A novel plant ferritin subunit from soybean that is related to a mechanism in iron release
A novel plant ferritin subunit from soybean that is related to a mechanism in iron release
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DOI：
10.1074/jbc.m011399200
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发表时间：
2001-06-01
影响因子：
4.8
通讯作者：
Yoshihara, T
中科院分区：
文献类型：
--
作者：
Masuda, T;Goto, F;Yoshihara, T
铁蛋白是由24个亚基组成的多聚体铁储存蛋白。从干燥的大豆种子中纯化的铁蛋白分解成26.5和28 kDa的两种肽。迄今为止，26.5-kDa亚基被认为是通过N-末端区域的切割从28-kDa亚基产生的。我们进行了氨基酸序列分析的28 kDa的亚基，发现它有一个不同的序列从26.5 kDa的亚基，从而使它在已知的大豆铁蛋白中的新的。我们克隆了一个cDNA编码这个新的亚基从10天龄的幼苗，其中每个包含发达的双叶，上胚轴和顶芽。26.5 kDa的亚基被发现是相同的，以前确定缺乏C-末端16个残基，对应于哺乳动物铁蛋白的E螺旋。然而，在本研究中确定的28 kDa大豆铁蛋白亚基的相应区域是不容易切割。我们提出的证据表明，两种不同的铁蛋白亚基大豆干种子显示差异敏感性蛋白酶diglysine和新的，未切割的28 kDa铁蛋白亚基似乎稳定铁蛋白壳共存的切割26.5 kDa的亚基。这些数据表明大豆铁蛋白至少由两种不同的亚基组成，它们在大豆种子中具有协同的功能作用。
Ferritin is a multimeric iron storage protein composed of 24 subunits. Ferritin purified from dried soybean seed resolves into two peptides of 26.5 and 28 kDa. To date, the 26.5-kDa subunit has been supposed to be generated from the 28-kDa subunit by cleavage of the N-terminal region. We performed amino acid sequence analysis of the 28-kDa subunit and found that it had a different sequence from the 26.5-kDa subunit, thus rendering it novel among known soybean ferritins, We cloned a cDNA encoding this novel subunit from 10-day-old seedlings, each of which contained developed bifoliates, an epicotyl and a terminal bud. The 26.5-kDa subunit was found to be identical to that identified previously lacking the C-terminal 16 residues that correspond to the E helix of mammalian ferritin. However, the corresponding region in the 28-kDa soybean ferritin subunit identified in this study was not susceptible to cleavage. We present evidence that the two different ferritin subunits in soybean dry seeds show differential sensitivity to protease digestions and that the novel, uncleaved 28-kDa ferritin subunit appears to stabilize the ferritin shell by co-existing with the cleaved 26.5-kDa subunit. These data demonstrate that soybean ferritin is composed of at least two different subunits, which have cooperative functional roles in soybean seeds.