Molecular and functional properties of three different peroxiredoxin isotypes in Chinese cabbage.
Peroxiredoxins (Prxs), which are classified into three isotypes in plants, play important roles in protection systems as peroxidases or molecular chaperones. The three Prx isotypes of Chinese cabbage, namely C1C-Prx, C2C-Prx, and C-PrxII, have recently been identified and characterized. The present study compares their molecular properties and biochemical functions to gain insights into their concerted roles in plants. The three Prx isotype genes were differentially expressed in tissue- and developmental stage-specific manners. The transcript level of the C1C-Prx gene was abundant at the seed stage, but rapidly decreased after imbibitions. In contrast, the C2C-Prx transcript was not detected in the seeds, but its expression level increased at germination and was maintained thereafter. The C-PrxII transcript level was mild at the seed stage, rapidly increased for 10 days after imbibitions, and gradually disappeared thereafter. In the localization analysis using GFP-fusion proteins, the three isotypes showed different cellular distributions. C1C-Prx was localized in the cytosol and nucleus, whereas C2C-Prx and C-Prx were found mainly in the chloroplast and cytosol, respectively. In vitro thiol-dependent antioxidant assays revealed that the relative peroxidase activities of the isotypes were CPrxII > C2C-Prx > C1C-Prx. C1C-Prx and C2C-Prx, but not C-PrxII, prevented aggregation of malate dehydrogenase as a molecular chaperone. Taken together, these results suggest that the three isotypes of Prx play specific roles in the cells in timely and spatially different manners, but they also cooperate with each other to protect the plant.
Division of Applied Life Sciences (Brain Korea 21 program), Gyeongsang National University, Jinju 660-701, Korea.
Sun Young
SY
Kim
Young Jun
YJ
Jung
Mi Rim
MR
Shin
Jung Hoon
JH
Park
Ganesh M
GM
Nawkar
Punyakishore
P
Maibam
Eun Seon
ES
Lee
Kang-San
KS
Kim
Seol Ki
SK
Paeng
Woe Yeon
WY
Kim
Kyun Oh
KO
Lee
Dae-Jin
DJ
Yun
Chang Ho
CH
Kang
Sang Yeol
SY
Lee
D000595:Amino Acid Sequence; D001937:Brassica / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D007527:Isoenzymes; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D054464:Peroxiredoxins / Q000378:metabolism*
D007527:Isoenzymes; D018832:Molecular Chaperones; D054464:Peroxiredoxins