This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (60) Citing Articles via Google Scholar Google Scholar Articles by Budde, R. J. A. Articles by Chollet, R. Search for Related Content PubMed PubMed Citation Articles by Budde, R. J. A. Articles by Chollet, R. Agricola Articles by Budde, R. J. A. Articles by Chollet, R.

Articles

In Vitro Phosphorylation of Maize Leaf Phosphoenolpyruvate Carboxylase ¹

Department of Agricultural Biochemistry, University of Nebraska-Lincoln, East Campus, Lincoln, Nebraska 68583-0718

Autoradiography of total soluble maize (Zea mays) leaf proteins incubated with ³²P-labeled adenylates and separated by denaturing electrophoresis revealed that many polypeptides were phosphorylated in vitro by endogenous protein kinase(s). The most intense band was at 94 to 100 kilodaltons and was observed when using either [-³²P]ATP or [-³²P]ADP as the phosphate donor. This band was comprised of the subunits of both pyruvate, Pi dikinase (PPDK) and phosphoenolpyruvate carboxylase (PEPCase). PPDK activity was previously shown to be dark/light-regulated via a novel ADP-dependent phosphorylation/Pi-dependent dephosphorylation of a threonyl residue. The identity of the acid-stable 94 to 100 kilodalton band phosphorylated by ATP was established unequivocally as PEPCase by two-dimensional gel electrophoresis and immunoblotting. The phosphorylated amino acid was a serine residue, as determined by two-dimensional thin-layer electrophoresis. While the in vitro phosphorylation of PEPCase from illuminated maize leaves by an endogenous protein kinase resulted in a partial inactivation (25%) of the enzyme when assayed at pH 7 and subsaturating levels of PEP, effector modulation by L-malate and glucose-6-phosphate was relatively unaffected. Changes in the aggregation state of maize PEPCase (homotetrameric native structure) were studied by nondenaturing electrophoresis and immunoblotting. Enzyme from leaves of illuminated plants dissociated upon dilution, whereas the protein from darkened tissue did not dissociate, thus indicating a physical difference between the enzyme from light- versus dark-adapted maize plants.

¹ Supported in part by Grant No. 85-CRCR-1-1585 from the United States Department of Agriculture, Competitive Research Grants Office. Paper No. 8072, Journal Series, Nebraska Agricultural Research Division.

This article has been cited by other articles:

				D. Wang, A. R. Portis Jr., S. P. Moose, and S. P. Long Cool C4 Photosynthesis: Pyruvate Pi Dikinase Expression and Activity Corresponds to the Exceptional Cold Tolerance of Carbon Assimilation in Miscanthus x giganteus Plant Physiology, September 1, 2008; 148(1): 557 - 567. [Abstract] [Full Text] [PDF]

				W. Xu, S. Ahmed, H. Moriyama, and R. Chollet The Importance of the Strictly Conserved, C-terminal Glycine Residue in Phosphoenolpyruvate Carboxylase for Overall Catalysis: MUTAGENESIS AND TRUNCATION OF GLY-961 IN THE SORGHUM C4 LEAF ISOFORM J. Biol. Chem., June 23, 2006; 281(25): 17238 - 17245. [Abstract] [Full Text] [PDF]

				L. H. Smith, J. A. Langdale, and R. Chollet A Functional Calvin Cycle Is Not Indispensable for the Light Activation of C4 Phosphoenolpyruvate Carboxylase Kinase and Its Target Enzyme in the Maize Mutant bundle sheath defective2-mutable1 Plant Physiology, September 1, 1998; 118(1): 191 - 197. [Abstract] [Full Text]

				C. J. Chastain, J. P. Fries, J. A. Vogel, C. L. Randklev, A. P. Vossen, S. K. Dittmer, E. E. Watkins, L. J. Fiedler, S. A. Wacker, K. C. Meinhover, et al. Pyruvate,Orthophosphate Dikinase in Leaves and Chloroplasts of C3 Plants Undergoes Light-/Dark-Induced Reversible Phosphorylation Plant Physiology, April 1, 2002; 128(4): 1368 - 1378. [Abstract] [Full Text] [PDF]