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Bernard L. Trumpower - One of the best experts on this subject based on the ideXlab platform.
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Intermediate Length Rieske Iron-Sulfur Protein Is Present and Functionally Active in the Cytochrome bc 1Complex of Saccharomyces cerevisiae
Journal of Biological Chemistry, 1999Co-Authors: Jürgen H. Nett, Bernard L. TrumpowerAbstract:Abstract To investigate the relationship between post-translational processing of the Rieske Iron-Sulfur Protein ofSaccharomyces cerevisiae and its assembly into the mitochondrial cytochrome bc 1 complex we used Iron-Sulfur Proteins in which the presequences had been changed by site-directed mutagenesis of the cloned Iron-Sulfur Protein gene, so that the recognition sites for the matrix processing peptidase or the mitochondrial intermediate peptidase (MIP) had been destroyed. When yeast strain JPJ1, in which the gene for the Iron-Sulfur Protein is deleted, was transformed with these constructs on a single copy expression vector, mitochondrial membranes andbc 1 complexes isolated from these strains accumulated intermediate length Iron-Sulfur Proteins in vivo. The cytochrome bc 1 complex activities of these membranes and bc 1 complexes indicate that intermediate Iron-Sulfur Protein (i-ISP) has full activity when compared with that of mature sized Iron-Sulfur Protein (m-ISP). Therefore the Iron-Sulfur cluster must have been inserted before processing of i-ISP to m-ISP by MIP. When Iron-Sulfur Protein is imported into mitochondria in vitro, i-ISP interacts with components of the bc 1 complex before it is processed to m-ISP. These results establish that the Iron-Sulfur cluster is inserted into the apoProtein before MIP cleaves off the second part of the presequence and that this second processing step takes place after i-ISP has been assembled into thebc 1 complex.
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Processing of the Presequence of the Schizosaccharomyces pombe Rieske Iron-Sulfur Protein Occurs in a Single Step and Can Be Converted to Two-step Processing by Mutation of a Single Proline to Serine in the Presequence
Journal of Biological Chemistry, 1998Co-Authors: Jürgen H. Nett, Hermann Schägger, Bernard L. TrumpowerAbstract:Abstract The Iron-Sulfur Proteins of the cytochromebc 1 complexes of Schizosaccharomyces pombe and Saccharomyces cerevisiae contain the three amino acid motif RX(↓)(F/L/I)XX(T/S/G)XXXX(↓) that is typical for Proteins that are cleaved sequentially in two steps by matrix processing peptidase (MPP) and mitochondrial intermediate peptidase (MIP). Despite the presence of this recognition sequence theS. pombe Iron-Sulfur Protein is processed only once during import into mitochondria, whereas the S. cerevisiae Protein is processed in two steps. Import of S. pombe Iron-Sulfur Protein in which the putative MIP or MPP recognition sites are eliminated by site-directed mutagenesis and import of Iron-Sulfur Protein into mitochondria from yeast mutants that lack MIP activity indicate that one step processing of the S. pombeIron-Sulfur Protein is independent of those sites and of MIP activity. Sequencing of the mature Protein obtained after import in vitro and of the endogenous Iron-Sulfur Protein isolated from mitochondrial membranes by preparative 2D-electrophoresis shows that MPP recognizes a second site in the presequence and processing occurs between residues 43 and 44. If proline-20 of the S. pombe presequence is changed into a serine, a second cleavage step is induced. Conversely, if serine-24 of the S. cerevisiae presequence is changed to a proline, the first cleavage step that is normally catalyzed by MPP is blocked, causing precursor Iron-Sulfur Protein to accumulate. Together these results indicate that a single amino acid change in the presequence is responsible for one-step processing in S. pombe versustwo-step processing in S. cerevisiae.
