Chaperone properties of mammalian mitochondrial translation elongation factor Tu
Chaperone properties of mammalian mitochondrial translation elongation factor Tu
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DOI：
10.1074/jbc.m608187200
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发表时间：
2007-02-09
影响因子：
4.8
通讯作者：
Takeuchi, Nono
中科院分区：
文献类型：
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作者：
Suzuki, Hiroaki;Ueda, Takuya;Takeuchi, Nono
原核生物翻译延长因子Tu(EF-Tu)及其真核转录因子eEF1a的主要功能是将氨基酰tRNA运送到核糖体上的A位。除了这一主要功能外，已有报道称来自不同来源的EF-Tu具有伴侣活性。目前，有关线粒体EF-Tu分子伴侣活性的信息很少。在本研究中，我们研究了哺乳动物线粒体EF-TU(EF-TUMT)的伴侣功能。我们证明了重组EF-TUMT在体外阻止了蛋白质的热聚集并增强了蛋白质的折叠，并且这种EF-TUMT的伴侣活性是以GTP不依赖的方式进行的。我们还证明，在热应激下，新合成的来自线粒体核糖体的多肽与EF-TUMT特异性地免疫共沉淀，并在EF-TUMT过表达的细胞中不稳定。我们发现大多数EF-TUMT定位于线粒体内膜，线粒体核糖体最多的地方。结合最近报道的eEF1a在体内的伴侣功能，我们讨论了EF-TUMT伴侣活性在线粒体蛋白质质量控制中的可能作用。
The main function of the prokaryotic translation elongation factor Tu (EF-Tu) and its eukaryotic counterpart eEF1A is to deliver aminoacyl-tRNA to the A-site on the ribosome. In addition to this primary function, it has been reported that EF-Tu from various sources has chaperone activity. At present, little information is available about the chaperone activity of mitochondrial EF-Tu. In the present study, we have examined the chaperone function of mammalian mitochondrial EF-Tu (EF-Tumt). We demonstrate that recombinant EF-Tumt prevents thermal aggregation of proteins and enhances protein refolding in vitro and that this EF-Tumt chaperone activity proceeds in a GTP-independent manner. We also demonstrate that, under heat stress, the newly synthesized peptides from the mitochondrial ribosome specifically co-immunoprecipitate with EF-Tumt and are destabilized in EF-Tumt-overexpressing cells. We show that most of the EF-Tumt localizes on the mitochondrial inner membrane where most mitochondrial ribosomes are found. We discuss the possible role of EF-Tumt chaperone activity in protein quality control in mitochondria, with regard to the recently reported in vivo chaperone function of eEF1A.