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Arabidopsis CTP:phosphocholine cytidylyltransferase 1 is phosphorylated and inhibited by sucrose nonfermenting 1-related protein kinase 1 (SnRK1).
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2019 Oct 25; Vol. 294 (43), pp. 15862-15874. Date of Electronic Publication: 2019 Aug 22. - Publication Year :
- 2019
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Abstract
- De novo phosphatidylcholine (PC) biosynthesis via the Kennedy pathway involves highly endergonic biochemical reactions that must be fine-tuned with energy homeostasis. Previous studies have shown that CTP:phosphocholine cytidylyltransferase (CCT) is an important regulatory enzyme in this pathway and that its activity can be controlled at both transcriptional and posttranslational levels. Here we identified an important additional mechanism regulating plant CCT1 activity. Comparative analysis revealed that Arabidopsis CCT1 (AtCCT1) contains catalytic and membrane-binding domains that are homologous to those of rat CCT1. In contrast, the C-terminal phosphorylation domain important for stringent regulation of rat CCT1 was apparently missing in AtCCT1. Instead, we found that AtCCT1 contains a putative consensus site (Ser-187) for modification by sucrose nonfermenting 1-related protein kinase 1 (SnRK1 or KIN10/SnRK1.1), involved in energy homeostasis. Phos-tag SDS-PAGE coupled with MS analysis disclosed that SnRK1 indeed phosphorylates AtCCT1 at Ser-187, and we found that AtCCT1 phosphorylation substantially reduces its activity by as much as 70%. An S187A variant exhibited decreased activity, indicating the importance of Ser-187 in catalysis, and this variant was less susceptible to SnRK1-mediated inhibition. Protein truncation and liposome binding studies indicated that SnRK1-mediated AtCCT1 phosphorylation directly affects the catalytic domain rather than interfering with phosphatidate-mediated AtCCT1 activation. Overexpression of the AtCCT1 catalytic domain in Nicotiana benthamiana leaves increased PC content, and SnRK1 co-expression reduced this effect. Taken together, our results suggest that SnRK1 mediates the phosphorylation and concomitant inhibition of AtCCT1, revealing an additional mode of regulation for this key enzyme in plant PC biosynthesis.<br /> (© 2019 Caldo et al.)
- Subjects :
- Animals
Arabidopsis Proteins chemistry
Catalytic Domain
Choline-Phosphate Cytidylyltransferase chemistry
Conserved Sequence
Evolution, Molecular
Kinetics
Models, Biological
Phosphorylation
Phosphorylcholine metabolism
Phosphoserine metabolism
Plant Leaves genetics
Protein Domains
Rats
Structural Homology, Protein
Nicotiana genetics
Arabidopsis enzymology
Arabidopsis Proteins antagonists & inhibitors
Arabidopsis Proteins metabolism
Choline-Phosphate Cytidylyltransferase antagonists & inhibitors
Choline-Phosphate Cytidylyltransferase metabolism
Protein Serine-Threonine Kinases metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1083-351X
- Volume :
- 294
- Issue :
- 43
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 31439667
- Full Text :
- https://doi.org/10.1074/jbc.RA119.008047