Label-free quantitative analysis of the casein kinase 2-responsive phosphoproteome of the marine minimal model species Ostreococcus tauri.
Casein kinase 2 (CK2) is a protein kinase that phosphorylates a plethora of cellular target proteins involved in processes including DNA repair, cell cycle control, and circadian timekeeping. CK2 is functionally conserved across eukaryotes, although the substrate proteins identified in a range of complex tissues are often different. The marine alga Ostreococcus tauri is a unicellular eukaryotic model organism ideally suited to efficiently study generic roles of CK2 in the cellular circadian clock. Overexpression of CK2 leads to a slow circadian rhythm, verifying functional conservation of CK2 in timekeeping. The proteome was analysed in wild-type and CK2-overexpressing algae at dawn and dusk, revealing that differential abundance of the global proteome across the day is largely unaffected by overexpression. However, CK2 activity contributed more strongly to timekeeping at dusk than at dawn. The phosphoproteome of a CK2 overexpression line and cells treated with CK2 inhibitor was therefore analysed and compared to control cells at dusk. We report an extensive catalogue of 447 unique CK2-responsive differential phosphopeptide motifs to inform future studies into CK2 activity in the circadian clock of more complex tissues. All MS data have been deposited in the ProteomeXchange with identifier PXD000975 (http://proteomecentral.proteomexchange.org/dataset/PXD000975).
School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
Thierry
T
Le Bihan
School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
Matthew
M
Hindle
School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
Sarah F
SF
Martin
School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
Martin E
ME
Barrios-Llerena
School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
Johanna
J
Krahmer
School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
Katalin
K
Kis
School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
Andrew J
AJ
Millar
School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
Gerben
G
van Ooijen
D047390:Casein Kinase II / Q000378:metabolism*; D000460:Chlorophyta / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D010940:Plant Proteins / Q000378:metabolism*; D020543:Proteome / Q000378:metabolism*
D010940:Plant Proteins; D020543:Proteome; D047390:Casein Kinase II
Casein kinase 2; Cell biology; Circadian clock; Marine algae; Ostreococcus tauri; Phosphoproteomics