HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 281, Issue 32, 22819-22826, August 11, 2006

This Article Full Text Full Text (PDF) All Versions of this Article: 281/32/22819    most recent M602679200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Meisinger, C. Articles by Pfanner, N. Search for Related Content PubMed PubMed Citation Articles by Meisinger, C. Articles by Pfanner, N. Social Bookmarking                      What's this?

Mitochondrial Protein Sorting

DIFFERENTIATION OF -BARREL ASSEMBLY BY Tom7-MEDIATED SEGREGATION OF Mdm10^*

Chris Meisinger¹, Nils Wiedemann¹, Michael Rissler, Andreas Strub², Dusanka Milenkovic, Birgit Schönfisch, Hanne Müller, Vera Kozjak³, and Nikolaus Pfanner⁴

From the Institut für Biochemie und Molekularbiologie and the Fakultät für Biologie, Universität Freiburg, 79104 Freiburg, Germany

The mitochondrial outer membrane contains two distinct machineries for protein import and protein sorting that function in a sequential manner: the general translocase of the outer membrane (TOM complex) and the sorting and assembly machinery (SAM complex), which is dedicated to -barrel proteins. The SAM_core complex consists of three subunits, Sam35, Sam37, and Sam50, that can associate with a fourth subunit, the morphology component Mdm10, to form the SAM_holo complex. Whereas the SAM_core complex is required for the biogenesis of all -barrel proteins, Mdm10 and the SAM_holo complex play a selective role in -barrel biogenesis by promoting assembly of Tom40 but not of porin. We report that Tom7, a conserved subunit of the TOM complex, functions in an antagonistic manner to Mdm10 in biogenesis of Tom40 and porin. We show that Tom7 promotes segregation of Mdm10 from the SAM_holo complex into a low molecular mass form. Upon deletion of Tom7, the fraction of Mdm10 in the SAM_holo complex is significantly increased, explaining the opposing functions of Tom7 and Mdm10 in -barrel sorting. Thus the role of Tom7 is not limited to the TOM complex. Tom7 functions in mitochondrial protein biogenesis by a new mechanism, segregation of a sorting component, leading to a differentiation of -barrel assembly.

Received for publication, March 22, 2006 , and in revised form, May 22, 2006.

^* This work was supported by the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 388, Gottfried Wilhelm Leibniz Program, Max Planck Research Award, Alexander von Humboldt Foundation, Bundesministerium für Bildung und Forschung, and the Fonds der Chemischen Industrie. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ Both authors contributed equally to this work.

² Present address: Dept. of Biochemistry, ALTANA Pharma AG, Byk-Gulden-Str. 2, D-78467 Konstanz, Germany.

³ Present address: Max-Planck-Institut für Infektionsbiologie, Schumannstrasse 21/22, D-10117 Berlin, Germany.

⁴ To whom correspondence should be addressed: Institut für Biochemie und Molekularbiologie, Universität Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany. Tel.: 49-761-203-5224; Fax: 49-761-203-5261; E-mail: nikolaus.pfanner{at}biochemie.uni-freiburg.de.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				Y. Tamura, T. Endo, M. Iijima, and H. Sesaki Ups1p and Ups2p antagonistically regulate cardiolipin metabolism in mitochondria J. Cell Biol., June 15, 2009; 185(6): 1029 - 1045. [Abstract] [Full Text] [PDF]

				T. Becker, S. Pfannschmidt, B. Guiard, D. Stojanovski, D. Milenkovic, S. Kutik, N. Pfanner, C. Meisinger, and N. Wiedemann Biogenesis of the Mitochondrial TOM Complex: Mim1 PROMOTES INSERTION AND ASSEMBLY OF SIGNAL-ANCHORED RECEPTORS J. Biol. Chem., January 4, 2008; 283(1): 120 - 127. [Abstract] [Full Text] [PDF]

				N. C. Chan and T. Lithgow The Peripheral Membrane Subunits of the SAM Complex Function Codependently in Mitochondrial Outer Membrane Biogenesis Mol. Biol. Cell, January 1, 2008; 19(1): 126 - 136. [Abstract] [Full Text] [PDF]

				D. Stojanovski, B. Guiard, V. Kozjak-Pavlovic, N. Pfanner, and C. Meisinger Alternative function for the mitochondrial SAM complex in biogenesis of {alpha}-helical TOM proteins J. Cell Biol., December 3, 2007; 179(5): 881 - 893. [Abstract] [Full Text] [PDF]

				S. Kutik, B. Guiard, H. E. Meyer, N. Wiedemann, and N. Pfanner Cooperation of translocase complexes in mitochondrial protein import J. Cell Biol., November 19, 2007; 179(4): 585 - 591. [Abstract] [Full Text] [PDF]

				L. J. Garcia-Rodriguez, A. C. Gay, and L. A. Pon Puf3p, a Pumilio family RNA binding protein, localizes to mitochondria and regulates mitochondrial biogenesis and motility in budding yeast J. Cell Biol., January 16, 2007; 176(2): 197 - 207. [Abstract] [Full Text] [PDF]