scholarly journals Sequences required for delivery and localization of the ADP/ATP translocator to the mitochondrial inner membrane.

1986 ◽  
Vol 6 (2) ◽  
pp. 626-634 ◽  
Author(s):  
G S Adrian ◽  
M T McCammon ◽  
D L Montgomery ◽  
M G Douglas
Keyword(s):  
Transmembrane Protein ◽  
Nuclear Gene ◽  
Translocator Protein ◽  
Gene Encoding ◽  
Inner Membrane ◽  
Amino Terminal ◽  
Mitochondrial Inner Membrane ◽  
Membrane Anchoring ◽  
High Degree

The ADP/ATP translocator, a transmembrane protein of the mitochondrial inner membrane, is coded in Saccharomyces cerevisiae by the nuclear gene PET9. DNA sequence analysis of the PET9 gene showed that it encoded a protein of 309 amino acids which exhibited a high degree of homology with mitochondrial translocator proteins from other sources. This mitochondrial precursor, in contrast to many others, does not contain a transient presequence which has been shown to direct the posttranslational localization of proteins in the organelle. Gene fusions between the PET9 gene and the gene encoding beta-galactosidase (lacZ) were constructed to define the location of sequences necessary for the mitochondrial delivery of the ADP/ATP translocator protein in vivo. These studies reveal that the information to target the hybrid molecule to the mitochondria is present within the first 115 residues of the protein. In addition, these studies suggest that the "import information" of the amino-terminal region of the ADP/ATP translocator precursor is twofold. In addition to providing targeting function of the precursor to the organelle, these amino-terminal sequences act to prevent membrane-anchoring sequences located between residues 78 and 98 from stopping import at the outer mitochondrial membrane. These results are discussed in light of the function of distinct protein elements at the amino terminus of mitochondrially destined precursors in both organelle delivery and correct membrane localization.

Sequences required for delivery and localization of the ADP/ATP translocator to the mitochondrial inner membrane

1986 ◽  
Vol 6 (2) ◽  
pp. 626-634
Author(s):  
G S Adrian ◽  
M T McCammon ◽  
D L Montgomery ◽  
M G Douglas
Keyword(s):  
Transmembrane Protein ◽  
Nuclear Gene ◽  
Translocator Protein ◽  
Gene Encoding ◽  
Inner Membrane ◽  
Amino Terminal ◽  
Mitochondrial Inner Membrane ◽  
Membrane Anchoring ◽  
High Degree

The ADP/ATP translocator, a transmembrane protein of the mitochondrial inner membrane, is coded in Saccharomyces cerevisiae by the nuclear gene PET9. DNA sequence analysis of the PET9 gene showed that it encoded a protein of 309 amino acids which exhibited a high degree of homology with mitochondrial translocator proteins from other sources. This mitochondrial precursor, in contrast to many others, does not contain a transient presequence which has been shown to direct the posttranslational localization of proteins in the organelle. Gene fusions between the PET9 gene and the gene encoding beta-galactosidase (lacZ) were constructed to define the location of sequences necessary for the mitochondrial delivery of the ADP/ATP translocator protein in vivo. These studies reveal that the information to target the hybrid molecule to the mitochondria is present within the first 115 residues of the protein. In addition, these studies suggest that the "import information" of the amino-terminal region of the ADP/ATP translocator precursor is twofold. In addition to providing targeting function of the precursor to the organelle, these amino-terminal sequences act to prevent membrane-anchoring sequences located between residues 78 and 98 from stopping import at the outer mitochondrial membrane. These results are discussed in light of the function of distinct protein elements at the amino terminus of mitochondrially destined precursors in both organelle delivery and correct membrane localization.

TMEM100 expression suppresses metastasis and enhances sensitivity to chemotherapy in gastric cancer

2020 ◽  
Vol 401 (2) ◽  
pp. 285-296 ◽  
Author(s):  
Jinfu Zhuang ◽  
Yongjian Huang ◽  
Wei Zheng ◽  
Shugang Yang ◽  
Guangwei Zhu ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Transmembrane Protein ◽  
Small Cell Lung Carcinoma ◽  
Migration And Invasion ◽  
Gene Encoding ◽  
Cell Lung Carcinoma ◽  
Chemotherapy Sensitivity ◽  
Promising Target ◽  
The Impact

