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Manabu Itakura - One of the best experts on this subject based on the ideXlab platform.

Mary Lou Guerinot - One of the best experts on this subject based on the ideXlab platform.

  • Succinate dehydrogenase (Sdh) from Bradyrhizobium japonicum is closely related to mitochondrial Sdh.
    Journal of Bacteriology, 1999
    Co-Authors: David J. Westenberg, Mary Lou Guerinot
    Abstract:

    The sdhCDAB operon, encoding succinate dehydrogenase, was cloned from the soybean symbiont Bradyrhizobium japonicum. Sdh from B. japonicum is phylogenetically related to Sdh from mitochondria. This is the first example of a mitochondrion-like Sdh functionally expressed in Escherichia coli.

  • Effect ofIronAvailability on Expression ofthe Bradyrhizobium japonicum hemAGene
    1994
    Co-Authors: Mary Lou Guerinot
    Abstract:

    bacterial cytochromes andoxidases whichoperate inthemicroaerophilic environment foundin nodules (20, 28)andFixL, abacterial hemoprotein (15) which isbelieved tofunction asanoxygen sensor toregulate expression ofthenitrogen fixation (nif) genes (10). Theuniversal first step inthesynthesis ofall tetrapyrroles, including heme, isthe formation ofA-aminolevulinic acid(ALA). Thesoybean symbiont Bradyrhizobium japonicum, like other members ofthe ao-subgroup ofpurple bacteria (2), produces ALA byaonestep condensation ofglycine andsuccinyl-coenzyme A toform

  • Effect of iron availability on expression of the Bradyrhizobium japonicum hemA gene.
    Journal of Bacteriology, 1994
    Co-Authors: K M Page, Erin L. Connolly, Mary Lou Guerinot
    Abstract:

    Abstract Bradyrhizobium japonicum produces delta-aminolevulinic acid, the universal precursor of tetrapyrroles, in a reaction catalyzed by the product of the hemA gene. Expression of the B. japonicum hemA gene is affected by iron availability. Activity of a hemA-lacZ fusion is increased approximately threefold by iron, and RNA analysis indicates that iron regulation is at the level of mRNA accumulation. To our knowledge, this is the first example of an iron-regulated heme biosynthetic gene in prokaryotes.

  • Siderophore Utilization by Bradyrhizobium japonicum
    Applied and Environmental Microbiology, 1993
    Co-Authors: Ora Plessner, Taryn Klapatch, Mary Lou Guerinot
    Abstract:

    Abstract Bradyrhizobium japonicum USDA 110 and 61A152 can utilize the hydroxamate-type siderophores ferrichrome and rhodotorulate, in addition to ferric citrate, to overcome iron starvation. These strains can also utilize the pyoverdin-type siderophore pseudobactin St3. The ability to utilize another organism's siderophores may confer a selective advantage in the rhizosphere.

  • Electroporation of Bradyrhizobium japonicum
    Molecular and General Genetics MGG, 1990
    Co-Authors: Mary Lou Guerinot, Barbara Anne Morisseau, Taryn Klapatch
    Abstract:

    Electroporation offers a fast, efficient and reproducible way to introduce DNA into bacteria. We have successfully used this technique to transform two commercially important strains of Bradyrhizobium japonicum , the nitrogen-fixing soybean symbiont. Initially, electroporation conditions were optimized using plasmid DNA which had been prepared from the same B. japonicum strain into which the{imDNA was to b}e transformed. Efficiencies of 10^5-10^6 transformants/μg DNA were obtained for strains USDA 110 and 61A152 with ready-to-use frozen cells. Successful electroporation of B. japonicum with plasmid DNA prepared from Escherichia coli varied with the E. coli strain from which the plasmid was purified. The highest transformation efficiencies (10^4 transformants/μg DNA) were obtained using DNA prepared from a dcm ^− dam ^− strain of E. coli . This suggests that routine isolation of DNA from an E. coli strain incapable of DNA modification should help in increasing transformation efficiencies for other strains of bacteria where DNA restriction appears to be a significant obstacle to successful transformation. We have also monitored the rate of spontaneous mutation in electroporated cells and saw no significant difference in the frequency of streptomycin resistance for electroporated cells compared to control cells.

Michael Göttfert - One of the best experts on this subject based on the ideXlab platform.

  • The genistein stimulon of Bradyrhizobium japonicum
    Molecular Genetics and Genomics, 2008
    Co-Authors: Kathrin Lang, Andrea Lindemann, Felix Hauser, Michael Göttfert
    Abstract:

    An initializing step in the rhizobia–legume symbiosis is the secretion of flavonoids by plants that leads to the expression of nodulation genes in rhizobia. Here we report the genome-wide transcriptional response of Bradyrhizobium japonicum to genistein, an isoflavone secreted by soybean. About 100 genes were induced in the wild type. This included all nod box-associated genes, the flagellar cluster and several genes that are likely to be involved in transport processes. To elucidate the role of known regulators, we analysed mutant strains. This revealed that the two-component response regulator NodW is essential for induction of almost all genistein-inducible genes, with the exception of 8 genes. The phenotype of the nodW mutant could be partially suppressed by overexpression of NwsB, which is also a two-component response regulator. These data indicate that genistein has a much broader function than mere induction of nod genes.

