scholarly journals In Vivo Regulatory Phosphorylation of Novel Phosphoenolpyruvate Carboxylase Isoforms in Endosperm of Developing Castor Oil Seeds

2005 ◽  
Vol 139 (2) ◽  
pp. 969-978 ◽  
Author(s):  
Karina E. Tripodi ◽  
William L. Turner ◽  
Sam Gennidakis ◽  
William C. Plaxton
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Castor Oil ◽  
Oil Seeds ◽  
Regulatory Phosphorylation

The bacterial-type phosphoenolpyruvate carboxylase isozyme from developing castor oil seeds is subject to in vivo regulatory phosphorylation at serine-451

FEBS Letters ◽  
2012 ◽  
Vol 586 (7) ◽  
pp. 1049-1054 ◽  
Author(s):  
Katie J. Dalziel ◽  
Brendan O'Leary ◽  
Carolyne Brikis ◽  
Srinath K. Rao ◽  
Yi-Min She ◽  
...  
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Castor Oil ◽  
Oil Seeds ◽  
Regulatory Phosphorylation ◽  
Bacterial Type

scholarly journals Bacterial- and plant-type phosphoenolpyruvate carboxylase isozymes from developing castor oil seeds interact in vivo and associate with the surface of mitochondria

2012 ◽  
Vol 71 (2) ◽  
pp. 251-262 ◽  
Author(s):  
Joonho Park ◽  
Nicholas Khuu ◽  
Alexander S. M. Howard ◽  
Robert T. Mullen ◽  
William C. Plaxton
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Castor Oil ◽  
Plant Type ◽  
Oil Seeds

scholarly journals Phosphorylation of bacterial-type phosphoenolpyruvate carboxylase at Ser425 provides a further tier of enzyme control in developing castor oil seeds

2010 ◽  
Vol 433 (1) ◽  
pp. 65-74 ◽  
Author(s):  
Brendan O'Leary ◽  
Srinath K. Rao ◽  
William C. Plaxton
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Castor Oil ◽  
Vascular Plant ◽  
Phosphorylation Site ◽  
Physiological Status ◽  
Spectrometric Analysis ◽  
Oil Seeds ◽  
Class 1 ◽  
Bacterial Type

PEPC [PEP (phosphoenolpyruvate) carboxylase] is a tightly controlled anaplerotic enzyme situated at a pivotal branch point of plant carbohydrate metabolism. Two distinct oligomeric PEPC classes were discovered in developing COS (castor oil seeds). Class-1 PEPC is a typical homotetramer of 107 kDa PTPC (plant-type PEPC) subunits, whereas the novel 910-kDa Class-2 PEPC hetero-octamer arises from a tight interaction between Class-1 PEPC and 118 kDa BTPC (bacterial-type PEPC) subunits. Mass spectrometric analysis of immunopurified COS BTPC indicated that it is subject to in vivo proline-directed phosphorylation at Ser425. We show that immunoblots probed with phosphorylation site-specific antibodies demonstrated that Ser425 phosphorylation is promoted during COS development, becoming maximal at stage IX (maturation phase) or in response to depodding. Kinetic analyses of a recombinant, chimaeric Class-2 PEPC containing phosphomimetic BTPC mutant subunits (S425D) indicated that Ser425 phosphorylation results in significant BTPC inhibition by: (i) increasing its Km(PEP) 3-fold, (ii) reducing its I50 (L-malate and L-aspartate) values by 4.5- and 2.5-fold respectively, while (iii) decreasing its activity within the physiological pH range. The developmental pattern and kinetic influence of Ser425 BTPC phosphorylation is very distinct from the in vivo phosphorylation/activation of COS Class-1 PEPC's PTPC subunits at Ser11. Collectively, the results establish that BTPC's phospho-Ser425 content depends upon COS developmental and physiological status and that Ser425 phosphorylation attenuates the catalytic activity of BTPC subunits within a Class-2 PEPC complex. To the best of our knowledge, this study provides the first evidence for protein phosphorylation as a mechanism for the in vivo control of vascular plant BTPC activity.

scholarly journals Kinetic and regulatory properties of cytosolic pyruvate kinase from germinating castor oil seeds

1991 ◽  
Vol 279 (2) ◽  
pp. 495-501 ◽  
Author(s):  
F E Podestá ◽  
W C Plaxton
Keyword(s):  
Pyruvate Kinase ◽  
Castor Oil ◽  
Mixed Type ◽  
Competitive Inhibition ◽  
Ricinus Communis ◽  
Cytosolic Ph ◽  
Oil Seeds ◽  
Saturation Kinetics ◽  
Regulatory Properties

