Cardiolipin's propensity for phase transition and its reorganization by dynamin-related protein 1 form a basis for mitochondrial membrane fission

Stepanyants, Natalia; Macdonald, Patrick J.; Francy, Christopher A.; Mears, Jason A.; Qi, Xin; Ramachandran, Rajesh

doi:10.1091/mbc.e15-06-0330

Cited by 147 publications

(197 citation statements)

References 74 publications

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“…1D). As expected from previous studies (Bustillo-Zabalbeitia et al, 2014; Macdonald et al, 2014; Montessuit et al, 2010; Stepanyants et al, 2015), Drp1 also preferentially bound liposomes containing a saturated CL. Although the exact role of this mitochondria specific phospholipid CL remains to be determined, binding to CL both stimulates the Drp1 GTPase activity that is required for mitochondrial division, and in a non-GTPase activity-dependent manner, enables cytochrome c release from mitochondria during apoptosis.…”

Section: Resultssupporting

confidence: 89%

Coincident Phosphatidic Acid Interaction Restrains Drp1 in Mitochondrial Division

et al. 2016

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Summary Mitochondria divide to control their size, distribution, turnover and function. Dynamin-related protein (Drp1) is a critical mechanochemical GTPase that drives constriction during mitochondrial division. It is generally believed that mitochondrial division is regulated during recruitment of Drp1 to mitochondria and its oligomerization into a division apparatus. Here, we report an unforeseen mechanism that regulates mitochondrial division by coincident interactions of Drp1 with the headgroup and acyl chains of phospholipids. Drp1 recognizes the headgroup of phosphatidic acid (PA) and two saturated acyl chains of another phospholipid by penetrating into the hydrophobic core of the membrane. The dual phospholipid interactions restrain Drp1 via inhibition of oligomerization-stimulated GTP hydrolysis that promotes membrane constriction. Moreover, a PA-producing phospholipase, MitoPLD, binds Drp1, creating a PA-rich microenvironment in the vicinity of a division apparatus. Thus, PA controls the activation of Drp1 after the formation of the division apparatus.

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Section: Resultssupporting

confidence: 89%

Coincident Phosphatidic Acid Interaction Restrains Drp1 in Mitochondrial Division

et al. 2016

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“…In fact, the accompanying article (42) clearly shows that Mff stimulation of Drp1 activity is synergistic with CL stimulation. These results are congruent with previous reports of VD interactions with CL that promote Drp1 recruitment to lipid bilayers (21,(23)(24)(25). Given that CL has been shown to stabilize dimeric Drp1 at the lipid surface to promote Drp1 self-assembly (23), we propose that CL interactions at the membrane directly promote Drp1 dimer interactions with Mff (Fig.…”

Section: Discussionsupporting

confidence: 93%

“…In vitro, the addition of negatively charged lipids increases Drp1 self-assembly to form larger helical assemblies that represent the contractile apparatus of mitochondrial fission (20), and these functional polymers exhibit stimulated GTPase activity (14,(21)(22)(23). The VD has recently been shown to act as a negative regulator of Drp1 self-assembly (14) with an inherent ability to interact with cardiolipin (CL) present in mitochondrial membranes (21,(23)(24)(25). Studies in yeast have shown that the VD is required for interactions with a mitochondrial adaptor protein (26), but the partner protein identified in that study is not conserved in higher eukaryotes, which suggests that the role of the VD may have evolved in higher organisms to accommodate different regulatory interactions in the cytosol and at the surface of mitochondria.…”

mentioning

confidence: 99%

Dynamin-related Protein 1 Oligomerization in Solution Impairs Functional Interactions with Membrane-anchored Mitochondrial Fission Factor

