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

The bacterium Klebsiella aerogenes (type 25) produced an inducible alginate lyase, whose major activity was located intracellularly during all growth phases. The enzyme was purified from the soluble fraction of sonicated cells by ammonium sulfate precipitation, anion- and cation-exchange chromatography and gel filtration. The apparent molecular weight of purified alginate lyase of 28,000 determined by gel filtration and of 31,600 determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the active enzyme was composed of a single polypeptide. The alginate lyase displayed a pH optimum around 7.0 and a temperature optimum around 37 degrees C. The purified enzyme depolymerized alginate by a lyase reaction in an endo manner releasing products which reacted in the thiobarbituric acid assay and absorbed strongly in the ultraviolet region at 235 nm. The alginate lyase was specific for guluronic acid-rich alginate preparations. Propylene glycol esters of alginate and O-acetylated bacterial alginates were poorly degraded by the lyase compared with unmodified polysaccharide. The guluronate-specific lyase activity was applied in an enzymatic method to detect mannuronan C-5 epimerase in three different mucoid (alginate-synthesizing) strains of Pseudomonas aeruginosa. This enzyme which converts polymannuronate to alginate could not be demonstrated either extracellularly or intracellularly in all strains suggesting the absence of a polymannuronate-modifying enzyme in P. aeruginosa.
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PMID:Isolation and characterization of an alginate lyase from Klebsiella aerogenes. 267 22

The enzyme propanediol oxidoreductase, which converts the lactaldehyde formed in the metabolism of fucose and rhamnose into propane-1,2-diol under anaerobic conditions, was investigated in Escherichia coli, Klebsiella pneumoniae and Salmonella typhimurium. Structural analysis indicated that the enzymes of E. coli and K. pneumoniae have the same Mr and pI, whereas that of Salm. typhimurium also has the same Mr but a slightly different pI. One-dimensional peptide mapping showed identity between the E. coli and K. pneumoniae enzymes when digested with alpha-chymotrypsin, Staphylococcus aureus V8 proteinase or subtilisin. In the case of Salm. typhimurium, this held only for the subtilisin-digested enzymes, indicating that the hydrophobic regions were preserved to a considerable extent. Anaerobically, the three species induced an active propanediol oxidoreductase when grown on fucose or rhamnose. An inactive propanediol oxidoreductase was induced in Salm. typhimurium by either fucose or rhamnose under aerobic conditions, and this was activated once anaerobiosis was established. An inactive propanediol oxidoreductase was also induced in E. coli under aerobic conditions, but only by growth on fucose. The inactive enzyme was not induced by either of the sugars in K. pneumoniae.
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PMID:Propanediol oxidoreductases of Escherichia coli, Klebsiella pneumoniae and Salmonella typhimurium. Aspects of interspecies structural and regulatory differentiation. 390 30

The aim of the study was to inquire about the diagnostic usefulness of determining the activity of glucuronidase and utilisation of propylene glycol in Enterobacteriaceae rods. The study included 1511 strains: 411- E. coli, 278 - Klebsiella, 231 - Salmonella, 159 - Yersinia, 97 - Citrobacter, 75 - Shigella and 260 strains representing 6 other kinds of enteric rods. Determination was performed in a liquid medium containing in 1 ml 25 mcg MUG and 100 mcg ONPG. Propylene glycol (PG) utilisation was observed in peptone water with 2% of the substrate and with the Andrade indicator. In comparative tests Rambach commercial medium and MacConkey agar from the Fluorocult series were used. In the test with MUG a positive result was obtained from 81.8% E. coli, 65% - Shigella and 13% - Salmonella subgenus I. Only exceptionally was this test positive with Providencia, Enterobacter and Yersinia strains (1-5%) but negative with Citrobacter, Klebsiella, Serratia, Hafnia, Proteus and Morganella strains. Glucuronidase production is not sufficiently characteristic of E. coli strains isolated from humans to be the only basis for the preliminary differentiation of these rods from other Enterobacteriaceae. The test with ONPG was positive from 95-100% E. coli, Yersinia, Citrobacter, Klebsiella, Enterobacter and Hafnia strains; 61% - Shigella, 9% - Salmonella and 3% - Providencia, but negative with Serratia, Proteus and Morganella strains. Propylene glycol was decomposed by 74% Salmonella strains of subgenus I, 65-94% - Klebsiella, Yersinia and Citrobacter. Shigella, Enterobacter, Serratia, Proteus, Providencia and Morganella rods did not decompose propylene glycol. Evidence that among strains non-decomposing propylene glycol were all the studied S. typhi, S. paratyphi A, S. paratyphi C, S. choleraesuis, S. virchow and S. gallinarum strains as well as a significant percentage of strains representing 8 other Salmonella serotypes frequently detected allows to believe that the use of activity against propylene glycol even simultaneously with the test for galactosidase as basis for the differentiation of Salmonella rods of subgenus I from other Enterobacteriaceae can lead to errors already at the onset of diagnostic procedure.
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PMID:[Evaluation of the usefulness of tests for production of Beta-D-glucuronidase and propylene glycol utilization for the differentiation of enterobacteriaceae rods]. 883 27

