Pfanner Lab Homepage

Institute of Biochemistry and Molecular Biology

Nikolaus Pfanner Professor of Biochemistry

We are always interested in qualified postdocs and graduate students.
Please send your application to:

Prof. N. Pfanner
Institute for Biochemistry and Molecular Biology
Hermann-Herder-Str. 7
D-79104 Freiburg
Germany
Telephone: +49 (0)761-203 -5223, Fax: +49 (0)761-203 -5261

e-mail: Nikolaus.Pfanner@biochemie.uni-freiburg.de

Research and Funding

Publications

Lab members

Research topic:

Targeting, translocation and folding of mitochondrial proteins

An important characteristic of eukaryotic cells is their subcellular organization into various compartments. This requires the targeted transport of precursor proteins from the cytosol into the different cell organelles. Major topics of our group are the specific recognition of the preproteins by receptors on the mitochondrial surface, the transport of this preproteins across the outer and inner mitochondrial membranes, and the role of molecular chaperones in the translocation and folding of proteins.

 to see the enlarged version click on the figure

We have identified a high molecular weight protein complex in the outer mitochondrial membrane of the model organism, the yeast Saccharomyces cerevisiae. This translocase of the outer membrane (TOM) contains three import receptors, Tom20, Tom22 and Tom70, and a general import pore (GIP). Tom40 that is essential for cell viability under all growth conditions forms a specific channel for translocation of preproteins. Together with one receptor (Tom22) and three small Tom proteins (Tom5, Tom6 and Tom7), Tom40 forms the stable core of the TOM machinery, the GIP complex of 400 kDa. The interaction of the receptors and GIP with the preproteins will be characterized in vivo, in organello and in vitro. Since all Tom proteins are themselves nuclear-encoded, they are synthesized as preproteins in the cytosol and must be imported into mitochondria. First studies indicate that the assembly of Tom precursors into the TOM machinery is a multi-step process, involving an ordered interaction with nearly all preexisting Tom proteins. The aim of our study is to understand the mechanism of preprotein recognition by receptors, the transport through the GIP and the assembly of the translocase at a molecular level. 

The transport of nuclear-encoded proteins into and across the inner mitochondrial membrane is mechanistically independent of the translocation across the outer membrane. The membrane potential is only necessary for the translocation across the inner membrane. Two major translocation pathways into the inner membrane can be distinguished.
(i) Preproteins with an amino-terminal signal sequence (presequence) are translocated by the TIM23 complex. We have characterized three components of this presequence translocase: Tim17, Tim23 and Tim44. Each protein is essential for the viability of yeast cells and seems to be in direct contact with preproteins during their translocation across the inner membrane. We could show that Tim23 forms a specific, voltage-activated channel for preproteins.
(ii) Hydrophobic proteins with multiple internal targeting signals use the same GIP of the outer membrane, but a different translocase of the inner membrane, termed the TIM22 complex. Tiny Tim proteins in the intermembrane space guide the hydrophobic proteins across this aqueous compartment to the membrane-embedded TIM22 complex that consists of at least three integral membrane proteins, Tim18, Tim22 and Tim54.
The aim is to understand the composition and mechanism of the import machineries in the inner mitochondrial membrane at a molecular level.

click to enlarge figure

A further major topic in our group is the characterization of the role of molecular chaperones in membrane translocation and folding of preproteins. The matrix heat shock protein Hsp70 associates with Tim44 of the inner membrane, binds the preprotein in transit and drives its translocation into the matrix. The co-chaperone Mge1 (mitochondrial GrpE) regulates the ATP-dependent reaction cycle of Hsp70. Mitochondrial Hsp70 and several partners, including Mdj1 (mitochondrial DnaJ), Mge1, Hsp60 and cyclophilin, are involved in the folding of imported proteins.

Funding:

Our work is supported by the German Reserach Foundation (DFG), Collaborative Research Center 746 (SFB 746), Cluster of Excellence - Centre of Biological Signalling Studies (bioss), Spemann Graduate School of Biology and Medicine, Gottfried Wilhelm Leibniz Program, Alexander von Humboldt Foundation, Bundesministerium für Bildung und Forschung and the Fonds der Chemischen Industrie.

