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Query: UNIPROT:P06889 (Mol)
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Rhizobium japonicum nifH'- and nifD'-'lacZ fusions were constructed using the translational fusion vector pMC1403. beta-Galactosidase activities from these fusion plasmids were measured in wild-type, ntrA- and delta(ntrBC) Escherichia coli strains carrying plasmids which overproduced the Klebsiella pneumoniae nifA or ntrC gene products. In contrast to results reported in R. meliloti (ref. in the text) neither nifH nor nifD promoters were activated by the ntrC product. In the presence of nifA gene product, however, beta-galactosidase activity from both nifH and nifD fusion plasmids increased substantially. NifA-mediated activation of these Rhizobium promoters was temperature sensitive and was dependent on the host ntrA product. In order to determine the point at which the fusion transcripts were initiated, RNA was extracted from the wild-type E. coli strain carrying each of the R. japonicum fusion plasmids plus the nifA overproducing plasmid. This RNA was used to perform S1 mapping experiments. NifA-mediated transcription from both R. japonicum promoters, began at the same point as previously determined in soybean root-nodule bacteroids (ref. in the text). The results obtained suggest that there may be differences in the mode of regulation between members of the fast- and slow-growing rhizobia. Also, the results of the S1 mapping experiments indicate that activation of the R. japonicum nitrogenase structural genes may be similar to the activation of nif genes in K. pneumoniae thus raising the possibility that R. japonicum may contain nifA and ntrA-like genes.
Mol Gen Genet 1985
PMID:Expression of Rhizobium japonicum nifH and nifDK operons can be activated by the Klebsiella pneumonia nifA protein but not by the product of ntrC. 286 69

Evolutionary events that generated the three regulatory isozymes of 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase present in contemporary strains of Escherichia coli have been proposed recently [Ahmad et al. (1986) J Bacteriol 165:146-154]. The phylogenetic subdivision of gram-negative prokaryotes studied (Superfamily B) includes enteric bacteria, an Oceanospirillum cluster, pseudomonad Group I (e.g., Pseudomonas aeruginosa), pseudomonad Group V (e.g., Xanthomonas), and the Acinetobacter grouping. DAHP synthase-phe, a regulatory isozyme subject to allosteric control by L-phenylalanine, was the last member of the isozyme family to evolve. Thus, DAHP synthase-phe is absent throughout Superfamily B except within the enteric lineage. Bacteria that make up the enteric lineage (Escherichia, Klebsiella, Erwinia, Serratia, Proteus, Aeromonas, and Alteromonas) were examined in detail; DAHP synthase-phe was present in each of these organisms. Therefore, the isozyme originated between the separation of the enteric and Oceanospirillum lineages, prior to the divergence of Alteromonas putrefaciens (44% homology with E. coli by DNA:rRNA hybridization) from the rest of the enteric lineage. DAHP synthase-tyr and DAHP synthase-trp were uniformly present within the enteric lineage, although it was often necessary to derepress DAHP synthase-trp by physiological manipulation in order to demonstrate its presence.
J Mol Evol 1987
PMID:The recent evolutionary origin of the phenylalanine-sensitive isozyme of 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase in the enteric lineage of bacteria. 288 1

The glnB gene of Klebsiella pneumoniae, which encodes the nitrogen regulation protein PII, has been cloned and sequenced. The gene encodes a 12429 dalton polypeptide and is highly homologous to the Escherichia coli glnB gene. The sequences of a glnB mutation which causes glutamine auxotrophy and of a Tn5 induced Gln+ suppressor of this mutation were also determined. The glutamine auxotrophy was deduced to be the result of a modification of the uridylylation site of PII, and the suppression was shown to be caused by Tn5 insertion in glnB. The 3' end of an open reading frame of unknown function was identified upstream of glnB and may be part of an operon containing glnB. Potential homologues of glnB encoding polypeptides extremely similar in sequence to PII were identified upstream of published sequences of the glutamine synthetase structural gene (glnA) in Rhizobium leguminosarum, Bradyrhizobium japonicum and Azospirillum brasilense.
Mol Gen Genet 1988 Dec
PMID:Identification of the Klebsiella pneumoniae glnB gene: nucleotide sequence of wild-type and mutant alleles. 290 69