AbstractThe gene encoding transmembrane protein 100 (TMEM100) was first discovered to be transcribed by the murine genome. It has been recently proven that TMEM100 contributes to hepatocellular carcinoma and non-small-cell lung carcinoma (NSCLC). This study investigates the impact of TMEM100 expression on gastric cancer (GC). TMEM100 expression was remarkably downregulated in GC samples compared to the surrounding non-malignant tissues (p < 0.01). Excessive TMEM100 expression prohibited the migration and invasion of GC cells without influencing their growth. However, TMEM100 knockdown restored their migration and invasion potential. Additionally, TMEM100 expression restored the sensitivity of GC cells to chemotherapeutic drugs such as 5-fluouracil (5-FU) and cisplatin. In terms of TMEM100 modulation, it was revealed that BMP9 rather than BMP10, is the upstream modulator of TM3M100. HIF1α downregulation modulated the impact of TMEM100 on cell migration, chemotherapy sensitivity and invasion in GC cells. Eventually, the in vivo examination of TMEM100 activity revealed that its upregulation prohibits the pulmonary metastasis of GC cells and increases the sensitivity of xenograft tumors to 5-FU treatment. In conclusion, TMEM100 serves as a tumor suppressor in GC and could be used as a promising target for the treatment of GC and as a predictor of GC clinical outcome.

scholarly journals Formation of Membrane-bound Ring Complexes by Prohibitins in Mitochondria

2005 ◽  
Vol 16 (1) ◽  
pp. 248-259 ◽  
Author(s):  
Takashi Tatsuta ◽  
Kirstin Model ◽  
Thomas Langer
Keyword(s):  
Cell Cycle Progression ◽  
Coiled Coil ◽  
Intermembrane Space ◽  
Inner Membrane ◽  
High Molecular Weight Complex ◽  
Amino Terminal ◽  
Mitochondrial Inner Membrane ◽  
Membrane Bound ◽  
Ring Complexes ◽  
Carboxy Terminal

Prohibitins comprise a remarkably conserved protein family in eukaryotic cells with proposed functions in cell cycle progression, senescence, apoptosis, and the regulation of mitochondrial activities. Two prohibitin homologues, Phb1 and Phb2, assemble into a high molecular weight complex of ∼1.2 MDa in the mitochondrial inner membrane, but a nuclear localization of Phb1 and Phb2 also has been reported. Here, we have analyzed the biogenesis and structure of the prohibitin complex in Saccharomyces cerevisiae. Both Phb1 and Phb2 subunits are targeted to mitochondria by unconventional noncleavable targeting sequences at their amino terminal end. Membrane insertion involves binding of newly imported Phb1 to Tim8/13 complexes in the intermembrane space and is mediated by the TIM23-translocase. Assembly occurs via intermediate-sized complexes of ∼120 kDa containing both Phb1 and Phb2. Conserved carboxy-terminal coiled-coil regions in both subunits mediate the formation of large assemblies in the inner membrane. Single particle electron microscopy of purified prohibitin complexes identifies diverse ring-shaped structures with outer dimensions of ∼270 × 200 Å. Implications of these findings for proposed cellular activities of prohibitins are discussed.

DNA sequence and transcript mapping of MOD5: features of the 5' region which suggest two translational starts

1987 ◽  
Vol 7 (1) ◽  
pp. 185-191
Author(s):  
D Najarian ◽  
M E Dihanich ◽  
N C Martin ◽  
A K Hopper
Keyword(s):  
Dna Sequence ◽  
Nuclear Gene ◽  
Open Reading Frame ◽  
Isopentenyl Transferase ◽  
Gene Encoding ◽  
Reading Frame ◽  
Amino Terminal ◽  
Initiation Of Translation ◽  
Cellular Compartments ◽  
Lines Of Evidence

A mutation in the yeast nuclear gene MOD5 drastically reduces the biosynthesis of the modified base isopentenyladenosine in tRNAs located in different cellular compartments: the mitochondria and the nucleus or cytoplasm. Several lines of evidence strongly suggest that MOD5 is the structural gene encoding the tRNA-modifying enzyme delta 2-isopentenyl pyrophosphate:tRNA isopentenyl transferase. DNA sequence analysis of MOD5 reveals an open reading frame of 428 amino acids. A set of mRNAs heterogeneous at both the 5' and 3' termini are transcribed from this gene. Although all of these transcripts initiate upstream of the first AUG codon of the open reading frame, a subset has an extremely short (greater than or equal to 1 base) 5' leader. Furthermore, in positions important for efficient initiation of translation and generally occupied by purines, this first AUG codon is flanked by a U (position -3) and a C (position +4). It is possible that two proteins, one with an amino-terminal extension of basic charge, could be generated from the MOD5 gene via differential translational starts.

scholarly journals Atp10p Assists Assembly of Atp6p into the F0Unit of the Yeast Mitochondrial ATPase

