scholarly journals Functional Analysis of Subunit e of the F1Fo-ATP Synthase of the Yeast Saccharomyces cerevisiae: Importance of the N-Terminal Membrane Anchor Region

2005 ◽  
Vol 4 (2) ◽  
pp. 346-355 ◽  
Author(s):  
Valerie Everard-Gigot ◽  
Cory D. Dunn ◽  
Brigid M. Dolan ◽  
Susanne Brunner ◽  
Robert E. Jensen ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Atp Synthase ◽  
Mitochondrial Membrane ◽  
Critical Role ◽  
Coiled Coil ◽  
Mitochondrial Morphology ◽  
Hydrophobic Region ◽  
Inner Membrane ◽  
E Protein ◽  
Subunit E

ABSTRACT Mitochondrial F1Fo-ATP synthase complexes do not exist as physically independent entities but rather form dimeric and possibly oligomeric complexes in the inner mitochondrial membrane. Stable dimerization of two F1Fo-monomeric complexes involves the physical association of two membrane-embedded Fo-sectors. Previously, formation of the ATP synthase dimeric-oligomeric network was demonstrated to play a critical role in modulating the morphology of the mitochondrial inner membrane. In Saccharomyces cerevisiae, subunit e (Su e) of the Fo-sector plays a central role in supporting ATP synthase dimerization. The Su e protein is anchored to the inner membrane via a hydrophobic region located at its N-terminal end. The hydrophilic C-terminal region of Su e resides in the intermembrane space and contains a conserved coiled-coil motif. In the present study, we focused on characterizing the importance of these regions for the function of Su e. We created a number of C-terminal-truncated derivatives of the Su e protein and expressed them in the Su e null yeast mutant. Mitochondria were isolated from the resulting transformant strains, and a number of functions of Su e were analyzed. Our results indicate that the N-terminal hydrophobic region plays important roles in the Su e-dependent processes of mitochondrial DNA maintenance, modulation of mitochondrial morphology, and stabilization of the dimer-specific Fo subunits, subunits g and k. Furthermore, we show that the C-terminal coiled-coil region of Su e functions to stabilize the dimeric form of detergent-solubilized ATP synthase complexes. Finally, we propose a model to explain how Su e supports the assembly of the ATP synthase dimers-oligomers in the mitochondrial membrane.

scholarly journals Prohibitins Regulate Membrane Protein Degradation by the m-AAA Protease in Mitochondria

1999 ◽  
Vol 19 (5) ◽  
pp. 3435-3442 ◽  
Author(s):  
Gregor Steglich ◽  
Walter Neupert ◽  
Thomas Langer
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Membrane Proteins ◽  
Eukaryotic Cells ◽  
Mitochondrial Morphology ◽  
Regulatory Effect ◽  
Inner Membrane ◽  
Functional Activities ◽  
Native Molecular Mass ◽  
Affect Cell Growth

ABSTRACT Prohibitins comprise a protein family in eukaryotic cells with potential roles in senescence and tumor suppression. Phb1p and Phb2p, members of the prohibitin family in Saccharomyces cerevisiae, have been implicated in the regulation of the replicative life span of the cells and in the maintenance of mitochondrial morphology. The functional activities of these proteins, however, have not been elucidated. We demonstrate here that prohibitins regulate the turnover of membrane proteins by the m-AAA protease, a conserved ATP-dependent protease in the inner membrane of mitochondria. The m-AAA protease is composed of the homologous subunits Yta10p (Afg3p) and Yta12p (Rca1p). Deletion ofPHB1 or PHB2 impairs growth of Δyta10 or Δyta12 cells but does not affect cell growth in the presence of the m-AAA protease. A prohibitin complex with a native molecular mass of approximately 2 MDa containing Phb1p and Phb2p forms a supercomplex with them-AAA protease. Proteolysis of nonassembled inner membrane proteins by the m-AAA protease is accelerated in mitochondria lacking Phb1p or Phb2p, indicating a negative regulatory effect of prohibitins on m-AAA protease activity. These results functionally link members of two conserved protein families in eukaryotes to the degradation of membrane proteins in mitochondria.

scholarly journals Mitochondrial Membrane Dynamics—Functional Positioning of OPA1

Antioxidants ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 186 ◽  
Author(s):  
Hakjoo Lee ◽  
Yisang Yoon
Keyword(s):  
Mitochondrial Membrane ◽  
Proteolytic Cleavage ◽  
Membrane Dynamics ◽  
Mitochondrial Morphology ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Functional Differences ◽  
New Information ◽  
New Development

