Nuclear basket localized proteasomes maintain circadian period through nuclear TOC1 proteolysis
Kim, Y. J.; Magill, B.; Yao, J.-W.; Shi, H.; Lee, Y. S.; Meier, I.; Somers, D. E.
Plant Signaling
Every tomato ripening on schedule, every morning glory opening at dawn, every photoperiod-sensitive crop flowering at the right time depends on a molecular clock this precise — and now we know one of the switches that keeps it ticking.
Plant cells have an internal clock that tells them what time of day it is, helping them open flowers, respond to light, and time growth. This clock relies on certain proteins building up and breaking down at exactly the right moments. Researchers found that a pair of proteins sitting at the edge of the cell's nucleus act like quality-control officers, making sure one key clock protein gets properly recycled — and when those officers are missing, the plant's internal clock runs slow.
Key Findings
Mutant Arabidopsis plants lacking NUA or NUP136 nuclear basket proteins show significantly longer circadian periods than wildtype plants.
NUP136 physically recruits both the clock protein TOC1 and proteasome (cellular recycling machinery) components to the inner nuclear rim, forming a degradation complex.
Loss of NUP136 or NUA causes aberrant accumulation of TOC1 in the nucleus, directly linking nuclear pore basket function to circadian period length.
chevron_right Technical Summary
Scientists discovered that special proteins at the nuclear pore — the cell's gatekeeper between nucleus and cytoplasm — help plants keep accurate 24-hour biological clocks by controlling the breakdown of a key clock protein called TOC1.
Abstract Preview
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....
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