Publications of Pfanner lab

2008

Kutik, S., Stojanovski, D., Becker, L., Becker, T., Meinecke, M., Krüger, V., Prinz, C., Meisinger, C., Guiard, B., Wagner, R., Pfanner, N., and Wiedemann, N. (2008). Dissecting membrane insertion of mitochondrial β-barrel proteins. Cell 132, 1011-1024.

Bolender, N., Sickmann, A., Wagner, R., Meisinger, C., and Pfanner, N. (2008). Multiple pathways for sorting mitochondrial precursor proteins. EMBO Rep. 9, 42-49.

Becker, T., Pfannschmidt, S., Guiard, B., Stojanovski, D., Milenkovic, D., Kutik, S., Pfanner, N., Meisinger, C., and Wiedemann, N., (2008). Biogenesis of the mitochondrial TOM complex: Mim1 promotes insertion and assembly of signal-anchored receptors. J. Biol. Chem. 283, 120-127.

Müller, J.M., Milenkovic, D., Guiard, B., Pfanner, N., and Chacinska, A. (2008). Precursor oxidation by Mia40 and Erv1 promotes vectorial transport of proteins into the mitochondrial intermembrane space. Mol. Biol. Cell 19, 226-236.

Stojanovski, D., Müller, J.M., Milenkovic, D., Guiard, B., Pfanner, N., and Chacinska, A. (2008). The MIA system for protein import into the mitochondrial intermembrane space. Biochim. Biophys. Acta, epub October 22, 2007, doi: 10.1016/j.bbamcr.2007.10.004

Gebert, N., Chacinska, A., Wagner, K., Guiard, B., Koehler, C.M., Rehling, P., Pfanner, N., and Wiedemann, N. (2008). Assembly of the three small Tim proteins precedes docking to the mitochondrial carrier translocase. EMBO Rep., in press.

2007

Kutik, S., Guiard, B., Meyer, H.E., Wiedemann, N., and Pfanner, N. (2007). Cooperation of translocase complexes in mitochondrial protein import. J. Cell Biol. 179, 585-591.

Stojanovski, D., Guiard, B., Kozjak-Pavlovic, V., Pfanner, N., and Meisinger, C. (2007). Alternative function for the mitochondrial SAM complex in biogenesis of alpha-helical TOM proteins. J. Cell Biol. 179, 881-893.

Wiedemann, N., van der Laan, M., Hutu, D.P., Rehling, P., and Pfanner, N. (2007). Sorting switch of mitochondrial presequence translocase involves coupling of motor module to respiratory chain. J. Cell Biol. 179, 1115-1122.

Meisinger, C., Pfannschmidt, S., Rissler, M., Milenkovic, D., Becker, T., Stojanovski, D., Youngman, M.J., Jensen, R.E., Chacinska, A., Guiard, B., Pfanner, N., and Wiedemann, N. (2007). The morphology proteins Mdm12/Mmm1 function in the major β-barrel assembly pathway of mitochondria. EMBO J. 26, 2229-2239.

Gabriel, K., Milenkovic, D., Chacinska, A., Müller, J., Guiard, B., Pfanner, N., and Meisinger, C. (2007). Novel mitochondrial intermembrane space proteins as substrates of the MIA import pathway. J. Mol. Biol. 365, 612-620.

Sanjuán Szklarz, L.K., Kozjak-Pavlovic, V., Vögtle, F.-N., Chacinska, A., Milenkovic, D., Vogel, S., Dürr, M., Westermann, B.,Guiard, B., Martinou, J.-C., Borner, C., Pfanner, N., and Meisinger, C. (2007). Preprotein transport machineries of yeast mitochondrial outer membrane are not required for Bax-induced release of intermembrane space proteins. J. Mol. Biol.368, 44-54.

van der Laan, M., Meinecke, M., Dudek, J., Hutu, D.P., Lind, M., Perschil, I., Guiard, B., Wagner, R., Pfanner, N., and Rehling, P. (2007). Motor-free mitochondrial presequence translocase drives membrane integration of preproteins. Nat. Cell Biol., 9, 1152-9.

Stojanovski, D., Pfanner, N., and Wiedemann, N. (2007). Import of proteins into mitochondria. Meth. Cell Biol. 80, 783-806.

Gabriel, K., and Pfanner, N. (2007). The mitochondrial machinery for import of precursor proteins: a review. Meth. Mol. Biol. 390, 99-118.

