title: period-1 encodes an ATP-dependent RNA helicase that influences nutritional compensation of the Neurospora circadian clock.
abstract: Mutants in the period-1 (prd-1) gene, characterized by a recessive allele, display a reduced growth rate and period lengthening of the developmental cycle controlled by the circadian clock. We refined the genetic location of prd-1 and used whole genome sequencing to find the mutation defining it, confirming the identity of prd-1 by rescuing the mutant circadian phenotype via transformation. PRD-1 is an RNA helicase whose orthologs, DDX5 [DEAD (Asp-Glu-Ala-Asp) Box Helicase 5] and DDX17 in humans and DBP2 (Dead Box Protein 2) in yeast, are implicated in various processes, including transcriptional regulation, elongation, and termination, ribosome biogenesis, and mRNA decay. Although prd-1 mutants display a long period (∼25 h) circadian developmental cycle, they interestingly display a WT period when the core circadian oscillator is tracked using a frq-luciferase transcriptional fusion under conditions of limiting nutritional carbon; the core oscillator in the prd-1 mutant strain runs with a long period under glucose-sufficient conditions. Thus, PRD-1 clearly impacts the circadian oscillator and is not only part of a metabolic oscillator ancillary to the core clock. PRD-1 is an essential protein, and its expression is neither light-regulated nor clock-regulated. However, it is transiently induced by glucose; in the presence of sufficient glucose, PRD-1 is in the nucleus until glucose runs out, which elicits its disappearance from the nucleus. Because circadian period length is carbon concentration-dependent, prd-1 may be formally viewed as a clock mutant with defective nutritional compensation of circadian period length.
authors.affiliation: Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755;
authors.forename: Jillian M
authors.initials: JM
authors.lastname: Emerson
authors.affiliation: Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755;
authors.forename: Bradley M
authors.initials: BM
authors.lastname: Bartholomai
authors.affiliation: Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755;
authors.forename: Carol S
authors.initials: CS
authors.lastname: Ringelberg
authors.affiliation: Environmental Molecular Sciences Laboratory, Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99354;
authors.forename: Scott E
authors.initials: SE
authors.lastname: Baker
authors.affiliation: Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755; Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Loros
authors.affiliation: Department of Genetics, Geisel School of Medicine at Dartmouth, Hanover, NH 03755; jay.c.dunlap@dartmouth.edu.
authors.forename: Jay C
authors.initials: JC
authors.lastname: Dunlap
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D002244:Carbon / Q000378:metabolism; D057906:Circadian Clocks / Q000502:physiology*; D005947:Glucose / Q000378:metabolism; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000502:physiology*; D056950:Period Circadian Proteins / Q000235:genetics* / Q000502:physiology; D020365:RNA Helicases / Q000502:physiology*
chemical_list: D056950:Period Circadian Proteins; D002244:Carbon; D000255:Adenosine Triphosphate; D020365:RNA Helicases; D005947:Glucose
keywords: DDX5; Dbp2p; FRQ; RNA helicase; circadian