In Vivo Cloning of Genes from Bradyrhizobium Japonicum

1987 ◽  
pp. 288-291 ◽  
Author(s):  
Ketan S. Shah ◽  
L. David Kuykendall
Keyword(s):  
Bradyrhizobium Japonicum

scholarly journals Interações entre fungos micorrízicos arbusculares, rizóbio e actinomicetos na rizosfera de soja

2013 ◽  
Vol 17 (12) ◽  
pp. 1249-1256 ◽  
Author(s):  
Marsílvio G. Pereira ◽  
Carolina E. R. S. Santos ◽  
Ana D. S. de Freitas ◽  
Newton P. Stamford ◽  
Gewerlys S. D. C. da Rocha ◽  
...  
Keyword(s):  
Bradyrhizobium Japonicum ◽  
Gigaspora Margarita ◽  
Glomus Clarum ◽  
De Se ◽  
Bradyrhizobium Elkanii

Isolados de actinomicetos e de fungos micorrízicos arbusculares foram avaliados em sistemas de inoculação conjunta in vivo, em plantas de soja inoculadas com rizóbios, com a finalidade de se observar interações microbianas. A pesquisa foi realizada no Centro Nacional de Pesquisa de Agrobiologia (Embrapa CNPAB). Foram utilizados, como substrato, solo da série Itaguaí (textura média) misturado com areia de rio na proporção 1:1 (v:v), com adição de isolados de actinomicetos (ACT-78 e ACT-370); estirpes de rizóbios (Bradyrhizobium elkanii - BR 29 e Bradyrhizobium japonicum - BR 33) e fungos micorrízicos arbusculares (Gigaspora margarita e Glomus clarum). Os resultados revelam que a inoculação com os fungos micorrízicos arbusculares influenciou de modo expressivo as variáveis de crescimento, nodulação e densidade de actinomicetos na rizosfera de soja, que apresentaram valores maiores do que as plantas sem o inóculo fúngico. Houve efeitos sinergísticos e antagônicos dos fungos micorrízicos arbusculares com os actinomicetos e com rizóbios.

scholarly journals Role of HrcA and CIRCE in the Heat Shock Regulatory Network of Bradyrhizobium japonicum

2000 ◽  
Vol 182 (1) ◽  
pp. 14-22 ◽  
Author(s):  
Alexander C. Minder ◽  
Hans-Martin Fischer ◽  
Hauke Hennecke ◽  
Franz Narberhaus
Keyword(s):  
Heat Shock ◽  
Bradyrhizobium Japonicum ◽  
Target Genes ◽  
Specific Binding ◽  
Regulatory Function ◽  
In The Wild ◽  
Number Of Bacteria

ABSTRACT A large number of bacteria regulate chaperone gene expression by the CIRCE-HrcA system in which a DNA element called CIRCE serves as binding site for the repressor protein HrcA under non-heat-shock conditions. We have cloned the two consecutive genes hrcAand grpE of Bradyrhizobium japonicum by using a complementation approach that screened for GrpE function. In vivo and in vitro transcript mapping demonstrated that both genes are transcribed separately from RpoH (ς32)-dependent promoters. To investigate the supposed negative regulatory function of HrcA, we compared the expression of putative target genes in the wild type with that in an hrcA mutant. Transcription of the CIRCE-associated chaperonin operons groESL 4 andgroESL 5, as well as the β-galactosidase activity derived from corresponding groE-lacZ fusions, was strongly elevated in the hrcA mutant even at physiological temperatures. Expression of other heat shock regulons (RpoH or ROSE dependent) was not affected. To study the activity of HrcA in vitro, we purified a histidine-tagged version of the protein under nondenaturing conditions. Specific binding to the CIRCE element was obtained with a soluble fraction of HrcA in gel retardation experiments.

