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