| Autor: |
Oldfield C, Pogrebinsky O; Energy Biosystems Corporation, 4200 Research Forest Drive, The Woodlands, TX 77381, USA., Simmonds J; Energy Biosystems Corporation, 4200 Research Forest Drive, The Woodlands, TX 77381, USA., Olson ES; Energy and Environmental Research Center, University of North Dakota, Grand Forks, ND 58202, USA., Kulpa CF; Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556-0309, USA. |
| Jazyk: |
angličtina |
| Zdroj: |
Microbiology (Reading, England) [Microbiology (Reading)] 1997 Sep; Vol. 143 ( Pt 9), pp. 2961-2973. |
| DOI: |
10.1099/00221287-143-9-2961 |
| Abstrakt: |
Rhodococcus sp. strain IGTS8 (ATCC 53968) is able to utilize dibenzothiophene (DBT) as a sole source of sulphur. The carbon skeleton of DBT is not metabolized and is conserved as 2-hydroxybiphenyl (HBP), which accumulates in the medium. This phenotype is due to the expression of the plasmid-encoded DBT-desulphurization (dsz) operon, which encodes three proteins, DszA, B and C. In this paper it is shown, using [35S]DBT radiolabelling studies, that sulphur is released in the form of inorganic sulphite. The pathway of DBT desulphurization is described in detail. In summary, DszC catalyses the stepwise S-oxidation of DBT, first to dibenzothiophene 5-oxide (DBTO) and then to dibenzothiophene 5,5-dioxide (DBTO2); DszA catalyses the conversion of DBTO2 to 2-(2'-hydroxyphenyl)benzene sulphinate (HBPSi-) and DszB catalyses the desulphination of HBPSi- to give HBP and sulphite. Studies with cell-free extracts show that DszA and DszC, but not DszB, require NADH for activity. 18O2-labelling studies show that each incorporated oxygen atom is derived directly from molecular oxygen. These results are consistent with the role of DszC as a mono-oxygenase, of DszA as an apparently unique enzyme which catalyses the reductive hydroxylation of DBTO2 leading to cleavage of the thiophene ring, and of DszB as an aromatic sulphinic acid hydrolase. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
|
