Rhodanese domain-containing sulfurtransferases: multifaceted proteins involved in sulfur trafficking in plants B Selles, A Moseler, N Rouhier, J Couturier. Journal of Experimental Botany
Sulfur is an essential element for the growth and development of plants that synthesize cysteine and methionine residues from the reductive assimilation of sulfate. Besides its incorporation into proteins, cysteine is the building block for the biosynthesis of numerous sulfur-containing molecules and cofactors. The required sulfur atoms are extracted either directly from cysteine by cysteine desulfurases or indirectly after its catabolic transformation in 3-mercaptopyruvate, a substrate for sulfurtransferases (STRs). Both enzymes are transiently persulfidated in their reaction cycle, i.e. the abstracted sulfur atom is bound to a reactive cysteine residue in the form of a persulfide group. Trans-persulfidation reactions occur when sulfur atoms are transferred to nucleophilic acceptors such as glutathione, proteins or small metabolites. STRs form a ubiquitous, multigenic protein family. They are characterized by the presence of at least one rhodanese homology domain (Rhd), that usually contains the catalytic, persulfidated cysteine. In this review, we focused on Arabidopsis thaliana STRs presenting the sequence characteristics of all family members as well as their biochemical and structural features. Then, the physiological functions of peculiar STRs in the biosynthesis of molybdenum cofactor, thio-modification of cytosolic tRNAs, arsenate tolerance, cysteine catabolism and hydrogen sulfide formation are discussed.