Bohnert, M., Pfanner, N., and van der Laan, M. (2007). A dynamic machinery for import of mitochondrial precursor proteins. FEBS Lett. 581, 2802-2810.

Milenkovic, D., Müller, J., Stojanovski, D., Pfanner, N., and Chacinska, A. (2007). Diverse mechanisms and machineries for import of mitochondrial proteins. Biol. Chem. 388, 891-897.

Milenkovic, D., Gabriel, K., Guiard, B., Schulze-Specking, A., Pfanner, N., and Chacinska, A. (2007). Biogenesis of the essential Tim9-Tim10 chaperone complex of mitochondria: site-specific recognition of cysteine residues by the intermembrane space receptor Mia40. J. Biol. Chem. 282, 22472-22480.

Reinders, J., Wagner, K., Zahedi, R.P., Stojanovski, D., Eyrich, B., van derLaan, M., Rehling, P., Sickmann, A., Pfanner, N., and Meisinger, C. (2007). Profiling phosphoproteins of yeast mitochondria reveals a role of phosphorylation in assembly of the ATP synthase. Mol. Cell. Proteomics,  6, 1896-906.

2006

Wiedemann, N., Urzica,E., Guiard, B., Müller, H., Lohaus, C., Meyer, H.E., Ryan, M.T., Meisinger, C., Mühlenhoff, U., Lill,R., and Pfanner, N. (2006). Essential role of Isd11 in mitochondrial iron-sulfur cluster synthesis on Isu scaffold proteins. EMBO J. 25, 184-195.

Meinecke, M., Wagner, R., Kovermann, P., Guiard, B., Mick, D.U., Hutu, D.P., Voos, W., Truscott, K.N., Chacinska, A., Pfanner, N., and Rehling, P. (2006). Tim50 maintains the permeability barrier of the mitochondrial inner membrane. Science 312, 1523-1526.

Meisinger, C., Wiedemann, N., Rissler, M., Strub, A., Milenkovic, D., Schönfisch, B., Müller, H., Kozjak, V., and Pfanner, N. (2006). Mitochondrial protein sorting: differentiation of b-barrel assembly by Tom7-mediated segregation of Mdm10. J. Biol. Chem. 281, 22819-22826.

Wiedemann, N., Pfanner, N., and Chacinska, A. (2006). Chaperoning through the mitochondrial intermembrane space. Mol. Cell 21, 145-148.

Zahedi, R.P., Sickmann, A., Boehm, A.M., Winkler, C., Zufall, N., Schönfisch, B., Guiard, B., Pfanner, N. and Meisinger, C. (2006). Proteomic analysis of the yeast mitochondrial outer membrane reveals accumulation of a subclass of preproteins. Mol. Biol. Cell 17, 1436-1450.

Stojanovski, D., Rissler, M., Pfanner, N., and Meisinger, C. (2006). Mitochondrial morphology and protein import – a tight connection? Biochim. Biophys. Acta 1763, 414-421.

Reinders, J., Zahedi, R.P., Pfanner, N., Meisinger, C., and Sickmann, A. (2006). Toward the complete yeast mitochondrial proteome: multidimensional separation techniques for mitochondrial proteomics. J. Proteome Res. 5, 1543-1554.

Meisinger, C., Pfanner, N., and Truscott, K.N. (2006). Isolation of yeast mitochondria. Meth. Mol. Biol. 313, 33-39.

Wiedemann, N., Pfanner, N., and Rehling, P. (2006). Import of precursor proteins into isolated yeast mitochondria. Meth. Mol. Biol. 313, 373-383.

Albrecht, R., Rehling, P., Chacinska, A., Brix, J., Cadamuro, S.A., Volkmer, R., Guiard, B., Pfanner, N., and Zeth, K. (2006). The Tim21 binding domain connects the preprotein translocases of both mitochondrial membranes. EMBO rep. 7, 1233-1238 (Cover Figure).

van der Laan, M., Wiedemann, N., Mick, D.U., Guiard, B., Rehling, P., and Pfanner, N. (2006). A role for Tim21 in membrane-potential-dependent preprotein sorting in mitochondria. Curr. Biol. 16, 2271-2276.

