Untersuchungen zur Proteintranslokation über die innere Mitochondrienmembran - Regulation der Aktivität des Proteinimportmotors

线粒体对于真核细胞的能量代谢是必不可少的。虽然它们含有自己的遗传装置，但绝大多数线粒体酶是在胞质溶胶中作为前体合成的，并且必须通过内膜的前序列易位酶。前蛋白的转运是通过输入马达的组分，即Tim 44、Pam 18、Pam 16、Mge 1和mtHsp 70的调节和协同作用来完成的。外周膜蛋白Tim44将线粒体伴侣蛋白mtHsp70（酵母中的Ssc1）拴在输入通道的出口，在那里它与输入的多肽链结合。通过mtHsp70与Tim44和肽底物的连续结合循环实现易位。尽管Tim44：mtHsp70相互作用在蛋白质输入中的核心作用，但对该调节蛋白质相互作用的分子机制知之甚少。为了阐明Tim44是如何参与蛋白质转运的，我们将对Tim44进行遗传、生化、生物物理和结构分析，以了解Tim44与mtHsp70相互作用在蛋白质转运到线粒体基质中的机制和调控。

Mitochondria are essential for the energy metabolism of the eukaryotic cell. Although they contain their own genetic apparatus, the vast majority of mitochondrial enzymes are synthesized as precursors in the cytosol and must pass through the presequence translocase of the inner membrane. Translocation of preproteins is accomplished by a regulated and concerted action of the components of the import motor, namely Tim44, Pam18, Pam16, Mge1 and mtHsp70. The peripheral membrane protein Tim44 tethers the mitochondrial chaperone mtHsp70 (Ssc1 in yeast) to the exit of the import channel where it binds to the incoming polypeptide chain. Translocation is achieved by cycles of consecutive binding of mtHsp70 to Tim44 and to the peptide substrate. Despite the central role of the Tim44:mtHsp70 interaction in protein import little is known about the molecular mechanism of that regulatory protein protein interaction. To elucidate how Tim44 is involved in protein translocation, genetic, biochemical, biophysical and structural analyses of Tim44 will be carried out to understand the mechanism and the regulation of the Tim44:mtHsp70 interaction in protein import into the mitochondrial matix.