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

A number of glutamine auxotrophs of Salmonella typhimurium were isolated and characterized genetically. Three of the mutations appear to be closely linked and are complemented by episomes carrying the glnA region of Escherichia coli. The lesions in these strains are approximately 20% linked by P1 transduction with a mutation in the rha gene, but are unlinked to ilv. Another mutation causing glutamine auxotrophy in strain JB674 is genetically distinct from the others. Strain JB674 grown in glucose medium containing ammonia as the nitrogen source has reduced levels of glutamine synthetase that is more adenylylated than in the parent strain, suggesting that the enzyme can not be deadenylylated normally. The lesion causing glutamine auxotrophy in JB674 lies in the region corresponding to the glnB and glnE genes affecting glutamine synthetase modification in Klebsiella areogenes. Four Gln+ revertants of JB674 have glutamine synthetase activities 4 to 6 fold higher than normal. One mutation causing this increased enzyme synthesis has been shown by three-factor crosses with the glnA mutations to lie near or within the glnA gene.
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PMID:Characterization of Salmonella typhimurium mutants with altered glutamine synthetase activity. 1 44

Nitrogen fixation (Nif)-derepressed mutants of Klebsiella pneumoniae consumed, under optimum conditions, 7.5 to 8.5 mol glucose per mol N2 fixed. The nitrogenase system of these mutants catalysed the production of about 1.3 mol H2 per mol N2 reduced. Almost one-third of the energy as ATP and reductant used by nitrogenase in vivo may be lost in H2 production, since an ATP/2e ratio of approximately 4 was obtained. Nitrogenase-catalysed H2 production was not substantially suppressed by increasing the partial pressure of N2 from 0.2 atm (20 kPa) to 1 atm (101 kPa). In the absence of N2, H2 production catalysed by nitrogenase increased about threefold. It is concluded that nitrogenase-catalysed H2 production is of major importance in the overall efficiency of biological N2 fixation in vivo.
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PMID:Energetics of biological nitrogen fixation: determination of the ratio of formation of H2 to NH4+ catalysed by nitrogenase of Klebsiella pneumoniae in vivo. 2 79

Klebsiella aerogenes formed two N2-acetylornithine 5-aminotransferases (ACOAT) which were separable by diethylaminoethyl-cellulose chromatography. One ACOAT was repressed when the cells grew on arginine-containing medium, indicating its function in arginine biosynthesis. The second ACOAT was induced when arginine or ornithine was present in the medium as the sole source of carbon or nitrogen, suggesting its function in the catabolism of these compounds. The induced enzyme was purified almost to homogeneity. Its molecular weight is 59,000; it is a pyridoxal 5-phosphate-dependent enzyme and exhibits activity with N2-acetylornithine (Km = 1.1 mM) as well as with ornithine (Km = 5.4 mM). ACOAT did not catalyze the transamination of putrescine or 4-aminobutyrate. The best amino acceptor was 2-ketoglutarate (Km = 0.7 mM). ACOAT formation was subject to catabolite repression exerted by glucose when ammonia was present in excess. When the cells were deprived of nitrogen, ACOAT escaped from catabolite repression. This activation was mediated by glutamine synthetase as shown by the fact that mutants affected in the regulation or synthesis of glutamine synthetase were also affected in the control of ACOAT formation.
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PMID:Catabolic N2-acetylornithine 5-aminotransferase of Klebsiella aerogenes: control of synthesis by induction, catabolite repression, and activation by glutamine synthetase. 2 39

Fine structure mapping of nif mutations of Klebsiella pneumoniae was accomplished by means of Pl-transductional crosses and the plasmid R144 drd mediated conjugations. The physical distance between nif mutations based on the percentage of co-transduction with hisD of the nif mutations was estimated. The maximal distance between two mutations was calculated about 3 Kb, and the average distance between different nif mutations was about 1 to 2 Kb. So no "silent region" was shown within the nif cluster nearby the histidine operon. Several hisD-unlinked nif mutants were isolated and investigated genetically and biochemically. They all differed from the glutamineless mutants, one of these mutants was tentatively assigned as a sort of N-assimilation mutant with little activity of glutamate synthetase. It differed from the known N-assimilation mutants in its absence of nitrogenase activity. Since the wild type hisD-linked nif genes carried by the plasmid RP4 failed to complement the defects of the hisD-unlinked nif genes in the recipient cells but they were effective to facilitate E. coli in acquiring the ability to fix nitrogen, which indicates that the hisD-unlinked nif genes necessary for the functioning of the hisD-linked nif genes are present in E. coli.
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PMID:Genetic analysis of the nitrogen fixation system in Klebsiella pneumoniae. 2 72

