Phosphoproteomic identification and phylogenetic analysis of ribosomal P-proteins in Populus dormant terminal buds.
To better understand the role that reversible phosphorylation plays in woody plant ribosomal P-protein function, we initiated a phosphoproteomic investigation of P-proteins from Populus dormant terminal buds. Using gel-free (in-solution) protein digestion and phosphopeptide enrichment combined with a nanoUPLC-ESI-MS/MS strategy, we identified six phosphorylation sites on eight P-proteins from Populus dormant terminal buds. Among these, six Ser sites and one Thr site were identified in the highly conserved C-terminal region of eight P-proteins of various P-protein subfamilies, including two P0, two P1, three P2 and one P3 protein. Among these, the Thr site was shown to be novel and has not been identified in any other organisms. Sequence analysis indicated that the phosphothreonine sites identified in the C-terminus of Ptr RPP2A exclusively occurred in woody species of Populus, etc. The identified phosphopeptides shared a common phosphorylation motif of (S/T)XX(D/E) and may be phosphorylated in vivo by casein kinase 2 as suggested by using Scansite analysis. Furthermore, phylogenetic analysis suggested that divergence of P2 also occurred in Populus, including type I and type II. To the best of our knowledge, this is the first systematic phosphoproteomic and phylogenetic analysis of P-proteins in woody plants, the results of which will provide a wealth of resources for future understanding and unraveling of the regulatory mechanisms of Populus P-protein phosphorylation during the maintenance of dormancy.
Liu
Chang-Cai
CC
Education Ministry Key Laboratory of Forest Tree Genetic Improvement and Biotechnology, Northeast Forestry University, 26 Hexing Road, 150040 Harbin, People's Republic of China.
Lu
Tian-Cong
TC
Li
Hua-Hua
HH
Wang
Hong-Xia
HX
Liu
Gui-Feng
GF
Ma
Ling
L
Yang
Chuan-Ping
CP
Wang
Bai-Chen
BC
D000595:Amino Acid Sequence; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics*; D010766:Phosphorylation; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D032107:Populus / Q000235:genetics* / Q000378:metabolism; D040901:Proteomics; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein
D010750:Phosphoproteins; D010940:Plant Proteins; D012269:Ribosomal Proteins