Gene

Quantum mechanics

Cell biology

Circadian rhythm

Voltage

Jitter

Cryptochrome

Neuroscience

Biology

Ubiquitin ligase

Telecommunications

Computer science

Acoustics

Phosphorylation

Ubiquitin

Clock network

Negative feedback

Genetics

Physics

Clock signal

Circadian clock

Post-translational regulation

Synchronous circuit

Timeless

Ubiquitin-Protein Ligases

Chemistry

Deubiquitinating enzyme

Period (music)

Journal of Neurochemistry

Circadian clocks are internal timing systems that enable organisms to adjust their behavioral and physiological rhythms to the daily changes of their environment. These clocks generate self‐sustained oscillations at the cellular, tissue, and behavioral level. The rhythm‐generating mechanism is based on a gene expression network with a delayed negative feedback loop that causes the transcripts to oscillate with a period of approximately 24 hr. This oscillatory nature of the proteins involved in this network necessitates that they are intrinsically unstable, with a short half‐life. Hence, post‐translational modifications (PTMs) are important to precisely time the presence, absence, and interactions of these proteins at appropriate times of the day. Ubiquitination and deubiquitination are counter‐balancing PTMs which play a key role in this regulatory process. In this review, we take a comprehensive look at the roles played by the processes of ubiquitination and deubiquitination in the clock machinery of the most commonly studied eukaryotic models of the circadian clock: plants, fungi, fruit flies, and mammals. We present the effects exerted by ubiquitinating and deubiquitinating enzymes on the stability, but also the activity, localization, and interactions of clock proteins. Overall, these PTMs have key roles in regulating not only the pace of the circadian clocks but also their response to external cues and their control of cellular functions. image

To Ub or not to Ub: Regulation of circadian clocks by ubiquitination and deubiquitination