The maintenance of mitochondrial energetics requires the proper regulation of mitochondrial morphology, and vice versa. Mitochondrial dynamins control mitochondrial morphology by mediating fission and fusion. One of them, optic atrophy 1 (OPA1), is the mitochondrial inner membrane remodeling protein. OPA1 has a dual role in maintaining mitochondrial morphology and energetics through mediating inner membrane fusion and maintaining the cristae structure. OPA1 is expressed in multiple variant forms through alternative splicing and post-translational proteolytic cleavage, but the functional differences between these variants have not been completely understood. Recent studies generated new information regarding the role of OPA1 cleavage. In this review, we will first provide a brief overview of mitochondrial membrane dynamics by describing fission and fusion that are mediated by mitochondrial dynamins. The second part describes OPA1-mediated fusion and energetic maintenance, the role of OPA1 cleavage, and a new development in OPA1 function, in which we will provide new insight for what OPA1 does and what proteolytic cleavage of OPA1 is for.

scholarly journals ROMO1 is required for mitochondrial metabolism during preimplantation embryo development in pigs

Cell Division ◽  
2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Dongjie Zhou ◽  
Ming-Hong Sun ◽  
Song-Hee Lee ◽  
Xiang-Shun Cui
Keyword(s):  
Embryo Development ◽  
Mitochondrial Membrane ◽  
Preimplantation Embryo ◽  
Critical Role ◽  
Ros Generation ◽  
Mitochondrial Morphology ◽  
Ros Production ◽  
Preimplantation Embryo Development ◽  
Induced Defects ◽  
The Impact

Abstract Background Reactive oxygen species (ROS) modulator 1 (ROMO1) is a mitochondrial membrane protein that is essential for the regulation of mitochondrial ROS production and redox sensing. ROMO1 regulates ROS generation within cells and is involved in cellular processes, such as cell proliferation, senescence, and death. Our purpose is to investigates the impact of ROMO1 on the mitochondria during porcine embryogenesis. Results We found that high expression of ROMO1 was associated with porcine preimplantation embryo development, indicating that ROMO1 may contribute to the progression of embryogenesis. Knockdown of ROMO1 disrupted porcine embryo development and blastocyst quality, thereby inducing ROS production and decreasing mitochondrial membrane potential. Knockdown of ROMO1 induced mitochondrial dysfunction by disrupting the balance of OPA1 isoforms to release cytochrome c, reduce ATP, and induce apoptosis. Meanwhile, ROMO1 overexpression showed similar effects as ROMO1 KD on the embryos. Overexpression of ROMO1 rescued the ROMO1 KD-induced defects in embryo development, mitochondrial fragmentation, and apoptosis. Conclusions ROMO1 plays a critical role in embryo development by regulating mitochondrial morphology, function, and apoptosis in pigs.

scholarly journals The SPA2 gene of Saccharomyces cerevisiae is important for pheromone-induced morphogenesis and efficient mating.

1990 ◽  
Vol 111 (4) ◽  
pp. 1451-1464 ◽  
Author(s):  
S Gehrung ◽  
M Snyder
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Critical Role ◽  
Coiled Coil ◽  
Large Deletion ◽  
Yeast Cells ◽  
Mating Pheromone ◽  
Reading Frame ◽  
Distinct Cell ◽  
Polarized Cell Growth ◽  
Mutant Cells

Upon exposure to mating pheromone, Saccharomyces cerevisiae undergoes cellular differentiation to form a morphologically distinct cell called a "shmoo". Double staining experiments revealed that both the SPA2 protein and actin localize to the shmoo tip which is the site of polarized cell growth. Actin concentrates as spots throughout the shmoo projection, while SPA2 localizes as a sharp patch at the shmoo tip. DNA sequence analysis of the SPA2 gene revealed an open reading frame 1,466 codons in length; the predicted protein sequence contains many internal repeats including a nine amino acid sequence that is imperfectly repeated 25 times. Portions of the SPA2 sequence exhibit a low-level similarity to proteins containing coiled-coil structures. Yeast cells containing a large deletion of the SPA2 gene are similar in growth rate to wild-type cells. However, spa2 mutant cells are impaired in their ability to form shmoos upon exposure to mating pheromone, and they do not mate efficiently with other spa2 mutant cells. Thus, we suggest that the SPA2 protein plays a critical role in cellular morphogenesis during mating, perhaps as a cytoskeletal protein.

