title: The 1-Cys peroxiredoxin, a regulator of seed dormancy, functions as a molecular chaperone under oxidative stress conditions.
abstract: Peroxiredoxins are antioxidative enzymes that catalyze the reduction of alkyl hydroperoxides to alcohols and hydrogen peroxide to water. 1-Cys peroxiredoxins (1-Cys Prxs) perform important roles during late seed development in plants. To characterize their biochemical functions in plants, a 1Cys-Prx gene was cloned from a Chinese cabbage cDNA library and designated as "C1C-Prx". Glutamine synthetase (GS) protection and hydrogen peroxide reduction assays indicated that C1C-Prx was functionally active as a peroxidase. Also C1C-Prx prevented the thermal- or chemical-induced aggregation of malate dehydrogenase and insulin. Hydrogen peroxide treatment changed the mobility of C1C-Prx on a two-dimensional gel, which implies overoxidation of the conserved Cys residue. Furthermore, after overoxidation, the chaperone activity of C1C-Prx increased approximately two-fold, but its peroxidase activity decreased to the basal level of the reaction mixture without enzyme. However, according to the structural analysis using far-UV circular dichroism spectra, intrinsic tryptophan fluorescence spectra, and native-PAGE, overoxidation did not lead to a conformational change in C1C-Prx. Therefore, our results suggest that 1-Cys Prxs function not only to relieve mild oxidative stresses but also as molecular chaperones under severe conditions during seed germination and plant development, and that overoxidation controls the switch in function of 1-Cys-Prxs from peroxidases to molecular chaperones.
authors.affiliation: Division of Applied Life Sciences, Gyeongsang National University, 900 Gajwa-dong, Jinju 660-701, Gyeongsangnam-do, Republic of Korea.
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Seol Ki
authors.initials: SK
authors.lastname: Paeng
authors.forename: Ganesh M
authors.initials: GM
authors.lastname: Nawkar
authors.forename: Punyakishore
authors.initials: P
authors.lastname: Maibam
authors.forename: Eun Seon
authors.initials: ES
authors.lastname: Lee
authors.forename: Kang-San
authors.initials: KS
authors.lastname: Kim
authors.forename: Deok Ho
authors.initials: DH
authors.lastname: Lee
authors.forename: Dong-Jin
authors.initials: DJ
authors.lastname: Park
authors.forename: Sun Bin
authors.initials: SB
authors.lastname: Kang
authors.forename: Mi Ri
authors.initials: MR
authors.lastname: Kim
authors.forename: Joo Hyeong
authors.initials: JH
authors.lastname: Lee
authors.forename: Young Hun
authors.initials: YH
authors.lastname: Kim
authors.forename: Woe Yeon
authors.initials: WY
authors.lastname: Kim
authors.forename: Chang Ho
authors.initials: CH
authors.lastname: Kang
mesh_terms: D000595:Amino Acid Sequence; D000975:Antioxidants / Q000378:metabolism; D001937:Brassica / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry; D035264:Flowers / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D018628:Gene Dosage; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D015723:Gene Library; D006861:Hydrogen Peroxide / Q000737:chemistry; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D018384:Oxidative Stress; D054464:Peroxiredoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D057445:Plant Dormancy / Q000502:physiology; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D011994:Recombinant Proteins; D012639:Seeds / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D016415:Sequence Alignment
chemical_list: D000975:Antioxidants; D018832:Molecular Chaperones; D011994:Recombinant Proteins; D006861:Hydrogen Peroxide; D054464:Peroxiredoxins; D003545:Cysteine