2005

Chacinska, A., Lind, M., Frazier, A.E., Dudek, J., Meisinger, C., Geissler, A., Sickmann, A., Meyer, H.E., Truscott, K.N., Guiard, B., Pfanner, N., and Rehling, P. (2005). Mitochondrial presequence translocase: switching between TOM tethering and motor recruitment involves Tim21 and Tim17. Cell 120, 817-829.

Sanjuán Szklarz, L.K., Guiard, B., Rissler, M., Wiedemann, N., Kozjak, V., van der Laan, M., Lohaus, C., Marcus, K., Meyer, H.E., Chacinska, A., Pfanner, N., and Meisinger, C. (2005). Inactivation of the mitochondrial heat shock protein Zim17 leads to aggregation of matrix Hsp70s followed by pleiotropic effects on morphology and protein biogenesis. J. Mol. Biol.351, 206-218.

van der Laan, M., Chacinska, A., Lind, M., Perschil, I., Sickmann, A., Meyer, H.E., Guiard, B., Meisinger, C., Pfanner, N., and Rehling, P. (2005). Pam17 is required for architecture and translocation activity of the mitochondrial protein import motor. Mol. Cell. Biol. 25, 7449-7458.

Rissler, M., Wiedemann, N., Pfannschmidt, S., Gabriel, K., Guiard, B., Pfanner, N., and Chacinska, A. (2005). The essential mitochondrial protein Erv1 cooperates with Mia40 in biogenesis of intermembrane space proteins. J. Mol. Biol. 353, 485-492.

Voos, W., and Pfanner, N. (2005). The chaperone system of mitochondria. Protein Folding Handbook, Part II (Buchner, J., and Kiefhaber, T., eds.), Wiley-VCH, Weinheim, pp. 1020-1046.

Becker, L., Bannwarth, M., Meisinger, C., Hill, K., Model, K., Krimmer, T., Casadio, R., Truscott, K.N., Schulz, G.E., Pfanner, N., and Wagner, R. (2005). Preprotein translocase of the outer mitochondrial membrane: reconstituted Tom40 forms a characteristic TOM pore. J. Mol. Biol. 353, 1011-1020.

2004

Meisinger, C., Rissler, M., Chacinska, A., Sanjuán Szklarz, L.K., Milenkovic, D., Kozjak, V., Schönfisch, B., Lohaus, C., Meyer, H.E., Yaffe, M.P., Guiard, B., Wiedemann, N., and Pfanner, N. (2004). The mitochondrial morphology protein Mdm10 functions in assembly of the preprotein translocase of the outer membrane. Dev. Cell 7, 61-71 (Cover Figure).

Pfanner, N., Wiedemann, N., Meisinger, C., and Lithgow, T. (2004). Assembling the mitochondrial outer membrane. Nat. Struct. Mol. Biol. 11, 1044-1048.

Frazier, A.E., Dudek, J., Guiard, B., Voos, W., Li, Y., Lind, M., Meisinger, C., Geissler, A., Sickmann, A., Meyer, H.E., Bilanchone, V., Cumsky, M.G., Truscott, K.N., Pfanner, N., and Rehling, P. (2004). Pam16 has an essential role in the mitochondrial protein import motor. Nat. Struct. Mol. Biol. 11, 226-233 (Cover Figure).

Wiedemann, N., Truscott, K.N., Pfannschmidt, S., Guiard, B., Meisinger, C., and Pfanner, N. (2004). Biogenesis of the protein import channel Tom40 of the mitochondrial outer membrane: intermembrane space components are involved in an early stage of the assembly pathway. J. Biol. Chem. 279, 18188-18194.

Rehling, P., Brandner, K., and Pfanner, N. (2004). Mitochondrial import and the twin-pore translocase. Nat. Rev. Mol. Cell Biol. 5, 519-530.

Taylor, R.D., and Pfanner, N. (2004). The protein import and assembly machinery of the mitochondrial outer membrane. Biochim. Biophys. Acta 1658, 37-43.

Milenkovic, D., Kozjak, V., Wiedemann, N., Lohaus, C., Meyer, H.E., Guiard, B., Pfanner, N., and Meisinger, C. (2004). Sam35 of the mitochondrial protein sorting and assembly machinery is a peripheral outer membrane protein essential for cell viability. J. Biol. Chem. 279, 22781-22785.

