Identification and characterization of single-domain thiosulfate sulfurtransferases from Arabidopsis thaliana.

Sulfurtransferases/rhodaneses (ST) are a group of enzymes widely distributed in all three phyla that catalyze the transfer of sulfur from a donor to a thiophilic acceptor substrate. All ST contain distinct structural domains, and can exist as single-domain proteins, as tandemly repeated modules in which the C-terminal domain bears the active site, or as members of multi-domain proteins. We identified several ST in Arabidopsis resembling the C-terminus of the Arabidopsis two-domain ST1 and the single-domain GlpE protein from Escherichia coli. Two of them (accession numbers BAB10422 and BAB10409) were expressed in E. coli and purified. Both proteins showed thiosulfate-specific ST enzyme activity.