Phospholipid Association Is Essential for Dynamin-related Protein Mgm1 to Function in Mitochondrial Membrane Fusion*
| Autor: | Jarungjit Rujiviphat, Gabriela Meglei, G. Angus McQuibban, John L. Rubinstein |
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| Jazyk: | angličtina |
| Rok vydání: | 2009 |
| Předmět: |
Dynamins
Saccharomyces cerevisiae Proteins Enzyme-Linked Immunosorbent Assay GTPase Biology Biochemistry Membrane Fusion Models Biological GTP Phosphohydrolases Fungal Proteins Mitochondrial Proteins Molecular Basis of Cell and Developmental Biology GTP-Binding Proteins Inner mitochondrial membrane Molecular Biology Phospholipids Dynamin Liposome Circular Dichroism Mitochondrial membrane fusion Lipid bilayer fusion Cell Biology Mitochondrial carrier Lipids Cell biology Protein Structure Tertiary Translocase of the inner membrane Liposomes Mitochondrial Membranes Mutation Chromatography Gel |
| Popis: | Mgm1, the yeast ortholog of mammalian OPA1, is a key component in mitochondrial membrane fusion and is required for maintaining mitochondrial dynamics and morphology. We showed recently that the purified short isoform of Mgm1 (s-Mgm1) possesses GTPase activity, self-assembles into low order oligomers, and interacts specifically with negatively charged phospholipids (Meglei, G., and McQuibban, G. A. (2009) Biochemistry 48, 1774-1784). Here, we demonstrate that s-Mgm1 binds to a mixture of phospholipids characteristic of the mitochondrial inner membrane. Binding to physiologically representative lipids results in approximately 50-fold stimulation of s-Mgm1 GTPase activity. s-Mgm1 point mutants that are defective in oligomerization and lipid binding do not exhibit such stimulation and do not function in vivo. Electron microscopy and lipid turbidity assays demonstrate that s-Mgm1 promotes liposome interaction. Furthermore, s-Mgm1 assembles onto liposomes as oligomeric rings with 3-fold symmetry. The projection map of negatively stained s-Mgm1 shows six monomers, consistent with two stacked trimers. Taken together, our data identify a lipid-binding domain in Mgm1, and the structural analysis suggests a model of how Mgm1 promotes the fusion of opposing mitochondrial inner membranes. |
| Databáze: | OpenAIRE |
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