The NADP-dependent glutamate dehydrogenase gene of Klebsiella aerogenes was cloned in E. coli in the expression plasmid pRK9. The cloned gene shows a high level of expression in E. coli in the hybrid plasmid pKG3 and such expression is independent of the vector promoter, as shown by experiments in which the promoter was deleted. Active hybrid GDH hexamers were shown in cell-free extracts of an E. coli strain carrying cloned gdhA genes of both E. coli and K. aerogenes. The nucleotide sequence of the N-terminal coding region of the K. aerogenes gdhA gene was determined and found to be strongly homologous with that of E. coli.
Mol Gen Genet 1985
PMID:The Klebsiella aerogenes glutamate dehydrogenase (gdhA) gene: cloning, high-level expression and hybrid enzyme formation in Escherichia coli. 298 45

Initiation of DNA replication from the Escherichia coli origin, oriC, is dependent on an RNA polymerase-mediated transcription event. The function of this RNA synthetic event in initiation, however, remains obscure. Since control of the synthesis of this RNA could serve a key role in the overall initiation process, transcription regulatory sites within and near oriC were identified using the galK fusion vector system. Our results confirm the existence of a transcription termination signal within oriC, first identified by Hansen et al. (1981), for the 16 kd transcript that is transcribed counterclockwise towards oriC. Termination is shown to be 92% efficient. A similar approach led to the detection of transcription termination within the chromosomal replication origin of Klebsiella pneumoniae. Approximately 50% of the E. coli 16 kd transcripts appear to terminate before reaching oriC between the XhoI (+416 bp) and the HindIII (+243 bp) sites. The predominant 3' ends of RNA that enter oriC, as determined by SI nuclease mapping, were located at positions +20 +/- 2, +23 +/- 2, +37, +39, +52, +66, +92, and +107. These termination sites, which map cl to RNA . DNA junctions identified by Kohara et al. (1985), appear as triplets and quadruplets. The E. coli oriC Pori-L promoter described in in vitro transcription studies by Lother and Messer (1981) was not detected in this study in either wildtype cells or isogenic dnaA mutants at the nonpermissive temperature. A new promoter activity, Pori-R1, was identified within the E. coli origin in the clockwise direction.
Mol Gen Genet 1986 Apr
PMID:Transcription termination within the Escherichia coli origin of DNA replication, oriC. 301 76

The complete nucleotide sequence of the regulatory operon nifLA of a nitrogen fixer Klebsiella oxytoca NG13 was determined, and the transcriptional start point was assigned by S1 mapping. The nifL protein (a repressor) was coded by an open reading frame of 1,485 bases, corresponding to a protein of 495 amino acids with a calculated molecular weight of 55,242. The open reading frame (1,572 bases) of the nifA protein (an activator), corresponding to a molecular weight of 58,649, was confirmed by in vitro transcription-translation experiments, using the wild type and artificially deleted nifA genes. The initiation codon (ATG) of nifA overlapped the termination codon(TGA) of nifL, sharing the two bases T and G. A conserved DNA contact point [Gln-(X)3-Ala-(X)3-Gly-(X)5-Val] common in many DNA binding proteins was found in the C-terminal region of the nifA sequence. The promoter sequences of nifLA, nifB and nifF in K. oxytoca coincided exactly with those of K. pneumoniae in the consensus regions at -12 and -26, although the overall homology in the promoter regions was 96%. Changes of four amino acids were found between the nifA coding sequences of K. oxytoca and K. pneumoniae.
Mol Gen Genet 1986 Nov
PMID:Nucleotide sequence of the nifLA operon of Klebsiella oxytoca NG13 and characterization of the gene products. 302 3

The Rhizobium leguminosarum biovar phaseoli symbiotic plasmid pRP2JI carries a gene, melA, specifying the enzyme tyrosinase, which is responsible for the production of the pigment melanin in these bacteria. Transcription of melA is activated by the nifA gene of Rhizobium and, when the cloned melA gene is transferred to Escherichia coli, melA is expressed if the recipients contain nifA gene of Klebsiella pneumoniae. This nifA-dependent activation was temperature sensitive and required the ntrA gene. The cloned nifA gene of K. pneumoniae, when transferred to a nifA mutant of Rhizobium phaseoli biovar phaseoli, corrected the Mel- but not the Fix- phenotype. nifA of R. leguminosarum biovar phaseoli activated melA at higher levels in cells grown in low concentrations of oxygen. Also, nifA of R. leguminosarum biovar phaseoli activated nifH of K. pneumoniae in Escherichia coli cells grown in low-oxygen concentrations.
Mol Microbiol 1988 May
PMID:Transcription of a Rhizobium leguminosarum biovar phaseoli gene needed for melanin synthesis is activated by nifA of Rhizobium and Klebsiella pneumoniae. 304 Dec 40