Clinton¹,

Francy²,

Ramachandran

et al. 2016

Journal of Biological Chemistry

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Mitochondrial fission is a crucial cellular process mediated by the mechanoenzymatic GTPase, dynamin-related protein 1 (Drp1). During mitochondrial division, Drp1 is recruited from the cytosol to the outer mitochondrial membrane by one, or several, integral membrane proteins. One such Drp1 partner protein, mitochondrial fission factor (Mff), is essential for mitochondrial division, but its mechanism of action remains unexplored. Previous studies have been limited by a weak interaction between Drp1 and Mff in vitro. Through refined in vitro reconstitution approaches and multiple independent assays, we show that removal of the regulatory variable domain (VD) in Drp1 enhances formation of a functional Drp1-Mff copolymer. This protein assembly exhibits greatly stimulated cooperative GTPase activity in solution. Moreover, when Mff was anchored to a lipid template, to mimic a more physiologic environment, significant stimulation of GTPase activity was observed with both WT and ⌬VD Drp1. Contrary to recent findings, we show that premature Drp1 self-assembly in solution impairs functional interactions with membrane-anchored Mff. Instead, dimeric Drp1 species are selectively recruited by Mff to initiate assembly of a functional fission complex. Correspondingly, we also found that the coiled-coil motif in Mff is not essential for Drp1 interactions, but rather serves to augment cooperative self-assembly of Drp1 proximal to the membrane. Taken together, our findings provide a mechanism wherein the multimeric states of both Mff and Drp1 regulate their collaborative interaction.Mitochondria undergo continuous cycles of fission and fusion to maintain a functional organelle network within eukaryotic cells. This mitochondrial network is crucial for ATP generation, apoptotic signaling, and calcium homeostasis. When the proper balance of mitochondrial dynamics is disrupted, mitochondrial dysfunction is observed (1, 2). This insult is associated with increased cell death in several human diseases, including neurodegenerative disorders (3, 4), ischemiareperfusion injury (5, 6), and glaucoma (7). Therefore, mitochondrial division has developed into a compelling therapeutic target for intervention with small molecule and peptide inhibitors that limit cell death in several of these pathologies (8 -13).The master regulator of mitochondrial fission, dynamin-related protein 1 (Drp1), 2 has been targeted in these diseases. Similar to other dynamin family members, Drp1 is a large GTPase that mediates membrane remodeling. The primary sequence of Drp1 is composed of four conserved regions (see Fig. 1A): the GTPase domain, middle domain, variable domain (VD), and GTPase effector domain (GED). Hydrolysis of GTP triggers conformational changes in Drp1 oligomers that generate the mechanical force needed to promote mitochondrial membrane scission (14, 15), and factors that inhibit Drp1 GTPase activity prevent mitochondrial division (8,16,17). The middle and GED domains promote Drp1 self-assembly, which is also critical for its role in facilitating...

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“…The importance of CL microdomains is of relevance during initiation of apoptosis, where caspase 8 is thought to localize to CL microdomains that would be spatially distributed at contact sites between the inner and outer mitochondrial membranes [71]. In another study, fission proteins were also reported to be associated with CL microdomains [72]. However, any conclusions about the existence of CL microdomains must account for the methodology used for isolating these membrane fractions, which may promote artifacts [73].…”

Section: 0 Discussionmentioning

confidence: 99%

Distinct membrane properties are differentially influenced by cardiolipin content and acyl chain composition in biomimetic membranes

Pennington¹,

Fix²,

Sullivan³

et al. 2017

Biochimica et Biophysica Acta (BBA) - Biomembranes

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Cardiolipin (CL) has a critical role in maintaining mitochondrial inner membrane structure. In several conditions such as heart failure and aging, there is loss of CL content and remodeling of CL acyl chains, which are hypothesized to impair mitochondrial inner membrane biophysical organization. Therefore, this study discriminated how CL content and acyl chain composition influenced select properties of simple and complex mitochondrial mimicking model membranes. We focused on monolayer excess area/molecule (a measure of lipid miscibility), bilayer phase transitions, and microdomain organization. In monolayer compression studies, loss of tetralinoleoyl [(18:2)4] CL content decreased the excess area/molecule. Replacement of (18:2)4CL acyl chains with tetraoleoyl [(18:1)4] CL or tetradocosahexaenoyl [(22:6)4] CL generally had little influence on monolayer excess area/molecule; in contrast, replacement of (18:2)4CL acyl chains with tetramyristoyl [(14:0)4] CL increased monolayer excess area/molecule. In bilayers, calorimetric studies showed that substitution of (18:2)4CL with (18:1)4CL or (22:6)4CL lowered the phase transition temperature of phosphatidylcholine vesicles whereas (14:0)4CL had no effect. Finally, quantitative imaging of giant unilamellar vesicles revealed differential effects of CL content and acyl chain composition on microdomain organization, visualized with the fluorescent probe Texas Red DHPE. Notably, microdomain areas were decreased by differing magnitudes upon lowering of (18:2)4CL content and substitution of (18:2)4CL with (14:0)4CL or (22:6)4CL. Conversely, exchanging (18:2)4CL with (18:1)4CL increased microdomain area. Altogether, these data demonstrate that CL content and fatty acyl composition differentially target membrane physical properties, which has implications for understanding how CL regulates mitochondrial activity and the design of CL-specific therapeutics.

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Cardiolipin's propensity for phase transition and its reorganization by dynamin-related protein 1 form a basis for mitochondrial membrane fission

Cited by 147 publications

References 74 publications

Coincident Phosphatidic Acid Interaction Restrains Drp1 in Mitochondrial Division

Coincident Phosphatidic Acid Interaction Restrains Drp1 in Mitochondrial Division

Dynamin-related Protein 1 Oligomerization in Solution Impairs Functional Interactions with Membrane-anchored Mitochondrial Fission Factor

Distinct membrane properties are differentially influenced by cardiolipin content and acyl chain composition in biomimetic membranes

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