PMID:14585826

Citation	Murmu, J, Chinthapalli, B and Raghavendra, AS (2003) Marked modulation by phosphate of phosphoenolpyruvate carboxylase in leaves of Amaranthus hypochondriacus, a NAD-ME type C4 plant: decrease in malate sensitivity but no change in the phosphorylation status. J. Exp. Bot. 54:2661-8
Abstract	The effect of Pi on the properties of phosphoenolpyruvate carboxylase (PEPC) from Amaranthus hypochondriacus, a NAD-ME type C4 plant, was studied in leaf extracts as well as with purified protein. Efforts were also made to modulate the Pi status of the leaf by feeding leaves with either Pi or mannose. Inclusion of 30 mM Pi during the assay enhanced the enzyme activity in leaf extracts or of purified protein by >2-fold. The effect of Pi on the enzyme purified from dark-adapted leaves was more pronounced than that from light-adapted ones. The Ki for malate increased >2.3-fold and >1.9-fold by Pi in the enzyme purified from dark-adapted leaves and light-adapted leaves, respectively. Pi also induced an almost 50-60% increase in Km for PEP or Ka for glucose-6-phosphate. Feeding the leaves with Pi also increased the activity of PEPC in leaf extracts, while decreasing the malate sensitivity of the enzyme. On the other hand, Pi sequestering by mannose marginally decreased the activity, while markedly suppressing the light activation, of PEPC. There was no change in phosphorylation of PEPC in leaves of A. hypochondriacus due to the feeding of 30 mM Pi. However, feeding with mannose decreased the light-enhanced phosphorylation of PEPC. The marked decrease in malate sensitivity of PEPC with no change in phosphorylation state indicates that the changes induced by Pi are independent of the phosphorylation of PEPC. It is suggested here that Pi is an important factor in regulating PEPC in vivo and could also be used as a tool to analyse the properties of PEPC.
Links	PubMed Online version:10.1093/jxb/erg305
Keywords	Amaranthus/enzymology; Enzyme Activation/radiation effects; Kinetics; Light; Phosphates/pharmacology; Phosphoenolpyruvate Carboxylase/drug effects; Phosphoenolpyruvate Carboxylase/isolation & purification; Phosphoenolpyruvate Carboxylase/metabolism; Phosphorylation; Plant Extracts/metabolism; Plant Leaves/enzymology
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
AMAHP:CAPP		GO:0008964: phosphoenolpyruvate carboxylase activity	ECO:0000314:		F		See figure 1A for the effect of addition of Pi during the enzyme assay on the activity with inhibition by 0.5 mM malate	complete CACAO 5605
AMAHP:CAPP	enables	GO:0008964: phosphoenolpyruvate carboxylase activity	ECO:0000314: direct assay evidence used in manual assertion		F		Seeded From UniProt	complete

References

See Help:References for how to manage references in GONUTS.