We used polyacrylamide gel electrophoresis to examine the regulation and adenylylation states of glutamine synthetases (GSs) from Escherichia coli (GS(E)) and Klebsiella aerogenes (GS(K)). In gels containing sodium dodecyl sulfate (SDS), we found that GS(K) had a mobility which differed significantly from that of GS(E). In addition, for both GS(K) and GS(E), adenylylated subunits (GS(K)-adenosine 5'-monophosphate [AMP] and GS(E)-AMP) had lesser mobilities in SDS gels than did the corresponding non-adenylylated subunits. The order of mobilities was GS(K)-AMP < GS(K) < GS(E)-AMP < GS(E). We were able to detect these mobility differences with purified and partially purified preparations of GS, crude cell extracts, and whole cell lysates. SDS gel electrophoresis thus provided a means of estimating the adenylylation state and the quantity of GS present independent of enzymatic activity measurements and of determining the strain origin. Using SDS gels, we showed that: (i) the constitutively produced GS in strains carrying the glnA4 allele was mostly adenylylated, (ii) the GS-like polypeptide produced by strains carrying the glnA51 allele was indistinguishable from wild-type GS(K), and (iii) strains carrying the glnA10 allele contained no polypeptide having the mobility of GS(K) or GS(K)-AMP. Using native polyacrylamide gels, we detected the increased amount of dodecameric GS present in cells grown under nitrogen limitation compared with cells grown under conditions of nitrogen excess. In native gels there was neither a significant difference in the mobilities of adenylylated and non-adenylylated GSs nor a GS-like protein in cells carrying the glnA10 allele.
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PMID:Glutamine synthetase regulation, adenylylation state, and strain specificity analyzed by polyacrylamide gel electrophoresis. 3 58

We have partially characterized the biochemical parameters of glutamine synthetase from Klebsiella pneumoniae and have shown that the differential affinity of adenylylated and unadenylylated glutamine synthetase for adenosine diphosphate provides a convenient means of determining the adenylylation state. Using this assay procedure, we examined the relationship between the adenylylation state and the expression of other genes involved in nitrogen assimilation. We observed no correlation between the adenylylation state and the expression of histidase, glutamine synthetase, glutamate synthase, glutamate dehydrogenase, and urease in aerobic cultures.
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PMID:Relation between the adenylylation state of glutamine synthetase and the expression of other genes involved in nitrogen metabolism. 3 15

The intracellular levels of glutamine synthetase (GS) in Anacystis nidulans grown under different conditions were determined using a whole-cell assay. Nitrate-grown cells have 64% more GS than cells grown in ammonium sulfate. Nitrogen starvation does not affect GS levels appreciably. Incubation of nitrate-grown cells with ammonium sulfate does not change the ratio of gamma-glutamyl transferase activities stimulated by Mg2+ and Mn2+ ions. An in vitro test of adenylylation indicates that algae do not have an endogenous adenylyl transferase (ATase) and that algal GS is not adenylylatable by the Klebsiella aerogenes ATase. Some characteristics of the GS-membrane complex were determined by centrifugation of the complex under varying conditions of pH and ionic strength. In this way, it was shown that acid pH (4.5) stabilizes the complex and high ionic strength tends to solubilize the enzyme. A simple partial purification of GS (89-fold) was developed based on the sedimentation properties of GS.
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PMID:Distinctive properties of glutamine synthetase from the cyanobacterium Anacystis nidulans. 3 92