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Alteration of the Midpoint Potential and Catalytic Activity of the Rieske Iron-Sulfur Protein by Changes of Amino Acids Forming Hydrogen Bonds to the Iron-Sulfur Cluster
Journal of Biological Chemistry, 1998Co-Authors: Elke Denke, Torsten Merbitz-zahradnik, Oliver M. Hatzfeld, Christopher H. Snyder, Thomas A. Link, Bernard L. TrumpowerAbstract:Abstract The crystal structure of the bovine Rieske Iron-Sulfur Protein indicates a Sulfur atom (S-1) of the Iron-Sulfur cluster and the Sulfur atom (Sγ) of a cysteine residue that coordinates one of the Iron atoms form hydrogen bonds with the hydroxyl groups of Ser-163 and Tyr-165, respectively. We have altered the equivalent Ser-183 and Tyr-185 in the Saccharomyces cerevisiae Rieske Iron-Sulfur Protein by site-directed mutagenesis of the Iron-Sulfur Protein gene to examine how these hydrogen bonds affect the midpoint potential of the Iron-Sulfur cluster and how changes in the midpoint potential affect the activity of the enzyme. Eliminating the hydrogen bond from the hydroxyl group of Ser-183 to S-1 of the cluster lowers the midpoint potential of the cluster by 130 mV, and eliminating the hydrogen bond from the hydroxyl group of Tyr-185 to Sγ of Cys-159 lowers the midpoint potential by 65 mV. Eliminating both hydrogen bonds has an approximately additive effect, lowering the midpoint potential by 180 mV. Thus, these hydrogen bonds contribute significantly to the positive midpoint potential of the cluster but are not essential for its assembly. The activity of thebc 1 complex decreases with the decrease in midpoint potential, confirming that oxidation of ubiquinol by the Iron-Sulfur Protein is the rate-limiting partial reaction in thebc 1 complex, and that the rate of this reaction is extensively influenced by the midpoint potential of the Iron-Sulfur cluster.
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Two-step Processing Is Not Essential for the Import and Assembly of Functionally Active Iron-Sulfur Protein into the Cytochrome bc1 Complex in Saccharomyces cerevisiae
Journal of Biological Chemistry, 1997Co-Authors: Jürgen H. Nett, Elke Denke, Bernard L. TrumpowerAbstract:Abstract The Iron-Sulfur Protein of the cytochrome bc1 complex is one of a small number of Proteins that are processed in two sequential steps by matrix processing peptidase (MPP) and mitochondrial intermediate peptidase (MIP) during import into Saccharomyces cerevisiae mitochondria. To test whether two-step processing is necessary for import and assembly of the Iron-Sulfur Protein into the cytochrome bc1 complex, we mutagenized the presequence of the Iron-Sulfur Protein to eliminate the original MPP site and replace the MIP site with a new MPP site. The mutated presequence is cleaved and forms mature-sized Protein in a single step, and the mature-sized Iron-Sulfur Protein is correctly targeted to the outer side of the inner mitochondrial membrane in vitro. Mutant Iron-Sulfur Protein which is processed to mature size in one step complements the respiratory deficient phenotype of a yeast strain in which the endogenous gene for the Iron-Sulfur Protein is deleted. These results establish that mature-sized Iron-Sulfur Protein can be formed by single-step processing and assembled into a functionally active form in the cytochrome bc1 complex in S. cerevisiae.
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DISSOCIATION OF IMPORT OF THE RIESKE Iron-Sulfur Protein INTO SACCHAROMYCES CEREVISIAE MITOCHONDRIA FROM PROTEOLYTIC PROCESSING OF THE PRESEQUENCE
Journal of Biological Chemistry, 1996Co-Authors: Jürgen H. Nett, Bernard L. TrumpowerAbstract:Abstract The correlation between the import of the Rieske Iron-Sulfur Protein into the mitochondrial matrix and processing of the precursor Protein by matrix processing peptidase was investigated using high concentrations of metal chelators and Iron-Sulfur Protein in which the recognition site for the matrix processing peptidase was destroyed by site-directed mutagenesis. High concentrations of EDTA and o-phenanthroline inhibit import of Iron-Sulfur Protein into the matrix. The non-chelating structural isomers m-phenanthroline and p-phenanthroline inhibit import similar to o-phenanthroline, indicating that inhibition of import is mainly independent of the metal chelating ability of the compounds. Iron-Sulfur Protein in which the recognition site for the matrix processing peptidase had been destroyed by a point mutation was efficiently imported into the matrix space. Import of this mutant Iron-Sulfur Protein was inhibited by the same concentrations of EDTA and o-phenanthroline which inhibit import of the wild-type Protein. These results indicate that import of the Iron-Sulfur Protein into the mitochondrial matrix is independent of proteolytic processing of the presequence, and that o-phenanthroline together with EDTA inhibits import of Iron-Sulfur Protein into the matrix space of mitochondria by inhibiting a step other than proteolysis of the presequence.
D S Beattie - One of the best experts on this subject based on the ideXlab platform.
