title: A cytosolic thioredoxin acts as a molecular chaperone for peroxisome matrix proteins as well as antioxidant in peroxisome.
abstract: Thioredoxin (TRX) is a disulfide reductase present ubiquitously in all taxa and plays an important role as a regulator of cellular redox state. Recently, a redox-independent, chaperone function has also been reported for some thioredoxins. We previously identified nodulin-35, the subunit of soybean uricase, as an interacting target of a cytosolic soybean thioredoxin, GmTRX. Here we report the further characterization of the interaction, which turns out to be independent of the disulfide reductase function and results in the co-localization of GmTRX and nodulin-35 in peroxisomes, suggesting a possible function of GmTRX in peroxisomes. In addition, the chaperone function of GmTRX was demonstrated in in vitro molecular chaperone activity assays including the thermal denaturation assay and malate dehydrogenase aggregation assay. Our results demonstrate that the target of GmTRX is not only confined to the nodulin-35, but many other peroxisomal proteins, including catalase (AtCAT), transthyretin-like protein 1 (AtTTL1), and acyl-coenzyme A oxidase 4 (AtACX4), also interact with the GmTRX. Together with an increased uricase activity of nodulin-35 and reduced ROS accumulation observed in the presence of GmTRX in our results, especially under heat shock and oxidative stress conditions, it appears that GmTRX represents a novel thioredoxin that is co-localized to the peroxisomes, possibly providing functional integrity to peroxisomal proteins.
authors.affiliation: Department of Biological Science, Sookmyung Women's University, Seoul 140-742, Korea.
authors.forename: Hui
authors.initials: H
authors.lastname: Du
authors.affiliation: Department of Plant Science, Seoul National University, Seoul 151-742, Korea.
authors.forename: Sunghan
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Biological Science, Sookmyung Women's University, Seoul 140-742, Korea.
authors.forename: Yoon-Sun
authors.initials: YS
authors.lastname: Hur
authors.affiliation: Department of Biological Science, Sookmyung Women's University, Seoul 140-742, Korea.
authors.forename: Myung-Sok
authors.initials: MS
authors.lastname: Lee
authors.affiliation: Department of Plant Science, Seoul National University, Seoul 151-742, Korea.
authors.forename: Suk-Ha
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Biological Science, Sookmyung Women's University, Seoul 140-742, Korea.
authors.forename: Choong-Ill
authors.initials: CI
authors.lastname: Cheon
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001665:Binding Sites; D003600:Cytosol / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism; D020675:Peroxisomes / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D011485:Protein Binding; D017382:Reactive Oxygen Species / Q000378:metabolism; D013025:Glycine max / Q000201:enzymology* / Q000378:metabolism; D013879:Thioredoxins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D008565:Membrane Proteins; D018832:Molecular Chaperones; D010940:Plant Proteins; D017382:Reactive Oxygen Species; C045625:nodulin; D013879:Thioredoxins
keywords: chaperone; peroxisome; thioredoxin; uricase