Regulatory phosphorylation of plant phosphoenolpyruvate carboxylase: role of a conserved basic residue upstream of the phosphorylation site.
In order to mimic regulatory phosphorylation of the Ser-15 of maize C4-form phosphoenolpyruvate carboxylase (PEPC), we replaced Ser-15 and Lys-12 with Asp (S15D) and Asn (K12N), respectively, by site-directed mutagenesis. Although both mutant enzymes were catalytically as active as the wild-type PEPC, they showed much less sensitivity to malate, an allosteric inhibitor, similarly to the phosphorylated wild-type PEPC. A maize protein kinase of 30 kDa which is known to be specific to PEPC (PEPC-PK), phosphorylated K12N as well as the wild-type PEPC but not S15D. The phosphorylation of K12N further diminished the sensitivity to malate. Thus, a positive charge of the conserved Lys-12 is not required for the recognition by PEPC-PK but contributes to the intrinsic sensitivity to malate inhibition.
Ueno
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Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Japan.
Hata
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Izui
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D001216:Asparagine; D001224:Aspartic Acid; D001665:Binding Sites; D017124:Conserved Sequence; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019298:Glucose-6-Phosphate / Q000494:pharmacology; D008239:Lysine; D008293:Malates / Q000494:pharmacology; D016297:Mutagenesis, Site-Directed; D010730:Phosphoenolpyruvate Carboxylase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012694:Serine; D003313:Zea mays / Q000201:enzymology
D004791:Enzyme Inhibitors; D008293:Malates; D011993:Recombinant Fusion Proteins; D001224:Aspartic Acid; D012694:Serine; D019298:Glucose-6-Phosphate; D001216:Asparagine; C030298:malic acid; C069767:phosphoenolpyruvate carboxylase kinase; D017346:Protein Serine-Threonine Kinases; D010730:Phosphoenolpyruvate Carboxylase; D008239:Lysine