Visualization of the interaction between precursor proteins and the outer mitochondrial translocase using cryoEM

  • This thesis investigates the structure of the translocase of the outer membrane (TOM) complex in mitochondria, focusing on the TOM holo complex through single-particle electron cryo-microscopy (cryoEM) complemented by mass spectrometry and computational structure prediction. Mitochondria, crucial for energy production in eukaryotic cells, import most of their proteins from the cytoplasm. These proteins enter through the TOM complex, which in its core form consists of a membrane-embedded homodimer of Tom40 pores, two Tom22 cytoplasmic receptors, and six small TOM stabilizing subunits (Tom7, Tom6, and Tom5). The holo complex includes two additional subunits, Tom70 and Tom20, whose stoichiometry and positioning are less understood due to their easy dissociation during isolation of the complex. CryoEM analysis revealed the high-resolution structure of the Neurospora crassa TOM core complex at 3.3 Å, containing all core subunits, and the presence of a central phospholipid causing the Tom40 dimer to tilt to 20°. Furthermore, a 4 Å resolution map indicated the binding of a precursor protein as it transitions through the translocation barrel. Finally, at 6-7 Å resolution, the structure of the TOM holo complex highlighted Tom20's flexibility as it interacts with the core complex, emphasizing its role in protein translocation. This work provides significant insights into the architecture and functioning of the TOM complex, contributing to the understanding of mitochondrial protein import mechanisms.

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Author:Pamela OrnelasORCiDGND
URN:urn:nbn:de:hebis:30:3-856563
DOI:https://doi.org/10.21248/gups.85656
Place of publication:Frankfurt am Main
Referee:Klaas Martinus PosORCiD, Werner KühlbrandtORCiDGND
Document Type:Doctoral Thesis
Language:English
Date of Publication (online):2024/06/11
Year of first Publication:2023
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Granting Institution:Johann Wolfgang Goethe-Universität
Date of final exam:2024/05/17
Release Date:2024/06/11
Page Number:171
HeBIS-PPN:519025296
Institutes:Biochemie, Chemie und Pharmazie / Biochemie und Chemie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - CC BY-NC - Namensnennung - Nicht kommerziell 4.0 International