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Structural analysis of a trimeric assembly of the mitochondrial dynamin-like GTPase Mgm1.


ABSTRACT: The fusion of inner mitochondrial membranes requires dynamin-like GTPases, Mgm1 in yeast and OPA1 in mammals, but how they mediate membrane fusion is poorly understood. Here, we determined the crystal structure of Saccharomyces cerevisiae short Mgm1 (s-Mgm1) in complex with GDP. It revealed an N-terminal GTPase (G) domain followed by two helix bundles (HB1 and HB2) and a unique C-terminal lipid-interacting stalk (LIS). Dimers can form through antiparallel HB interactions. Head-to-tail trimers are built by intermolecular interactions between the G domain and HB2-LIS. Biochemical and in vivo analyses support the idea that the assembly interfaces observed here are native and critical for Mgm1 function. We also found that s-Mgm1 interacts with negatively charged lipids via both the G domain and LIS. Based on these observations, we propose that membrane targeting via the G domain and LIS facilitates the in cis assembly of Mgm1, potentially generating a highly curved membrane tip to allow inner membrane fusion.

SUBMITTER: Yan L 

PROVIDER: S-EPMC7049166 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Structural analysis of a trimeric assembly of the mitochondrial dynamin-like GTPase Mgm1.

Yan Liming L   Qi Yuanbo Y   Ricketson Derek D   Li Lei L   Subramanian Kelly K   Zhao Jinghua J   Yu Caiting C   Wu Lijie L   Sarsam Reta R   Wong Melissa M   Lou Zhiyong Z   Rao Zihe Z   Nunnari Jodi J   Hu Junjie J  

Proceedings of the National Academy of Sciences of the United States of America 20200210 8


The fusion of inner mitochondrial membranes requires dynamin-like GTPases, Mgm1 in yeast and OPA1 in mammals, but how they mediate membrane fusion is poorly understood. Here, we determined the crystal structure of <i>Saccharomyces cerevisiae</i> short Mgm1 (s-Mgm1) in complex with GDP. It revealed an N-terminal GTPase (G) domain followed by two helix bundles (HB1 and HB2) and a unique C-terminal lipid-interacting stalk (LIS). Dimers can form through antiparallel HB interactions. Head-to-tail tri  ...[more]

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