TY  - JOUR
A1  - Fraesdorf, Benjamin
A1  - Radon, Christin
A1  - Leimkühler, Silke
T1  - Characterization and interaction studies of two isoforms of the dual localized 3-mercaptopyruvate sulfurtransferase TUM1 from humans
JF  - The journal of biological chemistry
N2  - Background: Localization and identification of interaction partners of two splice variants of the human 3-mercaptopyruvate sulfurtransferase TUM1. Results: We show that TUM1 interacts with proteins involved in Moco and FeS cluster biosynthesis. Conclusion: Human TUM1 is a dual localized protein in the cytosol and mitochondria with distinct roles in sulfur transfer and interaction partners. Significance: The study contributes to the sulfur transfer pathway for the biosynthesis of sulfur-containing biofactors.
 The human tRNA thiouridine modification protein (TUM1), also designated as 3-mercaptopyruvate sulfurtransferase (MPST), has been implicated in a wide range of physiological processes in the cell. The roles range from an involvement in thiolation of cytosolic tRNAs to the generation of H2S as signaling molecule both in mitochondria and the cytosol. TUM1 is a member of the sulfurtransferase family and catalyzes the conversion of 3-mercaptopyruvate to pyruvate and protein-bound persulfide. Here, we purified and characterized two novel TUM1 splice variants, designated as TUM1-Iso1 and TUM1-Iso2. The purified proteins showed similar kinetic behavior and comparable pH and temperature dependence. Cellular localization studies, however, showed a different localization pattern between the isoforms. TUM1-Iso1 is exclusively localized in the cytosol, whereas TUM1-Iso2 showed a dual localization both in the cytosol and mitochondria. Interaction studies were performed with the isoforms both in vitro using the purified proteins and in vivo by fluorescence analysis in human cells, using the split-EGFP system. The studies showed that TUM1 interacts with the l-cysteine desulfurase NFS1 and the rhodanese-like protein MOCS3, suggesting a dual function of TUM1 both in sulfur transfer for the biosynthesis of the molybdenum cofactor, and for the thiolation of tRNA. Our studies point to distinct roles of each TUM1 isoform in the sulfur transfer processes in the cell, with different compartmentalization of the two splice variants of TUM1.
KW  - Fluorescence
KW  - Mitochondria
KW  - Molybdenum
KW  - Sulfur
KW  - Transfer RNA (tRNA)
Y1  - 2014
U6  - https://doi.org/10.1074/jbc.M114.605733
SN  - 0021-9258
SN  - 1083-351X
VL  - 289
IS  - 50
SP  - 34543
EP  - 34556
PB  - American Society for Biochemistry and Molecular Biology
CY  - Bethesda
ER  -