Miro GTPase domains regulate assembly of the mitochondrial motor-adaptor complex

Abstract

Mitochondrial transport relies on a motor-adaptor complex containing Miro1, a mitochondrial outer membrane protein with two GTPase domains, as well as TRAK1/2, kinesin-1, and dynein. Using a peroxisome-directed Miro1, we quantified the ability of GTPase mutations to influence peroxisomal recruitment of complex components. Miro1 whose N-GTPase is locked in the GDP-state doesnt recruit TRAK1/2, kinesin or P135 to peroxisomes whereas the GTP-state does. Miro1 C-GTPase mutations have little influence on complex recruitment. Though Miro2 is thought to support mitochondrial motility, peroxisome-directed Miro2 did not recruit the other complex components regardless of the state of its GTPase domains. Neurons expressing peroxisomal Miro1 with the GTP-state form of the N-GTPase had markedly increased peroxisomal transport to growth cones while the GDP-state caused their retention in the soma. Thus, the N-GTPase of Miro1 is critical for regulating Miro1s interaction with the other components of the motor-adaptor complex and thereby for regulating mitochondrial motility. SummaryA Miro-containing complex mediates mitochondrial motility. Relocalizing Miro1 and 2 to peroxisomes and systematically manipulating each GTPase domain of Miro revealed the importance of the N-terminal GTPase domain of Miro1 for governing interaction with TRAK proteins, motors, and transport.