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sulfur relay protein TusD/DsrE The three proteins TusB, TusC, and TusD form a heterohexamer responsible for a sulfur relay reaction. In large numbers of proteobacterial species, this complex acts on a Cys-derived persulfide moiety, delivered by the cysteine desulfurase IscS to TusA, then to TusBCD. The activated sulfur group is then transferred to TusE (DsrC), then by MnmA (TrmU) for modification of an anticodon nucleotide in tRNAs for Glu, Lys, and Gln. The sulfur relay complex TusBCD is also found, under the designation DsrEFH, in phototrophic and chemotrophic sulfur bacteria, such as Chromatium vinosum. In these organisms, it seems the primary purpose is related to sulfur flux, such as oxidation from sulfide to molecular sulfur to sulfate. [Protein synthesis, tRNA and rRNA base modification]
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