PMID:19339505

Citation	Park, SK, Jung, YJ, Lee, JR, Lee, YM, Jang, HH, Lee, SS, Park, JH, Kim, SY, Moon, JC, Lee, SY, Chae, HB, Shin, MR, Jung, JH, Kim, MG, Kim, WY, Yun, DJ, Lee, KO and Lee, SY (2009) Heat-shock and redox-dependent functional switching of an h-type Arabidopsis thioredoxin from a disulfide reductase to a molecular chaperone. Plant Physiol. 150:552-61
Abstract	A large number of thioredoxins (Trxs), small redox proteins, have been identified from all living organisms. However, many of the physiological roles played by these proteins remain to be elucidated. We isolated a high M(r) (HMW) form of h-type Trx from the heat-treated cytosolic extracts of Arabidopsis (Arabidopsis thaliana) suspension cells and designated it as AtTrx-h3. Using bacterially expressed recombinant AtTrx-h3, we find that it forms various protein structures ranging from low and oligomeric protein species to HMW complexes. And the AtTrx-h3 performs dual functions, acting as a disulfide reductase and as a molecular chaperone, which are closely associated with its molecular structures. The disulfide reductase function is observed predominantly in the low M(r) forms, whereas the chaperone function predominates in the HMW complexes. The multimeric structures of AtTrx-h3 are regulated not only by heat shock but also by redox status. Two active cysteine residues in AtTrx-h3 are required for disulfide reductase activity, but not for chaperone function. AtTrx-h3 confers enhanced heat-shock tolerance in Arabidopsis, primarily through its chaperone function.
Links	PubMed PMC2689952 Online version:10.1104/pp.109.135426
Keywords	Arabidopsis/cytology; Arabidopsis/enzymology; Arabidopsis/genetics; Cysteine/metabolism; Heat-Shock Response; Models, Biological; Molecular Chaperones; Molecular Weight; Oxidation-Reduction; Photosynthesis; Plants, Genetically Modified; Protein Transport; Subcellular Fractions/metabolism; Thioredoxin h/chemistry; Thioredoxin h/metabolism; Thioredoxin-Disulfide Reductase/chemistry; Thioredoxin-Disulfide Reductase/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
ARATH:TRXH3	involved_in	GO:0010286: heat acclimation	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
ARATH:TRXH3	involved_in	GO:0009408: response to heat	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete
ARATH:TRXH3	located_in	GO:0005829: cytosol	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete
ARATH:TRXH3	enables	GO:0016671: oxidoreductase activity, acting on a sulfur group of donors, disulfide as acceptor	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete
ARATH:TRXH3	involved_in	GO:0006457: protein folding	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
ARATH:TRXH3	involved_in	GO:0051259: protein complex oligomerization	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete

References

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