Phosphoeno/pyruvate 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 e nzyme in C-4 photosynthesis, is controlled by reversible phosphorylation of a conserved Ser residue near the N-terminus. We now report the first cloni ng of a cDNA from a C-4 plant, Flaveria trinervia, which encodes the specif ic protein kinase (FtPEPC-PK) involved in the phosphorylation Of C-4-form P EPC. 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 ve ry 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 th e PEPC gene to participate in C-4 photosynthesis. (C) 2001 Published by Els evier Science B.V. on behalf of the Federation of European Biochemical Soci eties.