1,2-Propanediol (1,2-PD) is a major commodity chemical that is currently derived from propylene, a nonrenewable resource. A goal of our research is to develop fermentation routes to 1,2-PD from renewable resources. Here we report the production of enantiomerically pure R-1,2-PD from glucose in Escherichia coli expressing NADH-linked glycerol dehydrogenase genes (E. coli gldA or Klebsiella pneumoniae dhaD). We also show that E. coli overexpressing the E. coli methylglyoxal synthase gene (mgs) produced 1,2-PD. The expression of either glycerol dehydrogenase or methylglyoxal synthase resulted in the anaerobic production of approximately 0.25 g of 1,2-PD per liter. R-1,2-PD production was further improved to 0.7 g of 1,2-PD per liter when methylglyoxal synthase and glycerol dehydrogenase (gldA) were coexpressed. In vitro studies indicated that the route to R-1,2-PD involved the reduction of methylglyoxal to R-lactaldehyde by the recombinant glycerol dehydrogenase and the reduction of R-lactaldehyde to R-1, 2-PD by a native E. coli activity. We expect that R-1,2-PD production can be significantly improved through further metabolic and bioprocess engineering.
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PMID:Metabolic engineering of a 1,2-propanediol pathway in Escherichia coli. 1004 80

Recombinant glycerol dehydratase of Klebsiella pneumoniae was purified to homogeneity. The subunit composition of the enzyme was most probably alpha 2 beta 2 gamma 2. When (R)- and (S)-propane-1,2-diols were used independently as substrates, the rate with the (R)-enantiomer was 2.5 times faster than that with the (S)-isomer. In contrast to diol dehydratase, an isofunctional enzyme, the affinity of the enzyme for the (S)-isomer was essentially the same or only slightly higher than that for the (R)-isomer (Km(R)/Km(S) = 1.5). The crystal structure of glycerol dehydratase in complex with cyanocobalamin and propane-1,2-diol was determined at 2.1 A resolution. The enzyme exists as a dimer of the alpha beta gamma heterotrimer. Cobalamin is bound at the interface between the alpha and beta subunits in the so-called 'base-on' mode with 5,6-dimethylbenzimidazole of the nucleotide moiety coordinating to the cobalt atom. The electron density of the cyano group was almost unobservable, suggesting that the cyanocobalamin was reduced to cob(II)alamin by X-ray irradiation. The active site is in a (beta/alpha)8 barrel that was formed by a central region of the alpha subunit. The substrate propane-1,2-diol and essential cofactor K+ are bound inside the (beta/alpha)8 barrel above the corrin ring of cobalamin. K+ is hepta-coordinated by the two hydroxyls of the substrate and five oxygen atoms from the active-site residues. These structural features are quite similar to those of diol dehydratase. A closer contact between the alpha and beta subunits in glycerol dehydratase may be reminiscent of the higher affinity of the enzyme for adenosylcobalamin than that of diol dehydratase. Although racemic propane-1,2-diol was used for crystallization, the substrate bound to glycerol dehydratase was assigned to the (R)-isomer. This is in clear contrast to diol dehydratase and accounts for the difference between the two enzymes in the susceptibility of suicide inactivation by glycerol.
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PMID:The crystal structure of coenzyme B12-dependent glycerol dehydratase in complex with cobalamin and propane-1,2-diol. 1223 May 60