Homologous genes for the C4 isoform of phosphoenolpyruvate carboxylase in a C3 and a C4 Flaveria species

Abstract

The C4 isoform of phosphoenolpyruvate carboxylase (PEPCase) in Flaveria trinervia is encoded by the ppcA subgroup of the PEPCase gene family and is abundantly expressed in the mesophyll cells of leaves. The homologous ppcA genes in the C3 plant F pringlei are only weakly expressed and their transcripts do not show the strictly leaf-specific accumulation pattern observed for the F. trinervia genes. Two representative members of the ppcA subfamilies of F. trinervia (C4) and F. pringeli (C3)-named ppcA1-were characterized by Southern blotting, nucleotide sequencing and primer extension analysis. Comparison of the deduced amino acid sequences reveals a close similarity between C4 and C3 isoforms. Only few C4-specific positions can be detected when all known plant PEPCases are included in the comparison. A regulatory domain involved in light-dependent phosphorylation/dephosphorylation of the C4 and crassulacean acid metabolism (CAM) isoforms is present in the ppcA1 gene products of both the C3 and C4 Flaveria. The 5' flanking regions are essentially homologous. The putative promoter regions share several identical sequence motifs (CCAAT, AT-1 and GT-1 box III/III* elements). Additionally, alterations in elements that could contribute to differences in expression rates and light regulation are found. The significance of these findings is discussed with respect to the molecular evolution of C4 photosynthesis in Flaveria.

Evolution of the Enzymatic Characteristics of C4Phosphoenol Pyruvate Carboxylase

“…No sequence divergences could be detected between this cDNA clone and the coding sequence of the ppcAl gene of F: pringlei (Hermans and Westhoff, 1992) demonstrating that the cDNA and the gene correspond to each other. The two ppcA sequences of F: trinervia (C,) and E pringlei (C,) were observed to be 96% identical and the differences were scattered along the whole sequence (Fig.…”

“…Sequence analysis of the 5' and 3' end supported this suggestion for five of them. The sequence and restriction patterns were compared with the sequence of the coding region of the ppcA gene from E pringlei (Hermans and Westhoff, 1992). All investigated clones were shown to belong to the ppcA class, although ppcB is also expressed in the leaves of this C, plant (Ernst and Westhoff, 1997).…”

“…The strong indication that these isoenzymes stem directly from a common ancestor, i.e. that they are orthologous (Hermans and Westhoff, 1990Westhoff, , 1992 makes them ideal when studying the evolutionary changes from a C, to a C, P-pyruvate carboxylase. This may not be so easily accomplished by comparing C, and C, P-pyruvate carboxylases within the same species (Crktin et al, 1991 ;Pacquit et al, 1993) where the enzymes are more distantly related.…”

The Gene for the P-Subunit of Glycine Decarboxylase from the C4 SpeciesFlaveria trinervia: Analysis of Transcriptional Control in TransgenicFlaveria bidentis(C4) and Arabidopsis (C3)

“…5A). The ppcA1 gene encodes the C 4 isoform of PEPC (Hermans and Westhoff, 1992), and its complete 2,188-bp promoter directs high and mesophyll-specific GUS expression in transgenic F. bidentis (Stockhaus et al, 1997). In contrast, the activity of the 570-bp-long proximal ppcA promoter part (ppcA-PR Ft ) is extremely low and can hardly be visualized in histochemical GUS assays .…”

Site‐directed mutagenesis of Lys600 in phosphoenolpyruvate carboxylase of Flaveria trinervia: its roles in catalytic and regulatory functions

“…Alignment of the deduced amino acid sequences of the polypeptides from these organisms reveals some conserved amino acid residues or regions [4,5]. It would be reasonable to expect that the substrate-*Corresponding author.…”