Formation of an SCF <sup>ZTL</sup> complex is required for proper regulation of circadian timing
Bibliographic record
Abstract
The circadian timing system involves an autoregulatory transcription/translation feedback loop that incorporates a diverse array of factors to maintain a 24-h periodicity. In Arabidopsis a novel F-box protein, ZEITLUPE (ZTL), plays an important role in the control of the free-running period of the circadian clock. As a class, F-box proteins are well-established components of the Skp/Cullin/F-box (SCF) class of E3 ubiquitin ligases that link the target substrates to the core ubiquitinating activity of the ligase complex via direct association with the Skp protein. Here we identify and characterize the SCFZTL complex in detail. Yeast two-hybrid tests demonstrate the sufficiency and necessity of the F-box domain for Arabidopsis Skp-like protein (ASK) interactions and the dispensability of the unique N-terminal LOV domain in this association. Co-immunoprecipitation of full-length (FL) ZTL with the three known core components of SCF complexes (ASK1, AtCUL1 and AtRBX1) demonstrates that ZTL can assemble into an SCF complex in vivo. F-box-containing truncated versions of ZTL (LOV-F and F-kelch) can complex with SCF components in vivo, whereas stably expressed LOV or kelch domains alone cannot. Stable expression of F-box-mutated FL ZTL eliminates the shortened period caused by mild ZTL overexpression and also abolishes ASK1 interaction in vivo. Reduced levels of the core SCF component AtRBX1 phenocopy the long period phenotype of ztl loss-of-function mutations, demonstrating the functional significance of the SCFZTL complex. Taken together, our data establish SCFZTL as an essential SCF class E3 ligase controlling circadian period in plants.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".