期刊
BIOCHEMICAL JOURNAL
卷 456, 期 -, 页码 13-24出版社
PORTLAND PRESS LTD
DOI: 10.1042/BJ20130618
关键词
Arabidopsis thaliana; disulfide reductase; heat-shock-resistance; molecular chaperone; thioredoxin h
资金
- Rural Development Administration (RDA) for the Next-Generation BioGreen Program [SSAC (Systems and Synthetic Agrobiotech Center)] [PJ009495]
- Cooperative Research Program for Agricultural Science and Technology Development [PJ007850]
- Basic Science Research Program through the National Research Foundation (NRF) of Korea
- MOEST [2012R1A1A2044114]
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(Delta 19)] and site-directed mutagenesis of AtTrx-h3. AtTrx-h2-N(Delta 19) 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 Ala(100) and Ala(106) 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.
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