Identification and phenotypical characterization of a cluster of fix genes, including a nif regulatory gene, from Rhizobium leguminosarum PRE

1985 ◽  
Vol 200 (3) ◽  
pp. 368-374 ◽  
Author(s):  
Resie M. P. Schetgens ◽  
Jan G. J. Hontelez ◽  
Rommert C. van den Bos ◽  
Albert van Kammen
Keyword(s):  
Rhizobium Leguminosarum ◽  
Regulatory Gene ◽  
Fix Genes

scholarly journals Cloning and Characterization of a Chromosomal Class C β-Lactamase and Its Regulatory Gene in Laribacter hongkongensis

2005 ◽  
Vol 49 (5) ◽  
pp. 1957-1964 ◽  
Author(s):  
Susanna K. P. Lau ◽  
Pak-leung Ho ◽  
Maria W. S. Li ◽  
Hoi-wah Tsoi ◽  
Raymond W. H. Yung ◽  
...  
Keyword(s):  
Genomic Dna ◽  
Southern Hybridization ◽  
Regulatory Gene ◽  
Kinetic Properties ◽  
Restriction Fragments ◽  
Regulatory Systems ◽  
Laribacter Hongkongensis ◽  
Consensus Motifs ◽  
Class C

ABSTRACT Laribacter hongkongensis, a newly discovered bacterium recently shown to be associated with community-acquired gastroenteritis, is generally resistant to most β-lactams except the carbapenems. We describe the cloning and characterization of a novel chromosomal class C β-lactamase and its regulatory gene in L. hongkongensis. Two genes, ampC and ampR, were cloned by inserting restriction fragments of genomic DNA from L. hongkongensis strain HLHK5 into pBK-CMV to give the recombinant plasmid pBK-LHK-5. The ampR and ampC genes and their promoters were divergently oriented, with the ampR gene immediately upstream of the ampC gene and an intercistronic Lys-R motif, typical of inducible ampC-ampR regulatory systems. The deduced amino acid sequence of the cloned AmpC β-lactamase (pI 8.1) contained consensus motifs characteristic of class C β-lactamases but had identities no greater than 46% to known class C β-lactamases. The kinetic properties of this AmpC were also compatible with those of a class C β-lactamase. PCR of 20 clinical isolates of L. hongkongensis, including HLHK5, showed the presence of both ampC and ampR genes in all isolates. Southern hybridization suggested that the ampC gene of HLHK5 was chromosomally encoded. Subcloning experiments showed that the expression of the ampC gene of HLHK5 was regulated by its ampR gene, which acts as a repressor. The β-lactamase characterized from strain HLHK5 was named LHK-5 (gene, bla LHK-5) and represents the first example of AmpC β-lactamase in the β subdivision of proteobacteria.

scholarly journals Characterization of the Overlapping Promoters of nolB and nolW, Two Soybean Cultivar Specificity Genes from Rhizobium fredii Strain USDA257

1997 ◽  
Vol 10 (1) ◽  
pp. 138-141 ◽  
Author(s):  
Jun Gu ◽  
Pedro A. Balatti ◽  
Hari B. Krishnan ◽  
Steven G. Pueppke
Keyword(s):  
Regulatory Gene ◽  
Initiation Site ◽  
Dual Control ◽  
Start Site ◽  
Rhizobium Fredii ◽  
Normal Expression ◽  
Transcript Initiation ◽  
Cultivar Specificity ◽  
Transcript Start Site

The transcripts of nolW and nolB, two divergently oriented cultivar specificity genes of Rhizobium fredii strain USDA257, are known to be initiated 14 bp apart from promoters that face one another. We show here that expression of nolB is dependent both on induction with flavonoid signals and on the regulatory gene, nodD1. Expression of nolW is constitutive and independent of flavonoids and nodD1. Normal expression of nolB is retained with a promoter that extends only 61 bp upstream of the transcript start site, but it is lost if an additional 24 bp are removed. Substantial expression of nolW is retained with a promoter that contains only 34 bp of DNA upstream from the transcript initiation site. The dual control region for the two genes is thus only about 109 bp in length.

