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The genetic interactome of prohibitins: coordinated control of cardiolipin and phosphatidylethanolamine by conserved regulators in mitochondria.

Osman C, Haag M, Potting C, Rodenfels J, Dip PV, Wieland FT, Brügger B, Westermann B, Langer T - J. Cell Biol. (2009)

Bottom Line: We show that Ups1 and Gep1 regulate the levels of cardiolipin and phosphatidylethanolamine in mitochondria in a lipid-specific but coordinated manner.Lipid profiling by mass spectrometry of GEP-deficient mitochondria reveals a critical role of cardiolipin and phosphatidylethanolamine for survival of prohibitin-deficient cells.We propose that prohibitins control inner membrane organization and integrity by acting as protein and lipid scaffolds.

View Article: PubMed Central - PubMed

Affiliation: Institute for Genetics, Centre for Molecular Medicine (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne 50674, Germany.

ABSTRACT
Prohibitin ring complexes in the mitochondrial inner membrane regulate cell proliferation as well as the dynamics and function of mitochondria. Although prohibitins are essential in higher eukaryotes, prohibitin-deficient yeast cells are viable and exhibit a reduced replicative life span. Here, we define the genetic interactome of prohibitins in yeast using synthetic genetic arrays, and identify 35 genetic interactors of prohibitins (GEP genes) required for cell survival in the absence of prohibitins. Proteins encoded by these genes include members of a conserved protein family, Ups1 and Gep1, which affect the processing of the dynamin-like GTPase Mgm1 and thereby modulate cristae morphogenesis. We show that Ups1 and Gep1 regulate the levels of cardiolipin and phosphatidylethanolamine in mitochondria in a lipid-specific but coordinated manner. Lipid profiling by mass spectrometry of GEP-deficient mitochondria reveals a critical role of cardiolipin and phosphatidylethanolamine for survival of prohibitin-deficient cells. We propose that prohibitins control inner membrane organization and integrity by acting as protein and lipid scaffolds.

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The accumulation of PE in mitochondria depends on Gep1. (A) Overexpression of Gep2 or Cho1 allows growth of Δgep1Δphb1 cells. Δgep1Δphb1[PHB1] cells overexpressing Phb1, Gep2, or Cho1 were incubated at 30°C on media with or without 5′ fluoroorotic acid, which prevents growth of cells harboring the [PHB1] expression plasmid. (B) TLC analysis of mitochondrial phospholipids isolated from Δgep1 cells overexpressing Cho1, Ups1, or Gep2. The asterisk indicates an unidentified lipid species. (C) Gep1 and Psd2 interact genetically. Yeast cells were spotted on YP plates containing glucose (YPD) or glycerol (YPG) and incubated at 30°C or 37°C. (D) Synthetic lethal interaction of Δgep1 and Δcrd1. A diploid strain heterozygous for deletions of GEP1 and CRD1 was subjected to sporulation and tetrad dissection. Arrowheads indicate inviable double mutant progeny.
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fig4: The accumulation of PE in mitochondria depends on Gep1. (A) Overexpression of Gep2 or Cho1 allows growth of Δgep1Δphb1 cells. Δgep1Δphb1[PHB1] cells overexpressing Phb1, Gep2, or Cho1 were incubated at 30°C on media with or without 5′ fluoroorotic acid, which prevents growth of cells harboring the [PHB1] expression plasmid. (B) TLC analysis of mitochondrial phospholipids isolated from Δgep1 cells overexpressing Cho1, Ups1, or Gep2. The asterisk indicates an unidentified lipid species. (C) Gep1 and Psd2 interact genetically. Yeast cells were spotted on YP plates containing glucose (YPD) or glycerol (YPG) and incubated at 30°C or 37°C. (D) Synthetic lethal interaction of Δgep1 and Δcrd1. A diploid strain heterozygous for deletions of GEP1 and CRD1 was subjected to sporulation and tetrad dissection. Arrowheads indicate inviable double mutant progeny.

Mentions: To further define the role of Phb1 and Gep1 for mitochondrial morphogenesis and Mgm1 processing, we screened for genes whose overexpression promotes growth of cells lacking both genes. Δgep1Δphb1 cells expressing plasmid-borne PHB1 were transformed with a multicopy yeast library. After plasmid shuffling, the previously uncharacterized GEP2 gene (YDR185c), which codes for a homologue of Gep1, was identified as a multicopy suppressor of the synthetic lethal interaction of Δgep1 and Δphb1 (Fig. 4 A), indicating overlapping functions of members of this conserved protein family.