  • A single rRNA gene region in Bradyrhizobium japonicum.
    Journal of Bacteriology, 1995
    Co-Authors: C Kündig, Hauke Hennecke, Christoph F. Beck, Michael Göttfert
    Abstract:

    Bradyrhizobium japonicum contains only a single rRNA (rrn) gene region, despite its comparatively large genome size of 8,700 kb. The nucleotide sequence revealed an organization of rRNA and tRNA genes that is frequently found in bacteria: 5'-rrs (16S rRNA)-ileT (tRNA(Ile))-alaT (tRNA(Ala))-rrl (23S rRNA)-rrf (5S rRNA)-3'. The 5' end of the primary transcript, one of the 16S rRNA processing sites, and the 5' end of the mature 16S rRNA were determined by primer extension. DNA hybridization experiments showed that the slowly growing Bradyrhizobium strains generally have only a single copy of the 16S rRNA gene, whereas the faster-growing Rhizobium species contain three rrs copies.

Takakazu Kaneko - One of the best experts on this subject based on the ideXlab platform.

Hauke Hennecke - One of the best experts on this subject based on the ideXlab platform.

  • Characterization of the Bradyrhizobium japonicum ftsH Gene and Its Product
    Journal of Bacteriology, 1999
    Co-Authors: Franz Narberhaus, Carmen Urech, Hauke Hennecke
    Abstract:

    The Bradyrhizobium japonicum ftsH gene was cloned by using a set of widely applicable degenerated oligonucleotides. Western blot experiments indicated that the FtsH protein was produced under standard growth conditions and that it was not heat inducible. Attempts to delete the ftsH gene in B. japonicum failed, suggesting a pivotal cellular function of this gene. The expression of B. japonicum ftsH in an ftsH-negative Escherichia coli strain significantly enhanced the fitness of this mutant and reduced the steady-state level of ς32.

  • A Two-Component Regulatory System Ensures nifA Expression in Bradyrhizobium japonicum
    Biological Nitrogen Fixation for the 21st Century, 1998
    Co-Authors: Evelyne Bauer, Hans-martin Fischer, T. Kaspar, Kelnor Panglungtshang, Ralf Emmerich, Hauke Hennecke
    Abstract:

    Nitrogen fixation-associated genes in Bradyrhizobium japonicum are controlled by both the FixLJ-FixK2 and the NifA regulatory cascades. The fixRnifA operon is not only expressed under anaerobic but, to a lower level, also under aerobic conditions. One of two overlapping promoters and an upstream DNA region (UAS) are required for aerobic expression (Thony et al. 1989, Barrios et al. 1995). A protein (UBP) binding to the UAS was postulated previously to act as an activator. UBP has now been purified and the corresponding gene has been cloned.

  • Genetic Regulation and Bioenergetics of Symbiotic Nitrogen Fixation in Bradyrhizobium japonicum
    Biological Fixation of Nitrogen for Ecology and Sustainable Agriculture, 1997
    Co-Authors: Hauke Hennecke, Markus Babst, Hans-martin Fischer, T. Kaspar, I. Kullik, D. Nellen-anthamatten, O. Preisig, P. Rossi, Karin Schneider, Linda Thöny-meyer
    Abstract:

    The low free oxygen concentration (< 25 nM) within soybean root nodules leads to two consequences that are relevant for this report: (i) it induces the synthesis of a high-affinity terminal oxidase that enables endosymbiotic bacteroids to respire at these extremely microaerobic conditions; (ii) it triggers the derepression of genes involved in the formation of the nitrogenase complex. We summarize here how both events are genetically controlled in Bradyrhizobium japonicum, and report on some recently discovered functions of the regulated genes.

  • A single rRNA gene region in Bradyrhizobium japonicum.
    Journal of Bacteriology, 1995
    Co-Authors: C Kündig, Hauke Hennecke, Christoph F. Beck, Michael Göttfert
    Abstract:

    Bradyrhizobium japonicum contains only a single rRNA (rrn) gene region, despite its comparatively large genome size of 8,700 kb. The nucleotide sequence revealed an organization of rRNA and tRNA genes that is frequently found in bacteria: 5'-rrs (16S rRNA)-ileT (tRNA(Ile))-alaT (tRNA(Ala))-rrl (23S rRNA)-rrf (5S rRNA)-3'. The 5' end of the primary transcript, one of the 16S rRNA processing sites, and the 5' end of the mature 16S rRNA were determined by primer extension. DNA hybridization experiments showed that the slowly growing Bradyrhizobium strains generally have only a single copy of the 16S rRNA gene, whereas the faster-growing Rhizobium species contain three rrs copies.

  • Nitrogen fixation genes involved in the Bradyrhizobium japonicum-soybean symbiosis.
    FEBS Letters, 1990
    Co-Authors: Hauke Hennecke
    Abstract:

    The symbiotic nitrogen fixation genes (nif, fix) of Bradyrhizobium japonicum, the root nodule endosymbiont of soybean, are organized in at least two separate chromosomal gene clusters. These genes code for proteins of the nitrogenase complex, for proteins involved in their assembly with cofactors and for putative electron transport functions. One gene, nif A, codes for a transcriptional regulatory protein that plays a central role in the control of expression of the other genes in response to the cellular oxygen status. Only at low partial pressures of O2 will the target promoters be activated by NifA.