Phosphoenolpyruvate carboxylase kinase involved in C4 photosynthesis in Flaveria trinervia: cDNA cloning and characterization1

Abstract

In C₄ plants, phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31), a key enzyme in C₄ photosynthesis, is controlled by reversible phosphorylation of a conserved Ser residue near the N-terminus. We now report the first cloning of a cDNA from a C₄ plant, Flaveria trinervia, which encodes the specific protein kinase (FtPEPC-PK) involved in the phosphorylation of C₄-form PEPC. Several lines of supportive evidence are: strict substrate specificity of the recombinant enzyme, prominent light/dark response of the transcript level and abundant expression in leaves of C₄ plant (F. trinervia) but very low expression in a C₃ plant of the same genus (Flaveria pringlei). We also discuss the possibility that the FtPEPC-PK gene has co-evolved with the PEPC gene to participate in C₄ photosynthesis.