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A compensatory double mutation of the alanine-86 to leucine mutant located in the hinge region of the Iron-Sulfur Protein of the yeast cytochrome bc1 complex
Archives of Biochemistry and Biophysics, 2004Co-Authors: C.edward Ebert, D S BeattieAbstract:Abstract Mutations in the hinge region connecting the membrane anchor to the extra-membranous head-group of the Iron–Sulfur Protein can impede proper assembly and function of the cytochrome bc1 complex. Mutating the conserved alanines, residues 86, 90, and 92, located in the hinge region resulted in a 30–50% decrease in enzymatic activity without loss of the Iron–Sulfur Protein [J. Bioenerg. Biomembr. 31 (1999) 215]. The lowered enzymatic activity in the A86L mutant was shown to result from steric interference between the side chains of Leu-86 and Leu-89 [Biochemistry 40 (2001) 327]. The compensatory double mutant A86L/L89A restored activity to wild type levels and relieved the steric hindrance; however, the L89A mutant did not assemble properly into the bc1 complex. Molecular modeling studies of these mutants compared to the wild type have suggested that the hydrophobic residues located in the hinge region are critical to the motion of the head group of the Iron–Sulfur Protein during catalysis.
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Aspartate-186 in the head group of the yeast Iron-Sulfur Protein of the cytochrome bc1 complex contributes to the Protein conformation required for efficient electron transfer.
Biochimica et biophysica acta, 2003Co-Authors: C.edward Ebert, Yudong Wang, Mousumi Ghosh, D S BeattieAbstract:Two conserved charged amino acids, aspartate-186 and arginine-190, localized in the aqueous head region of the Iron-Sulfur Protein of the cytochrome bc(1) complex of yeast mitochondria, were mutated to alanine, glutamate, or asparagine and isoleucine, respectively. The R190I mutation resulted in the complete loss of antimycin- and myxothiazol-sensitive cytochrome c reductase activity due to loss of more than 60% of the Iron-Sulfur Protein in the complex. Mitochondria isolated from the D186A mutant had a 50% decrease in cytochrome c reductase activity but no loss of the Iron-Sulfur Protein or the [2Fe-2S] cluster. The midpoint potential of the [2Fe-2S] cluster of the D186A mutant was decreased from 281 to 178 mV. The D186E and D186N mutations did not result in a loss of cytochrome c reductase activity or content of Iron-Sulfur Protein; however, the redox potential of the [2Fe-2S] cluster of D186N was decreased from 281 to 241 mV. Molecular modeling/dynamics studies predicted that substituting an alanine for Asp-186 causes global structural changes in the head group of the Iron-Sulfur Protein resulting in changes in the orientation of the [2Fe-2S] cluster and consequently a lowered redox potential. The rate of electrogenic proton pumping in the bc(1) complex isolated from mutant D186A reconstituted into proteoliposomes decreased 64%; however, the H(+)/2e(-) ratio of 1.9 was identical in the mutant and the wild-type complexes. The carboxyl binding reagent, N-(ethoxycarbonyl)-2-ethoxyl-1,2-dihydroquinoline (EEDQ) blocked electrogenic proton pumping in the bc(1) complex reconstituted into proteoliposomes without affecting electron transfer resulting in a decrease in the H(+)/2e(-) ratio to 1.2 and 1.1, respectively. EEDQ was bound to the Iron-Sulfur Protein and core Protein II in both the wild type and the D186A mutant, indicating that Asp-186 of the Iron-Sulfur Protein is not required for proton translocation in the bc(1) complex.
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Aspartate-186 in the head group of the yeast Iron–Sulfur Protein of the cytochrome bc1 complex contributes to the Protein conformation required for efficient electron transfer
Biochimica et Biophysica Acta (BBA) - Bioenergetics, 2003Co-Authors: C.edward Ebert, Yudong Wang, Mousumi Ghosh, D S BeattieAbstract:AbstractTwo conserved charged amino acids, aspartate-186 and arginine-190, localized in the aqueous head region of the Iron–Sulfur Protein of the cytochrome bc1 complex of yeast mitochondria, were mutated to alanine, glutamate, or asparagine and isoleucine, respectively. The R190I mutation resulted in the complete loss of antimycin- and myxothiazol-sensitive cytochrome c reductase activity due to loss of more than 60% of the Iron–Sulfur Protein in the complex. Mitochondria isolated from the D186A mutant had a 50% decrease in cytochrome c reductase activity but no loss of the Iron–Sulfur Protein or the [2Fe–2S] cluster. The midpoint potential of the [2Fe–2S] cluster of the D186A mutant was decreased from 281 to 178 mV. The D186E and D186N mutations did not result in a loss of cytochrome c reductase activity or content of Iron–Sulfur Protein; however, the redox potential of the [2Fe–2S] cluster of D186N was decreased from 281 to 241 mV. Molecular modeling/dynamics studies predicted that substituting an alanine for Asp-186 causes global