scholarly journals A novel motif in the yeast mitochondrial dynamin Dnm1 is essential for adaptor binding and membrane recruitment

2012 ◽  
Vol 199 (4) ◽  
pp. 613-622 ◽  
Author(s):  
Huyen T. Bui ◽  
Mary A. Karren ◽  
Debjani Bhar ◽  
Janet M. Shaw
Keyword(s):  
Mitochondrial Membrane ◽  
Mitochondrial Fission ◽  
Adaptor Proteins ◽  
Structural Features ◽  
Outer Mitochondrial Membrane ◽  
Membrane Recruitment ◽  
Suppressor Mutations ◽  
Guanosine Triphosphatase ◽  
Related Proteins ◽  
Binding Interfaces

To initiate mitochondrial fission, dynamin-related proteins (DRPs) must bind specific adaptors on the outer mitochondrial membrane. The structural features underlying this interaction are poorly understood. Using yeast as a model, we show that the Insert B domain of the Dnm1 guanosine triphosphatase (a DRP) contains a novel motif required for association with the mitochondrial adaptor Mdv1. Mutation of this conserved motif specifically disrupted Dnm1–Mdv1 interactions, blocking Dnm1 recruitment and mitochondrial fission. Suppressor mutations in Mdv1 that restored Dnm1–Mdv1 interactions and fission identified potential protein-binding interfaces on the Mdv1 β-propeller domain. These results define the first known function for Insert B in DRP–adaptor interactions. Based on the variability of Insert B sequences and adaptor proteins, we propose that Insert B domains and mitochondrial adaptors have coevolved to meet the unique requirements for mitochondrial fission of different organisms.

scholarly journals Dnm1p Gtpase-Mediated Mitochondrial Fission Is a Multi-Step Process Requiring the Novel Integral Membrane Component Fis1p

2000 ◽  
Vol 151 (2) ◽  
pp. 367-380 ◽  
Author(s):  
A.D. Mozdy ◽  
J.M. McCaffery ◽  
J.M. Shaw
Keyword(s):  
Membrane Protein ◽  
Mitochondrial Membrane ◽  
Mitochondrial Fission ◽  
First Integral ◽  
Integral Membrane Protein ◽  
Morphological Evidence ◽  
Outer Mitochondrial Membrane ◽  
Step Process ◽  
Membrane Recruitment ◽  
New Genes

Yeast Dnm1p is a soluble, dynamin-related GTPase that assembles on the outer mitochondrial membrane at sites where organelle division occurs. Although these Dnm1p-containing complexes are thought to trigger constriction and fission, little is known about their composition and assembly, and molecules required for their membrane recruitment have not been isolated. Using a genetic approach, we identified two new genes in the fission pathway, FIS1 and FIS2. FIS1 encodes a novel, outer mitochondrial membrane protein with its amino terminus exposed to the cytoplasm. Fis1p is the first integral membrane protein shown to participate in a eukaryotic membrane fission event. In a related study (Tieu, Q., and J. Nunnari. 2000. J. Cell Biol. 151:353–365), it was shown that the FIS2 gene product (called Mdv1p) colocalizes with Dnm1p on mitochondria. Genetic and morphological evidence indicate that Fis1p, but not Mdv1p, function is required for the proper assembly and distribution of Dnm1p-containing fission complexes on mitochondrial tubules. We propose that mitochondrial fission in yeast is a multi-step process, and that membrane-bound Fis1p is required for the proper assembly, membrane distribution, and function of Dnm1p-containing complexes during fission.

scholarly journals Constriction and Dnm1p Recruitment Are Distinct Processes in Mitochondrial Fission

2003 ◽  
Vol 14 (5) ◽  
pp. 1953-1963 ◽  
Author(s):  
Aster Legesse-Miller ◽  
Ramiro H. Massol ◽  
Tom Kirchhausen
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fluorescence Imaging ◽  
Hot Spots ◽  
Mitochondrial Membrane ◽  
Mitochondrial Fission ◽  
Three Dimensional ◽  
Time Lapse ◽  
Outer Mitochondrial Membrane ◽  
Mitochondrial Matrix ◽  
Different Shapes

