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Dive into the research topics where Jan Dudek is active.

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Featured researches published by Jan Dudek.


Cell | 2005

Mitochondrial Presequence Translocase: Switching between TOM Tethering and Motor Recruitment Involves Tim21 and Tim17

Agnieszka Chacinska; Maria Lind; Ann E. Frazier; Jan Dudek; Chris Meisinger; Andreas Geissler; Albert Sickmann; Helmut E. Meyer; Kaye N. Truscott; Bernard Guiard; Nikolaus Pfanner; Peter Rehling

The presequence translocase of the inner mitochondrial membrane (TIM23 complex) operates at a central junction of protein import. It accepts preproteins from the outer membrane TOM complex and directs them to inner membrane insertion or, in cooperation with the presequence translocase-associated motor (PAM), to the matrix. Little is known of how the TIM23 complex coordinates these tasks. We have identified Tim21 (YGR033c) that interacts with the TOM complex. Tim21 is specific for a TIM23 form that cooperates with TOM and promotes inner membrane insertion. Protein translocation into the matrix requires a switch to a Tim21-free, PAM bound presequence translocase. Tim17 is crucial for the switch by performing two separable functions: promotion of inner membrane insertion and binding of Pam18 to form the functional TIM-PAM complex. Thus, the presequence translocase is not a static complex but switches between TOM tethering and PAM binding in a reaction cycle involving Tim21 and Tim17.


Journal of Cell Biology | 2003

A J-protein is an essential subunit of the presequence translocase–associated protein import motor of mitochondria

Kaye N. Truscott; Wolfgang Voos; Ann E. Frazier; Maria Lind; Yanfeng Li; Andreas Geissler; Jan Dudek; Hanne Müller; Albert Sickmann; Helmut E. Meyer; Chris Meisinger; Bernard Guiard; Peter Rehling; Nikolaus Pfanner

Transport of preproteins into the mitochondrial matrix is mediated by the presequence translocase–associated motor (PAM). Three essential subunits of the motor are known: mitochondrial Hsp70 (mtHsp70); the peripheral membrane protein Tim44; and the nucleotide exchange factor Mge1. We have identified the fourth essential subunit of the PAM, an essential inner membrane protein of 18 kD with a J-domain that stimulates the ATPase activity of mtHsp70. The novel J-protein (encoded by PAM18/YLR008c/TIM14) is required for the interaction of mtHsp70 with Tim44 and protein translocation into the matrix. We conclude that the reaction cycle of the PAM of mitochondria involves an essential J-protein.


Nature Structural & Molecular Biology | 2004

Pam16 has an essential role in the mitochondrial protein import motor.

Ann E. Frazier; Jan Dudek; Bernard Guiard; Wolfgang Voos; Yanfeng Li; Maria Lind; Chris Meisinger; Andreas Geissler; Albert Sickmann; Helmut E. Meyer; Virginia Bilanchone; M G Cumsky; Kaye N. Truscott; Nikolaus Pfanner; Peter Rehling

Mitochondrial preproteins destined for the matrix are translocated by two channel-forming transport machineries, the translocase of the outer membrane and the presequence translocase of the inner membrane. The presequence translocase-associated protein import motor (PAM) contains four essential subunits: the matrix heat shock protein 70 (mtHsp70) and its three cochaperones Mge1, Tim44 and Pam18. Here we report that the PAM contains a fifth essential subunit, Pam16 (encoded by Saccharomyces cerevisiae YJL104W), which is selectively required for preprotein translocation into the matrix, but not for protein insertion into the inner membrane. Pam16 interacts with Pam18 and is needed for the association of Pam18 with the presequence translocase and for formation of a mtHsp70–Tim44 complex. Thus, Pam16 is a newly identified type of motor subunit and is required to promote a functional PAM reaction cycle, thereby driving preprotein import into the matrix.


Biochimica et Biophysica Acta | 2013

Mitochondrial protein import: Common principles and physiological networks.

Jan Dudek; Peter Rehling; M. van der Laan

Most mitochondrial proteins are encoded in the nucleus. They are synthesized as precursor forms in the cytosol and must be imported into mitochondria with the help of different protein translocases. Distinct import signals within precursors direct each protein to the mitochondrial surface and subsequently onto specific transport routes to its final destination within these organelles. In this review we highlight common principles of mitochondrial protein import and address different mechanisms of protein integration into mitochondrial membranes. Over the last years it has become clear that mitochondrial protein translocases are not independently operating units, but in fact closely cooperate with each other. We discuss recent studies that indicate how the pathways for mitochondrial protein biogenesis are embedded into a functional network of various other physiological processes, such as energy metabolism, signal transduction, and maintenance of mitochondrial morphology. This article is part of a Special Issue entitled: Protein Import and Quality Control in Mitochondria and Plastids.


