Rhodanese domain-containing sulfurtransferases: multifaceted proteins involved in sulfur trafficking in plants

Abstract

Sulfur is an essential element for the growth and development of plants, which synthesize cysteine and methionine 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 to 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), which usually contains the catalytic, persulfidated cysteine. In this review, we focus on Arabidopsis STRs, presenting the sequence characteristics of all family members as well as their biochemical and structural features. The physiological functions of particular STRs in the biosynthesis of molybdenum cofactor, thio-modification of cytosolic tRNAs, arsenate tolerance, cysteine catabolism, and hydrogen sulfide formation are also discussed.

The cytosolic Arabidopsis thaliana cysteine desulfurase ABA3 delivers sulfur to the sulfurtransferase STR18

“…Noteworthy, STR2 and STR13 are present in all eukaryotic photosynthetic organisms whereas STR18 is present only in dicotyledonous plants (24). The physiological function(s) of STR2 and STR18 are yet unknown unlike STR13 which possesses a dual function, delivering the sulfur needed for the thio-modification of cytosolic tRNAs and for Moco biosynthesis owing to its N-terminal domain (31,41). In human cells, a cytosolic form of NFS1 (although its existence is debated) was proposed to provide sulfur to MOCS3 eventually involving a relay by TUM1, the ortholog of plant STR2 (28,42,43).…”

“…The results obtained with this chimeric protein prompted us to investigate the interaction between Arabidopsis thaliana orthologs that exist as separate proteins, focusing on the cytosolic ABA3 and STR18, a single Rhd-domain containing protein (22,24,30,31). The ABA3 and STR18 proteins possess CD and TST activity respectively, as already described (19,32).…”

“…STR18 possesses two cysteine residues, Cys47 and Cys89, the latter corresponding to the catalytic cysteine found in the CxxGxR signature typical of the Rhd domain (24,31). A TST activity assay was performed with STR18 and both C47S and C89S variants.…”

Novel insights into the diversity of the sulfurtransferase family in photosynthetic organisms with emphasis on oak

“…Natural fusion proteins combining an active Rhd domain to other protein domains have been described in several organisms including A. thaliana (Bordo & Bork, ; Cipollone et al ., ; Selles et al ., ). Both Qr STR12 and Qr STR13 have a two‐domain structure that consists of an N‐terminal rotamase or MoeB‐like domain (molybdopterin biosynthesis) respectively, followed by a C‐terminal Rhd domain with CHHGMR and CRRGND active site motifs (Figs a, ).…”

Tweaking Photosynthesis: FNR-TROL Interaction as Potential Target for Crop Fortification

“…Inactive RHO domains are implicated in redox-sensing and were shown to interact with quinolinediones (Brisson et al, 2005). Plant sulfur-transferases and rhodanases have recently been reviewed in two comprehensive papers (Moseler et al, 2019;Selles et al, 2019).…”