structural changes in the head group of the Iron–Sulfur Protein resulting in changes in the orientation of the [2Fe–2S] cluster and consequently a lowered redox potential. The rate of electrogenic proton pumping in the bc1 complex isolated from mutant D186A reconstituted into proteoliposomes decreased 64%; however, the H+/2e− ratio of 1.9 was identical in the mutant and the wild-type complexes. The carboxyl binding reagent, N-(ethoxycarbonyl)-2-ethoxyl-1,2-dihydroquinoline (EEDQ) blocked electrogenic proton pumping in the bc1 complex reconstituted into proteoliposomes without affecting electron transfer resulting in a decrease in the H+/2e− ratio to 1.2 and 1.1, respectively. EEDQ was bound to the Iron–Sulfur Protein and core Protein II in both the wild type and the D186A mutant, indicating that Asp-186 of the Iron–Sulfur Protein is not required for proton translocation in the bc1 complex
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Mutations in the tether region of the Iron–Sulfur Protein affect the activity and assembly of the cytochrome bc1 complex of yeast mitochondria
Biochimica et Biophysica Acta, 2000Co-Authors: Victor H. Obungu, Yudong Wang, Suzelle M Amyot, Christian B Gocke, D S BeattieAbstract:Abstract Resolution of the crystal structure of the mitochondrial cytochrome bc 1 complex has indicated that the extra-membranous extrinsic domain of the Iron–Sulfur Protein containing the 2Fe2S cluster is connected by a tether to the transmembrane helix that anchors the Iron–Sulfur Protein to the complex. To investigate the role of this tether in the cytochrome bc 1 complex, we have mutated the conserved amino acid residues Ala-86, Ala-90, Ala-92, Lys-93 and Glu-95 and constructed deletion mutants ΔVLA(88–90) and ΔAMA(90–92) and an insertion mutant I87AAA88 in the Iron–Sulfur Protein of the yeast, Saccharomyces cerevisiae . In cells grown at 30°C, enzymatic activities of the bc 1 complex were reduced 22–56% in mutants A86L, A90I, A92C, A92R and E95R, and the deletion mutants, ΔVLA(88–90) and ΔAMA(90–92), while activity of the insertion mutant was reduced 90%. No loss of cytochromes b or c–c 1 , detected spectrally, or the Iron–Sulfur Protein, determined by quantitative immunoblotting, was observed in these mutants with the exception of the mutants of Ala-92 in which the loss of activity paralleled a loss in the amount of the Iron–Sulfur Protein. EPR spectroscopy revealed no changes in the Iron–Sulfur cluster of mutants A86L, A90I, A92R or the deletion mutant ΔVLA(88–90). Greater losses of both Protein and activity were observed in all of the mutants of Ala-92 as well as in A90F grown at 37°C. suggesting that these conserved alanine residues may be involved in maintaining the stability of the Iron–Sulfur Protein and its assembly into the bc 1 complex. By contrast, no significant loss of Iron–Sulfur Protein was observed in the mutants of Ala-86 in cells grown at either 30°C or 37°C despite the 50–70% loss of enzymatic activity suggesting that Ala-86 may play a critical role in catalysis in the bc 1 complex.
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The Role of Charged Amino Acids in the α1-β4 Loop of the Iron-Sulfur Protein of the Cytochrome bc 1Complex of Yeast Mitochondria
Journal of Biological Chemistry, 1998Co-Authors: Victor H. Obungu, Yudong Wang, D S BeattieAbstract:Abstract Previous experiments using deletion mutants of the Iron-Sulfur Protein had indicated that amino acid residues 138–153 might be involved in the assembly of this Protein into the cytochromebc 1 complex. To determine which specific residues might be involved in the assembly process, charged amino acids located in the α1-β4 loop of the Iron-Sulfur Protein were mutated to uncharged residues and tryptophan 152 to phenylalanine. The mutant genes were used to transform yeast cells (JPJ1) lacking the Iron-Sulfur Protein gene. Mutants R146I and W152F had almost undetectable growth in medium containing glycerol/ethanol, whereas mutants D143A, K148I, and D149A grew more slowly than the wild type. Activity of the cytochromebc 1 complex was decreased 50, 90, 67, 89, and 90% in mutants D143A, R146I, K148I, D149A, and W152F, respectively, but unchanged in mutants D139A, Q141I, D145L, and V147S. In all of these mutants except W152F, the cytochrome c 1content, determined by immunoblotting, was comparable with that of wild-type cells. However, immunoblotting revealed that the content of the Iron-Sulfur Protein was decreased proportionately in the five mutants with lowered enzymatic activity and growth suggesting that these amino acids are critical for maintaining the stability of the Iron-Sulfur Protein. The efficiency of assembly in vitrocompared with the wild type determined by selective immunoprecipitation was unchanged in the mutants with the exception of R146I, D149A, and W152F where decreases of 80, 60, and 60%, respectively, were observed suggesting that these amino acids are critical for the proper assembly of the Iron-Sulfur Protein into the bc 1complex.
