The orchestration of mitochondria within the cell represents a critical aspect of cell biology. At the center of this process is the outer mitochondrial membrane protein, Miro. Miro coordinates diverse cellular processes by regulating connections between organelles and the cytoskeleton that range from mediating contacts between the endoplasmic reticulum and mitochondria to the regulation of both actin and microtubule motor proteins. Recently, a number of cell biological, biochemical, and protein structure studies have helped to characterize the myriad roles played by Miro. In addition to answering questions regarding Miro's function, these studies have opened the door to new avenues in the study of Miro in the cell. This review will focus on summarizing recent findings for Miro's structure, function, and activity while highlighting key questions that remain unanswered.
The outer-mitochondrial membrane protein Miro1 is critical for the regulation of mitochondrial trafficking. Miro1 contains two GTPase domains, where changes in the N-terminal GTPase nucleotide state strongly affects mitochondrial trafficking. Previous work showed that the GTP-locked mutation Miro1P13Vdecreases trafficking and affects mitochondrial dynamics. Despite showing a clear role in Miro1 function, the molecular basis for this activity remains unknown. Using in vitro reconstitution, we demonstrate that Miro1 self-associates to form dimers and higher-ordered species. Structural characterization of Miro1P13Vsuggests that the oligomers adopt a range of conformations in vitro. Additionally, Miro1P13Vhas diminished interaction with its downstream cargo adapter TRAK1. These results indicate that the NGTPase of Miro1 facilitates the formation of higher-ordered species and suggests that changes in the oligomeric state may regulate mitochondrial trafficking through reduced association with TRAK1.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.