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Query: UMLS:C0519030 (Klebsiella)
 21,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

From a gene bank of Klebsiella pneumoniae M5a1, a 1.7 kb gene fragment was isolated which was able to restore the Ntr+ phenotype and ammonium (methylammonium) transport, but not glutamate synthase in an Escherichia coli glt mutant (glutamate synthase deficiency). The fragment strongly hybridized with the gltF regulatory gene from E. coli. After subcloning the fragment into an overexpression vector, a protein with a molecular weight of 27,000 dalton was identified as the gene product. The results indicate that the fragment cloned contains the gltF gene from K.pneumoniae.
Mol Gen Genet 1991 Oct
PMID:The gltF gene of Klebsiella pneumoniae: cloning and initial characterization. 194 33

Clinical Klebsiella pneumoniae isolates as well as Escherichia coli transformants producing the beta-lactamases SHV-2 or SHV-2a demonstrate MIC values for cefotaxime of 4 mg l-1 or 64 to greater than 128 mg l-1, respectively. The beta-lactamases differ by one possibly insignificant amino acid exchange at position number 10 of the mature protein; their kinetic parameters are rather similar. The 5' untranslated regions of both corresponding genes show no homology starting 74 nucleotides upstream to the start codon. Hybridization of intragenically annealing oligonucleotides to dot-blotted serial dilutions of total cellular RNA from E. coli transformants harbouring these genes cloned into the same vector plasmid gave a positive signal down to 1.2 micrograms (SHV-2) and 0.32 to 0.16 micrograms (SHV-2a), indicating a four to eight times higher amount of specific transcript in the case of SHV-2a. By primer extension analysis and S1 nuclease digestion the starting point to transcription was located 100 nucleotides (SHV-2) and 50 nucleotides (SHV-2a) in front of the start codon. No other transcripts of different length could be detected after prolonged exposure. Northern blot analysis demonstrated the length of the beta-lactamase mRNA to be about 1.6 kb in both cases, thus comprising a potential open reading frame downstream of the two enzymes' genes. Selective PCR amplification of both promoter regions and of the structural gene of SHV-2 and subsequent combined cloning of each of the promoters and the SHV-2 gene into pBGS19 using a BamHI restriction site introduced by three point mutations into the cloned sequences was employed to transforms E. coli DH5 alpha.(ABSTRACT TRUNCATED AT 250 WORDS)
J Gen Microbiol 1991 Jul
PMID:Different promoters of SHV-2 and SHV-2a beta-lactamase lead to diverse levels of cefotaxime resistance in their bacterial producers. 195 59

Using glnT DNA of Rhizobium meliloti as a hybridization probe we identified a R. leguminosarum biovar phaseoli (R. l. phaseoli) locus (glnT) expressing a glutamine synthetase activity in Klebsiella pneumoniae. A 2.2 kb DNA fragment from R. l. phaseoli was cloned to give plasmid pMW5a, which shows interspecific complementation of a K. pneumoniae glnA mutant. The cloned sequence did not show cross-hybridization to glnA or glnII, the genes coding for two glutamine synthetase isozymes of Rhizobium spp. While in previous reports on glnT of R. meliloti and Agrobacterium tumefaciens no glutamine synthetase activity was detected, we do find activity with the glnT locus of R. l. phaseoli. The glutamine synthetase (GSIII) activity expressed in a K. pneumoniae glnA strain from pMW5a shows a ratio of biosynthetic to transferase activity 10(3)-fold higher than that observed for GSI or GSII. GSIII is similar in molecular weight and heat stability to GSI.
Mol Gen Genet 1990 Sep
PMID:A previously unrecognized glutamine synthetase expressed in Klebsiella pneumoniae from the glnT locus of Rhizobium leguminosarum. 198 Jan 42