Nature Cell Biology | 2007

Motor-free mitochondrial presequence translocase drives membrane integration of preproteins

Martin van der Laan; Michael Meinecke; Jan Dudek; Dana P. Hutu; Maria Lind; Inge Perschil; Bernard Guiard; Richard Wagner; Nikolaus Pfanner; Peter Rehling

The mitochondrial inner membrane is the central energy-converting membrane of eukaryotic cells. The electrochemical proton gradient generated by the respiratory chain drives the ATP synthase. To maintain this proton-motive force, the inner membrane forms a tight barrier and strictly controls the translocation of ions. However, the major preprotein transport machinery of the inner membrane, termed the presequence translocase, translocates polypeptide chains into or across the membrane. Different views exist of the molecular mechanism of the translocase, in particular of the coupling with the import motor of the matrix. We have reconstituted preprotein transport into the mitochondrial inner membrane by incorporating the purified presequence translocase into cardiolipin-containing liposomes. We show that the motor-free form of the presequence translocase integrates preproteins into the membrane. The reconstituted presequence translocase responds to targeting peptides and mediates voltage-driven preprotein translocation, lateral release and insertion into the lipid phase. Thus, the minimal system for preprotein integration into the mitochondrial inner membrane is the presequence translocase, a cardiolipin-rich membrane and a membrane potential.


Stem Cell Research | 2013

Cardiolipin deficiency affects respiratory chain function and organization in an induced pluripotent stem cell model of Barth syndrome

Jan Dudek; I‐Fen Cheng; Martina Balleininger; Frédéric M. Vaz; Katrin Streckfuss-Bömeke; Daniela Hübscher; Milena Vukotic; Peter Rehling; Kaomei Guan

Barth syndrome (BTHS) patients carrying mutations in tafazzin (TAZ1), which is involved in the final maturation of cardiolipin, present with dilated cardiomyopathy, skeletal myopathy, growth retardation and neutropenia. To study how mitochondrial function is impaired in BTHS patients, we generated induced pluripotent stem cells (iPSCs) to develop a novel and relevant human model system for BTHS. BTHS-iPSCs generated from dermal fibroblasts of three patients with different mutations in TAZ1 expressed pluripotency markers, and were able to differentiate into cells derived from all three germ layers both in vitro and in vivo. We used these cells to study the impact of tafazzin deficiency on mitochondrial oxidative phosphorylation. We found an impaired remodeling of cardiolipin, a dramatic decrease in basal oxygen consumption rate and in the maximal respiratory capacity in BTHS-iPSCs. Simultaneous measurement of extra-cellular acidification rate allowed us a thorough assessment of the metabolic deficiency in BTHS patients. Blue native gel analyses revealed that decreased respiration coincided with dramatic structural changes in respiratory chain supercomplexes leading to a massive increase in generation of reactive oxygen species. Our data demonstrate that BTHS-iPSCs are capable of modeling BTHS by recapitulating the disease phenotype and thus are important tools for studying the disease mechanism.


Cell Metabolism | 2015

Cooperation between COA6 and SCO2 in COX2 Maturation during Cytochrome c Oxidase Assembly Links Two Mitochondrial Cardiomyopathies

David Pacheu-Grau; Bettina Bareth; Jan Dudek; Lisa Juris; F. N. Vogtle; Mirjam Wissel; Scot C. Leary; Sven Dennerlein; Peter Rehling; Markus Deckers

Three mitochondria-encoded subunits form the catalytic core of cytochrome c oxidase, the terminal enzyme of the respiratory chain. COX1 and COX2 contain heme and copper redox centers, which are integrated during assembly of the enzyme. Defects in this process lead to an enzyme deficiency and manifest as mitochondrial disorders in humans. Here we demonstrate that COA6 is specifically required for COX2 biogenesis. Absence of COA6 leads to fast turnover of newly synthesized COX2 and a concomitant reduction in cytochrome c oxidase levels. COA6 interacts transiently with the copper-containing catalytic domain of newly synthesized COX2. Interestingly, similar to the copper metallochaperone SCO2, loss of COA6 causes cardiomyopathy in humans. We show that COA6 and SCO2 interact and that corresponding pathogenic mutations in each protein affect complex formation. Our analyses define COA6 as a constituent of the mitochondrial copper relay system, linking defects in COX2 metallation to cardiac cytochrome c oxidase deficiency.