2004 ◽  
Vol 279 (19) ◽  
pp. 19775-19780 ◽  
Author(s):  
Alexander Tzagoloff ◽  
Antoni Barrientos ◽  
Walter Neupert ◽  
Johannes M. Herrmann
Keyword(s):  
Nuclear Gene ◽  
Mitochondrial Atpase ◽  
Gene Products ◽  
Wild Type ◽  
Mitochondrial Translation ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Inner Membrane ◽  
Atpase Subunits ◽  
Specific Factors

The F0F1-ATPase complex of yeast mitochondria contains three mitochondrial and at least 17 nuclear gene products. The coordinate assembly of mitochondrial and cytosolic translation products relies on chaperones and specific factors that stabilize the pools of some unassembled subunits. Atp10p was identified as a mitochondrial inner membrane component necessary for the biogenesis of the hydrophobic F0sector of the ATPase. Here we show that, following its synthesis on mitochondrial ribosomes, subunit 6 of the ATPase (Atp6p) can be cross-linked to Atp10p. This interaction is required for the integration of Atp6p into a partially assembled subcomplex of the ATPase. Pulse labeling and chase of mitochondrial translation productsin vivoindicate that Atp6p is less stable and more rapidly degraded in anatp10null mutant than in wild type. Based on these observations, we propose Atp10p to be an Atp6p-specific chaperone that facilitates the incorporation of Atp6p into an intermediate subcomplex of ATPase subunits.

scholarly journals The inner membrane protein Mdm33 controls mitochondrial morphology in yeast

2003 ◽  
Vol 160 (4) ◽  
pp. 553-564 ◽  
Author(s):  
Marlies Messerschmitt ◽  
Stefan Jakobs ◽  
Frank Vogel ◽  
Stefan Fritz ◽  
Kai Stefan Dimmer ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Hollow Spheres ◽  
Ultrastructural Level ◽  
Mitochondrial Morphology ◽  
Membrane Structures ◽  
Matrix Space ◽  
Gene Encoding ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Inner Membrane Protein

Mitochondrial distribution and morphology depend on MDM33, a Saccharomyces cerevisiae gene encoding a novel protein of the mitochondrial inner membrane. Cells lacking Mdm33 contain ring-shaped, mostly interconnected mitochondria, which are able to form large hollow spheres. On the ultrastructural level, these aberrant organelles display extremely elongated stretches of outer and inner membranes enclosing a very narrow matrix space. Dilated parts of Δmdm33 mitochondria contain well-developed cristae. Overexpression of Mdm33 leads to growth arrest, aggregation of mitochondria, and generation of aberrant inner membrane structures, including septa, inner membrane fragments, and loss of inner membrane cristae. The MDM33 gene is required for the formation of net-like mitochondria in mutants lacking components of the outer membrane fission machinery, and mitochondrial fusion is required for the formation of extended ring-like mitochondria in cells lacking the MDM33 gene. The Mdm33 protein assembles into an oligomeric complex in the inner membrane where it performs homotypic protein–protein interactions. Our results indicate that Mdm33 plays a distinct role in the mitochondrial inner membrane to control mitochondrial morphology. We propose that Mdm33 is involved in fission of the mitochondrial inner membrane.

scholarly journals Effect of Tim23 knockdown in vivo on mitochondrial protein import and retrograde signaling to the UPRmt in muscle

2018 ◽  
Vol 315 (4) ◽  
pp. C516-C526 ◽  
Author(s):  
Ashley N. Oliveira ◽  
David A. Hood
Keyword(s):  
Protein Import ◽  
Protein Quality ◽  
Mitochondrial Protein ◽  
Nuclear Gene ◽  
Inhibitory Effect ◽  
Feedback Mechanism ◽  
Retrograde Signaling ◽  
Inner Membrane ◽  
The Face

The mitochondrial unfolded protein response (UPRmt) is a protein quality control mechanism that strives to achieve proteostasis in the face of misfolded proteins. Because of the reliance of mitochondria on both the nuclear and mitochondrial genomes, a perturbation of the coordination of these genomes results in a mitonuclear imbalance in which holoenzymes are unable to assume mature stoichiometry and thereby activates the UPRmt. Thus, we sought to perturb this genomic coordination by using a systemic antisense oligonucleotide (in vivo morpholino) targeted to translocase of the inner membrane channel subunit 23 (Tim23), the major channel of the inner membrane. This resulted in a 40% reduction in Tim23 protein content, a 32% decrease in matrix-destined protein import, and a trend to elevate reactive oxygen species (ROS) emission under maximal respiration conditions. This import defect activated the C/EBP homologous protein (CHOP) branch of the UPRmt, as evident from increases in caseinolytic mitochondrial matrix peptidase proteolytic subunit (ClpP) and chaperonin 10 (cpn10) but not the activating transcription factor 5 (ATF5) arm. Thus, in the face of proteotoxic stress, CHOP and ATF5 could be activated independently to regain proteostasis. Our second aim was to investigate the role of proteolytically derived peptides in mediating retrograde signaling. Peptides released from the mitochondrion following basal proteolysis were isolated and incubated with import reactions. Dose- and time-dependent effect of peptides on protein import was observed. Our data suggest that mitochondrial proteolytic byproducts exert an inhibitory effect on protein import, possibly to reduce excessive protein import as a potential negative feedback mechanism. The inhibition of import into the organelle also serves a retrograde function, possibly via ROS emission, to modify nuclear gene expression and ultimately improve folding capacity.