In Klebsiella pneumoniae, the ability to synthesize large amounts of capsular polysaccharide is an important correlate of virulence. We report the cloning of rcsA from K. pneumoniae serotype O1:K20 and demonstrate that rcsA is involved in the expression of the K antigen capsule. We have determined the nucleotide sequence for the rcsA gene from K. pneumoniae K20 and shown it to be identical to the sequence reported previously for rcsA from strain K21 (Allen et al., J. Gen. Microbiol. 133:331-340, 1987). Southern hybridization results indicate that this gene is widely distributed among different Klebsiella K serotypes. When cloned into Escherichia coli K-12, the K. pneumoniae rcsA gene caused a mucoid phenotype, resulting from the activation of colanic acid synthesis. Activation of colanic acid synthesis was not dependent on growth at low temperatures (less than or equal to 30 degrees C). The K. pneumoniae rcsA gene complemented E. coli K-12 rcsA mutations but could not complement defects in rcsB, suggesting that RcsA may be functionally homologous in these bacteria. The cloned rcsA gene also complemented a defect in nonmucoid strain K20 derivatives that normally produced only trace amounts of K20 antigen and were unable to assemble a wild-type capsular structure. Mutants that were K20-deficient were not complemented. The K antigen capsule of K. pneumoniae therefore joins a growing list of polysaccharide-synthetic systems in which "RcsA-like" proteins are involved.
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PMID:The rcsA gene of Klebsiella pneumoniae O1:K20 is involved in expression of the serotype-specific K (capsular) antigen. 198 69

Between 1986 and 1988, multiresistant Klebsiella pneumoniae strains exhibiting high-level cefotaxime resistance were isolated from patient specimens particularly of the intensive care units of the Aachen Technical University Hospital. The resistance gene responsible was shown to be encoded on a conjugative 66 kb plasmid designated pZMP1. The MIC values for cefotaxime of the original isolates and the transconjugants were greater than 128 mg l-1 and 64 mg l-1, respectively. Isoelectric focusing of protein preparations from the transconjugants showed a beta-lactamase with a pI of 7.6. A 3.6 kb BamHI fragment containing the beta-lactamase gene was cloned into pLG339 resulting in the recombinant plasmid pZMP1-1. A restriction map of the cloned insert was established and PstI subfragments of the insert were further subcloned into pBGS18. The nucleotide sequence of the complete 3.6 kb fragment was determined. Within 3663 bp an open reading frame of 858 kb was found to show 99% homology to the SHV-2 and -3 nucleotide sequences. The deduced amino acid sequence differed in one and two positions, respectively, from these established SHV enzymes. The 3' noncoding sequence exhibited nearly perfect homology to that of SHV-2, but the 5' upstream sequence showed homology of less than 50% to the corresponding SHV-2 sequence, indicating an altered promoter region of the variant SHV-enzyme. Kinetic analysis of the beta-lactamase revealed a 50-100% elevated hydrolytic effectivity on cefotaxime in comparison to other SHV enzymes. Cefoxitin, ceftazidime, aztreonam and imipenem were not hydrolysed by the enzyme. The variant enzyme was inhibited by commonly available beta-lactamase inhibitors. Clavulanic acid had the highest affinity for the enzyme and the greatest effectivity in blocking its action. Based on the genetic and kinetic data we propose to classify the enzyme as a new variant beta-lactamase of the SHV-type and name it SHV-2a.
J Gen Microbiol 1991 Mar
PMID:Molecular characterization of a new plasmid-encoded SHV-type beta-lactamase (SHV-2 variant) conferring high-level cefotaxime resistance upon Klebsiella pneumoniae. 203 79

Southern hybridization experiments strongly indicate that the regulatory region of the Azospirillum lipoferum nifH gene is located on a cloned 1.1 kb BamHI-XhoI restriction fragment. By cloning this fragment into a promoter-probe plasmid in Escherichia coli, a promoter was identified oriented towards the nifH gene. Using a set of several bacterial strains and plasmids, both NifA and the alternative sigma factor, sigma 54, from Klebsiella pneumoniae were shown to be required for the induction of the assumed nifH promoter in this particular heterologous system. However, NtrC from K. pneumoniae did not stimulate this promoter. No other promoter activity was detected in the direction opposite to the identified promoter, indicating that the transcription of the adjacent nifJ gene cannot be initiated from the 1.1 kb BamHI-XhoI fragment. Thus, the genes nifH and nifJ in A. lipoferum cannot be oriented divergently, in contrast to the situation in several other nitrogen-fixing bacteria.
Mol Gen Genet 1991 May
PMID:Identification of a promoter dependent on NifA and sigma 54 upstream of nifH in Azospirillum lipoferum. 204 61

