Defective ER associated degradation of a model luminal substrate in yeast carrying a mutation in the 4th ER luminal loop of Sec61p.
Defective ER associated degradation of a model luminal substrate in yeast carrying a mutation in the 4th ER luminal loop of Sec61p.
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DOI：
10.1016/j.bbrc.2012.09.136
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发表时间：
2012-11-02
影响因子：
3.1
通讯作者：
Gekakis, Nicholas
中科院分区：
文献类型：
--
作者：
Wheeler, Matthew C.;Gekakis, Nicholas
真核内质网蛋白易位通道的主要成分（酵母中的Sec61p，高等真核生物中的Sec61）从酵母到人类表现出高度的进化保守性。绝大多数真核生物在第4内质网腔环中有一个保守的二酪氨酸。先前，我们通过筛选乙基亚硝基脲（ENU-）诱变小鼠发现，用小鼠Sec61蛋白的组氨酸（Y344H）取代后者的这些酪氨酸会导致小鼠的糖尿病和肝脏脂肪变性，这是内质网应激的结果。为了进一步表征这些小鼠内质网应激的机制，我们在酵母Sec61p （Y345H）中进行了同源突变。我们发现这种突变增加了酵母对内质网应激剂的敏感性，并降低了肌醇需要酶1 （IRE1）的活性。此外，我们发现，虽然这种突变不影响易位，但它确实延迟了模型er相关降解（ERAD）底物CPY*的降解。用丙氨酸取代内质网内的两种酪氨酸导致Sec61蛋白的不稳定，通过过表达Sss1p来挽救Sec61蛋白。该双突变体在Sss1p稳定后仍然缺乏明显的易位缺陷，但在CPY*降解方面表现出类似的缺陷。
The major constituent of the eukaryotic ER protein-translocation channel (Sec61p in yeast, Sec61 in higher eukaryotes) shows a high degree of evolutionary conservation from yeast to humans. The vast majority of eukaryotic species have a conserved di-tyrosine in the 4th ER luminal loop. Previously, we discovered through a screen of ethylnitrosourea- (ENU-) mutagenized mice that substitution of the latter of these tyrosines with histidine (Y344H) of the murine Sec61 protein results in diabetes and hepatic steatosis in mice that is a result of ER stress. To further characterize the mechanism behind ER stress in these mice we made the homologous mutation in yeast Sec61p (Y345H). We found that this mutation increased sensitivity of yeast to ER stressing agents and to reduction of Inositol Requiring Enzyme 1 (IRE1) activity. Furthermore, we found that, while this mutation did not affect translocation, it did delay degradation of the model ER-associated degradation (ERAD) substrate CPY*. Replacing both ER luminal tyrosines with alanines resulted in a destabilization of the Sec61 protein that was rescued by over expression of Sss1p. This double mutant still lacked a noticeable translocation defect after stabilization by Sss1p, but exhibited a similar defect in CPY* degradation.
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Sec61alpha1中的一个点突变导致小鼠糖尿病和肝脏tososisosis。
影响因子：
7.7
作者：
Lloyd DJ;Wheeler MC;Gekakis N
通讯作者：
Gekakis N
影响因子：
4.8
作者：
Willer, Martin;Forte, Gabriella M. A.;Stirling, Colin J.
通讯作者：
Stirling, Colin J.
DOI：
10.1126/science.1209235
发表时间：
2011-11-25
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Smith MH;Ploegh HL;Weissman JS
通讯作者：
Weissman JS
影响因子：
64.5
作者：
Travers, KJ;Patil, CK;Walter, P
通讯作者：
Walter, P
影响因子：
4.8
作者：
Chavan, M;Yan, AX;Lennarz, WJ
通讯作者：
Lennarz, WJ