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Mitochondrial translocation contact sites: separation of dynamic and stabilizing elements in formation of a TOM–TIM–preprotein supercomplex
Author(s) -
Chacinska Agnieszka,
Rehling Peter,
Guiard Bernard,
Frazier Ann E.,
SchulzeSpecking Agnes,
Pfanner Nikolaus,
Voos Wolfgang,
Meisinger Chris
Publication year - 2003
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdg532
Subject(s) - translocase , intermembrane space , translocase of the outer membrane , translocase of the inner membrane , biology , inner membrane , microbiology and biotechnology , inner mitochondrial membrane , bacterial outer membrane , biophysics , atp–adp translocase , chromosomal translocation , mitochondrial membrane transport protein , mitochondrion , biochemistry , escherichia coli , gene
Preproteins with N‐terminal presequences are imported into mitochondria at translocation contact sites that include the translocase of the outer membrane (TOM complex) and the presequence translocase of the inner membrane (TIM23 complex). Little is known about the functional cooperation of these translocases. We have characterized translocation contact sites by a productive TOM–TIM–preprotein supercomplex to address the role of three translocase subunits that expose domains to the intermembrane space (IMS). The IMS domain of the receptor Tom22 is required for stabilization of the translocation contact site supercomplex. Surprisingly, the N‐terminal segment of the channel Tim23, which tethers the TIM23 complex to the outer membrane, is dispensable for both protein import and generation of the TOM–TIM supercomplex. Tim50, with its large IMS domain, is crucial for generation but not for stabilization of the supercomplex. Thus, Tim50 functions as a dynamic factor and the IMS domain of Tom22 represents a stabilizing element in formation of a productive translocation contact site supercomplex.