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- Title
Analysis of Arabidopsis thioredoxin-h isotypes identifies discrete domains that confer specific structural and functional properties.
- Authors
Young Jun JUNG; Yong Hun CHI; Ho Byoung CHAE; Mi Rim SHIN; Eun Seon LEE; Joon-Yung CHA; Seol Ki PAENG; Yuno LEE; Jin Ho PARK; Woe Yeon KIM; Chang Ho KANG; Kyun Oh LEE; Keun Woo LEE; Dae-Jin YUN; Sang Yeol LEE
- Abstract
Multiple isoforms of Arabidopsis thaliana h-type thioredoxins (AtTrx-hs) have distinct structural and functional specificities. AtTrx-h3 acts as both a disulfide reductase and as a molecular chaperone. We prepared five representative AtTrx-hs and compared their protein structures and disulfide reductase and molecular chaperone activities. AtTrx-h2 with an N-terminal extension exhibited distinct functional properties with respect to other AtTrx-hs. AtTrx-h2 formed low-molecular-mass structures and exhibited only disulfide reductase activity, whereas the other AtTrx-h isoforms formed high-molecular-mass complexes and displayed both disulfide reductase and molecular chaperone activities. The domains that determine the unique structural and functional properties of each AtTrx-hs protein were determined by constructing a domain-swap between the N- and C-terminal regions of AtTrx-h2 and AtTrx-h3 (designated AtTrx-h-2N3C and AtTrx-h-3N2C respectively), an N-terminal deletion mutant of AtTrx-h2 [AtTrx-h2-N(Δ19)] and site-directed mutagenesis of AtTrx-h3. AtTrx-h2-N(Δ19) and AtTrx-h-3N2C exhibited similar properties to those of AtTrx-h2, but AtTrx-h-2N3C behaved more like AtTrx-h3, suggesting that the structural and functional specificities of AtTrx-hs are determined by their C-terminal regions. Hydrophobicity profiling and molecular modelling revealed that Ala100 and Ala106 in AtTrx-h3 play critical roles in its structural and functional regulation. When these two residues in AtTrx-h3 were replaced with lysine, AtTrx-h3 functioned like AtTrx-h2. The chaperone function of AtTrx-hs conferred enhanced heat-shock-resistance on a thermosensitive trx1/2-null yeast mutant.
- Subjects
ARABIDOPSIS thaliana; THIOREDOXIN; DISULFIDES; MOLECULAR chaperones; PROTEIN structure; MUTAGENESIS
- Publication
Biochemical Journal, 2013, Vol 456, Issue 1, p13
- ISSN
0264-6021
- Publication type
Article
- DOI
10.1042/BJ20130618