Cloning, Sequencing and Characterization of the ‘Desulfurization Gene Cluster’ From an Isolated Strain Gordonia sp. IITR100

Abstract

Biodesulfurization of organosulfur compounds is mediated by activity of the enzymes DszA, DszB and DszC. Here, we report the nucleotide sequence of an 11.5 kb region, containing the dszABC genes along with 3.3 kb upstream and 4.5 kb down-stream region, from a desulfurizing strain Gordonia sp IITR100. The genes are organized together as dszABC in an operon, and their nucleotide sequence is > 99% identical to those from the Gordonia strains IB, RIPI90A & CYKS2. The sequence upstream to dszA, is identical to the reported -1 to -1800 bp from the corresponding region of CYKS2, but presence of two transposase genes was identified in the remaining 2.7 kb region. Sequence of the region downstream to dszC was found to be distinct from all the desulfurizing organisms. BLAST analysis suggested that the cloned 11.5 kb region was possibly formed by crossover between the genomes a Mycobacterium and a Gordonia strain at a site 206 bp downstream to dszC. The results have bearing on understanding the organization and horizontal transfer of the desulfurization genes.