title: Heat-shock and redox-dependent functional switching of an h-type Arabidopsis thioredoxin from a disulfide reductase to a molecular chaperone.
abstract: A large number of thioredoxins (Trxs), small redox proteins, have been identified from all living organisms. However, many of the physiological roles played by these proteins remain to be elucidated. We isolated a high M(r) (HMW) form of h-type Trx from the heat-treated cytosolic extracts of Arabidopsis (Arabidopsis thaliana) suspension cells and designated it as AtTrx-h3. Using bacterially expressed recombinant AtTrx-h3, we find that it forms various protein structures ranging from low and oligomeric protein species to HMW complexes. And the AtTrx-h3 performs dual functions, acting as a disulfide reductase and as a molecular chaperone, which are closely associated with its molecular structures. The disulfide reductase function is observed predominantly in the low M(r) forms, whereas the chaperone function predominates in the HMW complexes. The multimeric structures of AtTrx-h3 are regulated not only by heat shock but also by redox status. Two active cysteine residues in AtTrx-h3 are required for disulfide reductase activity, but not for chaperone function. AtTrx-h3 confers enhanced heat-shock tolerance in Arabidopsis, primarily through its chaperone function.
authors.affiliation: Environmental Biotechnology National Core Research Center, Plant Molecular Biology and Biotechnology Research Center , and Division of Applied Life Science (BK21 program), Korea.
authors.forename: Soo Kwon
authors.initials: SK
authors.lastname: Park
authors.forename: Young Jun
authors.initials: YJ
authors.lastname: Jung
authors.forename: Jung Ro
authors.initials: JR
authors.lastname: Lee
authors.forename: Young Mee
authors.initials: YM
authors.lastname: Lee
authors.forename: Ho Hee
authors.initials: HH
authors.lastname: Jang
authors.forename: Seung Sik
authors.initials: SS
authors.lastname: Lee
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Park
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Jeong Chan
authors.initials: JC
authors.lastname: Moon
authors.forename: Sun Yong
authors.initials: SY
authors.lastname: Lee
authors.forename: Ho Byoung
authors.initials: HB
authors.lastname: Chae
authors.forename: Mi Rim
authors.initials: MR
authors.lastname: Shin
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Jung
authors.forename: Min Gab
authors.initials: MG
authors.lastname: Kim
authors.forename: Woe Yeon
authors.initials: WY
authors.lastname: Kim
authors.forename: Dae-Jin
authors.initials: DJ
authors.lastname: Yun
authors.forename: Kyun Oh
authors.initials: KO
authors.lastname: Lee
authors.forename: Sang Yeol
authors.initials: SY
authors.lastname: Lee