Genetic characterization of Rhizobium sp. strain TAL1145 that nodulates tree legumes

1994 ◽  
Vol 40 (3) ◽  
pp. 208-215 ◽  
Author(s):  
M. L. C. George ◽  
J. P. W. Young ◽  
D. Borthakur
Keyword(s):  
Rhizobium Leguminosarum ◽  
Genetic Characterization ◽  
Rhizobium Meliloti ◽  
Wild Type ◽  
Tree Legumes ◽  
Wide Range ◽  
The Common ◽  
Rrna Sequences ◽  
Rhizobium Sp

Rhizobium sp. strain TALI 145 nodulates Leucaena ieucocephaia and Phaseolus vulgaris, in addition to a wide range of tropical tree legumes. Six overlapping clones that complemented nodulation defects in leucaena and bean rhizobia were isolated and a 40-kb map of the symbiosis region was constructed. The common nod and nifA genes were situated approximately 17 kb apart, with the nodlJ genes in between. These clones enabled a derivative of TAL1145 carrying a partially deleted pSym to form ineffective nodules on both leucaena and bean, and a similar derivative of Rhizobium etli TAL182 to form ineffective nodules on bean. When two representative clones, pUHR9 and pUHR114, were each transferred to wild-type rhizobial strains, they allowed ineffective nodulation by Rhizobium meliloti on both leucaena and bean and by Rhizobium leguminosarum bv. viciae on bean. Transconjugants of R. leguminosarum bv. trifolii formed effective nodules on leucaena and ineffective nodules on bean. Tn5 mutagenesis of the symbiosis region resulted in a variety of nodulation and fixation phenotypes on leucaena and bean. On the basis of 16S rRNA sequences, TAL1145 was found to be distinct from both R. tropici and NGR234, the two groups of leucaena symbionts that were previously described.Key words: Rhizobium, Leucaena leucocephala, nodulation, nitrogen fixation.

scholarly journals Identification and Characterization of a Bacteroid-Specific Dehydrogenase Complex in Rhizobium leguminosarum PRE

1988 ◽  
Vol 54 (12) ◽  
pp. 3008-3013 ◽  
Author(s):  
René M. Klein Lankhorst ◽  
Panagiotis Katinakis ◽  
Albert van Kammen ◽  
Rommert C. van den Bos
Keyword(s):  
Rhizobium Leguminosarum ◽  
Identification And Characterization ◽  
Dehydrogenase Complex

scholarly journals Chemical characterization of effective and ineffective strains of Rhizobium leguminosarum bv. viciae.

1999 ◽  
Vol 46 (4) ◽  
pp. 1001-1009
Author(s):  
S F Izmailov ◽  
G Y Zhiznevskaya ◽  
L V Kosenko ◽  
G N Troitskaya ◽  
N N Kudryavtseva ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Rhizobium Leguminosarum ◽  
Unsaturated Fatty Acids ◽  
Effective Strain ◽  
Chemical Characterization ◽  
Unsaturation Index ◽  
Fa Composition ◽  
Sds Page ◽  
Lower Molecular Mass