The Bradyrhizobium japonicum Fur protein is an iron-responsive regulator in vivo

2006 ◽  
Vol 276 (6) ◽  
pp. 555-564 ◽  
Author(s):  
Jianhua Yang ◽  
Indu Sangwan ◽  
Mark R. O’Brian
Keyword(s):  
Bradyrhizobium Japonicum ◽  
Fur Protein

scholarly journals The Bradyrhizobium japonicum Irr Protein Is a Transcriptional Repressor with High-Affinity DNA-Binding Activity

2008 ◽  
Vol 190 (15) ◽  
pp. 5172-5177 ◽  
Author(s):  
Indu Sangwan ◽  
Sandra K. Small ◽  
Mark R. O'Brian
Keyword(s):  
Dna Binding ◽  
Bradyrhizobium Japonicum ◽  
Iron Homeostasis ◽  
Transcriptional Repressor ◽  
Physiological Role ◽  
Iron Limitation ◽  
Dependent Manner ◽  
High Affinity

ABSTRACT The Irr protein is a global regulator of iron homeostasis in Bradyrhizobium japonicum, and a subset of genes within the Irr regulon are negatively controlled under iron limitation. However, repressor function, high-affinity DNA binding in vitro, or promoter occupancy in vivo of Irr for a negatively regulated gene has not been demonstrated. Here, we show that the blr7895 and bll6680 genes are negatively regulated by Irr as determined by derepression of transcript levels in iron-limited cells of an irr mutant strain. Electrophoretic gel mobility shift analysis showed that a component in extracts of wild-type cells grown under iron limitation bound the iron control elements (ICE) within the promoters of blr7895 and bll6680 identified previously (G. Rudolph, G. Semini, F. Hauser, A. Lindemann, M. Friberg, H. Hennecke, and H. M. Fischer, J. Bacteriol. 188:733-744, 2006). Binding was not observed with extracts of cells from the parent strain grown under high iron conditions or with those from an irr mutant. Furthermore, gel mobility supershift experiments identified Irr as a component of the binding complex. Purified recombinant Irr bound to ICE DNA with high affinity in the presence of divalent metal, with K d values of 7 to 19 nM, consistent with a physiological role for Irr as a transcriptional regulator. In addition, in vitro transcription initiated from the blr7895 promoter was inhibited by Irr. Whole-cell cross-linking and immunoprecipitation experiments showed that Irr occupies the promoters of blr7895 and bll6680 in vivo in an iron-dependent manner. The findings demonstrate that Irr is a transcriptional repressor that binds DNA with high affinity.

scholarly journals Replacement of Pro109 by His in TlpA, a thioredoxin-like protein from Bradyrhizobium japonicum , alters its redox properties but not its in vivo functions

FEBS Letters ◽  
1997 ◽  
Vol 406 (3) ◽  
pp. 249-254 ◽  
Author(s):  
Reinhild Rossmann ◽  
Dorothee Stern ◽  
Hannes Loferer ◽  
Alexander Jacobi ◽  
Rudi Glockshuber ◽  
...  
Keyword(s):  
Bradyrhizobium Japonicum ◽  
Redox Properties

scholarly journals Positive Control of Ferric Siderophore Receptor Gene Expression by the Irr Protein in Bradyrhizobium japonicum

2008 ◽  
Vol 191 (5) ◽  
pp. 1361-1368 ◽  
Author(s):  
Sandra K. Small ◽  
Sumant Puri ◽  
Indu Sangwan ◽  
Mark R. O'Brian
Keyword(s):  
Bradyrhizobium Japonicum ◽  
Iron Transport ◽  
Ferric Iron ◽  
Receptor Gene ◽  
Regulatory Protein ◽  
Transport Systems ◽  
Control Element ◽  
Iron Chelate ◽  
Cell Extracts

ABSTRACT Ferric siderophore receptors are components of high-affinity iron-chelate transport systems in gram-negative bacteria. The genes encoding these receptors are generally regulated by repression. Here, we show that the ferrichrome receptor gene bll4920 and four additional putative ferric siderophore receptor genes in Bradyrhizobium japonicum are positively controlled by the regulatory protein Irr, as observed by the low level of mRNA transcripts in an irr mutant in iron-limited cells. Potential Irr binding sites with iron control element (ICE)-like motifs were found upstream and distal to the transcription start sites of the five receptor genes. However, purified recombinant Irr bound only some of those elements. Nevertheless, dissection of the bll4920 promoter region showed that a component in extracts of wild-type cells grown in iron-limited media bound only in the ICE motif region of the promoter. This binding was not observed with extracts of cells from the parent strain grown under high-iron conditions or from an irr mutant strain. Furthermore, gel mobility supershift experiments identified Irr as the binding protein in cell extracts. Chromatin immunoprecipitation experiments demonstrated that Irr occupies the promoters of the five ferric iron transport genes in vivo. We conclude that Irr is a direct positive regulator of ferric iron transport in B. japonicum.

