Membrane protein degradation,by FtsH can be initiated from either end
Membrane protein degradation,by FtsH can be initiated from either end
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DOI：
10.1128/jb.184.17.4775-4782.2002
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发表时间：
2002-09-01
影响因子：
3.2
通讯作者：
Ito, K
中科院分区：
文献类型：
--
作者：
Chiba, S;Akiyama, Y;Ito, K
FtsH是一种膜结合的金属蛋白酶，具有细胞质金属蛋白酶和AAA-ATPase结构域，能降解大肠杆菌中的可溶膜蛋白和完整膜蛋白。在本文中，我们研究了膜包埋底物是如何被这种酶识别的。我们以前发现，FtsH可以通过识别膜蛋白的长度(20多个氨基酸残基)而不是确切的序列，在膜蛋白的N端胞浆尾部启动蛋白降解。随后的蛋白质分解应包括底物错位到胞浆中。我们现在证明，这种酶也可以在C末端的胞浆尾巴上启动蛋白质分解，并且启动效率取决于尾巴的长度。这种降解模式似乎也是进行性的，可以通过紧密折叠的周质结构域来中止。这些结果表明，FtsH可以在N-to-C或C-to-N方向上对膜嵌入的底物表现出处理能力。我们的结果还表明，一些膜蛋白同时受到双向降解。这些结果提出了关于FtsH催化的错位和蛋白质分解的分子方向性的有趣的问题。
FtsH, a membrane-bound metalloprotease, with cytoplasmic metalloprotease and AAA ATPase domains, degrades both soluble and integral membrane proteins in Escherichia coli. In this paper we investigated how membrane-embedded substrates are recognized by this enzyme. We showed previously that FtsH can initiate processive proteollysis at an N-terminal cytosolic tail of a membrane protein, by recognizing its length (more than 20 amino acid residues) but not exact sequence. Subsequent proteolysis should involve dislocation of the substrates into the cytosol. We now show that this enzyme can also initiate proteolysis at a C-terminal cytosolic tail and that the initiation efficiency depends on the length of the tail. This mode of degradation also appeared to be processive, which can be aborted by a tightly folded periplasmic domain. These results indicate that FtsH can exhibit processivity against membrane-embedded substrates in either the N-to-C or C-to-N direction. Our results also suggest that some membrane proteins receive bidirectional degradation simultaneously. These results raise intriguing questions about the molecular directionality of the dislocation and proteolysis catalyzed by FtsH.