Li, Y., Dudek, J,. Guiard, B., Pfanner, N., Rehling, P., and Voos, W. (2004). The presequence translocase-associated protein import motor of mitochondria: Pam16 functions in an antagonistic manner to Pam18. J. Biol. Chem. 279, 38047-38054.

Pfanner, N., Wiedemann, N., and Meisinger, C. (2004). Double membrane fusion. Science 305, 1723-1724.

Wiedemann, N., Frazier, A.E., and Pfanner, N. (2004). The protein import machinery of mitochondria. J. Biol. Chem. 279, 14473-14476.

Chacinska, A., Pfannschmidt, S., Wiedemann, N., Kozjak, V., Sanjuán Szklarz, L.K., Schulze-Specking, A., Truscott, K.N., Guiard, B., Meisinger, C., and Pfanner, N. (2004). Essential role of Mia40 in import and assembly of mitochondrial intermembrane space proteins. EMBO J. 23, 3735-3746.

Selected previous publications

Rehling, P., Model, K., Brandner, K., Kovermann, P., Sickmann, A., Meyer, H.E., Kühlbrandt, W., Wagner, R., Truscott, K.N., and Pfanner, N. (2003). Protein insertion into the mitochondrial inner membrane by a twin-pore translocase. Science 299, 1747-1751.

Wiedemann, N., Kozjak, V., Chacinska, A., Schönfisch, B., Rospert, S., Ryan, M.T., Pfanner, N., and Meisinger, C. (2003). Machinery for protein sorting and assembly in the mitochondrial outer membrane. Nature 424, 565-571.

Geissler, A., Chacinska, A., Truscott, K.N., Wiedemann, N., Brandner, K., Sickmann, A., Meyer, H.E., Meisinger, C., Pfanner, N., and Rehling, P. (2002). The mitochondrial presequence translocase: an essential role of Tim50 in directing preproteins to the import channel. Cell 111, 507-518.

van Wilpe, S., Ryan, M.T., Hill, K., Maarse, A.C., Meisinger, C., Brix, J., Dekker, P.J.T., Moczko, M., Wagner, R., Meijer, M., Guiard, B., Hönlinger, A., and Pfanner, N. (1999). Tom22 is a multifunctional organizer of the mitochondrial preprotein translocase. Nature 401, 485-489.

Voisine, C., Craig, E.A., Zufall, N., von Ahsen, O., Pfanner, N., and Voos, W. (1999). The protein import motor of mitochondria: unfolding and trapping of preproteins are distinct and separable functions of matrix Hsp70. Cell 97, 565-574.

Hill, K., Model, K., Ryan, M.T., Dietmeier, K., Martin, F., Wagner, R., and Pfanner, N. (1998). Tom40 forms the hydrophilic channel of the mitochondrial import pore for preproteins. Nature 395, 516-521.

Dietmeier, K., Hönlinger, A., Bömer, U., Dekker, P.J.T., Eckerskorn, C., Lottspeich, F., Kübrich, M., and Pfanner, N. (1997). Tom5 functionally links mitochondrial preprotein receptors to the general import pore. Nature 388, 195-200.

Kiebler, M., Keil, P., Schneider, H., van der Klei, I.J., Pfanner, N., and Neupert, W. (1993). The mitochondrial receptor complex: a central role of MOM22 in mediating preprotein transfer from receptors to the general insertion pore. Cell 74, 483-492.

Pfanner, N., Rassow, J., van der Klei, I.J., and Neupert, W. (1992). A dynamic model of the mitochondrial protein import machinery. Cell 68, 999-1002.

Söllner, T., Rassow, J., Wiedmann, M., Schloßmann, J., Keil, P., Neupert, W., and Pfanner, N. (1992). Mapping of the protein import machinery in the mitochondrial outer membrane by crosslinking of translocation intermediates. Nature355, 84-87.

Schneider, H., Söllner, T., Dietmeier, K., Eckerskorn, C., Lottspeich, F., Trülzsch, B., Neupert, W., and Pfanner, N. (1991). Targeting of the master receptor MOM19 to mitochondria. Science 254, 1659-1662.

Söllner, T., Pfaller, R., Griffiths, G., Pfanner, N., and Neupert, W. (1990). A mitochondrial import receptor for the ADP/ATP carrier. Cell 62, 107-115.