Jürgen H. Nett - One of the best experts on this subject based on the ideXlab platform.
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Intermediate Length Rieske Iron-Sulfur Protein Is Present and Functionally Active in the Cytochrome bc 1Complex of Saccharomyces cerevisiae
Journal of Biological Chemistry, 1999Co-Authors: Jürgen H. Nett, Bernard L. TrumpowerAbstract:Abstract To investigate the relationship between post-translational processing of the Rieske Iron-Sulfur Protein ofSaccharomyces cerevisiae and its assembly into the mitochondrial cytochrome bc 1 complex we used Iron-Sulfur Proteins in which the presequences had been changed by site-directed mutagenesis of the cloned Iron-Sulfur Protein gene, so that the recognition sites for the matrix processing peptidase or the mitochondrial intermediate peptidase (MIP) had been destroyed. When yeast strain JPJ1, in which the gene for the Iron-Sulfur Protein is deleted, was transformed with these constructs on a single copy expression vector, mitochondrial membranes andbc 1 complexes isolated from these strains accumulated intermediate length Iron-Sulfur Proteins in vivo. The cytochrome bc 1 complex activities of these membranes and bc 1 complexes indicate that intermediate Iron-Sulfur Protein (i-ISP) has full activity when compared with that of mature sized Iron-Sulfur Protein (m-ISP). Therefore the Iron-Sulfur cluster must have been inserted before processing of i-ISP to m-ISP by MIP. When Iron-Sulfur Protein is imported into mitochondria in vitro, i-ISP interacts with components of the bc 1 complex before it is processed to m-ISP. These results establish that the Iron-Sulfur cluster is inserted into the apoProtein before MIP cleaves off the second part of the presequence and that this second processing step takes place after i-ISP has been assembled into thebc 1 complex.
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Processing of the Presequence of the Schizosaccharomyces pombe Rieske Iron-Sulfur Protein Occurs in a Single Step and Can Be Converted to Two-step Processing by Mutation of a Single Proline to Serine in the Presequence
Journal of Biological Chemistry, 1998Co-Authors: Jürgen H. Nett, Hermann Schägger, Bernard L. TrumpowerAbstract:Abstract The Iron-Sulfur Proteins of the cytochromebc 1 complexes of Schizosaccharomyces pombe and Saccharomyces cerevisiae contain the three amino acid motif RX(↓)(F/L/I)XX(T/S/G)XXXX(↓) that is typical for Proteins that are cleaved sequentially in two steps by matrix processing peptidase (MPP) and mitochondrial intermediate peptidase (MIP). Despite the presence of this recognition sequence theS. pombe Iron-Sulfur Protein is processed only once during import into mitochondria, whereas the S. cerevisiae Protein is processed in two steps. Import of S. pombe Iron-Sulfur Protein in which the putative MIP or MPP recognition sites are eliminated by site-directed mutagenesis and import of Iron-Sulfur Protein into mitochondria from yeast mutants that lack MIP activity indicate that one step processing of the S. pombeIron-Sulfur Protein is independent of those sites and of MIP activity. Sequencing of the mature Protein obtained after import in vitro and of the endogenous Iron-Sulfur Protein isolated from mitochondrial membranes by preparative 2D-electrophoresis shows that MPP recognizes a second site in the presequence and processing occurs between residues 43 and 44. If proline-20 of the S. pombe presequence is changed into a serine, a second cleavage step is induced. Conversely, if serine-24 of the S. cerevisiae presequence is changed to a proline, the first cleavage step that is normally catalyzed by MPP is blocked, causing precursor Iron-Sulfur Protein to accumulate. Together these results indicate that a single amino acid change in the presequence is responsible for one-step processing in S. pombe versustwo-step processing in S. cerevisiae.
