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Updated: Jul 11, 2026
Circadian Entrainment of Drosophila Melanogaster
Published on: June 3, 2020
Drosophila DBT lacking protein kinase activity produces long-period and arrhythmic circadian behavioral and molecular
Michael J Muskus1, Fabian Preuss, Jin-Yuan Fan
1School of Biological Sciences, University of Missouri-Kansas City, 5100 Rockhill Rd., Kansas City, MO 64110, USA.
Abstract:
A mutation (K38R) which specifically eliminates kinase activity was created in the Drosophila melanogaster ckI gene (doubletime [dbt]). In vitro, DBT protein carrying the K38R mutation (DBT(K/R)) interacted with Period protein (PER) but lacked kinase activity. In cell culture and in flies, DBT(K/R) antagonized the phosphorylation and degradation of PER, and it damped the oscillation of PER in vivo. Overexpression of short-period, long-period, or wild-type DBT in flies produced the same circadian periods produced by the corresponding alleles of the endogenous gene. These mutations therefore dictate an altered "set point" for period length that is not altered by overexpression. Overexpression of the DBT(K/R) produced effects proportional to the titration of endogenous DBT, with long circadian periods at lower expression levels and arrhythmicity at higher levels. This first analysis of adult flies with a virtual lack of DBT activity demonstrates that DBT's kinase activity is necessary for normal circadian rhythms and that a general reduction of DBT kinase activity does not produce short periods.
Insights
The kinase activity of the double-time (dbt) gene is essential for normal circadian rhythms in Drosophila. Eliminating this kinase activity disrupts Period protein cycling, affecting daily rhythms.
Area of Science:
- Chronobiology
- Molecular Genetics
- Drosophila melanogaster research
Background:
- The circadian clock regulates daily rhythms in most organisms.
- The double-time (dbt) gene encodes a kinase crucial for circadian clock function in Drosophila.
- Understanding the specific role of DBT's kinase activity is key to deciphering circadian rhythm mechanisms.
Purpose of the Study:
- To investigate the necessity of the double-time (dbt) gene's kinase activity for Drosophila circadian rhythms.
- To determine the effects of eliminating DBT kinase activity on Period protein phosphorylation and degradation.
- To analyze the impact of DBT kinase activity modulation on circadian period length and rhythmicity.
Main Methods:
- Generated a kinase-dead mutant of the Drosophila ckI gene (doubletime [dbt]), denoted as DBT(K/R).
- Assessed in vitro interaction of DBT(K/R) with Period protein (PER).
- Analyzed PER phosphorylation, degradation, and oscillation in cell culture and in adult flies expressing DBT(K/R) or overexpressing DBT variants.
Main Results:
- DBT(K/R) protein binds PER but lacks kinase activity, antagonizing PER phosphorylation and degradation.
- Overexpression of wild-type, short-period, or long-period DBT alleles did not alter endogenous period length set points.
- Overexpression of DBT(K/R) mimicked titration of endogenous DBT, causing longer periods at low levels and arrhythmicity at high levels.
Conclusions:
- DBT kinase activity is essential for maintaining normal circadian rhythms in Drosophila.
- The kinase activity of DBT is required for proper Period protein cycling and degradation.
- Modulating DBT kinase activity levels provides insights into circadian rhythm regulation and period determination.
