enzymes and Metabolism
- Plant responses to water stress
- Nematode management and characterization studies
- Bacteriophages and microbial interactions
- Microbial Metabolites in Food Biotechnology
- Arsenic contamination and mitigation
- Biofuel production and bioconversion
- Porphyrin Metabolism and Disorders
- Methane Hydrates and Related Phenomena
- Microbial Metabolic Engineering and Bioproduction
- Diet, Metabolism, and Disease
McMaster University
2013-2024
Pennsylvania State University
2009
GTx (United States)
2009
Hainan Medical College Hospital
2009
University of Minnesota
2007
Bielefeld University
2001
Massachusetts Institute of Technology
1985-1987
The scarcity of usable nitrogen frequently limits plant growth. A tight metabolic association with rhizobial bacteria allows legumes to obtain compounds by bacterial reduction dinitrogen (N 2 ) ammonium (NH 4 + ). We present here the annotated DNA sequence α-proteobacterium Sinorhizobium meliloti , symbiont alfalfa. tripartite 6.7-megabase (Mb) genome comprises a 3.65-Mb chromosome, and 1.35-Mb pSymA 1.68-Mb pSymB megaplasmids. Genome analysis indicates that all three elements contribute, in...
Using physical and genetic data, we have demonstrated that Rhizobium meliloti SU47 has a symbiotic megaplasmid, pRmeSU47b, in addition to the previously described nod-nif megaplasmid pRmeSU47a. This plasmid includes four loci involved exopolysaccharide (exo) synthesis as well two thiamine biosynthesis. Mutations at exo been shown result formation of nodules which lack infection threads (Inf-) fail fix nitrogen (Fix-). Thus, both megaplasmids contain genes nitrogen-fixing root nodules. other...
Analysis of the 1,683,333-nt sequence pSymB megaplasmid from symbiotic N 2 -fixing bacterium Sinorhizobium meliloti revealed that replicon has a high gene density with total 1,570 protein-coding regions, few insertion elements and regions duplicated elsewhere in genome. The only copies an essential arg-tRNA minCDE genes are located on pSymB. Almost 20% carries encoding solute uptake systems, most which were ATP-binding cassette family. Many previously unsuspected involved polysaccharide...
General transduction by phage phi M12 in Rhizobium meliloti SU47 and its derivatives is described. Cotransduction selection for Tn5 insertions which are closely linked to specific loci were demonstrated. A derivative of carrying the recA::Tn5 allele R. 102F34 could be transduced plasmid R68.45 but not chromosomally located alleles. Phage morphologically similar Escherichia coli T4, restriction endonuclease analysis indicated that DNA was ca. 160 kilobases size.
The transport of succinate was studied in bacteroids an effective, streptomycin-resistant strain (GF160) Rhizobium leguminosarum. High levels occurred, and the kinetics, specificity, sensitivity to metabolic inhibitors were similar those previously described for free-living cells. symbiotic properties two transposon (Tn5)-mediated C4-dicarboxylate mutants (strains GF31 GF252) determined. Strain formed ineffective nodules, from these nodules showed no activity. GF252 partially effective about...
Many bacteria carry two or more chromosome-like replicons. This occurs in pathogens such as Vibrio cholerea and Brucella abortis well many N2-fixing plant symbionts including all isolates of the alfalfa root-nodule Sinorhizobium meliloti. Understanding evolution role this multipartite genome organization will provide significant insight into these important organisms; yet knowledge remains incomplete, part, because technical challenges large-scale manipulations have limited experimental...
We report a novel pathway for arsenic detoxification in the legume symbiont Sinorhizobium meliloti. Although majority of ars operons consist three genes, arsR (transcriptional regulator), arsB [As(OH)3/H+ antiporter], and arsC (arsenate reductase), S. meliloti operon includes an aquaglyceroporin (aqpS) place arsB. The presence AqpS resistance is interesting, since channels have previously been shown to adventitiously facilitate uptake arsenite into cells, rendering them sensitive arsenite....
Bacteria react to phosphate starvation by activating genes involved in the transport and assimilation of as well other phosphorous compounds. Some soil bacteria have evolved an additional mechanism for saving phosphorus. Under phosphate‐limiting conditions, they replace their membrane phospholipids lipids not containing Here, we show that lipid pattern free‐living microsymbiotic bacterium Rhizobium ( Sinorhizobium ) meliloti is altered at low concentrations. When growth limiting, increase...
The number of solute-binding protein-dependent transporters in rhizobia is dramatically increased compared with the majority other bacteria so far sequenced. This increase may be due to high affinity proteins for solutes, permitting acquisition a broad range growth-limiting nutrients from soil and rhizosphere. transcriptional induction these was studied by creating suite plasmid integrated fusions nearly all ATP-binding cassette (ABC) tripartite ATP-independent periplasmic (TRAP)...
A series of 120-600 kilobase deletions with defined endpoints were made in the 1600-kilobase Rhizobium meliloti megaplasmid pRmeSU47b, by homologous recombination between IS50 elements transposon insertions. Utilizing IS 50-mediated we also reductions deletion size and combined adjacent deletions. Deletion structure was confirmed phage transduction Southern hybridization analysis. Collectively these span 1400 kilobases indicating that majority plasmid is not essential for cell viability....