Chemical composition of lipopolysaccharide (LPS) isolated from an effective (97) and ineffective (87) strains of R. l. viciae has been determined. LPS preparations from the two strains contained: glucose, galactose, mannose, fucose, arabinose, heptose, glucosamine, galactosamine, quinovosamine, and 3-N-methyl-3,6-dideoxyhexose, as well as glucuronic, galacturonic and 3-deoxyoctulosonic acid. The following fatty acids were identified: 3-OH 14:0, 3-OH 15:0, 3-OH 16:0, 3-OH 18:0 and 27-OH 28:0. The ratio of 3-OH 14:0 to other major fatty acids in LPS 87 was higher that in LPS 97. SDS/PAGE profiles of LPS indicated that, in lipopolysaccharides, relative content of S form LPS I to that of lower molecular mass (LPS II) was much higher in the effective strain 97 than in 87. All types of polysaccharides exo-, capsular-, lipo, (EPS, CPS, LPS, respectively) examined possessed the ability to bind faba bean lectin. The degree of affinity of the host lectin to LPS 87 was half that to LPS 97. Fatty acids (FA) composition from bacteroids and peribacteroid membrane (PBM) was determined. Palmitic, stearic and hexadecenoic acids were common components found in both strains. There was a high content of unsaturated fatty acids in bacteroids as well as in PBM lipids. The unsaturation index in the PBM formed by strain 87 was lower than in the case of strain 97. Higher ratio of 16:0 to 18:1 fatty acids was characteristic for PMB of the ineffective strain.

scholarly journals Regulation and characterization of mutants of fixABCX in Rhizobium leguminosarum.

2021 ◽  
Author(s):  
Isabel Webb ◽  
Jiabao Xu ◽  
Carmen Sanchez-Cañizares ◽  
Ramakrishnan Karunakaran ◽  
Vinoy Ramachandran ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Rhizobium Leguminosarum ◽  
Redox Balance ◽  
Rna Seq ◽  
Wild Type ◽  
Transcription Start Sites ◽  
Sym Plasmid ◽  
Microaerobic Conditions ◽  
Type Infection

Symbiosis between Rhizobium leguminosarum and Pisum sativum requires tight control of redox balance in order to maintain respiration under the microaerobic conditions required for nitrogenase, whilst still producing the eight electrons and sixteen molecules of ATP needed for nitrogen fixation. FixABCX, electron transfer flavoproteins essential for nitrogen fixation, are encoded on the Sym plasmid (pRL10), immediately upstream of nifA, which encodes the general transcriptional regulator of nitrogen fixation. There is a symbiotically-regulated NifA-dependent promoter upstream of fixA (PnifA1), as well as an additional basal constitutive promoter driving background expression of nifA (PnifA2). These were confirmed by 5’-end mapping of transcription start sites using differential (d) RNA-seq. Complementation of polar fixAB and fixX mutants (Fix- strains) confirmed expression of nifA from PnifA1 in symbiosis. Electron microscopy combined with single-cell Raman microspectroscopy characterization of fixAB mutants revealed previously unknown heterogeneity in bacteroid morphology within a single nodule. Two morphotypes of mutant fixAB bacteroids were observed. One was larger than wild-type bacteroids and contained high levels of polyhydroxy-3-butyrate, a complex energy/reductant storage product. A second bacteroid phenotype was morphologically and compositionally different and resembled wild-type infection thread cells. From these two characteristic fixAB mutant bacteroid morphotypes, inferences can be drawn on the metabolism of wild-type nitrogen-fixing bacteroids.

Primary Pulmonary Pleomorphic Adenoma

2003 ◽  
Vol 127 (5) ◽  
pp. 621-622
Author(s):  
Keng Leong Ang ◽  
Venkata Ramana Dhannapuneni ◽  
William Ellis Morgan ◽  
Irshad Nabi Soomro
Keyword(s):  
Pleomorphic Adenoma ◽  
Regulatory Gene ◽  
Proliferation Index ◽  
Complete Excision ◽  
Long Term Follow Up ◽  
Uncommon Condition ◽  
P16 Ink4a

Abstract Primary pleomorphic adenoma of the lung is an uncommon condition. We present a case of primary pulmonary pleomorphic adenoma and its immunohistologic features. The presence of immunoreactivity to both anticytokeratin and antivimentin antibodies for its epithelial components is suggestive of a primary pulmonary lesion. Its high proliferation index and its immunoreactivity to tumor regulatory gene p16(INK4A) are features that, to our knowledge, have not been reported previously. They may have a role in the frequent recurrence of these tumors many years after their apparently complete excision. Detailed genetic investigation and long-term follow-up of this rare tumor will aid in the characterization of its biologic profile.

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