Mitochondria undergo cycles of fusion and fission crucial for organelle homeostasis. Fission is regulated partially by recruitment of the large GTPase Dnm1p to the outer mitochondrial membrane. Using three-dimensional time-lapse fluorescence imaging of Saccharomyces cerevisiae cells, we found that Dnm1p-EGFP appears and disappears at “hot spots” along mitochondrial tubes. It forms patches that convert rapidly into different shapes regardless of whether mitochondrial fission ensues or not. Moreover, the thickness of the mitochondrial matrix displays frequent temporal fluctuations apparently unrelated to fission or to recruitment of Dnm1p-EGFP. These results suggest that mitochondrial fission requires coordination of at least two distinct processes.

scholarly journals PINK1 disables the anti-fission machinery to segregate damaged mitochondria for mitophagy

2016 ◽  
Vol 213 (2) ◽  
pp. 163-171 ◽  
Author(s):  
Kenneth R. Pryde ◽  
Heather L. Smith ◽  
Kai-Yin Chau ◽  
Anthony H.V. Schapira
Keyword(s):  
Protein Kinase ◽  
Parkinson Disease ◽  
Protein Kinase A ◽  
Mitochondrial Membrane ◽  
Mitochondrial Fission ◽  
Scaffold Protein ◽  
Outer Mitochondrial Membrane ◽  
Related Protein ◽  
Anchoring Protein ◽  
Kinase A

Mitochondrial fission is essential for the degradation of damaged mitochondria. It is currently unknown how the dynamin-related protein 1 (DRP1)–associated fission machinery is selectively targeted to segregate damaged mitochondria. We show that PTEN-induced putative kinase (PINK1) serves as a pro-fission signal, independently of Parkin. Normally, the scaffold protein AKAP1 recruits protein kinase A (PKA) to the outer mitochondrial membrane to phospho-inhibit DRP1. We reveal that after damage, PINK1 triggers PKA displacement from A-kinase anchoring protein 1. By ejecting PKA, PINK1 ensures the requisite fission of damaged mitochondria for organelle degradation. We propose that PINK1 functions as a master mitophagy regulator by activating Parkin and DRP1 in response to damage. We confirm that PINK1 mutations causing Parkinson disease interfere with the orchestration of selective fission and mitophagy by PINK1.

scholarly journals Mitochondrial membrane tension governs fission

2018 ◽  
Author(s):  
Dora Mahecic ◽  
Lina Carlini ◽  
Tatjana Kleele ◽  
Adai Colom ◽  
Antoine Goujon ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Mitochondrial Membrane ◽  
Mitochondrial Fission ◽  
Outer Mitochondrial Membrane ◽  
Membrane Tension ◽  
Structured Illumination ◽  
Bending Energy ◽  
Structured Illumination Microscopy ◽  
Cellular Factors ◽  
Tension Sensor

AbstractDuring mitochondrial fission, key molecular and cellular factors assemble on the outer mitochondrial membrane, where they coordinate to generate constriction. Constriction sites can eventually divide, or reverse upon disassembly of the machinery. However, a role for membrane tension in mitochondrial fission, although speculated, has remained undefined. We captured the dynamics of constricting mitochondria in mammalian cells using live-cell structured illumination microscopy (SIM). By analyzing the diameters of tubules that emerge from mitochondria and implementing a fluorescence lifetime-based mitochondrial membrane tension sensor, we discovered that mitochondria are indeed under tension. Under perturbations that reduce mitochondrial tension, constrictions initiate at the same rate, but are less likely to divide. We propose a model based on our estimates of mitochondrial membrane tension and bending energy in living cells which accounts for the observed probability distribution for mitochondrial constrictions to divide.

scholarly journals The role of Fis1p–Mdv1p interactions in mitochondrial fission complex assembly

2005 ◽  
Vol 171 (2) ◽  
pp. 291-301 ◽  
Author(s):  
Mary Anne Karren ◽  
Emily M. Coonrod ◽  
Teresa K. Anderson ◽  
Janet M. Shaw
Keyword(s):  
Mitochondrial Membrane ◽  
Mitochondrial Fission ◽  
Coiled Coil ◽  
Cytoplasmic Domain ◽  
Tetratricopeptide Repeat ◽  
Outer Mitochondrial Membrane ◽  
Complex Assembly ◽  
Binding Surface ◽  
New Evidence