The kinetic and regulatory properties of cytosolic pyruvate kinase (PKc) isolated from endosperm of germinating castor oil seeds (Ricinus communis L.) have been studied. Optimal efficiency in substrate utilization (in terms of Vmax/Km for phosphoenolpyruvate or ADP) occurred between pH 6.7 and 7.4. Enzyme activity was absolutely dependent on the presence of a bivalent and a univalent metal cation, with Mg2+ and K+ fulfilling this requirement. Mg2+ binding showed positive and negative co-operativity at pH 6.5 (h = 1.6) and pH 7.2 (h = 0.69) respectively. Hyperbolic saturation kinetics were observed with phosphoenolpyruvate (PEP) and K+, whereas ADP acted as a mixed-type inhibitor over 1 mM. Glycerol (10%, v/v) increased the S0.5(ADP) 2.3-fold and altered the pattern of nucleotide binding from hyperbolic (h = 1.0) to sigmoidal (h = 1.79) without modifying PEP saturation kinetics. No activators were identified. ATP, AMP, isocitrate, 2-oxoglutarate, malate, 2-phosphoglycerate, 2,3-bisphosphoglycerate, 3-phosphoglycerate, glycerol 3-phosphate and phosphoglycolate were the most effective inhibitors. These metabolites yielded additive inhibition when tested in pairs. ATP and 3-phosphoglycerate were mixed-type inhibitors with respect to PEP, whereas competitive inhibition was observed for other inhibitors. Inhibition by malate, 2-oxoglutarate, phosphorylated triose sugars or phosphoglycolate was far more pronounced at pH 7.2 than at pH 6.5. Although 32P-labelling studies revealed that extensive phosphorylation in vivo of soluble endosperm proteins occurred between days 3 and 5 of seed germination, no alteration in the 32P-labelling pattern of 5-day-germinated endosperm was observed after 30 min of anaerobiosis. Moreover, no evidence was obtained that PKc was a phosphoprotein in aerobic or anoxic endosperms. It is proposed that endosperm PKc activity of germinating castor seeds is enhanced after anaerobiosis through concerted decreases in ATP levels, cytosolic pH and concentrations of several key inhibitors.

Phosphorylation of bacterial-type phosphoenolpyruvate carboxylase by a Ca2+-dependent protein kinase suggests a link between Ca2+ signalling and anaplerotic pathway control in developing castor oil seeds

2014 ◽  
Vol 458 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Allyson T. Hill ◽  
Sheng Ying ◽  
William C. Plaxton
Keyword(s):  
Protein Kinase ◽  
Phosphoenolpyruvate Carboxylase ◽  
Castor Oil ◽  
Dependent Protein Kinase ◽  
Oil Seeds ◽  
Dependent Protein ◽  
Bacterial Type ◽  
Anaplerotic Pathway

Inhibitory Ser451 phosphorylation of bacterial-type phosphoenolpyruvate carboxylase subunits of the Class-2 PEPC hetero-octameric complex of developing castor beans is catalysed by a Ca2+-dependent protein kinase. This suggests a relationship between Ca2+ signalling and the control of anaplerosis in developing oil seeds.

scholarly journals Bacterial- and plant-type phosphoenolpyruvate carboxylase polypeptides interact in the hetero-oligomeric Class-2 PEPC complex of developing castor oil seeds

2007 ◽  
Vol 52 (5) ◽  
pp. 839-849 ◽  
Author(s):  
Sam Gennidakis ◽  
Srinath Rao ◽  
Katie Greenham ◽  
R. Glen Uhrig ◽  
Brendan O’Leary ◽  
...  
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Castor Oil ◽  
Plant Type ◽  
Oil Seeds

scholarly journals Regulatory Monoubiquitination of Phosphoenolpyruvate Carboxylase in Germinating Castor Oil Seeds

2008 ◽  
Vol 283 (44) ◽  
pp. 29650-29657 ◽  
Author(s):  
R. Glen Uhrig ◽  
Yi-Min She ◽  
Craig A. Leach ◽  
William C. Plaxton
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Castor Oil ◽  
Oil Seeds

scholarly journals In Vivo Regulatory Phosphorylation Site in C4-Leaf Phosphoenolpyruvate Carboxylase from Maize and Sorghum

1991 ◽  
Vol 96 (1) ◽  
pp. 297-301 ◽  
Author(s):  
Jin-an Jiao ◽  
Jean Vidal ◽  
Cristina Echevarría ◽  
Raymond Chollet
Keyword(s):  
Phosphoenolpyruvate Carboxylase ◽  
Phosphorylation Site ◽  
Regulatory Phosphorylation
Sign in / Sign up

Export Citation Format

Share Document