Phosphorylation is an on/off switch for 5-hydroxyconiferaldehyde O -methyltransferase activity in poplar monolignol biosynthesis
| Autor: | Rui Shi, Philip L. Loziuk, Vincent L. Chiang, Hao Chen, Guan-Zheng Qu, Ronald R. Sederoff, David C. Muddiman, Ling Chuang, Ying-Chung Lin, Jack P. Wang |
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| Rok vydání: | 2015 |
| Předmět: |
Proteomics
inorganic chemicals Green Fluorescent Proteins Molecular Sequence Data Catechols macromolecular substances Biology Lignin Dephosphorylation chemistry.chemical_compound Biosynthesis Tandem Mass Spectrometry Amino Acid Sequence Acrolein Phosphorylation Binding site Plant Proteins chemistry.chemical_classification Binding Sites Microscopy Confocal Multidisciplinary Sequence Homology Amino Acid Kinase Protoplasts fungi Phosphoproteomics Methyltransferases Biological Sciences Phosphoproteins Isoenzymes enzymes and coenzymes (carbohydrates) Populus Enzyme chemistry Biochemistry Mutation Biocatalysis bacteria Electrophoresis Polyacrylamide Gel Monolignol Chromatography Liquid |
| Zdroj: | Proceedings of the National Academy of Sciences. 112:8481-8486 |
| ISSN: | 1091-6490 0027-8424 |
| DOI: | 10.1073/pnas.1510473112 |
| Popis: | Although phosphorylation has long been known to be an important regulatory modification of proteins, no unequivocal evidence has been presented to show functional control by phosphorylation for the plant monolignol biosynthetic pathway. Here, we present the discovery of phosphorylation-mediated on/off regulation of enzyme activity for 5-hydroxyconiferaldehyde O-methyltransferase 2 (PtrAldOMT2), an enzyme central to monolignol biosynthesis for lignification in stem-differentiating xylem (SDX) of Populus trichocarpa. Phosphorylation turned off the PtrAldOMT2 activity, as demonstrated in vitro by using purified phosphorylated and unphosphorylated recombinant PtrAldOMT2. Protein extracts of P. trichocarpa SDX, which contains endogenous kinases, also phosphorylated recombinant PtrAldOMT2 and turned off the recombinant protein activity. Similarly, ATP/Mn(2+)-activated phosphorylation of SDX protein extracts reduced the endogenous SDX PtrAldOMT2 activity by ∼ 60%, and dephosphorylation fully restored the activity. Global shotgun proteomic analysis of phosphopeptide-enriched P. trichocarpa SDX protein fractions identified PtrAldOMT2 monophosphorylation at Ser(123) or Ser(125) in vivo. Phosphorylation-site mutagenesis verified the PtrAldOMT2 phosphorylation at Ser(123) or Ser(125) and confirmed the functional importance of these phosphorylation sites for O-methyltransferase activity. The PtrAldOMT2 Ser(123) phosphorylation site is conserved across 93% of AldOMTs from 46 diverse plant species, and 98% of the AldOMTs have either Ser(123) or Ser(125). PtrAldOMT2 is a homodimeric cytosolic enzyme expressed more abundantly in syringyl lignin-rich fiber cells than in guaiacyl lignin-rich vessel cells. The reversible phosphorylation of PtrAldOMT2 is likely to have an important role in regulating syringyl monolignol biosynthesis of P. trichocarpa. |
| Databáze: | OpenAIRE |
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