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Two-step Processing Is Not Essential for the Import and Assembly of Functionally Active Iron-Sulfur Protein into the Cytochrome bc1 Complex in Saccharomyces cerevisiae
Journal of Biological Chemistry, 1997Co-Authors: Jürgen H. Nett, Elke Denke, Bernard L. TrumpowerAbstract:Abstract The Iron-Sulfur Protein of the cytochrome bc1 complex is one of a small number of Proteins that are processed in two sequential steps by matrix processing peptidase (MPP) and mitochondrial intermediate peptidase (MIP) during import into Saccharomyces cerevisiae mitochondria. To test whether two-step processing is necessary for import and assembly of the Iron-Sulfur Protein into the cytochrome bc1 complex, we mutagenized the presequence of the Iron-Sulfur Protein to eliminate the original MPP site and replace the MIP site with a new MPP site. The mutated presequence is cleaved and forms mature-sized Protein in a single step, and the mature-sized Iron-Sulfur Protein is correctly targeted to the outer side of the inner mitochondrial membrane in vitro. Mutant Iron-Sulfur Protein which is processed to mature size in one step complements the respiratory deficient phenotype of a yeast strain in which the endogenous gene for the Iron-Sulfur Protein is deleted. These results establish that mature-sized Iron-Sulfur Protein can be formed by single-step processing and assembled into a functionally active form in the cytochrome bc1 complex in S. cerevisiae.
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DISSOCIATION OF IMPORT OF THE RIESKE Iron-Sulfur Protein INTO SACCHAROMYCES CEREVISIAE MITOCHONDRIA FROM PROTEOLYTIC PROCESSING OF THE PRESEQUENCE
Journal of Biological Chemistry, 1996Co-Authors: Jürgen H. Nett, Bernard L. TrumpowerAbstract:Abstract The correlation between the import of the Rieske Iron-Sulfur Protein into the mitochondrial matrix and processing of the precursor Protein by matrix processing peptidase was investigated using high concentrations of metal chelators and Iron-Sulfur Protein in which the recognition site for the matrix processing peptidase was destroyed by site-directed mutagenesis. High concentrations of EDTA and o-phenanthroline inhibit import of Iron-Sulfur Protein into the matrix. The non-chelating structural isomers m-phenanthroline and p-phenanthroline inhibit import similar to o-phenanthroline, indicating that inhibition of import is mainly independent of the metal chelating ability of the compounds. Iron-Sulfur Protein in which the recognition site for the matrix processing peptidase had been destroyed by a point mutation was efficiently imported into the matrix space. Import of this mutant Iron-Sulfur Protein was inhibited by the same concentrations of EDTA and o-phenanthroline which inhibit import of the wild-type Protein. These results indicate that import of the Iron-Sulfur Protein into the mitochondrial matrix is independent of proteolytic processing of the presequence, and that o-phenanthroline together with EDTA inhibits import of Iron-Sulfur Protein into the matrix space of mitochondria by inhibiting a step other than proteolysis of the presequence.
Ulrich Mühlenhoff - One of the best experts on this subject based on the ideXlab platform.
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the role of mitochondria in cytosolic nuclear Iron Sulfur Protein biogenesis and in cellular Iron regulation
Current Opinion in Microbiology, 2014Co-Authors: Roland Lill, Vasundara Srinivasan, Ulrich MühlenhoffAbstract:Mitochondria are indispensable in eukaryotes because of their function in the maturation of cytosolic and nuclear Iron–Sulfur Proteins that are essential for DNA synthesis and repair, tRNA modification, and Protein translation. The mitochondrial Fe/S cluster assembly machinery not only generates the organelle's Iron–Sulfur Proteins, but also extra-mitochondrial ones. Biogenesis of the latter Proteins requires the mitochondrial ABC transporter Atm1 that exports a Sulfur-containing compound in a glutathione-dependent fashion. The process is further assisted by the cytosolic Iron–Sulfur Protein assembly machinery. Here, we discuss the knowns and unknowns of the mitochondrial export process that is also crucial for signaling the cellular Iron status to the regulatory systems involved in the maintenance of cellular Iron homeostasis.
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The role of mitochondria in cytosolic-nuclear Iron–Sulfur Protein biogenesis and in cellular Iron regulation.
Current Opinion in Microbiology, 2014Co-Authors: Roland Lill, Vasundara Srinivasan, Ulrich MühlenhoffAbstract:Mitochondria are indispensable in eukaryotes because of their function in the maturation of cytosolic and nuclear Iron–Sulfur Proteins that are essential for DNA synthesis and repair, tRNA modification, and Protein translation. The mitochondrial Fe/S cluster assembly machinery not only generates the organelle's Iron–Sulfur Proteins, but also extra-mitochondrial ones. Biogenesis of the latter Proteins requires the mitochondrial ABC transporter Atm1 that exports a Sulfur-containing compound in a glutathione-dependent fashion. The process is further assisted by the cytosolic Iron–Sulfur Protein assembly machinery. Here, we discuss the knowns and unknowns of the mitochondrial export process that is also crucial for signaling the cellular Iron status to the regulatory systems involved in the maintenance of cellular Iron homeostasis.
