%0 Journal Article %A Oldfield, Christopher %A Pogrebinsky, Olga %A Simmonds, Julie %A Olson, Edwin S. %A Kulpa, Charles F. %T Elucidation of the metabolic pathway for dibenzothiophene desulphurization by Rhodococcus sp. strain IGTS8 (ATCC 53968) %D 1997 %J Microbiology, %V 143 %N 9 %P 2961-2973 %@ 1465-2080 %R https://doi.org/10.1099/00221287-143-9-2961 %K fossil fuel desulphurization %K strain IGTS8 %K clean technologies %K Rhodococcus sp %K desulphurizing enzymes %I Microbiology Society, %X Summary: 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. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-143-9-2961