A phospho-dawn of protein modification anticipates light onset in the picoeukaryote O. tauri.
Zeenat B NoordallyMatthew M HindleSarah F MartinDaniel D SeatonT Ian SimpsonThierry Le BihanAndrew J MillarPublished in: Journal of experimental botany (2023)
Diel regulation of protein levels and protein modification had been less studied than transcript rhythms. Here, we compare transcriptome data under light-dark cycles to partial proteome and phosphoproteome data, assayed using shotgun mass-spectrometry, from the alga Ostreococcus tauri, the smallest free-living eukaryote. 10% of quantified proteins but two-thirds of phosphoproteins were rhythmic. Mathematical modelling showed that light-stimulated protein synthesis can account for the observed clustering of protein peaks in the daytime. Prompted by night-peaking and apparently dark-stable proteins, we also tested cultures under prolonged darkness, where the proteome changed less than under the diel cycle. Among the dark-stable proteins were prasinophyte-specific sequences that were also reported to accumulate when O. tauri formed lipid droplets. In the phosphoproteome, 39% of rhythmic phospho-sites reached peak levels just before dawn. This anticipatory phosphorylation suggests that a clock-regulated phospho-dawn prepares green cells for daytime functions. Acid-directed and proline-directed protein phosphorylation sites were regulated in antiphase, implicating the clock-related, casein kinases 1 and 2 in phase-specific regulation, alternating with the CMGC protein kinase family. Understanding the dynamic phosphoprotein network should be facilitated by the minimal kinome and proteome of O. tauri. The data are available from ProteomeXchange, with identifiers PXD001734, PXD001735 and PXD002909.
Keyphrases
- protein protein
- mass spectrometry
- protein kinase
- electronic health record
- transcription factor
- obstructive sleep apnea
- binding protein
- rna seq
- gene expression
- machine learning
- sleep quality
- genome wide
- cell death
- induced apoptosis
- depressive symptoms
- physical activity
- signaling pathway
- dna methylation
- high resolution
- small molecule
- data analysis
- ms ms
- artificial intelligence
- endoplasmic reticulum stress