Cryo-EM structures reveal a conformational change of SOPA1 during mitochondrial inner membrane fusion
bioRxiv(2019)
摘要
Mammalian mitochondrial inner membrane fusion is mediated by OPA1(optic atrophy 1). Under physiological condition, OPA1 undergoes proteolytic processing to form a membrane-anchored long isoform (L-OPA1) and a soluble short isoform (S-OPA1). A combination of L-OPA1 and S-OPA1 are required for membrane fusion, however, the relevant mechanism is not well understood. In this study, we investigate the cryo-EM structures of S-OPA1 coated liposome at nucleotide-free and GTPγS bound states. S-OPA1 exhibits a general structure of dynamin family. It can assemble onto membrane in a helical array with a building block of dimer and thus induce membrane tubulation. A predicted amphipathic helix is discovered to mediate the tubulation activity of S-OPA1. The binding of GTPγS triggers a conformational rotation between GTPase domain and stalk region, resulting the rearrangement of helical lattice and tube expansion. This observation is opposite to the behavior of other dynamin proteins, suggesting a unique role of S-OPA1 in the fusion of mitochondrial inner membrane.
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关键词
Cryo-electron microscopy,Conformational change,Mitochondrial fusion,Membrane tubulation,OPA1
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