Abstract

The plant mitochondrial thioredoxin (Trx) system has been described as containing an NADPH-dependent Trx reductase and Trx o. In addition to the mitochondrial isoform, Trx o, plants are known to contain several chloroplastic Trx isoforms and the cytosolic Trx h isoforms. We report here the presence in plant mitochondria of a Trx isoform (PtTrxh2) belonging to the Trx h group. Western blot analyses with mitochondrial proteins isolated from both poplar and GFP fusion constructs indicate that PtTrxh2 is targeted to plant mitochondria. The recombinant protein, PtTrxh2, has been shown to be reduced efficiently by the mitochondrial Trx reductase AtNTRA. PtTrxh2 is also able to reduce alternative oxidase homodimers and to allow its activation by pyruvate. In contrast, neither PtTrxh2 nor AtTrxo1 exhibits activity with several poplar glutathione peroxidases and especially a putative mitochondrial isoform. Incubation of PtTrxh2 with glutathione disulfide led to the formation of glutathionylated Trx, identified by mass spectrometry. The formation of a glutathione adduct increases the redox potential of PtTrxh2 from -290 to -225 mV. In addition to Trx o, this study shows that Trx h could also be present in mitochondria. This previously unrecognized complexity is not unexpected, considering the multiple redox-regulated processes found in plant mitochondria

Published in

Proceedings of the National Academy of Sciences
2004, Volume: 101, number: 40, pages: 14545-14550
Publisher: NATL ACAD SCIENCES

SLU Authors

• Wingsle, Gunnar

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Forest Science


Publication identifier

DOI: https://doi.org/10.1073/pnas.0405282101

Permanent link to this page (URI)

https://res.slu.se/id/publ/5780