Preprotein translocase of the outer mitochondrial membrane: Reconstituted Tom40 forms a characteristic TOM pore

被引:82
作者
Becker, L
Bannwarth, M
Meisinger, C
Hill, K
Model, K
Krimmer, T
Casadio, R
Truscott, KN
Schulz, GE
Pfanner, N [1 ]
Wagner, R
机构
[1] Univ Osnabruck, FB Biol Chem, D-49034 Osnabruck, Germany
[2] Univ Freiburg, Inst Organ Chem & Biochem, D-79104 Freiburg, Germany
[3] Univ Freiburg, Inst Biochem & Mol Biol, D-79104 Freiburg, Germany
[4] Univ Bologna, Dept Biol, CIRB, Lab Biocomp, I-40126 Bologna, Italy
关键词
mitochondria; Neurospora crassa; protein sorting; Saccharomyces cerevisiae; TOM complex;
D O I
10.1016/j.jmb.2005.09.019
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Tom40 is the central pore-forming component of the translocase of the outer mitochondrial membrane (TOM complex). Different views exist about the secondary structure and electrophysiological characteristics of Tom40 from Saccharomyces cerevisiae and Neurospora crassa. We have directly compared expressed and renatured Tom40 from both species and find a high content of beta-structure in circular dichroism measurements in agreement with refined secondary structure predictions. The electrophysiological characterization of renatured Torn,40 reveals the same characteristics as the purified TOM complex or mitochondrial outer membrane vesicles, with two exceptions. The total conductance of the TOM complex and outer membrane vesicles is twofold higher than the total conductance of renatured Tom40, consistent with the presence of two TOM pores. TOM complex and outer membrane vesicles possess a strongly enhanced sensitivity to a mitochondrial presequence compared to Tom40 alone, in agreement with the presence of several presequence binding sites in the TOM complex, suggesting a role of the non-channel Tom proteins in regulating channel activity. (c) 2005 Elsevier Ltd. All rights reserved.
引用
收藏
页码:1011 / 1020
页数:10
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