Molecular and Cellular Biology | 2012

The channel-forming Sym1 protein is transported by the TIM23 complex in a presequence-independent manner.

Robert Reinhold; Vivien Krüger; Michael Meinecke; Christian Schulz; Bernhard Schmidt; S. D. Grunau; Bernard Guiard; Nils Wiedemann; M. van der Laan; Richard F. Wagner; Peter Rehling; Jan Dudek

ABSTRACT The majority of multispanning inner mitochondrial membrane proteins utilize internal targeting signals, which direct them to the carrier translocase (TIM22 complex), for their import. MPV17 and its Saccharomyces cerevisiae orthologue Sym1 are multispanning inner membrane proteins of unknown function with an amino-terminal presequence that suggests they may be targeted to the mitochondria. Mutations affecting MPV17 are associated with mitochondrial DNA depletion syndrome (MDDS). Reconstitution of purified Sym1 into planar lipid bilayers and electrophysiological measurements have demonstrated that Sym1 forms a membrane pore. To address the biogenesis of Sym1, which oligomerizes in the inner mitochondrial membrane, we studied its import and assembly pathway. Sym1 forms a transport intermediate at the translocase of the outer membrane (TOM) complex. Surprisingly, Sym1 was not transported into mitochondria by an amino-terminal signal, and in contrast to what has been observed in carrier proteins, Sym1 transport and assembly into the inner membrane were independent of small translocase of mitochondrial inner membrane (TIM) and TIM22 complexes. Instead, Sym1 required the presequence of translocase for its biogenesis. Our analyses have revealed a novel transport mechanism for a polytopic membrane protein in which internal signals direct the precursor into the inner membrane via the TIM23 complex, indicating a presequence-independent function of this translocase.


FEBS Journal | 2013

Uth1 is a mitochondrial inner membrane protein dispensable for post-log-phase and rapamycin-induced mitophagy

Evelyn Welter; Marco Montino; Robert Reinhold; Petra Schlotterhose; Roswitha Krick; Jan Dudek; Peter Rehling; Michael Thumm

Mitochondria are turned over by an autophagic process termed mitophagy. This process is considered to remove damaged, superfluous and aged organelles. However, little is known about how defective organelles are recognized, what types of damage induce turnover, and whether an identical set of factors contributes to degradation under different conditions. Here we systematically compared the mitophagy rate and requirement for mitophagy‐specific proteins during post‐log‐phase and rapamycin‐induced mitophagy. To specifically assess mitophagy of damaged mitochondria, we analyzed cells accumulating proteins prone to degradation due to lack of the mitochondrial AAA‐protease Yme1. While autophagy 32 (Atg32) was required under all tested conditions, the function of Atg33 could be partially bypassed in post‐log‐phase and rapamycin‐induced mitophagy. Unexpectedly, we found that Uth1 was dispensable for mitophagy. A re‐evaluation of its mitochondrial localization revealed that Uth1 is a protein of the inner mitochondrial membrane that is targeted by a cleavable N‐terminal pre‐sequence. In agreement with our functional analyses, this finding excludes a role of Uth1 as a mitochondrial surface receptor.


Embo Molecular Medicine | 2015

Cardiac-specific succinate dehydrogenase deficiency in Barth syndrome.

Jan Dudek; I‐Fen Cheng; Arpita Chowdhury; Katharina Wozny; Martina Balleininger; Robert Reinhold; Silke Grunau; Sylvie Callegari; Karl Toischer; Gerd Hasenfuß; Britta Brügger; Kaomei Guan; Peter Rehling

Barth syndrome (BTHS) is a cardiomyopathy caused by the loss of tafazzin, a mitochondrial acyltransferase involved in the maturation of the glycerophospholipid cardiolipin. It has remained enigmatic as to why a systemic loss of cardiolipin leads to cardiomyopathy. Using a genetic ablation of tafazzin function in the BTHS mouse model, we identified severe structural changes in respiratory chain supercomplexes at a pre‐onset stage of the disease. This reorganization of supercomplexes was specific to cardiac tissue and could be recapitulated in cardiomyocytes derived from BTHS patients. Moreover, our analyses demonstrate a cardiac‐specific loss of succinate dehydrogenase (SDH), an enzyme linking the respiratory chain with the tricarboxylic acid cycle. As a similar defect of SDH is apparent in patient cell‐derived cardiomyocytes, we conclude that these defects represent a molecular basis for the cardiac pathology in Barth syndrome.

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Bernard Guiard

Centre national de la recherche scientifique

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Nikolaus Pfanner

Pierre-and-Marie-Curie University

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Kaomei Guan

Dresden University of Technology

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