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| 2. |
- Brandsch, Roderich, et al.
(författare)
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Expression and flavinylation of Arthrobacter oxydans 6-hydroxy-D-nicotine oxidase in Bacillus subtilis
- 1989
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Ingår i: Journal of General Microbiology. - : Microbiology Society. - 0022-1287. ; 135:1093-1099
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Tidskriftsartikel (refereegranskat)abstract
- 6-Hydroxy-d-nicotine oxidase (6-HDNO) of Arthrobacter oxydans, an enzyme inducible by dl-nicotine, contains FAD covalently bound via an 8α-N(3)His linkage. Expression of the gene encoding 6-HDNO and flavinylation of the protein were studied in Bacillus subtilis. In this heterologous system the following findings were made. 1. An enzymically active covalently flavinylated 6-HDNO of normal size can be expressed in B. subtilis. 2. The natural promoter of the 6-HDNO gene appeared inefficient in B. subtilis. The B. subtilis sdh promoter, when inserted upstream of the A. oxydans promoter, increased 6-HDNO expression >50-fold. 3. Expression of the 6-HDNO gene from plasmids in B. subtilis was, independently of the promoter construct used, stimulated more than fivefold by dl-nicotine in the growth medium. It is concluded that flavinylation of 6-HDNO is possibly autocatalytic and mediated by factors generally found in bacterial cells.
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| 7. |
- Nordlund, I, et al.
(författare)
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Conservation of regulatory and structural genes for a multi-component phenol hydroxylase within phenol-catabolizing bacteria that utilize a meta-cleavage pathway.
- 1993
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Ingår i: Journal of general microbiology. - : Microbiology Society. - 0022-1287. ; 139:11
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Tidskriftsartikel (refereegranskat)abstract
- Pseudomonas sp. strain CF600 can degrade phenol and some of its methylated derivatives via a plasmid (pVI150)-encoded pathway. The metabolic route involves hydroxylation by a multi-component phenol hydroxylase and a subsequent meta-cleavage pathway. All 15 structural genes involved are clustered in an operon that is regulated by a divergently transcribed transcriptional activator. The multi-component nature of the phenol hydroxylase is unusual since reactions of this type are usually accomplished by single component flavoproteins. We have isolated and analysed a number of marine bacterial isolates capable of degrading phenol and a range of other aromatic compounds as sole carbon and energy sources. Southern hybridization and enzyme assays were used to compare the catabolic pathways of these strains and of the archetypal phenol-degrader Pseudomonas U, with respect to known catabolic genes encoded by Pseudomonas CF600. All the strains tested that degraded phenol via a meta-cleavage pathway were found to have DNA highly homologous to each of the components of the multicomponent phenol hydroxylase. Moreover, DNA of the same strains also strongly hybridized to probes specific for pVI150-encoded meta-pathway genes and the specific regulator of its catabolic operon. These results demonstrate conservation of structural and regulatory genes involved in aromatic catabolism within strains isolated from diverse geographical locations (UK, Norway and USA) and a range of habitats that include activated sludge, sea water and fresh-water mud.
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| 9. |
- Rosen, S., et al.
(författare)
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Purification and characterization of a surface lectin from the nematode-trapping fungus Arthrobotrys oligospora
- 1992
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Ingår i: Journal of General Microbiology. - : Microbiology Society. - 0022-1287. ; 138:12, s. 2663-2672
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Tidskriftsartikel (refereegranskat)abstract
- Several studies have indicated that the capture of nematodes by the nematophagous fungus Arthrobotrys oligospora is mediated by a lectin on the fungal surface. One of the major surface proteins of this fungus showed haemagglutinating activity and was isolated by affinity chromatography using a mucin Sepharose column. Biochemical analysis showed that the protein was a dimeric glycoprotein with a molecular mass of 36 kDa and an isoelectric point of pH 6.5, and contained no sulphur amino acids. The protein was N-terminally blocked; four internal peptides were sequenced, and showed no significant similarity to sequences in the Swiss-Prot or PIR databases. The haemagglutinating activity of the isolated protein was not inhibited by any of the mono- or disaccharides tested, but it was inhibited by the glycoproteins fetuin and mucin. The haemagglutinating activity changed after incubating the protein in buffers of different pH, with maximal activity at pH 11.0 and no activity at pH 2.8. The lectin was tested for different enzymic activities but none were detected. Analysis of the haemagglutinating activity in various cell fractions indicated that the protein was associated with extracellular polymer layers and with the cell wall of the fungus. About the same amount of the haemagglutinating protein was recovered from samples of vegetative mycelium and of mycelium containing nematode-trapping cells.
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| 10. |
- Shingler, V, et al.
(författare)
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Molecular analysis of a plasmid-encoded phenol hydroxylase from Pseudomonas CF600.
- 1989
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Ingår i: Journal of general microbiology. - : Microbiology Society. - 0022-1287. ; 135:5
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Tidskriftsartikel (refereegranskat)abstract
- Pseudomonas strain CF600 is able to utilize phenol and 3,4-dimethylphenol as sole carbon and energy source. We demonstrate that growth on these substrates is by virtue of plasmid-encoded phenol hydroxylase and a meta-cleavage pathway. Screening of a genomic bank, with DNA from the previously cloned catechol 2,3-dioxygenase gene of the TOL plasmid pWW0, was used in the identification of a clone which could complement a phenol-hydroxylase-deficient transposon insertion mutant. Deletion mapping and polypeptide production analysis identified a 1.2 kb region of DNA encoding a 39.5 kDa polypeptide which mediated this complementation. Enzyme activities and growth properties of Pseudomonas strains harbouring this fragment on a broad-host-range expression vector indicate that phenol hydroxylase is a multicomponent enzyme containing the 39.5 kDa polypeptide as one component.
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