Haitanensis Pepck And Pepc Gene Cloning And Expression Analysis Of The Various Life Stages

Porphyra haitanensis TJ Chang et BF Zheng (Bangiales, Rhodophyta), is an economically important red algae cultivated in China and widely consumed in Asia, Based on the photosynthetic aaratus and dimorphic life cycle of porphyra, we cloned full-length cDNA of the phosphoenolpyruvate carboxykinase gene (PEPCK) and phosphoenolpyruvate carboxylase gene (PEPC). This study includes:1) PEPCK had a nucleotide sequence of 2300 bp that included a 5'-untranslated region (UTR) of 147 bp, a 3'-UTR of 329 bp, and an open reading frame (ORF). The ORF translated into a polypeptide of 607 amino acids. The predicted polypeptide had significant homology to the PCK gene from bacteria and unicellular algae. Phylogenetic tree analysis showed that ATP-dependent PEPCK was more closely related to the ancestral ATP-dependent PCK and might have evolved by primary endosymbiosis. The mRNA from conchospores, saprophytes, and gametophytes was examined by real-time fluorescence quantitative PCR, and the levels of PhPCK differed at different stages of the life cycle. The levels in the conchospores and saprophytes were 3.8-fold and 4.3-fold higher, respectively, than that in the gametophytes (P≤0.05).2) PEPC had a nucleotide sequence of 3145 bp that included a 5'-untranslated region (UTR) of 26 bp, a 3'-UTR of 191 bp, and an open reading frame (ORF). The ORF translated into a polypeptide of 975 amino acids. The predicted polypeptide had high identities with the PEPC gene from bacteria and unicellular algae to green plant. Sequence analysis and Phylogenetic tree analysis showed that the PEPC gene from the Porphyra haitanensis was a C3-like PEPC and more closely related to the ancestral type. Quantitative analysis showed that the PEPC gene was expressed at different stages of the P. haitanensis life cycle, and the gametophytes had the highest levels.3) Together with our previous work, we propose that a C4-like carbon-fixation mechanism might be functional in the organism; PEPCK played an important role in the sporophyte stage and PEPC didn't participate in the mechanism.