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Heat-shock dependent oligomeric status alters the function of a plant-specific thioredoxin-like protein, AtTDX

By Jung Ro Lee, Seung Sik Lee, Ho Hee Jang, Young Mee Lee, Jin Ho Park, Seong-Cheol Park, Jeong Chan Moon, Soo Kwon Park, Sun Young Kim, Sun Yong Lee, Ho Byoung Chae, Young Jun Jung, Woe Yeon Kim, Mi Rim Shin, Gang-Won Cheong, Min Gab Kim, Kee Ryeon Kang, Kyun Oh Lee, Dae-Jin Yun and Sang Yeol Lee


We found that Arabidopsis AtTDX, a heat-stable and plant-specific thioredoxin (Trx)-like protein, exhibits multiple functions, acting as a disulfide reductase, foldase chaperone, and holdase chaperone. The activity of AtTDX, which contains 3 tetratricopeptide repeat (TPR) domains and a Trx motif, depends on its oligomeric status. The disulfide reductase and foldase chaperone functions predominate when AtTDX occurs in the low molecular weight (LMW) form, whereas the holdase chaperone function predominates in the high molecular weight (HMW) complexes. Because deletion of the TPR domains results in a significant enhancement of AtTDX disulfide reductase activity and complete loss of the holdase chaperone function, our data suggest that the TPR domains of AtTDX block the active site of Trx and play a critical role in promoting the holdase chaperone function. The oligomerization status of AtTDX is reversibly regulated by heat shock, which causes a transition from LMW to HMW complexes with concomitant functional switching from a disulfide reductase and foldase chaperone to a holdase chaperone. Overexpression of AtTDX in Arabidopsis conferred enhanced heat shock resistance to plants, primarily via its holdase chaperone activity

Topics: Biological Sciences
Publisher: National Academy of Sciences
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Provided by: PubMed Central
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