p-Aminobenzoate synthase (PS) and anthranilate synthase (AS) are structurally related enzymes that catalyze similar reactions and produce similar products, para- and ortho-aminobenzoate (anthranilate). Each enzyme is composed of two non-identical subunits: a glutamine amidotransferase subunit (CoII) and a subunit that produces an aminobenzoate product (CoI). Nucleotide sequence comparisons of the Escherichia coli genes encoding each of the subunits suggest a common evolutionary origin for both subunits of the enzyme complexes. We report here the nucleotide sequences of the pabB genes that encode Salmonella typhimurium and Klebsiella aerogenes PS CoI. Comparative sequence information suggests that pabB is encoded as the first gene in a multicistronic transcript. Comparison of deduced amino acid sequences of PS CoI genes indicates that the majority of sequence identity occurs in the C-terminal two-thirds of the proteins. Similarly, identities in an alignment of eight PS and AS CoI sequences are confined to the C-terminal segments of the proteins. Secondary-structure predictions for the nine sequences suggest considerable similarity in the folding of the C-terminal portions of the aminobenzoate synthases.
Mol Biol Evol 1988 Sep
PMID:Evolution of aminobenzoate synthases: nucleotide sequences of Salmonella typhimurium and Klebsiella aerogenes pabB. 305 24

The complete nucleotide sequence (24,206 base-pairs) of the Klebsiella pneumoniae gene region for nitrogen fixation (nif) is presented. Coding regions corresponding to the 19 known nif genes (including nifW and nifZ) could be identified. An additional open reading frame of 216 base-pairs, called nifT, was detected between nifK and nifY. Search for transcriptional signal structures revealed some unusual features: (1) several possible NifA-binding motifs are present in the intergenic regions between nifJ and nifH as well as between nifX and nifU; (2) a perfect NifA-binding motif, preceding the nifENX promoter, is located within an inverted repeat structure; (3) structures resembling the consensus nif promoter are found within the coding regions of nifW and nifZ and, together with a NifA-binding motif, in nifN. Typical rho-independent termination structures were detected only downstream from the nifHDKTY and the nifBQ operons. Analysis of the deduced amino acid sequences revealed the presence of two Cys-X2-Cys-X2-Cys-X3-Cys-Pro clusters in the pyruvate-flavodoxin oxidoreductase NifJ. This arrangement of cysteine residues is normally present only in ferredoxins. A high degree of homology between the two gene products (NifE and NifN) involved in iron-molybdenum cofactor biosynthesis and the two nitrogenase component I structural proteins (NifD and NifK) was found. All four proteins are characterized by the conserved motif His-Gly-X2-Gly-Cys, which may play a role in binding the iron-molybdenum cofactor.
J Mol Biol 1988 Oct 05
PMID:Nucleotide sequence of a 24,206-base-pair DNA fragment carrying the entire nitrogen fixation gene cluster of Klebsiella pneumoniae. 306 78

Plasmids containing hybrid genes, in which different Klebsiella pneumoniae nif (nitrogen-fixation) promoters were fused with the structural part of the Escherichia coli lac operon, were introduced into a double auxotrophic derivative of Agrobacterium tumefaciens C58. A study of their expression in the new host was made simple by the inherent inability of A. tumefaciens C58 to produce beta-galactosidase unless provided with the wild-type lac operon of E. coli. As shown by quantitative measurements of the enzyme, all K. pneumoniae promoters were expressed well in A. tumefaciens C58, even under conditions known to repress them. It also has been shown that the activity of K. pneumoniae nif A is essential for the expression of nifHDK even when introduced into A. tumefaciens. After entering the new host the plasmids, the nif genes and the fusion alleles contained in them, remained stable. Possible mechanisms responsible for the constitutive behaviour of nif promoters in A. tumefaciens are discussed.
Mol Gen Genet 1987 Mar
PMID:Klebsiella pneumoniae nif-lac fusions are expressed in Agrobacterium tumefaciens C58. 310 28


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