Phosphoenolpyruvate carboxylase kinase involved in C(4) photosynthesis in Flaveria trinervia: cDNA cloning and characterization.

In C(4) plants, phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31), a key enzyme in C(4) 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 C(4) plant, Flaveria trinervia, which encodes the specific protein kinase (FtPEPC-PK) involved in the phosphorylation of C(4)-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 C(4) plant (F. trinervia) but very low expression in a C(3) 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 C(4) photosynthesis.