scholarly journals Promoter Selectivity of the Bradyrhizobium japonicum RpoH Transcription Factors In Vivo and In Vitro

1998 ◽  
Vol 180 (9) ◽  
pp. 2395-2401 ◽  
Author(s):  
Franz Narberhaus ◽  
Michael Kowarik ◽  
Christoph Beck ◽  
Hauke Hennecke
Keyword(s):  
Heat Shock ◽  
Rna Polymerase ◽  
Bradyrhizobium Japonicum ◽  
Normal Growth ◽  
Growth Conditions ◽  
Start Site ◽  
E Coli ◽  
Soluble C

ABSTRACT Expression of the dnaKJ andgroESL 1 heat shock operons ofBradyrhizobium japonicum depends on a ς32-like transcription factor. Three such factors (RpoH1, RpoH2, and RpoH3) have previously been identified in this organism. We report here that they direct transcription from some but not all ς32-type promoters when the respective rpoH genes are expressed inEscherichia coli. All three RpoH factors were purified as soluble C-terminally histidine-tagged proteins, although the bulk of overproduced RpoH3 was insoluble. The purified proteins were recognized by an anti-E. coli ς32 serum. While RpoH1 and RpoH2 productively interacted with E. coli core RNA polymerase and produced E. coli groE transcript in vitro, RpoH3 was unable to do so.B. japonicum core RNA polymerase was prepared and reconstituted with the RpoH proteins. Again, RpoH1 and RpoH2 were active, and they initiated transcription at theB. japonicum groESL 1 and dnaKJpromoters. In all cases, the in vitro start site was shown to be identical to the start site determined in vivo. Promoter competition experiments revealed that the B. japonicum dnaKJ andgroESL 1 promoters were suboptimal for transcription by RpoH1- or RpoH2-containing RNA polymerase from B. japonicum. In a mixture of different templates, the E. coli groESL promoter was preferred over any other promoter. Differences were observed in the specificities of both sigma factors toward B. japonicum rpoH-dependent promoters. We conclude that the primary function of RpoH2is to supply the cell with DnaKJ under normal growth conditions whereas RpoH1 is responsible mainly for increasing the level of GroESL1 after a heat shock.

Fine Structural Changes in the Microvasculature of the Mouse Pinna: Aging and Radiation Injury

1974 ◽  
Vol 32 ◽  
pp. 54-55
Author(s):  
S. Phyllis Steamer ◽  
Rosemarie L. Devine
Keyword(s):  
Structural Changes ◽  
Radiation Treatment ◽  
Arterial Stenosis ◽  
Ultrastructural Changes ◽  
Vascular Effects ◽  
Microvascular Changes ◽  
Surrounding Connective Tissue ◽  
Fission Neutrons ◽  
Total Body

The importance of radiation damage to the skin and its vasculature was recognized by the early radiologists. In more recent studies, vascular effects were shown to involve the endothelium as well as the surrounding connective tissue. Microvascular changes in the mouse pinna were studied in vivo and recorded photographically over a period of 12-18 months. Radiation treatment at 110 days of age was total body exposure to either 240 rad fission neutrons or 855 rad 60Co gamma rays. After in vivo observations in control and irradiated mice, animals were sacrificed for examination of changes in vascular fine structure. Vessels were selected from regions of specific interest that had been identified on photomicrographs. Prominent ultrastructural changes can be attributed to aging as well as to radiation treatment. Of principal concern were determinations of ultrastructural changes associated with venous dilatations, segmental arterial stenosis and tortuosities of both veins and arteries, effects that had been identified on the basis of light microscopic observations. Tortuosities and irregularly dilated vein segments were related to both aging and radiation changes but arterial stenosis was observed only in irradiated animals.

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