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 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 Quantitative analysis of APP axonal transport in neurons: role of JIP1 in enhanced APP anterograde transport

2014 ◽  
Vol 25 (22) ◽  
pp. 3569-3580 ◽  
Author(s):  
Kyoko Chiba ◽  
Masahiko Araseki ◽  
Keisuke Nozawa ◽  
Keiko Furukori ◽  
Yoichi Araki ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Axonal Transport ◽  
High Frequency ◽  
Coiled Coil ◽  
Tetratricopeptide Repeat ◽  
The Novel ◽  
Anterograde Transport ◽  
Interacting Protein ◽  
A Site

Alzheimer's β-amyloid precursor protein (APP) associates with kinesin-1 via JNK-interacting protein 1 (JIP1); however, the role of JIP1 in APP transport by kinesin-1 in neurons remains unclear. We performed a quantitative analysis to understand the role of JIP1 in APP axonal transport. In JIP1-deficient neurons, we find that both the fast velocity (∼2.7 μm/s) and high frequency (66%) of anterograde transport of APP cargo are impaired to a reduced velocity (∼1.83 μm/s) and a lower frequency (45%). We identified two novel elements linked to JIP1 function, located in the central region of JIP1b, that interact with the coiled-coil domain of kinesin light chain 1 (KLC1), in addition to the conventional interaction of the JIP1b 11–amino acid C-terminal (C11) region with the tetratricopeptide repeat of KLC1. High frequency of APP anterograde transport is dependent on one of the novel elements in JIP1b. Fast velocity of APP cargo transport requires the C11 domain, which is regulated by the second novel region of JIP1b. Furthermore, efficient APP axonal transport is not influenced by phosphorylation of APP at Thr-668, a site known to be phosphorylated by JNK. Our quantitative analysis indicates that enhanced fast-velocity and efficient high-frequency APP anterograde transport observed in neurons are mediated by novel roles of JIP1b.

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 Mff oligomerization is required for Drp1 activation and synergy with actin filaments during mitochondrial division

2021 ◽  
pp. mbc.E21-04-0224
Author(s):  
Ao Liu ◽  
Frieda Kage ◽  
Henry N. Higgs
Keyword(s):  
Actin Filaments ◽  
Total Internal Reflection ◽  
Mitochondrial Membrane ◽  
Coiled Coil ◽  
Outer Mitochondrial Membrane ◽  
Mitochondrial Division ◽  
Knock Out ◽  
Total Internal Reflection Microscopy ◽  
Peroxisome Division ◽  
Mitochondrial Membrane Protein

Mitochondrial division is an important cellular process in both normal and pathological conditions. The dynamin GTPase Drp1 is a central mitochondrial division protein, driving constriction of the outer mitochondrial membrane. In mammals, the outer mitochondrial membrane protein Mff is a key receptor for recruiting Drp1 from the cytosol to the mitochondrion. Actin filaments are also important in Drp1 recruitment and activation. The manner in which Mff and actin work together in Drp1 activation is unknown. Here, we show that Mff is an oligomer (most likely a trimer) that dynamically associates and disassociates through its C-terminal coiled-coil, with a Kd in the range of 10 µM. Dynamic Mff oligomerization is required for Drp1 activation. While not binding Mff directly, actin filaments enhance Mff-mediated Drp1 activation by lowering the effective Mff concentration 10-fold. Total internal reflection microscopy assays using purified proteins show that Mff interacts with Drp1 on actin filaments in a manner dependent on Mff oligomerization. In U2OS cells, oligomerization-defective Mff does not effectively rescue three defects in Mff knock-out cells: mitochondrial division, mitochondrial Drp1 recruitment, and peroxisome division. The ability of Mff to assemble into puncta on mitochondria depends on its oligomerization, as well as on actin filaments and Drp1.

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 How does the TOM complex mediate insertion of precursor proteins into the mitochondrial outer membrane?

2005 ◽  
Vol 171 (3) ◽  
pp. 419-423 ◽  
Author(s):  
Doron Rapaport
Keyword(s):  
Membrane Proteins ◽  
Outer Membrane ◽  
Mitochondrial Membrane ◽  
Mitochondrial Outer Membrane ◽  
Outer Face ◽  
Outer Mitochondrial Membrane ◽  
Lipid Core ◽  
Tom Complex ◽  
Precursor Proteins

A multisubunit translocase of the outer mitochondrial membrane (TOM complex) mediates both the import of mitochondrial precursor proteins into the internal compartments of the organelle and the insertion of proteins residing in the mitochondrial outer membrane. The proposed β-barrel structure of Tom40, the pore-forming component of the translocase, raises the question of how the apparent uninterrupted β-barrel topology can be compatible with a role of Tom40 in releasing membrane proteins into the lipid core of the bilayer. In this review, I discuss insertion mechanisms of proteins into the outer membrane and present alternative models based on the opening of a multisubunit β-barrel TOM structure or on the interaction of outer membrane precursors with the outer face of the Tom40 β-barrel structure.

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