The genetic interactome of prohibitins: coordinated control of cardiolipin and phosphatidylethanolamine by conserved regulators in mitochondria.

Osman C, Haag M, Potting C, Rodenfels J, Dip PV, Wieland FT, Brügger B, Westermann B, Langer T - J. Cell Biol. (2009)

The accumulation of PE in mitochondria depends on Gep1. (A) Overexpression of Gep2 or Cho1 allows growth of Δgep1Δphb1 cells. Δgep1Δphb1[PHB1] cells overexpressing Phb1, Gep2, or Cho1 were incubated at 30°C on media with or without 5′ fluoroorotic acid, which prevents growth of cells harboring the [PHB1] expression plasmid. (B) TLC analysis of mitochondrial phospholipids isolated from Δgep1 cells overexpressing Cho1, Ups1, or Gep2. The asterisk indicates an unidentified lipid species. (C) Gep1 and Psd2 interact genetically. Yeast cells were spotted on YP plates containing glucose (YPD) or glycerol (YPG) and incubated at 30°C or 37°C. (D) Synthetic lethal interaction of Δgep1 and Δcrd1. A diploid strain heterozygous for deletions of GEP1 and CRD1 was subjected to sporulation and tetrad dissection. Arrowheads indicate inviable double mutant progeny.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
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getmorefigures.php?uid=PMC2654118&req=5

fig4: The accumulation of PE in mitochondria depends on Gep1. (A) Overexpression of Gep2 or Cho1 allows growth of Δgep1Δphb1 cells. Δgep1Δphb1[PHB1] cells overexpressing Phb1, Gep2, or Cho1 were incubated at 30°C on media with or without 5′ fluoroorotic acid, which prevents growth of cells harboring the [PHB1] expression plasmid. (B) TLC analysis of mitochondrial phospholipids isolated from Δgep1 cells overexpressing Cho1, Ups1, or Gep2. The asterisk indicates an unidentified lipid species. (C) Gep1 and Psd2 interact genetically. Yeast cells were spotted on YP plates containing glucose (YPD) or glycerol (YPG) and incubated at 30°C or 37°C. (D) Synthetic lethal interaction of Δgep1 and Δcrd1. A diploid strain heterozygous for deletions of GEP1 and CRD1 was subjected to sporulation and tetrad dissection. Arrowheads indicate inviable double mutant progeny.
Mentions: To further define the role of Phb1 and Gep1 for mitochondrial morphogenesis and Mgm1 processing, we screened for genes whose overexpression promotes growth of cells lacking both genes. Δgep1Δphb1 cells expressing plasmid-borne PHB1 were transformed with a multicopy yeast library. After plasmid shuffling, the previously uncharacterized GEP2 gene (YDR185c), which codes for a homologue of Gep1, was identified as a multicopy suppressor of the synthetic lethal interaction of Δgep1 and Δphb1 (Fig. 4 A), indicating overlapping functions of members of this conserved protein family.

Bottom Line: We show that Ups1 and Gep1 regulate the levels of cardiolipin and phosphatidylethanolamine in mitochondria in a lipid-specific but coordinated manner.Lipid profiling by mass spectrometry of GEP-deficient mitochondria reveals a critical role of cardiolipin and phosphatidylethanolamine for survival of prohibitin-deficient cells.We propose that prohibitins control inner membrane organization and integrity by acting as protein and lipid scaffolds.

View Article: PubMed Central - PubMed

Affiliation: Institute for Genetics, Centre for Molecular Medicine (CMMC), Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne 50674, Germany.

ABSTRACT
Prohibitin ring complexes in the mitochondrial inner membrane regulate cell proliferation as well as the dynamics and function of mitochondria. Although prohibitins are essential in higher eukaryotes, prohibitin-deficient yeast cells are viable and exhibit a reduced replicative life span. Here, we define the genetic interactome of prohibitins in yeast using synthetic genetic arrays, and identify 35 genetic interactors of prohibitins (GEP genes) required for cell survival in the absence of prohibitins. Proteins encoded by these genes include members of a conserved protein family, Ups1 and Gep1, which affect the processing of the dynamin-like GTPase Mgm1 and thereby modulate cristae morphogenesis. We show that Ups1 and Gep1 regulate the levels of cardiolipin and phosphatidylethanolamine in mitochondria in a lipid-specific but coordinated manner. Lipid profiling by mass spectrometry of GEP-deficient mitochondria reveals a critical role of cardiolipin and phosphatidylethanolamine for survival of prohibitin-deficient cells. We propose that prohibitins control inner membrane organization and integrity by acting as protein and lipid scaffolds.

Show MeSH
Related in: MedlinePlus