The GxxxG motif of the transmembrane domain of subunit e is involved in the dimerization/oligomerization of the yeast ATP synthase complex in the mitochondrial membrane

2003 ◽  
Vol 270 (8) ◽  
pp. 1875-1884 ◽  
Author(s):  
Genevieve Arselin ◽  
Marie-France Giraud ◽  
Alain Dautant ◽  
Jacques Vaillier ◽  
Daniel Brethes ◽  
...  
Keyword(s):  
Atp Synthase ◽  
Mitochondrial Membrane ◽  
Transmembrane Domain ◽  
Gxxxg Motif ◽  
Subunit E

scholarly journals Evidence of the Proximity of ATP Synthase Subunits 6 (a) in the Inner Mitochondrial Membrane and in the Supramolecular Forms of Saccharomyces cerevisiae ATP Synthase

2011 ◽  
Vol 286 (41) ◽  
pp. 35477-35484 ◽  
Author(s):  
Jean Velours ◽  
Claire Stines-Chaumeil ◽  
Johan Habersetzer ◽  
Stéphane Chaignepain ◽  
Alain Dautant ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Atp Synthase ◽  
Mitochondrial Membrane ◽  
Transmembrane Helix ◽  
Disulfide Bridge ◽  
Cross Linking ◽  
Null Mutant ◽  
Terminal Part ◽  
Inner Mitochondrial Membrane ◽  
Membrane Spanning

The involvement of subunit 6 (a) in the interface between yeast ATP synthase monomers has been highlighted. Based on the formation of a disulfide bond and using the unique cysteine 23 as target, we show that two subunits 6 are close in the inner mitochondrial membrane and in the solubilized supramolecular forms of the yeast ATP synthase. In a null mutant devoid of supernumerary subunits e and g that are involved in the stabilization of ATP synthase dimers, ATP synthase monomers are close enough in the inner mitochondrial membrane to make a disulfide bridge between their subunits 6, and this proximity is maintained in detergent extract containing this enzyme. The cross-linking of cysteine 23 located in the N-terminal part of the first transmembrane helix of subunit 6 suggests that this membrane-spanning segment is in contact with its counterpart belonging to the ATP synthase monomer that faces it and participates in the monomer-monomer interface.

scholarly journals Pathways shaping the mitochondrial inner membrane

Open Biology ◽  
2021 ◽  
Vol 11 (12) ◽  
Author(s):  
Till Klecker ◽  
Benedikt Westermann
Keyword(s):  
Atp Synthase ◽  
Lipid Composition ◽  
Mitochondrial Membrane ◽  
Contact Site ◽  
Dimer Formation ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Mitochondrial Atp Synthase ◽  
Evolutionarily Conserved ◽  
Mitochondrial Lipid

Mitochondria are complex organelles with two membranes. Their architecture is determined by characteristic folds of the inner membrane, termed cristae. Recent studies in yeast and other organisms led to the identification of four major pathways that cooperate to shape cristae membranes. These include dimer formation of the mitochondrial ATP synthase, assembly of the mitochondrial contact site and cristae organizing system (MICOS), inner membrane remodelling by a dynamin-related GTPase (Mgm1/OPA1), and modulation of the mitochondrial lipid composition. In this review, we describe the function of the evolutionarily conserved machineries involved in mitochondrial cristae biogenesis with a focus on yeast and present current models to explain how their coordinated activities establish mitochondrial membrane architecture.

scholarly journals Ups1p, a conserved intermembrane space protein, regulates mitochondrial shape and alternative topogenesis of Mgm1p

2006 ◽  
Vol 173 (5) ◽  
pp. 651-658 ◽  
Author(s):  
Hiromi Sesaki ◽  
Cory D. Dunn ◽  
Miho Iijima ◽  
Kelly A. Shepard ◽  
Michael P. Yaffe ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitochondrial Protein ◽  
Yeast Cells ◽  
Mitochondrial Morphology ◽  
Intermembrane Space ◽  
Genome Maintenance ◽  
Human Homologue ◽  
Inner Membrane ◽  
Rhomboid Protease ◽  
And Control

Mgm1p is a conserved dynamin-related GTPase required for fusion, morphology, inheritance, and the genome maintenance of mitochondria in Saccharomyces cerevisiae. Mgm1p undergoes unconventional processing to produce two functional isoforms by alternative topogenesis. Alternative topogenesis involves bifurcate sorting in the inner membrane and intramembrane proteolysis by the rhomboid protease Pcp1p. Here, we identify Ups1p, a novel mitochondrial protein required for the unique processing of Mgm1p and for normal mitochondrial shape. Our results demonstrate that Ups1p regulates the sorting of Mgm1p in the inner membrane. Consistent with its function, Ups1p is peripherally associated with the inner membrane in the intermembrane space. Moreover, the human homologue of Ups1p, PRELI, can fully replace Ups1p in yeast cells. Together, our findings provide a conserved mechanism for the alternative topogenesis of Mgm1p and control of mitochondrial morphology.

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