scholarly journals Mitochondrial inner-membrane protease Yme1 degrades outer-membrane proteins Tom22 and Om45

2017 ◽  
Vol 217 (1) ◽  
pp. 139-149 ◽  
Author(s):  
Xi Wu ◽  
Lanlan Li ◽  
Hui Jiang
Keyword(s):  
Outer Membrane ◽  
Outer Membrane Proteins ◽  
Ubiquitin Proteasome System ◽  
Mitochondrial Outer Membrane ◽  
Intermembrane Space ◽  
Inner Membrane ◽  
Mitochondrial Proteome ◽  
Mitochondrial Inner Membrane ◽  
Ubiquitin Proteasome

Mitochondria are double-membraned organelles playing essential metabolic and signaling functions. The mitochondrial proteome is under surveillance by two proteolysis systems: the ubiquitin–proteasome system degrades mitochondrial outer-membrane (MOM) proteins, and the AAA proteases maintain the proteostasis of intramitochondrial compartments. We previously identified a Doa1–Cdc48-Ufd1-Npl4 complex that retrogradely translocates ubiquitinated MOM proteins to the cytoplasm for degradation. In this study, we report the unexpected identification of MOM proteins whose degradation requires the Yme1-Mgr1-Mgr3 i-AAA protease complex in mitochondrial inner membrane. Through immunoprecipitation and in vivo site-specific photo–cross-linking experiments, we show that both Yme1 adapters Mgr1 and Mgr3 recognize the intermembrane space (IMS) domains of the MOM substrates and facilitate their recruitment to Yme1 for proteolysis. We also provide evidence that the cytoplasmic domain of substrate can be dislocated into IMS by the ATPase activity of Yme1. Our findings indicate a proteolysis pathway monitoring MOM proteins from the IMS side and suggest that the MOM proteome is surveilled by mitochondrial and cytoplasmic quality control machineries in parallel.

scholarly journals GCS1, an Arf Guanosine Triphosphatase-activating Protein in Saccharomyces cerevisiae, Is Required for Normal Actin Cytoskeletal Organization In Vivo and Stimulates Actin Polymerization In Vitro

1999 ◽  
Vol 10 (3) ◽  
pp. 581-596 ◽  
Author(s):  
Ira J. Blader ◽  
M. Jamie T. V. Cope ◽  
Trevor R. Jackson ◽  
Adam A. Profit ◽  
Angela F. Greenwood ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Actin Cytoskeleton ◽  
Actin Polymerization ◽  
Synthetic Lethality ◽  
Null Alleles ◽  
Gene Encoding ◽  
Amino Terminal ◽  
Guanosine Triphosphatase

Recent cloning of a rat brain phosphatidylinositol 3,4,5-trisphosphate binding protein, centaurin α, identified a novel gene family based on homology to an amino-terminal zinc-binding domain. In Saccharomyces cerevisiae, the protein with the highest homology to centaurin α is Gcs1p, the product of theGCS1 gene. GCS1 was originally identified as a gene conditionally required for the reentry of cells into the cell cycle after stationary phase growth. Gcs1p was previously characterized as a guanosine triphosphatase-activating protein for the small guanosine triphosphatase Arf1, and gcs1 mutants displayed vesicle-trafficking defects. Here, we have shown that similar to centaurin α, recombinant Gcs1p bound phosphoinositide-based affinity resins with high affinity and specificity. A novelGCS1 disruption strain (gcs1Δ) exhibited morphological defects, as well as mislocalization of cortical actin patches. gcs1Δ was hypersensitive to the actin monomer-sequestering drug, latrunculin-B. Synthetic lethality was observed between null alleles of GCS1 andSLA2, the gene encoding a protein involved in stabilization of the actin cytoskeleton. In addition, synthetic growth defects were observed between null alleles of GCS1 andSAC6, the gene encoding the yeast fimbrin homologue. Recombinant Gcs1p bound to actin filaments, stimulated actin polymerization, and inhibited actin depolymerization in vitro. These data provide in vivo and in vitro evidence that Gcs1p interacts directly with the actin cytoskeleton in S. cerevisiae.

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