title: The band mutation in Neurospora crassa is a dominant allele of ras-1 implicating RAS signaling in circadian output.
abstract: band, an allele enabling clear visualization of circadianly regulated spore formation (conidial banding), has remained an integral tool in the study of circadian rhythms for 40 years. bd was mapped using single-nucleotide polymorphisms (SNPs), cloned, and determined to be a T79I point mutation in ras-1. Alterations in light-regulated gene expression in the ras-1(bd) mutant suggests that the Neurospora photoreceptor WHITE COLLAR-1 is a target of RAS signaling, and increases in transcription of both wc-1 and fluffy show that regulators of conidiation are elevated in ras-1(bd). Comparison of ras-1(bd) with dominant active and dominant-negative ras-1 mutants and biochemical assays of RAS function indicate that RAS-1(bd) displays a modest enhancement of GDP/GTP exchange and no change in GTPase activity. Because the circadian clock in ras-1(bd) appears to be normal, ras-1(bd) apparently acts to amplify a subtle endogenous clock output signal under standard assay conditions. Reactive oxygen species (ROS), which can affect and be affected by RAS signaling, increase conidiation, suggesting a link between generation of ROS and RAS-1 signaling; surprisingly, however, ROS levels are not elevated in ras-1(bd). The data suggest that interconnected RAS- and ROS-responsive signaling pathways regulate the amplitude of circadian- and light-regulated gene expression in Neurospora.
authors.affiliation: Dartmouth Medical School, Genetics Department, Hanover, New Hampshire 03755, USA.
authors.forename: William J
authors.initials: WJ
authors.lastname: Belden
authors.forename: Luis F
authors.initials: LF
authors.lastname: Larrondo
authors.forename: Allan C
authors.initials: AC
authors.lastname: Froehlich
authors.forename: Mi
authors.initials: M
authors.lastname: Shi
authors.forename: Chen-Hui
authors.initials: CH
authors.lastname: Chen
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Loros
authors.forename: Jay C
authors.initials: JC
authors.lastname: Dunlap
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D005799:Genes, Dominant; D005800:Genes, Fungal; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000235:genetics* / Q000502:physiology*; D017354:Point Mutation; D017382:Reactive Oxygen Species / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013172:Spores, Fungal / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D018631:ras Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D017382:Reactive Oxygen Species; D014157:Transcription Factors; C105589:wc-1 protein, Neurospora crassa; D018631:ras Proteins