Previous studies have implicated glutamine synthetase (L-glutamate:ammonia ligase [adenosine diphosphate for-ing], EC 6.6.1.2) as a major controlling element of the nitrogen fixation (nif) genes in Klebsiella pneumoniae. We report here the isolation of a new class of K. pneumoniae mutants which exhibit altered patterns of nif and hut (histidine utlization) regulation. The expression of nif in these mutants, which were isolated as Gln+ (glutamine nonrequiring) revertants of a particular glnA mutation, is extremely sensitive to ammonia repression. These mutants have a Nif- Hut- phenotype at external ammonia concentrations at which wild-type strains are Nif+ Hut+. On the other hand, these mutants can be fully derepressed for nif at very low ammonia concentrations. We adopted the nomenclature "GlnR- (Nif- Hut-)" to facilitate discussion of the phenotype of these mutant strains. The mutations in these strains which confer the GlnR- phenotype map at or near glnA, the structural gene for glutamine synthetase.
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PMID:Glutamine synthetase mutations which affect expression of nitrogen fixation genes in Klebsiella pneumoniae. 4 Sep 60

Arranged in descending order of nitrogen-fixing (acetylene-reducing) potential the sites examined were mesic meadow and peat polygon troughs (equal rank), transition zone between mesic meadow and gravel ridge, gravel ridge, polar dessert, and peat polygon tops. The dominant nitrogen-fixing microorganisms, as in other Arctic areas, were blue-green bacteria, especially those epiphytic on Arctic mosses. The epiphytic association exhibited an optimum temperature for fixation of 20 degrees C. Other bacteria potentially able to fix nitrogen were present in the soils examined but their activity was severely restricted by low soil temperatures and lack of readily utilizable energy sources. These bacteria included members of the genera Klebsiella (the most numerous), Bacillus, Clostridium, and Beijerinckia (scarce). Also present at many of the sites was an unidentified yellow-pigmented fixer which was not Mycobacterium flavum. All fixers were psychotrophic rather than psychrophilic, having an optimum temperature greater than 20 degrees C but capable of slow growth at 5 degrees C or lower. The rate of acetylene reduction by the epiphytic system increased with the number of successive exposures to acetylene, a phenomenon of some significance in any calculations designed to measure the amount of nitrogen fixed in certain ecosystems.
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PMID:Biological nitrogen fixation in the terrestrial environment of a high Arctic ecosystem (Truelove Lowland, Devon Island, N.W.T.). 9 27

In combination with the Mo-Fe protein of nitrogenase from Klebsiella pneumoniae, the Fe protein of nitrogenase from Clostridium pasteurianum forms an active enzyme with novel properties different from those of either of the homologous nitrogenases. The steady-state rates of reduction of acetylene and H+ are 12% of those of the homologous system from C.pasteurianim. Acetylene reductase activity exhibited an approx. 10min lag at 30 degrees C before the rate of reduction became linear, consistent with a once-only activation step being necessary for acetylene reduction to occur. No such lag was observed for H2 evolution. The activity with N2 as a reducible substrate was very low, implying that acetylene reductase activity is not necessarily an accurate indication of nitrogen-fixing ability. This is of particular relevance to studies on mutant and agronomically important organisms. Stopped-flow spectrophotometric studies showed unimolecular electron transfer from the Fe protein to the Mo-Fe protein to occur at the same rate (k2 = 2.5 X 10(2)s-1) and with the same dependence on ATP concentration (apparent KD = 400 muM) as with the homologous Klebsiella nitrogenase. However, an ATP/2e ratio of 50 was obtained for H2 evolution, indicating that ATP hydrolysis had been uncoupled from electron transfer to substrate. These data indicate that ATP has at least two roles in the mechanism of nitrogenase action. The combination of the Mo-Fe protein of nitrogenase of C.pasteurianim and the Fe protein of K.pneumoniae were inactive in all the above reactions, except for a weak adenosine triphosphatase activity, 0.5% of that of the homologous K.pneumoniae system.
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PMID:Nitrogenases from Klebsiella pneumoniae and Clostridium pasteurianum. Kinetic investigations of cross-reactions as a probe of the enzyme mechanism. 13


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