title: Inactivation of the Neurospora crassa gene encoding the mitochondrial protein import receptor MOM19 by the technique of "sheltered RIP".
abstract: We have used a technique referred to as "sheltered RIP" (repeat induced point mutation) to create mutants of the mom-19 gene of Neurospora crassa, which encodes an import receptor for nuclear encoded mitochondrial precursor proteins. Sheltered RIP permits the isolation of a mutant gene in one nucleus, even if that gene is essential for the survival of the organism, by sheltering the nucleus carrying the mutant gene in a heterokaryon with an unaffected nucleus. Furthermore, the nucleus harboring the RIPed gene contains a selectable marker so that it is possible to shift nuclear ratios in the heterokaryons to a state in which the nucleus containing the RIPed gene predominates in cultures grown under selective conditions. This results in a condition where the target gene product should be present at very suboptimal levels and allows the study of the mutant phenotype. One allele of mom-19 generated by this method contains 44 transitions resulting in 18 amino acid substitutions. When the heterokaryon containing this allele was grown under conditions favoring the RIPed nucleus, no MOM19 protein was detectable in the mitochondria of the strain. Homokaryotic strains containing the RIPed allele exhibit a complex and extremely slow growth phenotype suggesting that the product of the mom-19 gene is important in N. crassa.
authors.affiliation: Department of Genetics, University of Alberta, Edmonton, Canada.
authors.forename: T A
authors.initials: TA
authors.lastname: Harkness
authors.forename: R L
authors.initials: RL
authors.lastname: Metzenberg
authors.forename: H
authors.initials: H
authors.lastname: Schneider
authors.forename: R
authors.initials: R
authors.lastname: Lill
authors.forename: W
authors.initials: W
authors.lastname: Neupert
authors.forename: F E
authors.initials: FE
authors.lastname: Nargang
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D015153:Blotting, Western; D004271:DNA, Fungal / Q000235:genetics / Q000302:isolation & purification; D005656:Fungal Proteins; D005800:Genes, Fungal; D005838:Genotype; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009492:Neurospora crassa / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids; D017354:Point Mutation; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D014170:Transformation, Genetic
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; C066557:MOM19 protein, Neurospora crassa; D018160:Receptors, Cytoplasmic and Nuclear; D011994:Recombinant Proteins