Sa. Denome et al., CHARACTERIZATION OF THE DESULFURIZATION GENES FROM RHODOCOCCUS SP STRAIN IGTS8, Journal of bacteriology, 176(21), 1994, pp. 6707-6716
Rhodococcus sp. strain IGTS8 possesses an enzymatic pathway that can r
emove covalenty bound sulfur from dibenzothiophene (DBT) without break
ing carbon-carbon bonds. The DNA sequence of a 4.0-kb BstBI-BsiWI frag
ment that carries the genes for this pathway was determined. Frameshif
t and deletion mutations established that three open reading frames we
re required for DBT desulfurization, and the genes were designated sox
ABC (for sulfur oxidation). Each sox gene was subcloned independently
and expressed in Escherichia coli MZ1 under control of the inducible l
ambda p(L) promoter with a lambda cII ribosomal binding site. SoxC is
an similar to-45-kDa protein that oxidizes DBT to DBT-5,5'-dioxide. So
xA is an -similar to-50-kDa protein responsible for metabolizing DBT-5
,5'-dioxide to an unidentified intermediate. SoxB is an similar to-40-
kDa protein that, together with the SoxA protein, completes the desulf
urization of DBT-5,5'-dioxide to 2-hydroxybiphenyl. Protein sequence c
omparisons revealed that the predicted SoxC protein is similar to memb
ers of the acyl coenzyme A dehydrogenase family but that the SoxA and
SoxB proteins have no significant identities to other known proteins.
The sox genes are plasmidborne and appear to be expressed as an operon
in Rhodococcus sp. strain IGTS8 and in E. coli.