title: Enhancement of Chaperone Activity of Plant-Specific Thioredoxin through γ-Ray Mediated Conformational Change.
abstract: AtTDX, a thioredoxin-like plant-specific protein present in Arabidopsis is a thermo-stable and multi-functional enzyme. This enzyme is known to act as a thioredoxin and as a molecular chaperone depending upon its oligomeric status. The present study examines the effects of γ-irradiation on the structural and functional changes of AtTDX. Holdase chaperone activity of AtTDX was increased and reached a maximum at 10 kGy of γ-irradiation and declined subsequently in a dose-dependent manner, together with no effect on foldase chaperone activity. However, thioredoxin activity decreased gradually with increasing irradiation. Electrophoresis and size exclusion chromatography analysis showed that AtTDX had a tendency to form high molecular weight (HMW) complexes after γ-irradiation and γ-ray-induced HMW complexes were tightly associated with a holdase chaperone activity. The hydrophobicity of AtTDX increased with an increase in irradiation dose till 20 kGy and thereafter decreased further. Analysis of the secondary structures of AtTDX using far UV-circular dichroism spectra revealed that the irradiation remarkably increased the exposure of β-sheets and random coils with a dramatic decrease in α-helices and turn elements in a dose-dependent manner. The data of the present study suggest that γ-irradiation may be a useful tool for increasing holdase chaperone activity without adversely affecting foldase chaperone activity of thioredoxin-like proteins.
authors.affiliation: Research Division for Biotechnology, Advanced Radiation Technology Institute (ARTI), Korea Atomic Energy Research Institute (KAERI), 29 Geumgu-gil, Jeongeup 580-185, Korea. sslee@kaeri.re.kr.
authors.forename: Seung Sik
authors.initials: SS
authors.lastname: Lee
authors.affiliation: Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 200-701, Korea. hsjung@kangwon.ac.kr.
authors.forename: Hyun Suk
authors.initials: HS
authors.lastname: Jung
authors.affiliation: Crop Foundation Division, National Institute of Crop Science, Rural Development Administration, 181 Hyeoksin-ro, Iseo-myeon, Wanju-gun 565-851, Korea. sookwonpark@korea.kr.
authors.forename: Soo-Kwon
authors.initials: SK
authors.lastname: Park
authors.affiliation: Research Division for Biotechnology, Advanced Radiation Technology Institute (ARTI), Korea Atomic Energy Research Institute (KAERI), 29 Geumgu-gil, Jeongeup 580-185, Korea. neeunmi@nate.com.
authors.forename: Eun Mi
authors.initials: EM
authors.lastname: Lee
authors.affiliation: Research Division for Biotechnology, Advanced Radiation Technology Institute (ARTI), Korea Atomic Energy Research Institute (KAERI), 29 Geumgu-gil, Jeongeup 580-185, Korea. sudhir4u@gmail.com.
authors.forename: Sudhir
authors.initials: S
authors.lastname: Singh
authors.affiliation: Division of Applied Life Science (Brain Korea 21 Program), Gyeongsang National University, 501 Jinju-daero, Jinju 660-701, Korea. yunolee1@gmail.com.
authors.forename: Yuno
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Division of Applied Life Science (Brain Korea 21 Program), Gyeongsang National University, 501 Jinju-daero, Jinju 660-701, Korea. leeko@gnu.ac.kr.
authors.forename: Kyun Oh
authors.initials: KO
authors.lastname: Lee
authors.affiliation: Division of Applied Life Science (Brain Korea 21 Program), Gyeongsang National University, 501 Jinju-daero, Jinju 660-701, Korea. sylee@gnu.ac.kr.
authors.forename: Sang Yeol
authors.initials: SY
authors.lastname: Lee
authors.affiliation: Research Division for Biotechnology, Advanced Radiation Technology Institute (ARTI), Korea Atomic Energy Research Institute (KAERI), 29 Geumgu-gil, Jeongeup 580-185, Korea. bychung@kaeri.re.kr.
authors.forename: Byung Yeoup
authors.initials: BY
authors.lastname: Chung
mesh_terms: D004789:Enzyme Activation; D005720:Gamma Rays; D057927:Hydrophobic and Hydrophilic Interactions / Q000528:radiation effects; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation / Q000528:radiation effects*; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship; D013879:Thioredoxins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D018832:Molecular Chaperones; D010940:Plant Proteins; D013879:Thioredoxins
keywords: chaperone; protein; structural change; thioredoxin; γ-ray