ArabidopsisPASTICCINO2 Is an Antiphosphatase Involved in Regulation of Cyclin-Dependent Kinase A

Abstract

PASTICCINO2 (PAS2), a member of the protein Tyr phosphatase-like family, is conserved among all eukaryotes and is characterized by a mutated catalytic site. The cellular functions of the Tyr phosphatase-like proteins are still unknown, even if they are essential in yeast and mammals. Here, we demonstrate that PAS2 interacts with a cyclin-dependent kinase (CDK) that is phosphorylated on Tyr and not with its unphosphorylated isoform. Phosphorylation of the conserved regulatory Tyr-15 is involved in the binding of CDK to PAS2. Loss of the PAS2 function dephosphorylated Arabidopsis thaliana CDKA;1 and upregulated its kinase activity. In accordance with its role as a negative regulator of the cell cycle, overexpression of PAS2 slowed down cell division in suspension cell cultures at the G2-to-M transition and early mitosis and inhibited Arabidopsis seedling growth. The latter was accompanied by altered leaf development and accelerated cotyledon senescence. PAS2 was localized in the cytoplasm of dividing cells but moved into the nucleus upon cell differentiation, suggesting that the balance between cell division and differentiation is regulated through the interaction between CDKA;1 and the antiphosphatase PAS2.

The very-long-chain hydroxy fatty acyl-CoA dehydratase PASTICCINO2 is essential and limiting for plant development

“…The link between VLCFA and cell division was also reported in yeast (7,27). In plants, the overexpression of PAS2 delayed cell cycle progression, in particular during mitosis (19). PAS2 was described as interacting directly with phosphorylated cell cycle regulator CDKA (19).…”

“…One scenario we considered was that the plant PAS2 function might still have evolved, compared with its yeast orthologue, by the acquisition of new biochemical functions such as the regulation of cell cycle proteins (15,19). We thus investigated whether the yeast PHS1 gene could complement the developmental phenotype of the plant pas2 mutant.…”

“…In plants, the overexpression of PAS2 delayed cell cycle progression, in particular during mitosis (19). PAS2 was described as interacting directly with phosphorylated cell cycle regulator CDKA (19). The presence of a protein tyrosine phosphatase (PTP) motif that is conserved in eukaryotes led originally to the definition of the PAS2/Phs1p family as PTP-like proteins.…”

“…Mutations in the PAS2 gene lead to strong developmental defects associated with ectopic cell division, cell differentiation, and hormonal responses (15)(16)(17)(18). Finally, PAS2 was demonstrated to be able to interact with phosphorylated cyclin-dependent kinase (CDK) and subsequently to prevent its dephosphorylation by CDC25-like phosphatase(s), preventing premature entry in mitosis (19). However, the fact that PAS2 shows significant sequence similarity with Phs1p and that it was able to rescue phs1 mutant argues in favor of PAS2 being the dehydratase component of the microsomal elongase complex.…”

Signal processing by protein tyrosine phosphorylation in plants

“…It functions as an anti-phosphatase by binding a kinase and preventing its dephosphorylation by other activating phosphatases. 63 It has been shown finally that PAS2 is a dehydratase which functions in the elongase complex required for the production of very-long-chain fatty acids. 64 Another plant of Oryza sativa ssp.…”