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cellular and mitochondrial remodeling upon defects in Iron Sulfur Protein biogenesis
Journal of Biological Chemistry, 2008Co-Authors: Anja Hausmann, Roland Lill, Birgit Samans, Ulrich MühlenhoffAbstract:Abstract Biogenesis of Iron-Sulfur (Fe/S) Proteins in eukaryotes is an essential process involving the mitochondrial Iron-Sulfur cluster (ISC) assembly and export machineries and the cytosolic Iron/Sulfur Protein assembly (CIA) apparatus. To define the integration of Fe/S Protein biogenesis into cellular homeostasis, we compared the global transcriptional responses to defects in the three biogenesis systems in Saccharomyces cerevisiae using DNA microarrays. Depletion of a member of the CIA machinery elicited only weak (up to 2-fold) alterations in gene expression with no clear preference for any specific cellular process. In contrast, depletion of components of the mitochondrial ISC assembly and export systems induced strong and largely overlapping transcriptional responses of more than 200 genes (2–100-fold changes). These alterations were strikingly similar, yet not identical, to the transcriptional profiles developed upon Iron starvation. Hence, mitochondria and their ISC systems serve as primary physiological regulators exerting a global control of numerous Iron-dependent processes. First, ISC depletion activates the Iron-responsive transcription factors Aft1/2p leading to increased cellular Iron acquisition. Second, respiration and heme metabolism are repressed ensuring the balanced utilization of Iron by the two major Iron-consuming processes, Iron-Sulfur Protein and heme biosynthesis. Third, the decreased respiratory activity is compensated by induction of genes involved in glucose acquisition. Finally, transcriptional remodeling of the citric acid cycle and the biosyntheses of ergosterol and biotin reflect the Iron dependence of these pathways. Together, our data suggest a model in which mitochondria perform a global regulatory role in numerous cellular processes linked to Iron homeostasis.
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the cfd1 nbp35 complex acts as a scaffold for Iron Sulfur Protein assembly in the yeast cytosol
Nature Chemical Biology, 2007Co-Authors: Daili J A Netz, Ulrich Mühlenhoff, Antonio J Pierik, Martin Stumpfig, Roland LillAbstract:The Cfd1–Nbp35 complex acts as a scaffold for Iron-Sulfur Protein assembly in the yeast cytosol
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Iron Sulfur Protein biogenesis in eukaryotes components and mechanisms
Annual Review of Cell and Developmental Biology, 2006Co-Authors: Roland Lill, Ulrich MühlenhoffAbstract:Iron-Sulfur (Fe/S) clusters require a complex set of Proteins to become assembled and incorporated into apoProteins in a living cell. Researchers have described three distinct assembly systems in eukaryotes that are involved in the maturation of cellular Fe/S Proteins. Mitochondria are central for biogenesis. They contain the ISC-the Iron-Sulfur cluster assembly machinery that was inherited from a similar system of eubacteria in evolution and is involved in biogenesis of all cellular Fe/S Proteins. The basic principle of mitochondrial (and bacterial) Fe/S Protein maturation is the synthesis of the Fe/S cluster on a scaffold Protein before the cluster is transferred to apoProteins. Biogenesis of cytosolic and nuclear Fe/S Proteins is facilitated by the cytosolic Iron-Sulfur Protein assembly (CIA) apparatus. This process requires the participation of mitochondria that export a still unknown component via the ISC export machinery, including an ABC transporter.
Roland Lill - One of the best experts on this subject based on the ideXlab platform.
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the role of mitochondria in cytosolic nuclear Iron Sulfur Protein biogenesis and in cellular Iron regulation
Current Opinion in Microbiology, 2014Co-Authors: Roland Lill, Vasundara Srinivasan, Ulrich MühlenhoffAbstract:Mitochondria are indispensable in eukaryotes because of their function in the maturation of cytosolic and nuclear Iron–Sulfur Proteins that are essential for DNA synthesis and repair, tRNA modification, and Protein translation. The mitochondrial Fe/S cluster assembly machinery not only generates the organelle's Iron–Sulfur Proteins, but also extra-mitochondrial ones. Biogenesis of the latter Proteins requires the mitochondrial ABC transporter Atm1 that exports a Sulfur-containing compound in a glutathione-dependent fashion. The process is further assisted by the cytosolic Iron–Sulfur Protein assembly machinery. Here, we discuss the knowns and unknowns of the mitochondrial export process that is also crucial for signaling the cellular Iron status to the regulatory systems involved in the maintenance of cellular Iron homeostasis.
