Phosphoproteomic analysis provides novel insights into stress responses in Phaeodactylum tricornutum, a model diatom.
Protein phosphorylation on serine, threonine, and tyrosine (Ser/Thr/Tyr) is well established as a key regulatory posttranslational modification used in signal transduction to control cell growth, proliferation, and stress responses. However, little is known about its extent and function in diatoms. Phaeodactylum tricornutum is a unicellular marine diatom that has been used as a model organism for research on diatom molecular biology. Although more than 1000 protein kinases and phosphatases with specificity for Ser/Thr/Tyr residues have been predicted in P. tricornutum, no phosphorylation event has so far been revealed by classical biochemical approaches. Here, we performed a global phosphoproteomic analysis combining protein/peptide fractionation, TiO(2) enrichment, and LC-MS/MS analyses. In total, we identified 264 unique phosphopeptides, including 434 in vivo phosphorylated sites on 245 phosphoproteins. The phosphorylated proteins were implicated in the regulation of diverse biological processes, including signaling, metabolic pathways, and stress responses. Six identified phosphoproteins were further validated by Western blotting using phospho-specific antibodies. The functions of these proteins are discussed in the context of signal transduction networks in P. tricornutum. Our results advance the current understanding of diatom biology and will be useful for elucidating the phosphor-relay signaling networks in this model diatom.
State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, China.
Zhuo
Z
Chen
Ming-kun
MK
Yang
Chong-yang
CY
Li
Yan
Y
Wang
Jia
J
Zhang
Dian-bing
DB
Wang
Xian-en
XE
Zhang
Feng
F
Ge
D001426:Bacterial Proteins / Q000378:metabolism*; D001665:Binding Sites; D015153:Blotting, Western; D002853:Chromatography, Liquid; D017377:Diatoms / Q000378:metabolism*; D053858:Metabolic Networks and Pathways; D008954:Models, Biological; D010748:Phosphopeptides / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D020543:Proteome / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*; D015398:Signal Transduction; D013312:Stress, Physiological; D053719:Tandem Mass Spectrometry
D001426:Bacterial Proteins; D010748:Phosphopeptides; D010750:Phosphoproteins; D020543:Proteome