MOLECULAR CLONING AND EXPRESSION ANALYSIS OF TWO CALMODULIN GENES ENCODING AN IDENTICAL PROTEIN FROM CAMELLIA OLEIFERA

Abstract

Calmodulins, members of the EF-hand family of Ca2+-binding proteins, play significant regulatory roles in the processes of plant cell proliferation, growth, development, photosynthesis and stress resistance. Here, the two full-length complementary DNA (cDNA) clones were isolated from the constructed Camellia oleifera cDNA library. They are 953 base pair (bp) and 1024 bp in the length, respectively, and designated as CoCaM1 and CoCaM2 (GenBank access numbers EU856536 and FJ649316). They contain the complete protein-coding region of 447 bp encoded an identical polypeptide of 149 amino acids and various lengths of untranslated segments. The result supported the hypothesis “Multigenes possess an identical amino acid sequence”. The structure analyzed results indicated the putative CoCaM protein possessed four EFhand domains, hydrophobic residues and crucial residues, in which the amphipathic helices might possess lipid affinity via binding and altering the associated plasma or organelle membranes. In addition, the protein had one to seven substitutions, and displayed more than 89% identity at the amino acid level in comparison to other species CaMs. Finally, the expression of the 2 cDNA genes in matured seeds of 6 C. oleifera varieties was analyzed by real-time fluorescence quantitative PCR, and the result showed that there were different expression levels. In conclusion, the structure properties together with the observed expression levels indicate that they may play different roles in the processes of development, lipid biosynthesis and stress responses of C. oleifera seeds.