Molecular characterization of artemin and ferritin from Artemia franciscana
Molecular characterization of artemin and ferritin from Artemia franciscana
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DOI：
10.1046/j.1432-1033.2003.03373.x
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发表时间：
2003-01-01
期刊：
影响因子：
--
通讯作者：
MacRae, TH
中科院分区：
文献类型：
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作者：
Chen, T;Amons, R;MacRae, TH
丰年虾（Artemia franciscana）的胚胎表现出对生理应激的显着抵抗力，这在时间上与两种蛋白质的存在相关，一种是称为 p26 的小型热休克/α-晶状体蛋白，另一种称为 artemin，功能未知。 Artemin 之前通过 Edman 降解进行了测序，并确定了它与铁蛋白（一种铁储存蛋白）的关系。从 Artemia 表达的 artemin 和铁蛋白 cDNA 序列标签库中分离扩展了这项工作。 Artemin cDNA含有693个核苷酸的ORF，其推导的氨基酸序列（除起始子蛋氨酸外）与之前确定的一致。铁蛋白 cDNA 长度为 725 bp，ORF 为 516 个核苷酸。 Artemin 氨基酸残基 32-185 与铁蛋白最相似，但 Artemin 富含半胱氨酸。半胱氨酸的丰度及其分子内空间分布表明，artemin 可以保护胚胎免受氧化损伤和/或其功能受到氧化还原调节。 artemin 和铁蛋白单体中的保守区域在结构上彼此相似，并且两种蛋白质都组装成寡聚物。然而，四级结构的建模表明，artemin 多聚体缺乏铁蛋白寡聚体特征的用于金属存储的中心空间，这意味着该蛋白质具有不同的作用。 Northern 印迹的探测揭示了两个 artemin 转录本，一个为 3.5 kb，另一个为 2.2 kb。这些转录本同时减少，并在发育 16 小时时几乎消失。 0.8 kb 的铁蛋白转录物在重新开始发育期间略有增加，然后下降，并在 16 小时时几乎完全消失。显然，胚胎发育过程中artemin和铁蛋白的损失是由于蛋白质的转录调节和蛋白水解降解造成的。
Embryos of the brine shrimp, Artemia franciscana , exhibit remarkable resistance to physiological stress, which is temporally correlated with the presence of two proteins, one a small heat shock/alpha-crystallin protein termed p26 and the other called artemin, of unknown function. Artemin was sequenced previously by Edman degradation, and its relationship to ferritin, an iron storage protein, established. The isolation from an Artemia expressed sequence tag library of artemin and ferritin cDNAs extends this work. Artemin cDNA was found to contain an ORF of 693 nucleotides, and its deduced amino-acid sequence, except for the initiator methionine, was identical with that determined previously. Ferritin cDNA is 725 bp in length with an ORF of 516 nucleotides. Artemin amino-acid residues 32-185 are most similar to ferritin, but artemin is enriched in cysteines. The abundance of cysteines and their intramolecular spatial distribution suggest that artemin protects embryos against oxidative damage and/or that its function is redox regulated. The conserved regions in artemin and ferritin monomers are structurally similar to one another and both proteins assemble into oligomers. However, modeling of the quaternary structure indicated that artemin multimers lack the central space used for metal storage that characterizes ferritin oligomers, implying different roles for this protein. Probing of Northern blots revealed two artemin transcripts, one of 3.5 kb and another of 2.2 kb. These transcripts decreased in parallel and had almost disappeared by 16 h of development. The ferritin transcript of 0.8 kb increased slightly during reinitiation of development, then declined, and was almost completely gone by 16 h. Clearly, the loss of artemin and ferritin during embryo development is due to transcriptional regulation and proteolytic degradation of the proteins.