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Molecular cloning of rhodanese gene from soil metagenome of cold desert of North-West Himalayas: sequence and structural features of the rhodanese enzyme

Bhat, Archana, Riyaz-Ul-Hassan, Syed, Srivastava, Nidhi, Johri, Sarojini
3 Biotech 2015 v.5 no.4 pp. 513-521
Cyanobacterium (genus), Synechococcus, Wolinella succinogenes, active sites, cyanides, cysteine, genes, genomic libraries, metagenomics, microorganisms, models, molecular cloning, open reading frames, polypeptides, screening, sequence analysis, soil, thiosulfate sulfurtransferase, Himalayan region, India
Rhodanese is a multifunctional, sulfur transferase that catalyzes the detoxification of cyanide by sulphuration in a double displacement (ping pong) mechanistic reaction. In the present study, small-insert metagenomic library from soil sample collected from Ladakh (3,000–3,600 m.a.s.l) in northwestern Himalayas, India was constructed. Function-driven screening of ~8,500 colonies led to the isolation of one esterase-positive clone (clone-est) harboring 2.43 kb insert. Sequence analysis of the insert identified two ORF’s, phosM encoding phosphoesterase and rodM encoding rhodanese. The 800 bp rodM gene encoded a polypeptide of 227 amino acids (RodM). The RodM showed maximum homology with the rhodanese-like protein from Cyanobacterium synechococcus species with a score identity of only 51 %. Putative 3D structure of RodM developed by homology modeling resembles to homodimeric protein of SUD sulfur transferase of Wolinella succinogenes with properly structured active-site cysteine (Cys) residue. Rhodanese has been reported from few culturable microorganisms.