Regulatory phosphorylation of serine-15 in maize phosphoenolpyruvate carboxylase by a C4-leaf protein-serine kinase.
We have recently reported that the light-induced changes in the enzymatic and regulatory properties of maize leaf phosphoenolpyruvate carboxylase are attributed to the regulatory seryl phosphorylation of this C4-photosynthesis enzyme. In the present study, the darkform target enzyme was phosphorylated/activated in vitro by a maize leaf protein-serine kinase, and the 32P-labeled regulatory site phosphopeptide was purified from a tryptic digest by metal-ion affinity and reversed-phase chromatography. Automated Edman degradation analysis by covalent protein sequencing technology revealed that the amino acid sequence of this phosphoseryl peptide is His-His-Ser(P)-Ile-Asp-Ala-Gln-Leu-Arg. This nonapeptide, which corresponds exactly to residues 13-21 in the deduced primary sequence of the maize leaf carboxylase, is far removed from recently identified active-site cysteine (Cys-553) and lysine (Lys-606) residues in the C-terminal region of the primary structure. Comparative analysis of the deduced N-terminal sequences of C3-, C4-, and Crassulacean acid metabolism (CAM)-leaf phosphoenolpyruvate carboxylases suggests that the motif of Lys/Arg-X-X-Ser is an important structural requirement of the C4- and CAM-leaf protein-serine kinases.
Jiao
J A
JA
Department of Biochemistry, University of Nebraska-Lincoln 68583-0718.
Chollet
R
R
D000595:Amino Acid Sequence; D004789:Enzyme Activation; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism*; D010748:Phosphopeptides / Q000302:isolation & purification; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D012689:Sequence Homology, Nucleic Acid; D012694:Serine; D014357:Trypsin; D003313:Zea mays / Q000201:enzymology*
D010446:Peptide Fragments; D010748:Phosphopeptides; D012694:Serine; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D014357:Trypsin; D010730:Phosphoenolpyruvate Carboxylase