Abstract
Biodesulfurization helps in removal of sulfur from organosulfur present in petroleum fractions. All microorganisms isolated to date harbor a desulfurization operon consisting of three genes dszA, -B and -C which encode for monooxygenases (DszA & C) and desulfinase (DszB). Most of the studies have been carried out using dibenzothiophene as the model organosulfur compound, which is converted into 2 hydroxybiphenyl by a 4S pathway which maintains the calorific value of fuel. There are few studies reported on the regulation of this operon. However, there are no reports on the proteins which can enhance the activity of the operon. In the present study, we used in vitro and in vivo methods to identify a novel TetR family transcriptional regulator from Gordonia sp. IITR100 which functions as an activator of the dsz operon. Activation by TetR family regulator resulted in enhanced levels of desulfurization enzymes in Gordonia sp. IITR100. Activation was observed only when the 385 bp full length promoter was used. Upstream sequences between − 385 and − 315 were found to be responsible for activation. We provide evidence that the TetR family transcription regulator serves as an activator in other biodesulfurizing microorganisms such as Rhodococcus erythropolis IGTS8 and heterologous host Escherichia coli. This is the first report on the isolation of a possible transcriptional regulator that activates the desulfurization operon resulting in improved biodesulfurization.
Highlights
Biodesulfurization is a process for removal of sulfur from organosulfur compounds present in petroleum fractions
Our findings suggest that a regulatory protein belonging to TetR family (Protein ID: WP_010840674.1) when supplied in trans activates the operon and results in enhanced biodesulfurization activity in E. coli, R. erythropolis IGTS8 and Gordonia sp
Isolation and cloning of Pdsz binding proteins To isolate the protein(s) that bind to dsz promoter (385 bp) from Gordonia sp
Summary
Biodesulfurization is a process for removal of sulfur from organosulfur compounds present in petroleum fractions. Several biodesulfurizing microorganisms have been isolated to date from different parts of the world. All have been shown to contain desulfurization genes in the form of an operon in the order dszA, -B and -C. The genes dszA and dszC code for monooxygenases and dszB encodes a desulfinase. Dibenzothiophene (DBT) is converted into dibenzothiophene sulfone (DBT sulfone) by the enzyme DszC. DBT sulfone is converted into 2-hydroxybiphenyl sulfinic acid by the enzyme DszA, which in turn is converted into 2 hydroxybiphenyl and sulfite by DszB. There is an unlinked dszD gene present which encodes for a FMN oxidoreductase.
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