DNA sequence analysis, Tnpho and Tntac-1, mutagenesis, deletion analysis, expression under bacteriophage T7 gene 10 promoter control, subcellular fractionation and complementation tests were used to study the function of DNA located in the centre of the pulC-O operon from Klebsiella oxytoca strain UNF5023. The characterized region of the operon includes five genes (pulG, pulH, pulI, pulJ and pulK) coding for apparently integral inner membrane proteins which are required for pullulanase secretion. The results presented here and previously show that the pulC-O operon contains at least 11 pullulanase secretion genes.
Mol Gen Genet 1990 Jul
PMID:Five additional genes in the pulC-O operon of the gram-negative bacterium Klebsiella oxytoca UNF5023 which are required for pullulanase secretion. 212 43

A generally applicable method is described for reintroduction of mutant plasmid-borne alleles to the chromosome of Klebsiella pneumoniae using bacteriophage lambda. We used this method to make stable chromosomal transposon insertions in genes for biosynthesis of pyrroloquinoline quinone in K. pneumoniae.
Mol Gen Genet 1990 Feb
PMID:A general method for the transfer of plasmid-borne mutant alleles to the chromosome of Klebsiella pneumoniae using bacteriophage lambda: transfer of pqq genes. 216 55

Klebsiella pneumoniae synthesized only b-type and d-type cytochromes under the wide range of growth conditions tested, and reaction with CO revealed two potential oxidases. The o-type oxidase was produced only in the presence of O2 and appeared to be repressed by glucose. The d-type oxidase was, by contrast, produced only in the absence of measurable O2 (less than 1 microM), and was the only oxidase expressed in nitrogen-fixing conditions. It was extracted from the membrane, purified and shown to be similar to that from E. coli in being a heterodimer (subunits of Mr 52,000 and 35,000), in containing two distinguishable b haems and haem d (one or two molecules per molecule of oxidase), and in being able to react with O2 to give a stable oxygenated intermediate. The purified d-type cytochrome oxidase had a very high affinity for O2 (Km 20 nM; measured by the spectral properties of leghaemoglobin). It is proposed that this provides a role for this oxidase in lowering the O2 concentration to allow nitrogenase synthesis and function, and to provide a terminal oxidase to permit electron-transport-coupled ATP synthesis which supports the increase in efficiency of nitrogen fixation observed under microaerobic conditions.
J Gen Microbiol 1990 Jan
PMID:The purification, characterization and role of the d-type cytochrome oxidase of Klebsiella pneumoniae during nitrogen fixation. 219 Oct 76

The spectrum of specific activities and the electrophoretic mobilities of esterases produced by 550 strains of Enterobacteriaceae belonging to 36 species and subclassified into six groups (group 1, Escherichia coli, Shigella and Escherichia hermanii; group 2, genus Salmonella and genus Citrobacter; group 3, genus Klebsiella and genus Enterobacter; group 4, genus Serratia and Serratia fonticola; group 5, genus Proteus, genus Providencia and genus Morganella; and group 6, genus Yersinia) were analysed by acrylamide/agarose gel electrophoresis using standardized methods for staining and mobility comparisons. Nineteen types of esterase were defined by their respective esterase specific-activity profile (ESAP). A multiple correspondence analysis (MCA) of the ESAP data enabled 82% of the strains in the 36 species to be correctly classified. In each group, the species were clearly delineated after MCA on both ESAP and electrophoretic mobility data. In addition, the smallest number of characters providing species identification of Yersinia strains by esterase polymorphism was identified by means of a binary segmentation tree technique.
J Gen Microbiol 1990 Mar
PMID:Characterization of enterobacteria by esterase specific-activity profiles. 220 80


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