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J Biol Chem. 2014 Aug 13. pii: jbc.M114.591669. [Epub ahead of print]

Thiosulfate transfer mediated by DsrE/TusA homologs from acidothermophilic sulfur-oxidizing archaeon Metallosphaera cuprina.

Author information

  • 1Chinese Academy of Sciences, China;
  • 2Rheinische Friedrich-Wilhelms-Universitaet Bonn, Germany;
  • 3University of Bonn, Germany;
  • 4Chinese Academy of Sciences, China; liusj@sun.im.ac.cn.
  • 5Rhein Frederick Whilelm University Bonn, Germany.


Conserved clusters of genes encoding DsrE and TusA homologs occur in many archaeal and bacterial sulfur oxidizers. TusA has a well-documented function as a sulfur transferase in tRNA modification and molybdenum cofactor biosynthesis in E. coli, and DsrE is an active-site subunit of the DsrEFH complex that is essential for sulfur-trafficking in the phototrophic sulfur oxidizing Allochromatium vinosum. In the acidothermophilic sulfur- and tetrathionate-oxidizing Metallosphaera cuprina Ar-4 a dsrE3A-dsrE2B-tusA arrangement is situated immediately between genes encoding dihydrolipoamide dehydrogenase and a heterodisulfide reductase-like complex. In this study, the biochemical features and sulfur transferring abilities of the DsrE2B, DsrE3A and TusA proteins were investigated. DsrE3A and TusA proved to react with tetrathionate, but not with NaSH, glutathione persulfide, polysulfide, thiosulfate or sulfite. The products were identified as protein-Cys-S-thiosulfonates. DsrE3A was also able to cleave the thiosulfate group from TusA-Cys18-S- thiosulfonate. DsrE2B did not react with any of the tested sulfur compounds. DsrE3A and TusA physically interacted with each other and formed a heterocomplex. The cysteine residue (Cys18) of TusA is crucial for the interaction. The single cysteine mutants Dsr3A-C93S and DsrE3A-C101S retained the ability to transfer the thiosulfonate group to TusA. TusA-C18S neither reacted with tetrathionate, nor was it loaded with thiosulfate with DsrE3A-Cys-S- thiosulfonate as the donor. Transfer of thiosulfate mediated by DsrE-like and TusA is unprecedented not only in M. cuprina but also in other sulfur oxidizing prokaryotes. The results of this study provide new knowledge on oxidative microbial sulfur metabolism.

Copyright © 2014, The American Society for Biochemistry and Molecular Biology.


DsrE/TusA-like proteins; Metallosphaera cuprina; Thiosulfate transfer; archaea; energy metabolism; microbiology; oxidation-reduction (redox); sulfur; tetrathionate

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