Heat-shock dependent oligomeric status alters the function of a plant-specific thioredoxin-like protein, AtTDX.
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.
Lee
Jung Ro
JR
Environmental Biotechnology National Core Research Center, Division of Applied Life Sciences, Gyeongsang National University, Jinju 660-701, Korea.
Lee
Seung Sik
SS
Jang
Ho Hee
HH
Lee
Young Mee
YM
Park
Jin Ho
JH
Park
Seong-Cheol
SC
Moon
Jeong Chan
JC
Park
Soo Kwon
SK
Kim
Sun Young
SY
Lee
Sun Yong
SY
Chae
Ho Byoung
HB
Jung
Young Jun
YJ
Kim
Woe Yeon
WY
Shin
Mi Rim
MR
Cheong
Gang-Won
GW
Kim
Min Gab
MG
Kang
Kee Ryeon
KR
Lee
Kyun Oh
KO
Yun
Dae-Jin
DJ
Lee
Sang Yeol
SY
D029681:Arabidopsis Proteins / Q000502:physiology*; D019281:Dimerization; D018869:Heat-Shock Response / Q000235:genetics; D018832:Molecular Chaperones; D008970:Molecular Weight; D009247:NADH, NADPH Oxidoreductases; D013879:Thioredoxins / Q000502:physiology*
D029681:Arabidopsis Proteins; C504764:AtTDX protein, Arabidopsis; D018832:Molecular Chaperones; D013879:Thioredoxins; D009247:NADH, NADPH Oxidoreductases; C014703:disulfide reductase (NADH)