Summary A 5.1 kbp DNA fragment was isolated which complemented C 4 ‐dicarboxylate transport mutants ( dct ) of Rhizobium meliloti. Characterization this by subcloning, transposon mutagenesis, and complementation analysis revealed three loci, designated dctA, dctB , dctD. TnphoA‐generated alkaline phosphatase fusions to dctA suggested that gene encodes the structural protein allowed determination its direction transcription. Analysis in various mutant backgrounds demonstrated dctB, dctD ntrA...
We characterized mutants of Rhizobium meliloti SU47 that were unable to grow on succinate as the carbon source. The fell into five groups based complementation mutations by individual recombinant plasmids isolated from a R. clone bank. Enzyme analysis showed in following lacked indicated common enzyme activities: group II, enolase (Eno); III, phosphoenolpyruvate carboxykinase (Pck); IV, glyceraldehyde-3-phosphate dehydrogenase (Gap), and 3-phosphoglycerate kinase (Pgk). Mutants I V...
In proteobacteria, genes whose expression is modulated in response to the external concentration of inorganic phosphate are often regulated by PhoB protein which binds a conserved motif (Pho box) within their promoter regions. Using position weight matrix algorithm derived from known Pho box sequences, we identified 96 putative regulon members regions contained one or more boxs Sinorhizobium meliloti genome. Expression these was examined through assays reporter gene fusions and comparison...
The transport of succinate was studied in an effective streptomycin-resistant strain Rhizobium leguminosarum. High levels occurred when cells were grown on succinate, fumarate, or malate, whereas low activity found glucose, sucrose, arabinose, pyruvate as the sole carbon source. Because rapid metabolism after into cells, a dehydrogenase-deficient mutant isolated which intracellular accumulated to over 400 times external concentration. Succinate completely abolished presence metabolic...
Rhizobia are Gram-negative soil bacteria able to establish nitrogen-fixing root nodules with their respective legume host plants. Besides phosphatidylglycerol, cardiolipin, and phosphatidylethanolamine, rhizobial membranes contain phosphatidylcholine (PC) as a major membrane lipid. Under phosphate-limiting conditions of growth, some replace phospholipids lipids lacking phosphorus. In Sinorhizobium meliloti, these phosphorus-free sulfoquinovosyl diacylglycerol, ornithine-containing lipid,...
Abstract The genome of about 10% bacterial species is divided among two or more large chromosome-sized replicons. contribution each replicon to the microbial life cycle (for example, environmental adaptations and/or niche switching) remains unclear. Here we report a genome-scale metabolic model legume symbiont Sinorhizobium meliloti that integrated with carbon utilization data for 1,500 genes 192 substrates. Growth S. modelled in three ecological niches (bulk soil, rhizosphere and nodule)...
The bacterium Rhizobium meliloti forms N2-fixing root nodules on alfalfa plants. ndvF locus, located the 1,700-kb pEXO megaplasmid of R. meliloti, is required for nodule invasion and N2 fixation. Here we report that contains four genes, phoCDET, which encode an ABC-type transport system uptake Pi into bacteria. PhoC PhoD proteins are homologous to Escherichia coli phosphonate PhnC PhnD. PhoT PhoE each other E. protein PhnE. We show phoD phoE genes induced in response phosphate starvation...
Summary DEAE‐cellulose chromatography of extracts free‐living Rhizobium meliloti cells revealed separate NAD + ‐dependent and NADP malic enzyme activities. The exhibited more activity with as cofactor, but also showed some . only when was supplied cofactor. Three independent transposon‐induced mutants R. which lacked ( dme ) retained were isolated. In an otherwise wild‐type background, the mutations did not alter carbon utilization phenotype; however, nodules induced by these failed to fix N...
The properties and regulation of the pstSCAB-encoded Pi uptake system from alfalfa symbiont Sinorhizobium meliloti are reported. We present evidence that pstSCAB genes regulatory phoUB transcribed a single promoter contains two PhoB binding sites transcription requires PhoB. S. strain 1021 (Rm1021) its derivatives were found to carry C deletion frameshift mutation in pstC gene (designated pstC1021) severely impairs activity PstSCAB transport system. This is absent RCR2011, parent Rm1021....
Bacterial genome evolution is characterized by gains, losses, and rearrangements of functional genetic segments. The extent to which large-scale genomic alterations influence genotype-phenotype relationships has not been investigated in a high-throughput manner. In the symbiotic soil bacterium Sinorhizobium meliloti, composed chromosome two large extrachromosomal replicons (pSymA pSymB, together constitute 45% genome). Massively parallel transposon insertion sequencing (Tn-seq) was employed...
Maintenance of cellular phosphate homeostasis is essential for life. The PhoU protein has emerged as a key regulator this process in bacteria, and it suggested to modulate import by PstSCAB control activation the limitation response PhoR-PhoB two-component system. However, proper understanding remained elusive due numerous complications mutating phoU, including loss viability genetic instability mutants. Here, we developed two sets strains Sinorhizobium meliloti that overcame these...