Article
- The EMBO Journal (2004) 23, 3735 - 3746
- doi:10.1038/sj.emboj.7600389
Published online: 9 September 2004
Subject Categories:
Essential role of Mia40 in import and assembly of mitochondrial intermembrane space proteins
Agnieszka Chacinska1, Sylvia Pfannschmidt1,2, Nils Wiedemann1, Vera Kozjak1,2, Luiza K Sanjuán Szklarz1,2, Agnes Schulze-Specking1, Kaye N Truscott1,a, Bernard Guiard3, Chris Meisinger1 and Nikolaus Pfanner1
- Institut für Biochemie und Molekularbiologie, Universität Freiburg, Freiburg, Germany
- Fakultät für Biologie, Universität Freiburg, Freiburg, Germany
- Centre de Génétique Moléculaire, Laboratoire propre du CNRS associeté à l'Université Pierre et Marie Curie, Gif-sur-Yvette, France
Correspondence to:
Nikolaus Pfanner, Institut für Biochemie und Molekularbiologie, Universität Freiburg, Hermann-Herder-Str. 7, 79104 Freiburg im Breisgau, Germany. Tel.: +49 761 203 5224; Fax: +49 761 203 5261; E-mail: nikolaus.pfanner@biochemie.uni-freiburg.de
aPresent address: Department of Biochemistry, La Trobe University 3086, Melbourne, Australia
Received 9 June 2004; Accepted 9 August 2004
Abstract
Mitochondria import nuclear-encoded precursor proteins to four different subcompartments. Specific import machineries have been identified that direct the precursor proteins to the mitochondrial outer membrane, inner membrane or matrix, respectively. However, a machinery dedicated to the import of mitochondrial intermembrane space (IMS) proteins has not been found so far. We have identified the essential IMS protein Mia40 (encoded by the Saccharomyces cerevisiae open reading frame YKL195w). Mitochondria with a mutant form of Mia40 are selectively inhibited in the import of several small IMS proteins, including the essential proteins Tim9 and Tim10. The import of proteins to the other mitochondrial subcompartments does not depend on functional Mia40. The binding of small Tim proteins to Mia40 is crucial for their transport across the outer membrane and represents an initial step in their assembly into IMS complexes. We conclude that Mia40 is a central component of the protein import and assembly machinery of the mitochondrial IMS.
Keywords:
- mitochondrial intermembrane space,
- protein assembly,
- protein sorting,
- Saccharomyces cerevisiae,
- Tim proteins
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