Kiebler, M., Pfaller, R., Söllner, T., Griffiths, G., Horstmann, H., Pfanner, N., and Neupert, W. (1990). Identification of a mitochondrial receptor complex required for recognition and membrane insertion of precursor proteins. Nature 348, 610-616.

Neupert, W., Hartl, F.-U., Craig, E.A., and Pfanner, N. (1990). How do polypeptides cross the mitochondrial membranes? Cell 63, 447-450.

Kang, P.-J., Ostermann, J., Shilling, J., Neupert, W., Craig, E.A., and Pfanner, N. (1990). Requirement for hsp70 in the mitochondrial matrix for translocation and folding of precursor proteins. Nature 348, 137-143.

Söllner, T., Griffiths, G., Pfaller, R., Pfanner, N., and Neupert, W. (1989). MOM19, an import receptor for mitochondrial precursor proteins. Cell 59, 1061-1070.

Pfanner, N., Orci, L., Glick, B.S., Amherdt, M., Arden, S.R., Malhotra, V., and Rothman, J.E. (1989). Fatty acyl-coenzyme A is required for budding of transport vesicles from Golgi cisternae. Cell 59, 95-102.

Pfanner, N., Tropschug, M., and Neupert, W. (1987). Mitochondrial protein import: nucleoside triphosphates are involved in conferring import-competence to precursors. Cell 49, 815-823.

Group members of Pfanner lab:

Former coworkers:

Dr. Agustin Alconada (Biocenter Basel, Switzerland)
Dr. Ulf Bömer (Schering, Berlin)
Dr. Katrin Brandner (Universität Strasbourg)
Dr. Peter Dekker (DSM Food Specialities R&D, Amsterdam, Netherlands)
Dr. Klaus Dietmeier (Jerini Biotools, Berlin)
Dr. Ann Frazier (La Trobe University Melbourne, Australien)
Dr. Kip Gabriel (University of Melbourne, Australia)
Dr. Frank Gärtner (Howard Hughes Medical School, Boston, USA)
Dr. Andreas Geissler (Curacyte AG München)
Dr. Angelika Hönlinger (Novartis, Kundl, Austria)
Dr. Petra Keil (Boston Consulting, Zürich; aktuell Pfizer, New York)
Dr. Vera Kozjak (Universität Berlin)
Dr. Thomas Krimmer (Thieme, Stuttgart)
Dr. Michael Kübrich (Novartis, Nürnberg)
Dr. Martin Kurz (Universitätsklinikum Freiburg)
Dr. Joo Hyun Lim (University of Seoul, Korea)
Dr. Maria Lind (Uppsala University, Schweden)
Dr. Heiko Martin (University of Osaka, Japan)
Dr. Alessio Merlin (Schering, Berlin)
Dr. Martin Moczko (Roche, Penzberg)
Dr. Kirstin Model (MPI Frankfurt)
Hanne Müller (retirement)
Dr. Sylvia Pfannschmidt (ICON Clinical Research GmbH, Langen)
Dr. Thorsten Prinz  (Xzillion GmbH & Co. KG, Frankfurt-Höchst)
Prof. Dr. Joachim Rassow (Universität Bochum)
Prof. Dr. Peter Rehling (Universität Göttingen)
Dr. Sebastian Reif (Universitätsklinikum Freiburg)
Dr. Michael Rissler (Novartis, Basel)
Prof. Dr. Mike T. Ryan (La Trobe University, Melbourne, Australien)
Dr. Sigune Schmidt (Universitätsklinikum Freiburg)
Dr. Andreas Strub (Altana AG, Konstanz)
Dr. Luiza Sanjuan Szklarz (University of Padua, Italy)
Dr. Rebecca Taylor (Agriculture & Agri-Food, Ottawa, Canada)
Dr. Kaye Truscott (La Trobe University, Melbourne, Australien)
Dr. Oliver von Ahsen (La Jolla Institute for Allergy and Immunology, La Jolla, USA)
Prof. Dr. Wolfgang Voos (Universität Bonn)
 

SFB 746 "Funktionelle Spezifität durch Kopplung und Modifikation von Proteinen"

Last updated 07 Apr 08 Jan Brix