Mitochondrial division requires coordinated interactions among Fis1p, Mdv1p, and the Dnm1p GTPase, which assemble into fission complexes on the outer mitochondrial membrane. The integral outer membrane protein Fis1p contains a cytoplasmic domain consisting of a tetratricopeptide repeat (TPR)–like fold and a short NH2-terminal helix. Although it is known that the cytoplasmic domain is necessary for assembly of Mdv1p and Dnm1p into fission complexes, the molecular details of this assembly are not clear. In this study, we provide new evidence that the Fis1p–Mdv1p interaction is direct. Furthermore, we show that conditional mutations in the Fis1p TPR-like domain cause fission complex assembly defects that are suppressed by mutations in the Mdv1p-predicted coiled coil. We also define separable functions for the Fis1p NH2-terminal arm and TPR-like fold. These studies suggest that the concave binding surface of the Fis1p TPR-like fold interacts with Mdv1p during mitochondrial fission and that Mdv1p facilitates Dnm1p recruitment into functional fission complexes.

scholarly journals Parkin-independent mitophagy via Drp1-mediated outer membrane severing and inner membrane ubiquitination

2021 ◽  
Vol 220 (6) ◽  
Author(s):  
Yumiko Oshima ◽  
Etienne Cartier ◽  
Liron Boyman ◽  
Nicolas Verhoeven ◽  
Brian M. Polster ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Outer Membrane ◽  
Mitochondrial Membrane ◽  
Mitochondrial Fission ◽  
Outer Mitochondrial Membrane ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Translation ◽  
Inner Membrane ◽  
Translation Fidelity ◽  
Mosaic Distribution

Here, we report that acute reduction in mitochondrial translation fidelity (MTF) causes ubiquitination of the inner mitochondrial membrane (IMM) proteins, including TRAP1 and CPOX, which occurs selectively in mitochondria with a severed outer mitochondrial membrane (OMM). Ubiquitinated IMM recruits the autophagy machinery. Inhibiting autophagy leads to increased accumulation of mitochondria with severed OMM and ubiquitinated IMM. This process occurs downstream of the accumulation of cytochrome c/CPOX in a subset of mitochondria heterogeneously distributed throughout the cell (“mosaic distribution”). Formation of mosaic mitochondria, OMM severing, and IMM ubiquitination require active mitochondrial translation and mitochondrial fission, but not the proapoptotic proteins Bax and Bak. In contrast, in Parkin-overexpressing cells, MTF reduction does not lead to the severing of the OMM or IMM ubiquitination, but it does induce Drp1-independent ubiquitination of the OMM. Furthermore, high–cytochrome c/CPOX mitochondria are preferentially targeted by Parkin, indicating that in the context of reduced MTF, they are mitophagy intermediates regardless of Parkin expression. In sum, Parkin-deficient cells adapt to mitochondrial proteotoxicity through a Drp1-mediated mechanism that involves the severing of the OMM and autophagy targeting ubiquitinated IMM proteins.

Glucose metabolism in cancer cells: immunogold localization of hexokinase to the outer mitochondrial membrane

1995 ◽  
Vol 53 ◽  
pp. 1044-1045
Author(s):  
Krishan K. Arora ◽  
Glenn L. Decker ◽  
Peter L. Pedersen
Keyword(s):  
Tumor Cells ◽  
Mitochondrial Membrane ◽  
Present Report ◽  
Large Fraction ◽  
Mitochondrial Fraction ◽  
Immunogold Labeling ◽  
Outer Mitochondrial Membrane ◽  
Immunogold Localization ◽  
Hexokinase Activity ◽  
Normal Tissues

Hexokinase (ATP: D-hexose 6-phophotransferase EC 2.7.1.1) is the first enzyme of the glycolytic pathway which commits glucose to catabolism by catalyzing the phosphorylation of glucose with ATP. Previous studies have shown diat hexokinase activity is markedly elevated in rapidly growing tumor cells exhibiting high glucose catabolic rates. A large fraction (50-80%) of this enzyme activity is bound to the mitochondrial fraction (1,2) where it has preferred access to ATP (3). In contrast,the hexokinase activity of normal tissues is quite low, with one exception being brain which is a glucose-utilizing tissue (4). Biochemical evidence involving rigorous subfractionation studies have revealed striking differences between the subcellular distribution of hexokinase in normal and tumor cells [See review by Arora et al (4)].In the present report, we have utilized immunogold labeling techniques to evaluate die subcellular localization of hexokinase in highly glycolytic AS-30D hepatoma cells and in the tissue of its origin, i.e., rat liver.

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