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The role of mitochondria in cytosolic-nuclear Iron–Sulfur Protein biogenesis and in cellular Iron regulation.
Current Opinion in Microbiology, 2014Co-Authors: Roland Lill, Vasundara Srinivasan, Ulrich MühlenhoffAbstract:Mitochondria are indispensable in eukaryotes because of their function in the maturation of cytosolic and nuclear Iron–Sulfur Proteins that are essential for DNA synthesis and repair, tRNA modification, and Protein translation. The mitochondrial Fe/S cluster assembly machinery not only generates the organelle's Iron–Sulfur Proteins, but also extra-mitochondrial ones. Biogenesis of the latter Proteins requires the mitochondrial ABC transporter Atm1 that exports a Sulfur-containing compound in a glutathione-dependent fashion. The process is further assisted by the cytosolic Iron–Sulfur Protein assembly machinery. Here, we discuss the knowns and unknowns of the mitochondrial export process that is also crucial for signaling the cellular Iron status to the regulatory systems involved in the maintenance of cellular Iron homeostasis.
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cellular and mitochondrial remodeling upon defects in Iron Sulfur Protein biogenesis
Journal of Biological Chemistry, 2008Co-Authors: Anja Hausmann, Roland Lill, Birgit Samans, Ulrich MühlenhoffAbstract:Abstract Biogenesis of Iron-Sulfur (Fe/S) Proteins in eukaryotes is an essential process involving the mitochondrial Iron-Sulfur cluster (ISC) assembly and export machineries and the cytosolic Iron/Sulfur Protein assembly (CIA) apparatus. To define the integration of Fe/S Protein biogenesis into cellular homeostasis, we compared the global transcriptional responses to defects in the three biogenesis systems in Saccharomyces cerevisiae using DNA microarrays. Depletion of a member of the CIA machinery elicited only weak (up to 2-fold) alterations in gene expression with no clear preference for any specific cellular process. In contrast, depletion of components of the mitochondrial ISC assembly and export systems induced strong and largely overlapping transcriptional responses of more than 200 genes (2–100-fold changes). These alterations were strikingly similar, yet not identical, to the transcriptional profiles developed upon Iron starvation. Hence, mitochondria and their ISC systems serve as primary physiological regulators exerting a global control of numerous Iron-dependent processes. First, ISC depletion activates the Iron-responsive transcription factors Aft1/2p leading to increased cellular Iron acquisition. Second, respiration and heme metabolism are repressed ensuring the balanced utilization of Iron by the two major Iron-consuming processes, Iron-Sulfur Protein and heme biosynthesis. Third, the decreased respiratory activity is compensated by induction of genes involved in glucose acquisition. Finally, transcriptional remodeling of the citric acid cycle and the biosyntheses of ergosterol and biotin reflect the Iron dependence of these pathways. Together, our data suggest a model in which mitochondria perform a global regulatory role in numerous cellular processes linked to Iron homeostasis.
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the cfd1 nbp35 complex acts as a scaffold for Iron Sulfur Protein assembly in the yeast cytosol
Nature Chemical Biology, 2007Co-Authors: Daili J A Netz, Ulrich Mühlenhoff, Antonio J Pierik, Martin Stumpfig, Roland LillAbstract:The Cfd1–Nbp35 complex acts as a scaffold for Iron-Sulfur Protein assembly in the yeast cytosol
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Iron Sulfur Protein biogenesis in eukaryotes components and mechanisms
Annual Review of Cell and Developmental Biology, 2006Co-Authors: Roland Lill, Ulrich MühlenhoffAbstract:Iron-Sulfur (Fe/S) clusters require a complex set of Proteins to become assembled and incorporated into apoProteins in a living cell. Researchers have described three distinct assembly systems in eukaryotes that are involved in the maturation of cellular Fe/S Proteins. Mitochondria are central for biogenesis. They contain the ISC-the Iron-Sulfur cluster assembly machinery that was inherited from a similar system of eubacteria in evolution and is involved in biogenesis of all cellular Fe/S Proteins. The basic principle of mitochondrial (and bacterial) Fe/S Protein maturation is the synthesis of the Fe/S cluster on a scaffold Protein before the cluster is transferred to apoProteins. Biogenesis of cytosolic and nuclear Fe/S Proteins is facilitated by the cytosolic Iron-Sulfur Protein assembly (CIA) apparatus. This process requires the participation of mitochondria that export a still unknown component via the ISC export machinery, including an ABC transporter.