The intrinsically disordered membrane protein selenoprotein S is a reductase in vitro.
The intrinsically disordered membrane protein selenoprotein S is a reductase in vitro.
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DOI：
10.1021/bi4001358
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发表时间：
2013-05-07
期刊：
影响因子：
2.9
通讯作者：
Rozovsky S
中科院分区：
文献类型：
--
作者：
Liu J;Li F;Rozovsky S
硒蛋白 S（SelS、VIMP）是一种本质上无序的膜酶，可针对活性氧化物质提供保护。 SelS 是内质网相关蛋白质降解途径的成员，但其精确的酶功能尚不清楚。由于它含有稀有氨基酸硒代半胱氨酸，因此它属于硒蛋白家族，通常是氧化还原酶。其确切的酶功能是了解细胞如何调节氧化应激反应从而影响人类健康和衰老的关键。为了鉴定其酶功能，我们依靠不具有这种反应残基的形式的聚集来分离出含硒代半胱氨酸的酶。这使我们能够确定 SelS 主要是一种硫氧还蛋白依赖性还原酶。它能够还原过氧化氢，但不是高效或广谱的过氧化物酶。只有含硒代半胱氨酸的酶具有活性。此外，使用电喷雾电离质谱法测定SelS的还原电位为-234 mV。该值与 SelS 作为硫氧还蛋白的伙伴一致。基于这些信息，SelS 可以直接对抗活性氧，但也可能通过尚未识别的底物参与信号传导途径。
Selenoprotein S (SelS, VIMP) is an intrinsically disordered membrane enzyme that provides protection against reactive oxidative species. SelS is a member of the endoplasmic reticulum associated protein degradation pathway but its precise enzymatic function is unknown. Since it contains the rare amino acid selenocysteine, it belongs to the family of selenoproteins, which are typically oxidoreductases. Its exact enzymatic function is key to understanding how the cell regulates the response to oxidative stress and thus influences human health and aging. In order to identify its enzymatic function, we have isolated the selenocysteine-containing enzyme by relying on the aggregation of forms that do not have this reactive residue. That allows us to establish that SelS is primarily a thioredoxin-dependent reductase. It is capable of reducing hydrogen peroxide but is not an efficient or broad-spectrum peroxidase. Only the selenocysteine-containing enzyme is active. In addition, the reduction potential of SelS was determined to be −234 mV using electrospray ionization mass spectrometry. This value agrees with SelS being a partner of thioredoxin. Based on this information, SelS can directly combat reactive oxygen species but is also likely to participate in a signaling pathway, via a yet unidentified substrate.
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