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This study identifies two nuclear basket proteins, NUA and NUP136, as regulators of circadian rhythm in the plant Arabidopsis thaliana. The authors demonstrate that NUP136 forms a complex with NUA and proteasome components at the inner nuclear rim, where it recruits and promotes the degradation of TOC1, a core circadian clock protein. When either NUP136 or NUA is absent, TOC1 accumulates abnormally in the nucleus, causing a measurable lengthening of the circadian period in mutant plants compared to wildtype.
Why it matters
Understanding how circadian clocks are regulated at the molecular level in plants could inform agricultural strategies to optimize crop growth cycles and stress responses. More broadly, the discovery that nuclear pore-associated proteasomes play a role in timekeeping may have implications for circadian biology across eukaryotic organisms.
⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Post-translational control of circadian period can involve changes in protein intracellular localization to affect clock function. Many clock proteins rely on a nuclear presence for their activity. As the primary gateway regulating the movement of molecules between the cytosol and the nucleus, the nuclear pore may assist in circadian system maintenance. We describe roles for the nuclear basket proteins, NUA and NUP136, in the maintenance of Arabidopsis circadian period, through effects on the stability of the core clock protein, TOC1. The circadian period of nua and nup136 mutants is significantly longer than that of wildtype plants. We show that NUP136 interacts with NUA, proteasome components and TOC1 in vivo, recruiting them to the inner nuclear rim. TOC1 interaction with the NUP136-NUA complex leads to a proteasome-dependent degradation of TOC1. Loss of NUP136 or NUA disrupts this regulatory environment, leading to aberrant nuclear TOC1 accumulation and consequent lengthening of circadian period. Our work thus identifies nuclear basket-localized proteasomes as key to the maintenance of circadian period.
Source: Nuclear basket localized proteasomes maintain circadian period through nuclear TOC1 proteolysis