title: A uvs-5 strain is deficient for a mitofusin gene homologue, fzo1, involved in maintenance of long life span in Neurospora crassa.
abstract: Mitochondria are highly dynamic organelles that continuously fuse and divide. To maintain mitochondria, cells establish an equilibrium of fusion and fission events, which are mediated by dynamin-like GTPases. We previously showed that an mus-10 strain, a mutagen-sensitive strain of the filamentous fungus Neurospora crassa, is defective in an F-box protein that is essential for the maintenance of mitochondrial DNA (mtDNA), long life span, and mitochondrial morphology. Similarly, a uvs-5 mutant accumulates deletions within its mtDNA, has a shortened life span, and harbors fragmented mitochondria, the latter of which is indicative of an imbalance between mitochondrial fission and fusion. Since the uvs-5 mutation maps very close to the locus of fzo1, encoding a mitofusin homologue thought to mediate mitochondrial outer membrane fusion, we determined the sequence of the fzo1 gene in the uvs-5 mutant. A single amino acid substitution (Q368R) was found in the GTPase domain of the FZO1 protein. Expression of wild-type FZO1 in the uvs-5 strain rescued the mutant phenotypes, while expression of a mutant FZO1 protein did not. Moreover, when knock-in of the Q368R mutation was performed on a wild-type strain, the resulting mutant displayed phenotypes identical to those of the uvs-5 mutant. Therefore, we concluded that the previously unidentified uvs-5 gene is fzo1. Furthermore, we used immunoprecipitation analysis to show that the FZO1 protein interacts with MUS-10, which suggests that these two proteins may function together to maintain mitochondrial morphology.
authors.affiliation: Laboratory of Genetics, Department of Regulatory Biology, Faculty of Science, Saitama University, Japan.
authors.forename: Kiminori
authors.initials: K
authors.lastname: Kurashima
authors.forename: Michael
authors.initials: M
authors.lastname: Chae
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Inoue
authors.forename: Shin
authors.initials: S
authors.lastname: Hatakeyama
authors.forename: Shuuitsu
authors.initials: S
authors.lastname: Tanaka
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D002874:Chromosome Mapping; D029721:Drosophila Proteins / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008040:Genetic Linkage; D008136:Longevity; D008565:Membrane Proteins / Q000235:genetics; D050296:Microbial Viability; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D025282:Mycelium / Q000502:physiology; D009492:Neurospora crassa / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D010641:Phenotype; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013172:Spores, Fungal / Q000502:physiology
chemical_list: D029721:Drosophila Proteins; D005656:Fungal Proteins; C527117:Marf protein, Drosophila; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D020558:GTP Phosphohydrolases