A novel strategy of natural plant ferritin to protect DNA from oxidative damage during iron oxidation
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- 作者：Xiayun Liao ; Chenyan Lv ; Xiuqing Zhang ; Taro Masuda ; Meiliang Li ; Guanghua Zhao
- 关键词：ROS ; reactive oxygen species ; nSSF ; naturally occurring soybean seed ferritin ; TP ; transit peptide ; EP ; extension peptide ; hSSF ; heteropolymeric soybean seed ferritin ; rH-2 ; recombinant soybean seed H-2 chain ferritin ; rH-1 ; recombinant soybean seed H-1 c
- 刊名：Free Radical Biology and Medicine
- 出版年：2012
- 出版时间：15 July, 2012
- 年：2012
- 卷：53
- 期：2
- 页码：375-382
- 全文大小：704 K
文摘
Plant ferritin is a naturally occurring heteropolymer in plastids, where Fe2+ is oxidatively deposited into the protein. However, the effect of this process on the coexistence of DNA and plant ferritin in the plastids is unknown. To investigate this effect, we built a system in which various plant ferritins and DNA coexist, followed by treatment with ferrous ions under aerobic conditions. Interestingly, naturally occurring soybean seed ferritin (SSF), a heteropolymer with an H-1/H-2 ratio of 1 to 1 in the apo form, completely protected DNA from oxidative damage during iron oxidative deposition into protein, and a similar result was obtained with its recombinant form, but not with its homopolymeric counterparts, apo rH-1 and apo rH-2. We demonstrate that the difference in DNA protection between heteropolymeric and homopolymeric plant ferritins stems from their different strategies to control iron chemistry during the above oxidative process. For example, the detoxification reaction occurs only in the presence of apo heteropolymeric SSF (hSSF), thereby preventing the production of hydroxyl radicals. In contrast, hydroxyl radicals are apparently generated via the Fenton reaction when apo rH-1 or rH-2 is used instead of apo hSSF. Thus, a combination of H-1 and H-2 subunits in hSSF seems to impart a unique DNA-protective function to the protein, which was previously unrecognized. This new finding advances our understanding of the structure and function of ferritin and of the widespread occurrence of heteropolymeric plant ferritin in nature.