Role of Unc104/KIF1-related Motor Proteins in Mitochondrial Transport inNeurospora crassa
- 1 January 2005
- journal article
- research article
- Published by American Society for Cell Biology (ASCB) in Molecular Biology of the Cell
- Vol. 16 (1) , 153-161
- https://doi.org/10.1091/mbc.e04-05-0413
Abstract
Eukaryotic cells use diverse cytoskeleton-dependent machineries to control inheritance and intracellular positioning of mitochondria. In particular, microtubules play a major role in mitochondrial motility in the filamentous fungus Neurospora crassa and in mammalian cells. We examined the role of two novel Unc104/KIF1-related members of the kinesin family, Nkin2 and Nkin3, in mitochondrial motility in Neurospora. The Nkin2 protein is required for mitochondrial interactions with microtubules in vitro. Mutant hyphae lacking Nkin2 show mitochondrial motility defects in vivo early after germination of conidiospores. Nkin3, a member of a unique fungal-specific subgroup of small Unc104/KIF1-related proteins, is not associated with mitochondria in wild-type cells. However, it is highly expressed and recruited to mitochondria in Δnkin-2 mutants. Mitochondria lacking Nkin2 require Nkin3 for binding to microtubules in vitro, and mitochondrial motility defects in Δnkin-2 mutants disappear with up-regulation of Nkin3 in vivo. We propose that mitochondrial transport is mediated by Nkin2 in Neurospora, and organelle motility defects in Δnkin-2 mutants are rescued by Nkin3. Apparently, a highly versatile complement of organelle motors allows the cell to efficiently respond to exogenous challenges, a process that might also account for the great variety of different mitochondrial transport systems that have evolved in eukaryotic cells.Keywords
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